[libcxx-commits] [libcxx] [libc++][C++03] Fix modules (PR #165706)

Nikolas Klauser via libcxx-commits libcxx-commits at lists.llvm.org
Thu Oct 30 04:56:51 PDT 2025


https://github.com/philnik777 created https://github.com/llvm/llvm-project/pull/165706

None

>From b0312015a9f6640665da278a8648c5534e922e39 Mon Sep 17 00:00:00 2001
From: Nikolas Klauser <nikolasklauser at berlin.de>
Date: Thu, 30 Oct 2025 12:56:25 +0100
Subject: [PATCH] [libc++][C++03] Fix modules

---
 libcxx/include/__cxx03/__algorithm/find.h     |    1 +
 .../__cxx03/__algorithm/is_permutation.h      |    1 +
 libcxx/include/__cxx03/__algorithm/sort.h     |    1 +
 libcxx/include/__cxx03/__functional/bind.h    |    2 +
 .../__cxx03/__random/generate_canonical.h     |    1 +
 libcxx/include/__cxx03/array                  |    1 +
 libcxx/include/__cxx03/cmath                  |    4 +-
 libcxx/include/__cxx03/cstring                |    2 +-
 libcxx/include/__cxx03/future                 |    1 +
 libcxx/include/__cxx03/map                    |    3 +
 libcxx/include/__cxx03/module.modulemap       |   52 +-
 libcxx/include/__cxx03/set                    |    1 +
 libcxx/include/__cxx03/string.h               |    5 +-
 libcxx/include/__cxx03/unordered_map          |    1 +
 libcxx/include/__cxx03/unordered_set          |    1 +
 libcxx/include/module.modulemap.in            | 3338 +++++++++--------
 libcxx/include/string.h                       |    8 +-
 .../clang/clang_modules_include.gen.py        |    2 -
 18 files changed, 1786 insertions(+), 1639 deletions(-)

diff --git a/libcxx/include/__cxx03/__algorithm/find.h b/libcxx/include/__cxx03/__algorithm/find.h
index baa8e4ccd052f..1c25d78e7e3b3 100644
--- a/libcxx/include/__cxx03/__algorithm/find.h
+++ b/libcxx/include/__cxx03/__algorithm/find.h
@@ -20,6 +20,7 @@
 #include <__cxx03/__fwd/bit_reference.h>
 #include <__cxx03/__iterator/segmented_iterator.h>
 #include <__cxx03/__string/constexpr_c_functions.h>
+#include <__cxx03/__type_traits/invoke.h>
 #include <__cxx03/__type_traits/is_integral.h>
 #include <__cxx03/__type_traits/is_same.h>
 #include <__cxx03/__type_traits/is_signed.h>
diff --git a/libcxx/include/__cxx03/__algorithm/is_permutation.h b/libcxx/include/__cxx03/__algorithm/is_permutation.h
index 9402fdf5ce1c3..8df0e99987634 100644
--- a/libcxx/include/__cxx03/__algorithm/is_permutation.h
+++ b/libcxx/include/__cxx03/__algorithm/is_permutation.h
@@ -17,6 +17,7 @@
 #include <__cxx03/__iterator/distance.h>
 #include <__cxx03/__iterator/iterator_traits.h>
 #include <__cxx03/__iterator/next.h>
+#include <__cxx03/__type_traits/integral_constant.h>
 #include <__cxx03/__type_traits/invoke.h>
 #include <__cxx03/__type_traits/is_callable.h>
 #include <__cxx03/__utility/move.h>
diff --git a/libcxx/include/__cxx03/__algorithm/sort.h b/libcxx/include/__cxx03/__algorithm/sort.h
index 41df4d9ff3830..8d7ec90ec244c 100644
--- a/libcxx/include/__cxx03/__algorithm/sort.h
+++ b/libcxx/include/__cxx03/__algorithm/sort.h
@@ -27,6 +27,7 @@
 #include <__cxx03/__iterator/iterator_traits.h>
 #include <__cxx03/__type_traits/conditional.h>
 #include <__cxx03/__type_traits/disjunction.h>
+#include <__cxx03/__type_traits/integral_constant.h>
 #include <__cxx03/__type_traits/is_arithmetic.h>
 #include <__cxx03/__type_traits/is_constant_evaluated.h>
 #include <__cxx03/__utility/move.h>
diff --git a/libcxx/include/__cxx03/__functional/bind.h b/libcxx/include/__cxx03/__functional/bind.h
index 17228448c6efb..c65026935010e 100644
--- a/libcxx/include/__cxx03/__functional/bind.h
+++ b/libcxx/include/__cxx03/__functional/bind.h
@@ -13,9 +13,11 @@
 #include <__cxx03/__config>
 #include <__cxx03/__functional/weak_result_type.h>
 #include <__cxx03/__fwd/functional.h>
+#include <__cxx03/__type_traits/conditional.h>
 #include <__cxx03/__type_traits/decay.h>
 #include <__cxx03/__type_traits/invoke.h>
 #include <__cxx03/__type_traits/is_reference_wrapper.h>
+#include <__cxx03/__type_traits/is_same.h>
 #include <__cxx03/__type_traits/is_void.h>
 #include <__cxx03/__type_traits/remove_cvref.h>
 #include <__cxx03/cstddef>
diff --git a/libcxx/include/__cxx03/__random/generate_canonical.h b/libcxx/include/__cxx03/__random/generate_canonical.h
index c9381a1c58d5d..f62dcdeb442dc 100644
--- a/libcxx/include/__cxx03/__random/generate_canonical.h
+++ b/libcxx/include/__cxx03/__random/generate_canonical.h
@@ -11,6 +11,7 @@
 
 #include <__cxx03/__config>
 #include <__cxx03/__random/log2.h>
+#include <__cxx03/cstddef>
 #include <__cxx03/cstdint>
 #include <__cxx03/limits>
 
diff --git a/libcxx/include/__cxx03/array b/libcxx/include/__cxx03/array
index cacab3e86f0a7..cae85589b7099 100644
--- a/libcxx/include/__cxx03/array
+++ b/libcxx/include/__cxx03/array
@@ -135,6 +135,7 @@ template <size_t I, class T, size_t N> const T&& get(const array<T, N>&&) noexce
 #include <__cxx03/__utility/integer_sequence.h>
 #include <__cxx03/__utility/move.h>
 #include <__cxx03/__utility/unreachable.h>
+#include <__cxx03/cstddef>
 #include <__cxx03/stdexcept>
 #include <__cxx03/version>
 
diff --git a/libcxx/include/__cxx03/cmath b/libcxx/include/__cxx03/cmath
index 4de9c59406c12..5d35b53f77f95 100644
--- a/libcxx/include/__cxx03/cmath
+++ b/libcxx/include/__cxx03/cmath
@@ -324,9 +324,9 @@ constexpr long double lerp(long double a, long double b, long double t) noexcept
 #include <__cxx03/limits>
 #include <__cxx03/version>
 
-#include <__cxx03/math.h>
+#include <math.h>
 
-#ifndef _LIBCPP___CXX03_MATH_H
+#ifndef _LIBCPP_MATH_H
 #   error <cmath> tried including <math.h> but didn't find libc++'s <math.h> header. \
           This usually means that your header search paths are not configured properly. \
           The header search paths should contain the C++ Standard Library headers before \
diff --git a/libcxx/include/__cxx03/cstring b/libcxx/include/__cxx03/cstring
index 4d57420f54f54..0b3c5b13880be 100644
--- a/libcxx/include/__cxx03/cstring
+++ b/libcxx/include/__cxx03/cstring
@@ -59,7 +59,7 @@ size_t strlen(const char* s);
 #include <__cxx03/__config>
 #include <__cxx03/__type_traits/is_constant_evaluated.h>
 
-#include <__cxx03/string.h>
+#include <string.h>
 
 #ifndef _LIBCPP___CXX03_STRING_H
 #   error <cstring> tried including <string.h> but didn't find libc++'s <string.h> header. \
diff --git a/libcxx/include/__cxx03/future b/libcxx/include/__cxx03/future
index 20e739885ad0e..08c8a96251cd7 100644
--- a/libcxx/include/__cxx03/future
+++ b/libcxx/include/__cxx03/future
@@ -384,6 +384,7 @@ template <class R, class Alloc> struct uses_allocator<packaged_task<R>, Alloc>;
 #  include <__cxx03/__system_error/error_code.h>
 #  include <__cxx03/__system_error/error_condition.h>
 #  include <__cxx03/__type_traits/aligned_storage.h>
+#  include <__cxx03/__type_traits/invoke.h>
 #  include <__cxx03/__type_traits/strip_signature.h>
 #  include <__cxx03/__utility/auto_cast.h>
 #  include <__cxx03/__utility/forward.h>
diff --git a/libcxx/include/__cxx03/map b/libcxx/include/__cxx03/map
index f4bf7107e8281..49300fe075a93 100644
--- a/libcxx/include/__cxx03/map
+++ b/libcxx/include/__cxx03/map
@@ -584,6 +584,9 @@ erase_if(multimap<Key, T, Compare, Allocator>& c, Predicate pred);  // C++20
 #include <__cxx03/__memory/allocator.h>
 #include <__cxx03/__tree>
 #include <__cxx03/__type_traits/is_allocator.h>
+#include <__cxx03/__type_traits/is_empty.h>
+#include <__cxx03/__type_traits/is_final.h>
+#include <__cxx03/__type_traits/type_identity.h>
 #include <__cxx03/__utility/forward.h>
 #include <__cxx03/__utility/piecewise_construct.h>
 #include <__cxx03/__utility/swap.h>
diff --git a/libcxx/include/__cxx03/module.modulemap b/libcxx/include/__cxx03/module.modulemap
index 34a2d0f25fc45..ea5983cb09c6b 100644
--- a/libcxx/include/__cxx03/module.modulemap
+++ b/libcxx/include/__cxx03/module.modulemap
@@ -457,7 +457,7 @@ module cxx03_std_locale_h [system] {
   export *
 }
 module cxx03_std_math_h [system] {
-  header "math.h"
+  textual header "math.h"
   export *
 }
 // <setjmp.h> provided by C library.
@@ -515,48 +515,6 @@ module cxx03_std_wctype_h [system] {
   export *
 }
 
-// Experimental C++ standard library interfaces
-module cxx03_std_experimental [system] {
-  module iterator {
-    header "experimental/iterator"
-    export *
-  }
-  module memory {
-    header "experimental/memory"
-    export *
-  }
-  module propagate_const {
-    header "experimental/propagate_const"
-    export *
-  }
-  module simd {
-    module aligned_tag          { private header "experimental/__simd/aligned_tag.h" }
-    module declaration          { private header "experimental/__simd/declaration.h" }
-    module reference            { private header "experimental/__simd/reference.h" }
-    module scalar               { private header "experimental/__simd/scalar.h" }
-    module simd                 { private header "experimental/__simd/simd.h" }
-    module simd_mask            { private header "experimental/__simd/simd_mask.h" }
-    module traits               { private header "experimental/__simd/traits.h" }
-    module utility              { private header "experimental/__simd/utility.h" }
-    module vec_ext              { private header "experimental/__simd/vec_ext.h" }
-
-    header "experimental/simd"
-    export *
-  }
-  module type_traits {
-    header "experimental/type_traits"
-    export *
-  }
-  module utility {
-    header "experimental/utility"
-    export *
-  }
-  module __config {
-    textual header "experimental/__config"
-    export *
-  }
-}
-
 // Convenience method to get all of the above modules in a single import statement.
 // Importing only the needed modules is likely to be more performant.
 module cxx03_std [system] {
@@ -1109,8 +1067,8 @@ module cxx03_std_private_chrono_formatter              [system] {
 module cxx03_std_private_chrono_hh_mm_ss               [system] { header "__chrono/hh_mm_ss.h" }
 module cxx03_std_private_chrono_high_resolution_clock  [system] {
   header "__chrono/high_resolution_clock.h"
-  export std_private_chrono_steady_clock
-  export std_private_chrono_system_clock
+  export cxx03_std_private_chrono_steady_clock
+  export cxx03_std_private_chrono_system_clock
 }
 module cxx03_std_private_chrono_leap_second            [system] { header "__chrono/leap_second.h" }
 module cxx03_std_private_chrono_literals               [system] { header "__chrono/literals.h" }
@@ -1130,7 +1088,7 @@ module cxx03_std_private_chrono_parser_std_format_spec [system] {
 module cxx03_std_private_chrono_statically_widen       [system] { header "__chrono/statically_widen.h" }
 module cxx03_std_private_chrono_steady_clock           [system] {
   header "__chrono/steady_clock.h"
-  export std_private_chrono_time_point
+  export cxx03_std_private_chrono_time_point
 }
 module cxx03_std_private_chrono_time_zone              [system] {
   header "__chrono/time_zone.h"
@@ -1980,7 +1938,7 @@ module cxx03_std_private_type_traits_is_member_pointer                         [
 module cxx03_std_private_type_traits_is_nothrow_assignable                     [system] { header "__type_traits/is_nothrow_assignable.h" }
 module cxx03_std_private_type_traits_is_nothrow_constructible                  [system] {
   header "__type_traits/is_nothrow_constructible.h"
-  export std_private_type_traits_integral_constant
+  export cxx03_std_private_type_traits_integral_constant
 }
 module cxx03_std_private_type_traits_is_nothrow_convertible                    [system] { header "__type_traits/is_nothrow_convertible.h" }
 module cxx03_std_private_type_traits_is_nothrow_destructible                   [system] {
diff --git a/libcxx/include/__cxx03/set b/libcxx/include/__cxx03/set
index 8ddb425333eb6..ea3e6f762f165 100644
--- a/libcxx/include/__cxx03/set
+++ b/libcxx/include/__cxx03/set
@@ -523,6 +523,7 @@ erase_if(multiset<Key, Compare, Allocator>& c, Predicate pred);  // C++20
 #include <__cxx03/__memory/allocator.h>
 #include <__cxx03/__tree>
 #include <__cxx03/__type_traits/is_allocator.h>
+#include <__cxx03/__type_traits/type_identity.h>
 #include <__cxx03/__utility/forward.h>
 #include <__cxx03/version>
 
diff --git a/libcxx/include/__cxx03/string.h b/libcxx/include/__cxx03/string.h
index 49595fecc591d..317559624bc62 100644
--- a/libcxx/include/__cxx03/string.h
+++ b/libcxx/include/__cxx03/string.h
@@ -52,15 +52,12 @@ size_t strlen(const char* s);
 */
 
 #include <__cxx03/__config>
+#include <__cxx03/cstddef>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
 #endif
 
-#if __has_include_next(<string.h>)
-#  include_next <string.h>
-#endif
-
 // MSVCRT, GNU libc and its derivates may already have the correct prototype in
 // <string.h>. This macro can be defined by users if their C library provides
 // the right signature.
diff --git a/libcxx/include/__cxx03/unordered_map b/libcxx/include/__cxx03/unordered_map
index db5c8b60ab65b..b497226baab28 100644
--- a/libcxx/include/__cxx03/unordered_map
+++ b/libcxx/include/__cxx03/unordered_map
@@ -594,6 +594,7 @@ template <class Key, class T, class Hash, class Pred, class Alloc>
 #include <__cxx03/__memory/addressof.h>
 #include <__cxx03/__memory/allocator.h>
 #include <__cxx03/__type_traits/is_allocator.h>
+#include <__cxx03/__type_traits/is_final.h>
 #include <__cxx03/__type_traits/type_identity.h>
 #include <__cxx03/__utility/forward.h>
 #include <__cxx03/stdexcept>
diff --git a/libcxx/include/__cxx03/unordered_set b/libcxx/include/__cxx03/unordered_set
index e354bd973aa13..d902012ce7778 100644
--- a/libcxx/include/__cxx03/unordered_set
+++ b/libcxx/include/__cxx03/unordered_set
@@ -542,6 +542,7 @@ template <class Value, class Hash, class Pred, class Alloc>
 #include <__cxx03/__memory/addressof.h>
 #include <__cxx03/__memory/allocator.h>
 #include <__cxx03/__type_traits/is_allocator.h>
+#include <__cxx03/__type_traits/type_identity.h>
 #include <__cxx03/__utility/forward.h>
 #include <__cxx03/version>
 
diff --git a/libcxx/include/module.modulemap.in b/libcxx/include/module.modulemap.in
index 11ab61d959e22..c9070406a0542 100644
--- a/libcxx/include/module.modulemap.in
+++ b/libcxx/include/module.modulemap.in
@@ -13,6 +13,7 @@ module std_config [system] {
 
 module std_core [system] {
   module cstddef {
+    requires cplusplus11
     module byte         { header "__cstddef/byte.h" }
     module max_align_t  {
       header "__cstddef/max_align_t.h"
@@ -29,6 +30,7 @@ module std_core [system] {
   }
 
   module fwd {
+    requires cplusplus11
     module byte         { header "__fwd/byte.h" }
     module functional   { header "__fwd/functional.h" }
     module pair         { header "__fwd/pair.h" }
@@ -41,6 +43,7 @@ module std_core [system] {
   }
 
   module math {
+    requires cplusplus11
     module abs                              { header "__math/abs.h" }
     module copysign                         { header "__math/copysign.h" }
     module error_functions                  { header "__math/error_functions.h" }
@@ -64,327 +67,330 @@ module std_core [system] {
   }
 
   module type_traits {
-    module add_cv_quals                               { header "__type_traits/add_cv_quals.h" }
-    module add_pointer                                { header "__type_traits/add_pointer.h" }
-    module add_reference                              { header "__type_traits/add_reference.h" }
-    module aligned_storage                            { header "__type_traits/aligned_storage.h" }
-    module aligned_union                              { header "__type_traits/aligned_union.h" }
-    module alignment_of                               { header "__type_traits/alignment_of.h" }
-    module common_reference                           { header "__type_traits/common_reference.h" }
-    module common_type {
-      header "__type_traits/common_type.h"
-      // We need to export those because common_type inherits from either of those based on __builtin_common_type.
-      export std_core.type_traits.type_identity
-      export std_core.utility_core.empty
-    }
-    module conditional                                { header "__type_traits/conditional.h" }
-    module conjunction                                { header "__type_traits/conjunction.h" }
-    module container_traits                           { header "__type_traits/container_traits.h" }
-    module copy_cv                                    { header "__type_traits/copy_cv.h" }
-    module copy_cvref                                 { header "__type_traits/copy_cvref.h" }
-    module datasizeof                                 { header "__type_traits/datasizeof.h" }
-    module decay                                      { header "__type_traits/decay.h" }
-    module dependent_type                             { header "__type_traits/dependent_type.h" }
-    module desugars_to                                { header "__type_traits/desugars_to.h" }
-    module detected_or                                { header "__type_traits/detected_or.h" }
-    module disjunction                                { header "__type_traits/disjunction.h" }
-    module enable_if                                  { header "__type_traits/enable_if.h" }
-    module extent                                     { header "__type_traits/extent.h" }
-    module has_unique_object_representation           { header "__type_traits/has_unique_object_representation.h" }
-    module has_virtual_destructor                     { header "__type_traits/has_virtual_destructor.h" }
-    module integer_traits                             { header "__type_traits/integer_traits.h" }
-    module integral_constant                          { header "__type_traits/integral_constant.h" }
-    module invoke                                     { header "__type_traits/invoke.h" }
-    module is_abstract {
-      header "__type_traits/is_abstract.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_aggregate {
-      header "__type_traits/is_aggregate.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_allocator { header "__type_traits/is_allocator.h" }
-    module is_always_bitcastable {
-      header "__type_traits/is_always_bitcastable.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_arithmetic {
-      header "__type_traits/is_arithmetic.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_array {
-      header "__type_traits/is_array.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_assignable {
-      header "__type_traits/is_assignable.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_base_of {
-      header "__type_traits/is_base_of.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_bounded_array {
-      header "__type_traits/is_bounded_array.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_callable {
-      header "__type_traits/is_callable.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_char_like_type {
-      header "__type_traits/is_char_like_type.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_class {
-      header "__type_traits/is_class.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_compound {
-      header "__type_traits/is_compound.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_const {
-      header "__type_traits/is_const.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_constant_evaluated {
-      header "__type_traits/is_constant_evaluated.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_constructible {
-      header "__type_traits/is_constructible.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_convertible {
-      header "__type_traits/is_convertible.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_core_convertible {
-      header "__type_traits/is_core_convertible.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_destructible {
-      header "__type_traits/is_destructible.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_empty {
-      header "__type_traits/is_empty.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_enum {
-      header "__type_traits/is_enum.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_equality_comparable {
-      header "__type_traits/is_equality_comparable.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_execution_policy {
-      header "__type_traits/is_execution_policy.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_final {
-      header "__type_traits/is_final.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_floating_point {
-      header "__type_traits/is_floating_point.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_function {
-      header "__type_traits/is_function.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_fundamental {
-      header "__type_traits/is_fundamental.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_generic_transparent_comparator { header "__type_traits/is_generic_transparent_comparator.h" }
-    module is_implicit_lifetime {
-      header "__type_traits/is_implicit_lifetime.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_implicitly_default_constructible {
-      header "__type_traits/is_implicitly_default_constructible.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_integral {
-      header "__type_traits/is_integral.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_literal_type {
-      header "__type_traits/is_literal_type.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_member_pointer {
-      header "__type_traits/is_member_pointer.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_nothrow_assignable {
-      header "__type_traits/is_nothrow_assignable.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_nothrow_constructible {
-      header "__type_traits/is_nothrow_constructible.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_nothrow_destructible {
-      header "__type_traits/is_nothrow_destructible.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_null_pointer {
-      header "__type_traits/is_null_pointer.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_object {
-      header "__type_traits/is_object.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_pod {
-      header "__type_traits/is_pod.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_pointer {
-      header "__type_traits/is_pointer.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_polymorphic {
-      header "__type_traits/is_polymorphic.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_primary_template {
-      header "__type_traits/is_primary_template.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_reference_wrapper {
-      header "__type_traits/is_reference_wrapper.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_reference {
-      header "__type_traits/is_reference.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_referenceable {
-      header "__type_traits/is_referenceable.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_replaceable {
-      header "__type_traits/is_replaceable.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_same {
-      header "__type_traits/is_same.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_scalar {
-      header "__type_traits/is_scalar.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_signed {
-      header "__type_traits/is_signed.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_specialization {
-      header "__type_traits/is_specialization.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_standard_layout {
-      header "__type_traits/is_standard_layout.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_swappable {
-      header "__type_traits/is_swappable.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_trivial {
-      header "__type_traits/is_trivial.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_trivially_assignable {
-      header "__type_traits/is_trivially_assignable.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_trivially_constructible {
-      header "__type_traits/is_trivially_constructible.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_trivially_copyable {
-      header "__type_traits/is_trivially_copyable.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_trivially_destructible {
-      header "__type_traits/is_trivially_destructible.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_trivially_lexicographically_comparable {
-      header "__type_traits/is_trivially_lexicographically_comparable.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_trivially_relocatable {
-      header "__type_traits/is_trivially_relocatable.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_unbounded_array {
-      header "__type_traits/is_unbounded_array.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_union {
-      header "__type_traits/is_union.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_unqualified { header "__type_traits/is_unqualified.h" }
-    module is_unsigned {
-      header "__type_traits/is_unsigned.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_valid_expansion {
-      header "__type_traits/is_valid_expansion.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_void {
-      header "__type_traits/is_void.h"
-      export std_core.type_traits.integral_constant
-    }
-    module is_volatile {
-      header "__type_traits/is_volatile.h"
-      export std_core.type_traits.integral_constant
-    }
-    module lazy                                       { header "__type_traits/lazy.h" }
-    module make_32_64_or_128_bit                      { header "__type_traits/make_32_64_or_128_bit.h" }
-    module make_const_lvalue_ref                      { header "__type_traits/make_const_lvalue_ref.h" }
-    module make_signed                                { header "__type_traits/make_signed.h" }
-    module make_transparent                           { header "__type_traits/make_transparent.h" }
-    module make_unsigned                              { header "__type_traits/make_unsigned.h" }
-    module maybe_const                                { header "__type_traits/maybe_const.h" }
-    module nat                                        { header "__type_traits/nat.h" }
-    module negation                                   { header "__type_traits/negation.h" }
-    module promote                                    { header "__type_traits/promote.h" }
-    module rank                                       { header "__type_traits/rank.h" }
-    module reference_constructs_from_temporary {
-      header "__type_traits/reference_constructs_from_temporary.h"
-      export std_core.type_traits.integral_constant
-    }
-    module reference_converts_from_temporary {
-      header "__type_traits/reference_converts_from_temporary.h"
-      export std_core.type_traits.integral_constant
+    module cxx11 {
+      requires cplusplus11
+      module add_cv_quals                               { header "__type_traits/add_cv_quals.h" }
+      module add_pointer                                { header "__type_traits/add_pointer.h" }
+      module add_reference                              { header "__type_traits/add_reference.h" }
+      module aligned_storage                            { header "__type_traits/aligned_storage.h" }
+      module aligned_union                              { header "__type_traits/aligned_union.h" }
+      module alignment_of                               { header "__type_traits/alignment_of.h" }
+      module common_reference                           { header "__type_traits/common_reference.h" }
+      module common_type {
+        header "__type_traits/common_type.h"
+        // We need to export those because common_type inherits from either of those based on __builtin_common_type.
+        export std_core.type_traits.type_identity
+        export std_core.utility_core.empty
+      }
+      module conditional                                { header "__type_traits/conditional.h" }
+      module conjunction                                { header "__type_traits/conjunction.h" }
+      module container_traits                           { header "__type_traits/container_traits.h" }
+      module copy_cv                                    { header "__type_traits/copy_cv.h" }
+      module copy_cvref                                 { header "__type_traits/copy_cvref.h" }
+      module datasizeof                                 { header "__type_traits/datasizeof.h" }
+      module decay                                      { header "__type_traits/decay.h" }
+      module dependent_type                             { header "__type_traits/dependent_type.h" }
+      module desugars_to                                { header "__type_traits/desugars_to.h" }
+      module detected_or                                { header "__type_traits/detected_or.h" }
+      module disjunction                                { header "__type_traits/disjunction.h" }
+      module enable_if                                  { header "__type_traits/enable_if.h" }
+      module extent                                     { header "__type_traits/extent.h" }
+      module has_unique_object_representation           { header "__type_traits/has_unique_object_representation.h" }
+      module has_virtual_destructor                     { header "__type_traits/has_virtual_destructor.h" }
+      module integer_traits                             { header "__type_traits/integer_traits.h" }
+      module integral_constant                          { header "__type_traits/integral_constant.h" }
+      module invoke                                     { header "__type_traits/invoke.h" }
+      module is_abstract {
+        header "__type_traits/is_abstract.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_aggregate {
+        header "__type_traits/is_aggregate.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_allocator { header "__type_traits/is_allocator.h" }
+      module is_always_bitcastable {
+        header "__type_traits/is_always_bitcastable.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_arithmetic {
+        header "__type_traits/is_arithmetic.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_array {
+        header "__type_traits/is_array.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_assignable {
+        header "__type_traits/is_assignable.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_base_of {
+        header "__type_traits/is_base_of.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_bounded_array {
+        header "__type_traits/is_bounded_array.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_callable {
+        header "__type_traits/is_callable.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_char_like_type {
+        header "__type_traits/is_char_like_type.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_class {
+        header "__type_traits/is_class.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_compound {
+        header "__type_traits/is_compound.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_const {
+        header "__type_traits/is_const.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_constant_evaluated {
+        header "__type_traits/is_constant_evaluated.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_constructible {
+        header "__type_traits/is_constructible.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_convertible {
+        header "__type_traits/is_convertible.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_core_convertible {
+        header "__type_traits/is_core_convertible.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_destructible {
+        header "__type_traits/is_destructible.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_empty {
+        header "__type_traits/is_empty.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_enum {
+        header "__type_traits/is_enum.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_equality_comparable {
+        header "__type_traits/is_equality_comparable.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_execution_policy {
+        header "__type_traits/is_execution_policy.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_final {
+        header "__type_traits/is_final.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_floating_point {
+        header "__type_traits/is_floating_point.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_function {
+        header "__type_traits/is_function.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_fundamental {
+        header "__type_traits/is_fundamental.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_generic_transparent_comparator { header "__type_traits/is_generic_transparent_comparator.h" }
+      module is_implicit_lifetime {
+        header "__type_traits/is_implicit_lifetime.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_implicitly_default_constructible {
+        header "__type_traits/is_implicitly_default_constructible.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_integral {
+        header "__type_traits/is_integral.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_literal_type {
+        header "__type_traits/is_literal_type.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_member_pointer {
+        header "__type_traits/is_member_pointer.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_nothrow_assignable {
+        header "__type_traits/is_nothrow_assignable.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_nothrow_constructible {
+        header "__type_traits/is_nothrow_constructible.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_nothrow_destructible {
+        header "__type_traits/is_nothrow_destructible.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_null_pointer {
+        header "__type_traits/is_null_pointer.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_object {
+        header "__type_traits/is_object.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_pod {
+        header "__type_traits/is_pod.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_pointer {
+        header "__type_traits/is_pointer.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_polymorphic {
+        header "__type_traits/is_polymorphic.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_primary_template {
+        header "__type_traits/is_primary_template.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_reference_wrapper {
+        header "__type_traits/is_reference_wrapper.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_reference {
+        header "__type_traits/is_reference.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_referenceable {
+        header "__type_traits/is_referenceable.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_replaceable {
+        header "__type_traits/is_replaceable.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_same {
+        header "__type_traits/is_same.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_scalar {
+        header "__type_traits/is_scalar.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_signed {
+        header "__type_traits/is_signed.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_specialization {
+        header "__type_traits/is_specialization.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_standard_layout {
+        header "__type_traits/is_standard_layout.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_swappable {
+        header "__type_traits/is_swappable.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_trivial {
+        header "__type_traits/is_trivial.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_trivially_assignable {
+        header "__type_traits/is_trivially_assignable.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_trivially_constructible {
+        header "__type_traits/is_trivially_constructible.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_trivially_copyable {
+        header "__type_traits/is_trivially_copyable.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_trivially_destructible {
+        header "__type_traits/is_trivially_destructible.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_trivially_lexicographically_comparable {
+        header "__type_traits/is_trivially_lexicographically_comparable.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_trivially_relocatable {
+        header "__type_traits/is_trivially_relocatable.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_unbounded_array {
+        header "__type_traits/is_unbounded_array.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_union {
+        header "__type_traits/is_union.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_unqualified { header "__type_traits/is_unqualified.h" }
+      module is_unsigned {
+        header "__type_traits/is_unsigned.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_valid_expansion {
+        header "__type_traits/is_valid_expansion.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_void {
+        header "__type_traits/is_void.h"
+        export std_core.type_traits.integral_constant
+      }
+      module is_volatile {
+        header "__type_traits/is_volatile.h"
+        export std_core.type_traits.integral_constant
+      }
+      module lazy                                       { header "__type_traits/lazy.h" }
+      module make_32_64_or_128_bit                      { header "__type_traits/make_32_64_or_128_bit.h" }
+      module make_const_lvalue_ref                      { header "__type_traits/make_const_lvalue_ref.h" }
+      module make_signed                                { header "__type_traits/make_signed.h" }
+      module make_transparent                           { header "__type_traits/make_transparent.h" }
+      module make_unsigned                              { header "__type_traits/make_unsigned.h" }
+      module maybe_const                                { header "__type_traits/maybe_const.h" }
+      module nat                                        { header "__type_traits/nat.h" }
+      module negation                                   { header "__type_traits/negation.h" }
+      module promote                                    { header "__type_traits/promote.h" }
+      module rank                                       { header "__type_traits/rank.h" }
+      module reference_constructs_from_temporary {
+        header "__type_traits/reference_constructs_from_temporary.h"
+        export std_core.type_traits.integral_constant
+      }
+      module reference_converts_from_temporary {
+        header "__type_traits/reference_converts_from_temporary.h"
+        export std_core.type_traits.integral_constant
+      }
+      module remove_all_extents                         { header "__type_traits/remove_all_extents.h" }
+      module remove_const_ref                           { header "__type_traits/remove_const_ref.h" }
+      module remove_const                               { header "__type_traits/remove_const.h" }
+      module remove_cv                                  { header "__type_traits/remove_cv.h" }
+      module remove_cvref                               { header "__type_traits/remove_cvref.h" }
+      module remove_extent                              { header "__type_traits/remove_extent.h" }
+      module remove_pointer                             { header "__type_traits/remove_pointer.h" }
+      module remove_reference                           { header "__type_traits/remove_reference.h" }
+      module remove_volatile                            { header "__type_traits/remove_volatile.h" }
+      module result_of                                  { header "__type_traits/result_of.h" }
+      module strip_signature                            { header "__type_traits/strip_signature.h" }
+      module type_identity                              { header "__type_traits/type_identity.h" }
+      module type_list                                  { header "__type_traits/type_list.h" }
+      module underlying_type                            { header "__type_traits/underlying_type.h" }
+      module unwrap_ref                                 { header "__type_traits/unwrap_ref.h" }
+      module void_t                                     { header "__type_traits/void_t.h" }
     }
-    module remove_all_extents                         { header "__type_traits/remove_all_extents.h" }
-    module remove_const_ref                           { header "__type_traits/remove_const_ref.h" }
-    module remove_const                               { header "__type_traits/remove_const.h" }
-    module remove_cv                                  { header "__type_traits/remove_cv.h" }
-    module remove_cvref                               { header "__type_traits/remove_cvref.h" }
-    module remove_extent                              { header "__type_traits/remove_extent.h" }
-    module remove_pointer                             { header "__type_traits/remove_pointer.h" }
-    module remove_reference                           { header "__type_traits/remove_reference.h" }
-    module remove_volatile                            { header "__type_traits/remove_volatile.h" }
-    module result_of                                  { header "__type_traits/result_of.h" }
-    module strip_signature                            { header "__type_traits/strip_signature.h" }
-    module type_identity                              { header "__type_traits/type_identity.h" }
-    module type_list                                  { header "__type_traits/type_list.h" }
-    module underlying_type                            { header "__type_traits/underlying_type.h" }
-    module unwrap_ref                                 { header "__type_traits/unwrap_ref.h" }
-    module void_t                                     { header "__type_traits/void_t.h" }
 
     header "type_traits"
     export *
@@ -392,466 +398,490 @@ module std_core [system] {
 
   // Only the truly dependency-free parts of __utility are here
   module utility_core {
+    requires cplusplus11
     module declval  { header "__utility/declval.h" }
     module empty    { header "__utility/empty.h" }
     module forward  { header "__utility/forward.h" }
   }
 } // module std_core
 
+module std_assertion_handling [system] {
+  module assertion_handler {
+    header "__assertion_handler" // generated via CMake
+    export *
+  }
+
+  module log_hardening_failure {
+    requires cplusplus11
+    header "__log_hardening_failure"
+  }
+  module verbose_abort {
+    requires cplusplus11
+    header "__verbose_abort"
+  }
+  module verbose_trap {
+    requires cplusplus11
+    header "__verbose_trap"
+  }
+}
+
 module std [system] {
   module algorithm {
-    module adjacent_find                          { header "__algorithm/adjacent_find.h" }
-    module all_of                                 { header "__algorithm/all_of.h" }
-    module any_of                                 { header "__algorithm/any_of.h" }
-    module binary_search                          { header "__algorithm/binary_search.h" }
-    module clamp                                  { header "__algorithm/clamp.h" }
-    module comp_ref_type                          { header "__algorithm/comp_ref_type.h" }
-    module comp                                   { header "__algorithm/comp.h" }
-    module copy_backward                          { header "__algorithm/copy_backward.h" }
-    module copy_if                                { header "__algorithm/copy_if.h" }
-    module copy_move_common                       { header "__algorithm/copy_move_common.h" }
-    module copy_n                                 {
-      header "__algorithm/copy_n.h"
-      export std.iterator_traits
-    }
-    module copy                                   { header "__algorithm/copy.h" }
-    module count_if                               { header "__algorithm/count_if.h" }
-    module count                                  { header "__algorithm/count.h" }
-    module equal_range                            { header "__algorithm/equal_range.h" }
-    module equal                                  { header "__algorithm/equal.h" }
-    module fill_n                                 { header "__algorithm/fill_n.h" }
-    module fill                                   { header "__algorithm/fill.h" }
-    module find_end                               { header "__algorithm/find_end.h" }
-    module find_first_of                          { header "__algorithm/find_first_of.h" }
-    module find_if_not                            { header "__algorithm/find_if_not.h" }
-    module find_if                                { header "__algorithm/find_if.h" }
-    module find_segment_if                        { header "__algorithm/find_segment_if.h" }
-    module find                                   { header "__algorithm/find.h" }
-    module for_each_n                             { header "__algorithm/for_each_n.h" }
-    module for_each_n_segment                     { header "__algorithm/for_each_n_segment.h" }
-    module for_each_segment                       { header "__algorithm/for_each_segment.h" }
-    module for_each                               { header "__algorithm/for_each.h" }
-    module generate_n                             { header "__algorithm/generate_n.h" }
-    module generate                               { header "__algorithm/generate.h" }
-    module half_positive                          { header "__algorithm/half_positive.h" }
-    module in_found_result                        { header "__algorithm/in_found_result.h" }
-    module in_fun_result                          { header "__algorithm/in_fun_result.h" }
-    module in_in_out_result                       { header "__algorithm/in_in_out_result.h" }
-    module in_in_result                           { header "__algorithm/in_in_result.h" }
-    module in_out_out_result                      { header "__algorithm/in_out_out_result.h" }
-    module in_out_result                          { header "__algorithm/in_out_result.h" }
-    module includes                               { header "__algorithm/includes.h" }
-    module inplace_merge                          { header "__algorithm/inplace_merge.h" }
-    module is_heap_until                          { header "__algorithm/is_heap_until.h" }
-    module is_heap                                { header "__algorithm/is_heap.h" }
-    module is_partitioned                         { header "__algorithm/is_partitioned.h" }
-    module is_permutation                         { header "__algorithm/is_permutation.h" }
-    module is_sorted_until                        { header "__algorithm/is_sorted_until.h" }
-    module is_sorted                              { header "__algorithm/is_sorted.h" }
-    module iter_swap                              { header "__algorithm/iter_swap.h" }
-    module iterator_operations {
-      header "__algorithm/iterator_operations.h"
-      export std.iterator.advance
-      export std.iterator.distance
-      export std.iterator.iter_move
-      export std.iterator.iter_swap
-      export std.iterator.next
-      export std.iterator.prev
-    }
-    module lexicographical_compare_three_way      { header "__algorithm/lexicographical_compare_three_way.h" }
-    module lexicographical_compare                { header "__algorithm/lexicographical_compare.h" }
-    module lower_bound                            { header "__algorithm/lower_bound.h" }
-    module make_heap                              { header "__algorithm/make_heap.h" }
-    module make_projected                         { header "__algorithm/make_projected.h" }
-    module max_element                            { header "__algorithm/max_element.h" }
-    module max                                    { header "__algorithm/max.h" }
-    module merge                                  { header "__algorithm/merge.h" }
-    module min_element                            { header "__algorithm/min_element.h" }
-    module min_max_result                         { header "__algorithm/min_max_result.h" }
-    module min                                    { header "__algorithm/min.h" }
-    module minmax_element                         { header "__algorithm/minmax_element.h" }
-    module minmax {
-      header "__algorithm/minmax.h"
-      export std.utility.pair // return type
-    }
-    module mismatch {
-      header "__algorithm/mismatch.h"
-      export std.utility.pair // return type
-    }
-    module move_backward                          { header "__algorithm/move_backward.h" }
-    module move                                   { header "__algorithm/move.h" }
-    module next_permutation                       { header "__algorithm/next_permutation.h" }
-    module none_of                                { header "__algorithm/none_of.h" }
-    module nth_element                            { header "__algorithm/nth_element.h" }
-    module out_value_result                       { header "__algorithm/out_value_result.h" }
-    module partial_sort_copy                      { header "__algorithm/partial_sort_copy.h" }
-    module partial_sort                           { header "__algorithm/partial_sort.h" }
-    module partition_copy                         { header "__algorithm/partition_copy.h" }
-    module partition_point                        { header "__algorithm/partition_point.h" }
-    module partition                              { header "__algorithm/partition.h" }
-    module pop_heap                               { header "__algorithm/pop_heap.h" }
-    module prev_permutation                       { header "__algorithm/prev_permutation.h" }
-    module pstl                                   { header "__algorithm/pstl.h" }
-    module push_heap                              { header "__algorithm/push_heap.h" }
-    module radix_sort                             { header "__algorithm/radix_sort.h" }
-    module ranges_adjacent_find                   { header "__algorithm/ranges_adjacent_find.h" }
-    module ranges_all_of                          { header "__algorithm/ranges_all_of.h" }
-    module ranges_any_of                          { header "__algorithm/ranges_any_of.h" }
-    module ranges_binary_search {
-      header "__algorithm/ranges_binary_search.h"
-      export std.functional.ranges_operations
-    }
-    module ranges_clamp {
-      header "__algorithm/ranges_clamp.h"
-      export std.functional.ranges_operations
-    }
-    module ranges_contains_subrange {
-      header "__algorithm/ranges_contains_subrange.h"
-    }
-    module ranges_contains {
-      header "__algorithm/ranges_contains.h"
-    }
-    module ranges_copy_backward {
-      header "__algorithm/ranges_copy_backward.h"
-      export std.algorithm.in_out_result
-    }
-    module ranges_copy_if {
-      header "__algorithm/ranges_copy_if.h"
-      export std.algorithm.in_out_result
-    }
-    module ranges_copy_n {
-      header "__algorithm/ranges_copy_n.h"
-      export std.algorithm.in_out_result
-    }
-    module ranges_copy {
-      header "__algorithm/ranges_copy.h"
-      export std.algorithm.in_out_result
-    }
-    module ranges_count_if                        { header "__algorithm/ranges_count_if.h" }
-    module ranges_count                           { header "__algorithm/ranges_count.h" }
-    module ranges_ends_with                       { header "__algorithm/ranges_ends_with.h" }
-    module ranges_equal_range {
-      header "__algorithm/ranges_equal_range.h"
-      export std.functional.ranges_operations
-    }
-    module ranges_equal {
-      header "__algorithm/ranges_equal.h"
-      export std.functional.identity
-    }
-    module ranges_fill_n                          { header "__algorithm/ranges_fill_n.h" }
-    module ranges_fill                            { header "__algorithm/ranges_fill.h" }
-    module ranges_find_end {
-      header "__algorithm/ranges_find_end.h"
-      export std.ranges.subrange // return type
-    }
-    module ranges_find_first_of                   { header "__algorithm/ranges_find_first_of.h" }
-    module ranges_find_if_not                     { header "__algorithm/ranges_find_if_not.h" }
-    module ranges_find_if                         { header "__algorithm/ranges_find_if.h" }
-    module ranges_find_last {
-      header "__algorithm/ranges_find_last.h"
-      export std.ranges.subrange // return type
-    }
-    module ranges_find                            { header "__algorithm/ranges_find.h" }
-    module ranges_fold                            { header "__algorithm/ranges_fold.h" }
-    module ranges_for_each_n {
-      header "__algorithm/ranges_for_each_n.h"
-      export std.algorithm.in_fun_result
-    }
-    module ranges_for_each {
-      header "__algorithm/ranges_for_each.h"
-      export std.algorithm.in_fun_result
-    }
-    module ranges_generate_n {
-      header "__algorithm/ranges_generate_n.h"
-    }
-    module ranges_generate {
-      header "__algorithm/ranges_generate.h"
-    }
-    module ranges_includes {
-      header "__algorithm/ranges_includes.h"
-      export std.functional.ranges_operations
-    }
-    module ranges_inplace_merge {
-      header "__algorithm/ranges_inplace_merge.h"
-      export std.functional.ranges_operations
-    }
-    module ranges_is_heap_until {
-      header "__algorithm/ranges_is_heap_until.h"
-      export std.functional.ranges_operations
-    }
-    module ranges_is_heap {
-      header "__algorithm/ranges_is_heap.h"
-      export std.functional.ranges_operations
-    }
-    module ranges_is_partitioned {
-      header "__algorithm/ranges_is_partitioned.h"
-    }
-    module ranges_is_permutation {
-      header "__algorithm/ranges_is_permutation.h"
-    }
-    module ranges_is_sorted_until {
-      header "__algorithm/ranges_is_sorted_until.h"
-      export std.functional.ranges_operations
-    }
-    module ranges_is_sorted {
-      header "__algorithm/ranges_is_sorted.h"
-      export std.functional.ranges_operations
-    }
-    module ranges_iterator_concept {
-      header "__algorithm/ranges_iterator_concept.h"
-    }
-    module ranges_lexicographical_compare {
-      header "__algorithm/ranges_lexicographical_compare.h"
-      export std.functional.ranges_operations
-    }
-    module ranges_lower_bound {
-      header "__algorithm/ranges_lower_bound.h"
-      export std.functional.ranges_operations
-    }
-    module ranges_make_heap {
-      header "__algorithm/ranges_make_heap.h"
-      export std.functional.ranges_operations
-    }
-    module ranges_max_element {
-      header "__algorithm/ranges_max_element.h"
-      export std.functional.ranges_operations
-    }
-    module ranges_max {
-      header "__algorithm/ranges_max.h"
-      export std.functional.ranges_operations
-    }
-    module ranges_merge {
-      header "__algorithm/ranges_merge.h"
-      export std.functional.ranges_operations
-      export std.algorithm.in_in_out_result
-    }
-    module ranges_min_element {
-      header "__algorithm/ranges_min_element.h"
-      export std.functional.ranges_operations
-    }
-    module ranges_min {
-      header "__algorithm/ranges_min.h"
-      export std.functional.ranges_operations
-    }
-    module ranges_minmax_element {
-      header "__algorithm/ranges_minmax_element.h"
-      export std.functional.ranges_operations
-      export std.algorithm.min_max_result
-    }
-    module ranges_minmax {
-      header "__algorithm/ranges_minmax.h"
-      export std.functional.ranges_operations
-      export std.algorithm.min_max_result
-    }
-    module ranges_mismatch {
-      header "__algorithm/ranges_mismatch.h"
-      export std.algorithm.in_in_result
-    }
-    module ranges_move_backward {
-      header "__algorithm/ranges_move_backward.h"
-      export std.algorithm.in_out_result
-    }
-    module ranges_move {
-      header "__algorithm/ranges_move.h"
-      export std.algorithm.in_out_result
-    }
-    module ranges_next_permutation {
-      header "__algorithm/ranges_next_permutation.h"
-      export std.functional.ranges_operations
-      export std.algorithm.in_found_result
-    }
-    module ranges_none_of {
-      header "__algorithm/ranges_none_of.h"
-    }
-    module ranges_nth_element {
-      header "__algorithm/ranges_nth_element.h"
-      export std.functional.ranges_operations
-    }
-    module ranges_partial_sort_copy {
-      header "__algorithm/ranges_partial_sort_copy.h"
-      export std.functional.ranges_operations
-    }
-    module ranges_partial_sort {
-      header "__algorithm/ranges_partial_sort.h"
-      export std.functional.ranges_operations
-    }
-    module ranges_partition_copy {
-      header "__algorithm/ranges_partition_copy.h"
-      export std.algorithm.in_out_out_result
-    }
-    module ranges_partition_point {
-      header "__algorithm/ranges_partition_point.h"
-    }
-    module ranges_partition {
-      header "__algorithm/ranges_partition.h"
-      export std.ranges.subrange // return type
-    }
-    module ranges_pop_heap {
-      header "__algorithm/ranges_pop_heap.h"
-      export std.functional.ranges_operations
-    }
-    module ranges_prev_permutation {
-      header "__algorithm/ranges_prev_permutation.h"
-      export std.functional.ranges_operations
-      export std.algorithm.in_found_result
-    }
-    module ranges_push_heap {
-      header "__algorithm/ranges_push_heap.h"
-      export std.functional.ranges_operations
-    }
-    module ranges_remove_copy_if {
-      header "__algorithm/ranges_remove_copy_if.h"
-      export std.algorithm.in_out_result
-    }
-    module ranges_remove_copy {
-      header "__algorithm/ranges_remove_copy.h"
-      export std.algorithm.in_out_result
-    }
-    module ranges_remove_if {
-      header "__algorithm/ranges_remove_if.h"
-    }
-    module ranges_remove {
-      header "__algorithm/ranges_remove.h"
-      export std.ranges.subrange // return type
-    }
-    module ranges_replace_copy_if {
-      header "__algorithm/ranges_replace_copy_if.h"
-      export std.algorithm.in_out_result
-    }
-    module ranges_replace_copy {
-      header "__algorithm/ranges_replace_copy.h"
-      export std.algorithm.in_out_result
-    }
-    module ranges_replace_if {
-      header "__algorithm/ranges_replace_if.h"
-    }
-    module ranges_replace {
-      header "__algorithm/ranges_replace.h"
-    }
-    module ranges_reverse_copy {
-      header "__algorithm/ranges_reverse_copy.h"
-      export std.algorithm.in_out_result
-    }
-    module ranges_reverse {
-      header "__algorithm/ranges_reverse.h"
-    }
-    module ranges_rotate_copy {
-      header "__algorithm/ranges_rotate_copy.h"
-      export std.ranges.subrange // return type
-    }
-    module ranges_rotate                          { header "__algorithm/ranges_rotate.h" }
-    module ranges_sample                          { header "__algorithm/ranges_sample.h" }
-    module ranges_search_n {
-      header "__algorithm/ranges_search_n.h"
-      export std.ranges.subrange // return type
-    }
-    module ranges_search {
-      header "__algorithm/ranges_search.h"
-      export std.ranges.subrange // return type
-    }
-    module ranges_set_difference {
-      header "__algorithm/ranges_set_difference.h"
-      export std.functional.ranges_operations
-      export std.algorithm.in_out_result
-    }
-    module ranges_set_intersection {
-      header "__algorithm/ranges_set_intersection.h"
-      export std.functional.ranges_operations
-      export std.algorithm.in_in_out_result
-    }
-    module ranges_set_symmetric_difference {
-      header "__algorithm/ranges_set_symmetric_difference.h"
-      export std.functional.ranges_operations
-      export std.algorithm.in_in_out_result
-    }
-    module ranges_set_union {
-      header "__algorithm/ranges_set_union.h"
-      export std.functional.ranges_operations
-      export std.algorithm.in_in_out_result
-    }
-    module ranges_shuffle {
-      header "__algorithm/ranges_shuffle.h"
-    }
-    module ranges_sort_heap {
-      header "__algorithm/ranges_sort_heap.h"
-      export std.functional.ranges_operations
-    }
-    module ranges_sort {
-      header "__algorithm/ranges_sort.h"
-      export std.functional.ranges_operations
-      export std.algorithm.sort
-      export std.algorithm.make_projected
-    }
-    module ranges_stable_partition {
-      header "__algorithm/ranges_stable_partition.h"
-      export std.ranges.subrange // return type
-    }
-    module ranges_stable_sort {
-      header "__algorithm/ranges_stable_sort.h"
-      export std.functional.ranges_operations
-    }
-    module ranges_starts_with {
-      header "__algorithm/ranges_starts_with.h"
-    }
-    module ranges_swap_ranges {
-      header "__algorithm/ranges_swap_ranges.h"
-      export std.algorithm.in_in_result
-    }
-    module ranges_transform {
-      header "__algorithm/ranges_transform.h"
-      export std.algorithm.in_out_result
-      export std.algorithm.in_in_out_result
-    }
-    module ranges_unique_copy {
-      header "__algorithm/ranges_unique_copy.h"
-    }
-    module ranges_unique {
-      header "__algorithm/ranges_unique.h"
-    }
-    module ranges_upper_bound {
-      header "__algorithm/ranges_upper_bound.h"
-      export std.functional.ranges_operations
-    }
-    module remove_copy_if                         { header "__algorithm/remove_copy_if.h" }
-    module remove_copy                            { header "__algorithm/remove_copy.h" }
-    module remove_if                              { header "__algorithm/remove_if.h" }
-    module remove                                 { header "__algorithm/remove.h" }
-    module replace_copy_if                        { header "__algorithm/replace_copy_if.h" }
-    module replace_copy                           { header "__algorithm/replace_copy.h" }
-    module replace_if                             { header "__algorithm/replace_if.h" }
-    module replace                                { header "__algorithm/replace.h" }
-    module reverse_copy                           { header "__algorithm/reverse_copy.h" }
-    module reverse                                { header "__algorithm/reverse.h" }
-    module rotate_copy                            { header "__algorithm/rotate_copy.h" }
-    module rotate                                 { header "__algorithm/rotate.h" }
-    module sample                                 { header "__algorithm/sample.h" }
-    module search_n                               { header "__algorithm/search_n.h" }
-    module search                                 { header "__algorithm/search.h" }
-    module set_difference                         { header "__algorithm/set_difference.h" }
-    module set_intersection                       { header "__algorithm/set_intersection.h" }
-    module set_symmetric_difference               { header "__algorithm/set_symmetric_difference.h" }
-    module set_union                              { header "__algorithm/set_union.h" }
-    module shift_left                             { header "__algorithm/shift_left.h" }
-    module shift_right                            { header "__algorithm/shift_right.h" }
-    module shuffle                                { header "__algorithm/shuffle.h" }
-    module sift_down                              { header "__algorithm/sift_down.h" }
-    module simd_utils                             { header "__algorithm/simd_utils.h" }
-    module sort_heap                              { header "__algorithm/sort_heap.h" }
-    module sort                                   { header "__algorithm/sort.h" }
-    module stable_partition                       { header "__algorithm/stable_partition.h" }
-    module stable_sort {
-      header "__algorithm/stable_sort.h"
-      export std.memory.unique_temporary_buffer // TODO: Workaround for https://llvm.org/PR120108
+    module cxx11 {
+      requires cplusplus11
+      module adjacent_find                          { header "__algorithm/adjacent_find.h" }
+      module all_of                                 { header "__algorithm/all_of.h" }
+      module any_of                                 { header "__algorithm/any_of.h" }
+      module binary_search                          { header "__algorithm/binary_search.h" }
+      module clamp                                  { header "__algorithm/clamp.h" }
+      module comp_ref_type                          { header "__algorithm/comp_ref_type.h" }
+      module comp                                   { header "__algorithm/comp.h" }
+      module copy_backward                          { header "__algorithm/copy_backward.h" }
+      module copy_if                                { header "__algorithm/copy_if.h" }
+      module copy_move_common                       { header "__algorithm/copy_move_common.h" }
+      module copy_n                                 {
+        header "__algorithm/copy_n.h"
+        export std.iterator_traits
+      }
+      module copy                                   { header "__algorithm/copy.h" }
+      module count_if                               { header "__algorithm/count_if.h" }
+      module count                                  { header "__algorithm/count.h" }
+      module equal_range                            { header "__algorithm/equal_range.h" }
+      module equal                                  { header "__algorithm/equal.h" }
+      module fill_n                                 { header "__algorithm/fill_n.h" }
+      module fill                                   { header "__algorithm/fill.h" }
+      module find_end                               { header "__algorithm/find_end.h" }
+      module find_first_of                          { header "__algorithm/find_first_of.h" }
+      module find_if_not                            { header "__algorithm/find_if_not.h" }
+      module find_if                                { header "__algorithm/find_if.h" }
+      module find_segment_if                        { header "__algorithm/find_segment_if.h" }
+      module find                                   { header "__algorithm/find.h" }
+      module for_each_n                             { header "__algorithm/for_each_n.h" }
+      module for_each_n_segment                     { header "__algorithm/for_each_n_segment.h" }
+      module for_each_segment                       { header "__algorithm/for_each_segment.h" }
+      module for_each                               { header "__algorithm/for_each.h" }
+      module generate_n                             { header "__algorithm/generate_n.h" }
+      module generate                               { header "__algorithm/generate.h" }
+      module half_positive                          { header "__algorithm/half_positive.h" }
+      module in_found_result                        { header "__algorithm/in_found_result.h" }
+      module in_fun_result                          { header "__algorithm/in_fun_result.h" }
+      module in_in_out_result                       { header "__algorithm/in_in_out_result.h" }
+      module in_in_result                           { header "__algorithm/in_in_result.h" }
+      module in_out_out_result                      { header "__algorithm/in_out_out_result.h" }
+      module in_out_result                          { header "__algorithm/in_out_result.h" }
+      module includes                               { header "__algorithm/includes.h" }
+      module inplace_merge                          { header "__algorithm/inplace_merge.h" }
+      module is_heap_until                          { header "__algorithm/is_heap_until.h" }
+      module is_heap                                { header "__algorithm/is_heap.h" }
+      module is_partitioned                         { header "__algorithm/is_partitioned.h" }
+      module is_permutation                         { header "__algorithm/is_permutation.h" }
+      module is_sorted_until                        { header "__algorithm/is_sorted_until.h" }
+      module is_sorted                              { header "__algorithm/is_sorted.h" }
+      module iter_swap                              { header "__algorithm/iter_swap.h" }
+      module iterator_operations {
+        header "__algorithm/iterator_operations.h"
+        export std.iterator.advance
+        export std.iterator.distance
+        export std.iterator.iter_move
+        export std.iterator.iter_swap
+        export std.iterator.next
+        export std.iterator.prev
+      }
+      module lexicographical_compare_three_way      { header "__algorithm/lexicographical_compare_three_way.h" }
+      module lexicographical_compare                { header "__algorithm/lexicographical_compare.h" }
+      module lower_bound                            { header "__algorithm/lower_bound.h" }
+      module make_heap                              { header "__algorithm/make_heap.h" }
+      module make_projected                         { header "__algorithm/make_projected.h" }
+      module max_element                            { header "__algorithm/max_element.h" }
+      module max                                    { header "__algorithm/max.h" }
+      module merge                                  { header "__algorithm/merge.h" }
+      module min_element                            { header "__algorithm/min_element.h" }
+      module min_max_result                         { header "__algorithm/min_max_result.h" }
+      module min                                    { header "__algorithm/min.h" }
+      module minmax_element                         { header "__algorithm/minmax_element.h" }
+      module minmax {
+        header "__algorithm/minmax.h"
+        export std.utility.pair // return type
+      }
+      module mismatch {
+        header "__algorithm/mismatch.h"
+        export std.utility.pair // return type
+      }
+      module move_backward                          { header "__algorithm/move_backward.h" }
+      module move                                   { header "__algorithm/move.h" }
+      module next_permutation                       { header "__algorithm/next_permutation.h" }
+      module none_of                                { header "__algorithm/none_of.h" }
+      module nth_element                            { header "__algorithm/nth_element.h" }
+      module out_value_result                       { header "__algorithm/out_value_result.h" }
+      module partial_sort_copy                      { header "__algorithm/partial_sort_copy.h" }
+      module partial_sort                           { header "__algorithm/partial_sort.h" }
+      module partition_copy                         { header "__algorithm/partition_copy.h" }
+      module partition_point                        { header "__algorithm/partition_point.h" }
+      module partition                              { header "__algorithm/partition.h" }
+      module pop_heap                               { header "__algorithm/pop_heap.h" }
+      module prev_permutation                       { header "__algorithm/prev_permutation.h" }
+      module pstl                                   { header "__algorithm/pstl.h" }
+      module push_heap                              { header "__algorithm/push_heap.h" }
+      module radix_sort                             { header "__algorithm/radix_sort.h" }
+      module ranges_adjacent_find                   { header "__algorithm/ranges_adjacent_find.h" }
+      module ranges_all_of                          { header "__algorithm/ranges_all_of.h" }
+      module ranges_any_of                          { header "__algorithm/ranges_any_of.h" }
+      module ranges_binary_search {
+        header "__algorithm/ranges_binary_search.h"
+        export std.functional.ranges_operations
+      }
+      module ranges_clamp {
+        header "__algorithm/ranges_clamp.h"
+        export std.functional.ranges_operations
+      }
+      module ranges_contains_subrange {
+        header "__algorithm/ranges_contains_subrange.h"
+      }
+      module ranges_contains {
+        header "__algorithm/ranges_contains.h"
+      }
+      module ranges_copy_backward {
+        header "__algorithm/ranges_copy_backward.h"
+        export std.algorithm.in_out_result
+      }
+      module ranges_copy_if {
+        header "__algorithm/ranges_copy_if.h"
+        export std.algorithm.in_out_result
+      }
+      module ranges_copy_n {
+        header "__algorithm/ranges_copy_n.h"
+        export std.algorithm.in_out_result
+      }
+      module ranges_copy {
+        header "__algorithm/ranges_copy.h"
+        export std.algorithm.in_out_result
+      }
+      module ranges_count_if                        { header "__algorithm/ranges_count_if.h" }
+      module ranges_count                           { header "__algorithm/ranges_count.h" }
+      module ranges_ends_with                       { header "__algorithm/ranges_ends_with.h" }
+      module ranges_equal_range {
+        header "__algorithm/ranges_equal_range.h"
+        export std.functional.ranges_operations
+      }
+      module ranges_equal {
+        header "__algorithm/ranges_equal.h"
+        export std.functional.identity
+      }
+      module ranges_fill_n                          { header "__algorithm/ranges_fill_n.h" }
+      module ranges_fill                            { header "__algorithm/ranges_fill.h" }
+      module ranges_find_end {
+        header "__algorithm/ranges_find_end.h"
+        export std.ranges.subrange // return type
+      }
+      module ranges_find_first_of                   { header "__algorithm/ranges_find_first_of.h" }
+      module ranges_find_if_not                     { header "__algorithm/ranges_find_if_not.h" }
+      module ranges_find_if                         { header "__algorithm/ranges_find_if.h" }
+      module ranges_find_last {
+        header "__algorithm/ranges_find_last.h"
+        export std.ranges.subrange // return type
+      }
+      module ranges_find                            { header "__algorithm/ranges_find.h" }
+      module ranges_fold                            { header "__algorithm/ranges_fold.h" }
+      module ranges_for_each_n {
+        header "__algorithm/ranges_for_each_n.h"
+        export std.algorithm.in_fun_result
+      }
+      module ranges_for_each {
+        header "__algorithm/ranges_for_each.h"
+        export std.algorithm.in_fun_result
+      }
+      module ranges_generate_n {
+        header "__algorithm/ranges_generate_n.h"
+      }
+      module ranges_generate {
+        header "__algorithm/ranges_generate.h"
+      }
+      module ranges_includes {
+        header "__algorithm/ranges_includes.h"
+        export std.functional.ranges_operations
+      }
+      module ranges_inplace_merge {
+        header "__algorithm/ranges_inplace_merge.h"
+        export std.functional.ranges_operations
+      }
+      module ranges_is_heap_until {
+        header "__algorithm/ranges_is_heap_until.h"
+        export std.functional.ranges_operations
+      }
+      module ranges_is_heap {
+        header "__algorithm/ranges_is_heap.h"
+        export std.functional.ranges_operations
+      }
+      module ranges_is_partitioned {
+        header "__algorithm/ranges_is_partitioned.h"
+      }
+      module ranges_is_permutation {
+        header "__algorithm/ranges_is_permutation.h"
+      }
+      module ranges_is_sorted_until {
+        header "__algorithm/ranges_is_sorted_until.h"
+        export std.functional.ranges_operations
+      }
+      module ranges_is_sorted {
+        header "__algorithm/ranges_is_sorted.h"
+        export std.functional.ranges_operations
+      }
+      module ranges_iterator_concept {
+        header "__algorithm/ranges_iterator_concept.h"
+      }
+      module ranges_lexicographical_compare {
+        header "__algorithm/ranges_lexicographical_compare.h"
+        export std.functional.ranges_operations
+      }
+      module ranges_lower_bound {
+        header "__algorithm/ranges_lower_bound.h"
+        export std.functional.ranges_operations
+      }
+      module ranges_make_heap {
+        header "__algorithm/ranges_make_heap.h"
+        export std.functional.ranges_operations
+      }
+      module ranges_max_element {
+        header "__algorithm/ranges_max_element.h"
+        export std.functional.ranges_operations
+      }
+      module ranges_max {
+        header "__algorithm/ranges_max.h"
+        export std.functional.ranges_operations
+      }
+      module ranges_merge {
+        header "__algorithm/ranges_merge.h"
+        export std.functional.ranges_operations
+        export std.algorithm.in_in_out_result
+      }
+      module ranges_min_element {
+        header "__algorithm/ranges_min_element.h"
+        export std.functional.ranges_operations
+      }
+      module ranges_min {
+        header "__algorithm/ranges_min.h"
+        export std.functional.ranges_operations
+      }
+      module ranges_minmax_element {
+        header "__algorithm/ranges_minmax_element.h"
+        export std.functional.ranges_operations
+        export std.algorithm.min_max_result
+      }
+      module ranges_minmax {
+        header "__algorithm/ranges_minmax.h"
+        export std.functional.ranges_operations
+        export std.algorithm.min_max_result
+      }
+      module ranges_mismatch {
+        header "__algorithm/ranges_mismatch.h"
+        export std.algorithm.in_in_result
+      }
+      module ranges_move_backward {
+        header "__algorithm/ranges_move_backward.h"
+        export std.algorithm.in_out_result
+      }
+      module ranges_move {
+        header "__algorithm/ranges_move.h"
+        export std.algorithm.in_out_result
+      }
+      module ranges_next_permutation {
+        header "__algorithm/ranges_next_permutation.h"
+        export std.functional.ranges_operations
+        export std.algorithm.in_found_result
+      }
+      module ranges_none_of {
+        header "__algorithm/ranges_none_of.h"
+      }
+      module ranges_nth_element {
+        header "__algorithm/ranges_nth_element.h"
+        export std.functional.ranges_operations
+      }
+      module ranges_partial_sort_copy {
+        header "__algorithm/ranges_partial_sort_copy.h"
+        export std.functional.ranges_operations
+      }
+      module ranges_partial_sort {
+        header "__algorithm/ranges_partial_sort.h"
+        export std.functional.ranges_operations
+      }
+      module ranges_partition_copy {
+        header "__algorithm/ranges_partition_copy.h"
+        export std.algorithm.in_out_out_result
+      }
+      module ranges_partition_point {
+        header "__algorithm/ranges_partition_point.h"
+      }
+      module ranges_partition {
+        header "__algorithm/ranges_partition.h"
+        export std.ranges.subrange // return type
+      }
+      module ranges_pop_heap {
+        header "__algorithm/ranges_pop_heap.h"
+        export std.functional.ranges_operations
+      }
+      module ranges_prev_permutation {
+        header "__algorithm/ranges_prev_permutation.h"
+        export std.functional.ranges_operations
+        export std.algorithm.in_found_result
+      }
+      module ranges_push_heap {
+        header "__algorithm/ranges_push_heap.h"
+        export std.functional.ranges_operations
+      }
+      module ranges_remove_copy_if {
+        header "__algorithm/ranges_remove_copy_if.h"
+        export std.algorithm.in_out_result
+      }
+      module ranges_remove_copy {
+        header "__algorithm/ranges_remove_copy.h"
+        export std.algorithm.in_out_result
+      }
+      module ranges_remove_if {
+        header "__algorithm/ranges_remove_if.h"
+      }
+      module ranges_remove {
+        header "__algorithm/ranges_remove.h"
+        export std.ranges.subrange // return type
+      }
+      module ranges_replace_copy_if {
+        header "__algorithm/ranges_replace_copy_if.h"
+        export std.algorithm.in_out_result
+      }
+      module ranges_replace_copy {
+        header "__algorithm/ranges_replace_copy.h"
+        export std.algorithm.in_out_result
+      }
+      module ranges_replace_if {
+        header "__algorithm/ranges_replace_if.h"
+      }
+      module ranges_replace {
+        header "__algorithm/ranges_replace.h"
+      }
+      module ranges_reverse_copy {
+        header "__algorithm/ranges_reverse_copy.h"
+        export std.algorithm.in_out_result
+      }
+      module ranges_reverse {
+        header "__algorithm/ranges_reverse.h"
+      }
+      module ranges_rotate_copy {
+        header "__algorithm/ranges_rotate_copy.h"
+        export std.ranges.subrange // return type
+      }
+      module ranges_rotate                          { header "__algorithm/ranges_rotate.h" }
+      module ranges_sample                          { header "__algorithm/ranges_sample.h" }
+      module ranges_search_n {
+        header "__algorithm/ranges_search_n.h"
+        export std.ranges.subrange // return type
+      }
+      module ranges_search {
+        header "__algorithm/ranges_search.h"
+        export std.ranges.subrange // return type
+      }
+      module ranges_set_difference {
+        header "__algorithm/ranges_set_difference.h"
+        export std.functional.ranges_operations
+        export std.algorithm.in_out_result
+      }
+      module ranges_set_intersection {
+        header "__algorithm/ranges_set_intersection.h"
+        export std.functional.ranges_operations
+        export std.algorithm.in_in_out_result
+      }
+      module ranges_set_symmetric_difference {
+        header "__algorithm/ranges_set_symmetric_difference.h"
+        export std.functional.ranges_operations
+        export std.algorithm.in_in_out_result
+      }
+      module ranges_set_union {
+        header "__algorithm/ranges_set_union.h"
+        export std.functional.ranges_operations
+        export std.algorithm.in_in_out_result
+      }
+      module ranges_shuffle {
+        header "__algorithm/ranges_shuffle.h"
+      }
+      module ranges_sort_heap {
+        header "__algorithm/ranges_sort_heap.h"
+        export std.functional.ranges_operations
+      }
+      module ranges_sort {
+        header "__algorithm/ranges_sort.h"
+        export std.functional.ranges_operations
+        export std.algorithm.sort
+        export std.algorithm.make_projected
+      }
+      module ranges_stable_partition {
+        header "__algorithm/ranges_stable_partition.h"
+        export std.ranges.subrange // return type
+      }
+      module ranges_stable_sort {
+        header "__algorithm/ranges_stable_sort.h"
+        export std.functional.ranges_operations
+      }
+      module ranges_starts_with {
+        header "__algorithm/ranges_starts_with.h"
+      }
+      module ranges_swap_ranges {
+        header "__algorithm/ranges_swap_ranges.h"
+        export std.algorithm.in_in_result
+      }
+      module ranges_transform {
+        header "__algorithm/ranges_transform.h"
+        export std.algorithm.in_out_result
+        export std.algorithm.in_in_out_result
+      }
+      module ranges_unique_copy {
+        header "__algorithm/ranges_unique_copy.h"
+      }
+      module ranges_unique {
+        header "__algorithm/ranges_unique.h"
+      }
+      module ranges_upper_bound {
+        header "__algorithm/ranges_upper_bound.h"
+        export std.functional.ranges_operations
+      }
+      module remove_copy_if                         { header "__algorithm/remove_copy_if.h" }
+      module remove_copy                            { header "__algorithm/remove_copy.h" }
+      module remove_if                              { header "__algorithm/remove_if.h" }
+      module remove                                 { header "__algorithm/remove.h" }
+      module replace_copy_if                        { header "__algorithm/replace_copy_if.h" }
+      module replace_copy                           { header "__algorithm/replace_copy.h" }
+      module replace_if                             { header "__algorithm/replace_if.h" }
+      module replace                                { header "__algorithm/replace.h" }
+      module reverse_copy                           { header "__algorithm/reverse_copy.h" }
+      module reverse                                { header "__algorithm/reverse.h" }
+      module rotate_copy                            { header "__algorithm/rotate_copy.h" }
+      module rotate                                 { header "__algorithm/rotate.h" }
+      module sample                                 { header "__algorithm/sample.h" }
+      module search_n                               { header "__algorithm/search_n.h" }
+      module search                                 { header "__algorithm/search.h" }
+      module set_difference                         { header "__algorithm/set_difference.h" }
+      module set_intersection                       { header "__algorithm/set_intersection.h" }
+      module set_symmetric_difference               { header "__algorithm/set_symmetric_difference.h" }
+      module set_union                              { header "__algorithm/set_union.h" }
+      module shift_left                             { header "__algorithm/shift_left.h" }
+      module shift_right                            { header "__algorithm/shift_right.h" }
+      module shuffle                                { header "__algorithm/shuffle.h" }
+      module sift_down                              { header "__algorithm/sift_down.h" }
+      module simd_utils                             { header "__algorithm/simd_utils.h" }
+      module sort_heap                              { header "__algorithm/sort_heap.h" }
+      module sort                                   { header "__algorithm/sort.h" }
+      module stable_partition                       { header "__algorithm/stable_partition.h" }
+      module stable_sort {
+        header "__algorithm/stable_sort.h"
+        export std.memory.unique_temporary_buffer // TODO: Workaround for https://llvm.org/PR120108
+      }
+      module swap_ranges                            { header "__algorithm/swap_ranges.h" }
+      module three_way_comp_ref_type                { header "__algorithm/three_way_comp_ref_type.h" }
+      module transform                              { header "__algorithm/transform.h" }
+      module uniform_random_bit_generator_adaptor   { header "__algorithm/uniform_random_bit_generator_adaptor.h" }
+      module unique_copy                            { header "__algorithm/unique_copy.h" }
+      module unique                                 { header "__algorithm/unique.h" }
+      module unwrap_iter                            { header "__algorithm/unwrap_iter.h" }
+      module unwrap_range                           { header "__algorithm/unwrap_range.h" }
+      module upper_bound                            { header "__algorithm/upper_bound.h" }
     }
-    module swap_ranges                            { header "__algorithm/swap_ranges.h" }
-    module three_way_comp_ref_type                { header "__algorithm/three_way_comp_ref_type.h" }
-    module transform                              { header "__algorithm/transform.h" }
-    module uniform_random_bit_generator_adaptor   { header "__algorithm/uniform_random_bit_generator_adaptor.h" }
-    module unique_copy                            { header "__algorithm/unique_copy.h" }
-    module unique                                 { header "__algorithm/unique.h" }
-    module unwrap_iter                            { header "__algorithm/unwrap_iter.h" }
-    module unwrap_range                           { header "__algorithm/unwrap_range.h" }
-    module upper_bound                            { header "__algorithm/upper_bound.h" }
 
     header "algorithm"
     export *
@@ -863,7 +893,10 @@ module std [system] {
   }
 
   module array {
-    module fwd { header "__fwd/array.h" }
+    module cxx11 {
+      requires cplusplus11
+      module fwd { header "__fwd/array.h" }
+    }
 
     header "array"
     export *
@@ -871,29 +904,32 @@ module std [system] {
   }
 
   module atomic {
-    module aliases                { header "__atomic/aliases.h" }
-    module atomic_flag            { header "__atomic/atomic_flag.h" }
-    module atomic_init            { header "__atomic/atomic_init.h" }
-    module atomic_lock_free       { header "__atomic/atomic_lock_free.h" }
-    module atomic_ref             { header "__atomic/atomic_ref.h" }
-    module atomic_sync            { header "__atomic/atomic_sync.h" }
-    module atomic {
-      header "__atomic/atomic.h"
-      export std.atomic.atomic_base // most of std::atomic methods are defined there
-    }
-    module check_memory_order     { header "__atomic/check_memory_order.h" }
-    module contention_t           { header "__atomic/contention_t.h" }
-    module fence                  { header "__atomic/fence.h" }
-    module floating_point_helper  { header "__atomic/floating_point_helper.h" }
-    module is_always_lock_free    { header "__atomic/is_always_lock_free.h" }
-    module kill_dependency        { header "__atomic/kill_dependency.h" }
-    module memory_order           { header "__atomic/memory_order.h" }
-    module to_gcc_order           { header "__atomic/to_gcc_order.h" }
-
-    module support {
-      header "__atomic/support.h"
-      textual header "__atomic/support/c11.h"
-      textual header "__atomic/support/gcc.h"
+    module cxx11 {
+      requires cplusplus11
+      module aliases                { header "__atomic/aliases.h" }
+      module atomic_flag            { header "__atomic/atomic_flag.h" }
+      module atomic_init            { header "__atomic/atomic_init.h" }
+      module atomic_lock_free       { header "__atomic/atomic_lock_free.h" }
+      module atomic_ref             { header "__atomic/atomic_ref.h" }
+      module atomic_sync            { header "__atomic/atomic_sync.h" }
+      module atomic {
+        header "__atomic/atomic.h"
+        export std.atomic.atomic_base // most of std::atomic methods are defined there
+      }
+      module check_memory_order     { header "__atomic/check_memory_order.h" }
+      module contention_t           { header "__atomic/contention_t.h" }
+      module fence                  { header "__atomic/fence.h" }
+      module floating_point_helper  { header "__atomic/floating_point_helper.h" }
+      module is_always_lock_free    { header "__atomic/is_always_lock_free.h" }
+      module kill_dependency        { header "__atomic/kill_dependency.h" }
+      module memory_order           { header "__atomic/memory_order.h" }
+      module to_gcc_order           { header "__atomic/to_gcc_order.h" }
+
+      module support {
+        header "__atomic/support.h"
+        textual header "__atomic/support/c11.h"
+        textual header "__atomic/support/gcc.h"
+      }
     }
 
     header "atomic"
@@ -906,20 +942,23 @@ module std [system] {
   }
 
   module bit {
-    module bit_cast         { header "__bit/bit_cast.h" }
-    module bit_ceil         { header "__bit/bit_ceil.h" }
-    module bit_floor        { header "__bit/bit_floor.h" }
-    module bit_log2         { header "__bit/bit_log2.h" }
-    module bit_width        { header "__bit/bit_width.h" }
-    module blsr             { header "__bit/blsr.h" }
-    module byteswap         { header "__bit/byteswap.h" }
-    module countl           { header "__bit/countl.h" }
-    module countr           { header "__bit/countr.h" }
-    module endian           { header "__bit/endian.h" }
-    module has_single_bit   { header "__bit/has_single_bit.h" }
-    module invert_if        { header "__bit/invert_if.h" }
-    module popcount         { header "__bit/popcount.h" }
-    module rotate           { header "__bit/rotate.h" }
+    module cxx11 {
+      requires cplusplus11
+      module bit_cast         { header "__bit/bit_cast.h" }
+      module bit_ceil         { header "__bit/bit_ceil.h" }
+      module bit_floor        { header "__bit/bit_floor.h" }
+      module bit_log2         { header "__bit/bit_log2.h" }
+      module bit_width        { header "__bit/bit_width.h" }
+      module blsr             { header "__bit/blsr.h" }
+      module byteswap         { header "__bit/byteswap.h" }
+      module countl           { header "__bit/countl.h" }
+      module countr           { header "__bit/countr.h" }
+      module endian           { header "__bit/endian.h" }
+      module has_single_bit   { header "__bit/has_single_bit.h" }
+      module invert_if        { header "__bit/invert_if.h" }
+      module popcount         { header "__bit/popcount.h" }
+      module rotate           { header "__bit/rotate.h" }
+    }
 
     header "bit"
     export *
@@ -931,101 +970,107 @@ module std [system] {
   }
 
   module charconv {
-    module chars_format               { header "__charconv/chars_format.h" }
-    module from_chars_floating_point  { header "__charconv/from_chars_floating_point.h" }
-    module from_chars_integral        { header "__charconv/from_chars_integral.h" }
-    module from_chars_result          {
-      header "__charconv/from_chars_result.h"
-      export std.system_error.errc
-    }
-    module tables                     { header "__charconv/tables.h" }
-    module to_chars                   { header "__charconv/to_chars.h" }
-    module to_chars_base_10           { header "__charconv/to_chars_base_10.h" }
-    module to_chars_floating_point    { header "__charconv/to_chars_floating_point.h" }
-    module to_chars_integral          {
-      header "__charconv/to_chars_integral.h"
-      export std.charconv.to_chars_result
+    module cxx11 {
+      requires cplusplus11
+      module chars_format               { header "__charconv/chars_format.h" }
+      module from_chars_floating_point  { header "__charconv/from_chars_floating_point.h" }
+      module from_chars_integral        { header "__charconv/from_chars_integral.h" }
+      module from_chars_result          {
+        header "__charconv/from_chars_result.h"
+        export std.system_error.errc
+      }
+      module tables                     { header "__charconv/tables.h" }
+      module to_chars                   { header "__charconv/to_chars.h" }
+      module to_chars_base_10           { header "__charconv/to_chars_base_10.h" }
+      module to_chars_floating_point    { header "__charconv/to_chars_floating_point.h" }
+      module to_chars_integral          {
+        header "__charconv/to_chars_integral.h"
+        export std.charconv.to_chars_result
+      }
+      module to_chars_result            { header "__charconv/to_chars_result.h" }
+      module traits                     { header "__charconv/traits.h" }
     }
-    module to_chars_result            { header "__charconv/to_chars_result.h" }
-    module traits                     { header "__charconv/traits.h" }
 
     header "charconv"
     export *
   }
 
   module chrono {
-    module calendar                   { header "__chrono/calendar.h" }
-    module concepts                   { header "__chrono/concepts.h" }
-    module convert_to_timespec        { header "__chrono/convert_to_timespec.h" }
-    module convert_to_tm              { header "__chrono/convert_to_tm.h" }
-    module day                        { header "__chrono/day.h" }
-    module duration                   { header "__chrono/duration.h" }
-    module exception                  { header "__chrono/exception.h" }
-    module file_clock                 { header "__chrono/file_clock.h" }
-    module formatter                  { header "__chrono/formatter.h" }
-    module gps_clock {
-      header "__chrono/gps_clock.h"
-      export std.chrono.time_point
-    }
-    module hh_mm_ss                   { header "__chrono/hh_mm_ss.h" }
-    module high_resolution_clock {
-      header "__chrono/high_resolution_clock.h"
-      export *
-    }
-    module leap_second {
-      header "__chrono/leap_second.h"
-    }
-    module literals {
-      header "__chrono/literals.h"
-    }
-    module local_info {
-      header "__chrono/local_info.h"
-      export std.chrono.sys_info
-    }
-    module month_weekday              { header "__chrono/month_weekday.h" }
-    module month                      { header "__chrono/month.h" }
-    module monthday                   { header "__chrono/monthday.h" }
-    module ostream                    { header "__chrono/ostream.h" }
-    module parser_std_format_spec     { header "__chrono/parser_std_format_spec.h" }
-    module statically_widen           { header "__chrono/statically_widen.h" }
-    module steady_clock {
-      header "__chrono/steady_clock.h"
-      export std.chrono.time_point
-    }
-    module sys_info {
-      header "__chrono/sys_info.h"
-    }
-    module system_clock {
-      header "__chrono/system_clock.h"
-      export std.chrono.time_point
-    }
-    module tai_clock {
-      header "__chrono/tai_clock.h"
-      export std.chrono.time_point
-    }
-    module time_point                 { header "__chrono/time_point.h" }
-    module time_zone_link             { header "__chrono/time_zone_link.h" }
-    module time_zone                  { header "__chrono/time_zone.h" }
-    module tzdb_list {
-      header "__chrono/tzdb_list.h"
-      export std.forward_list // forward_list iterators are used to implement this API
-      export std.string_view // by-value argument of type std::string_view
-    }
-    module tzdb {
-      header "__chrono/tzdb.h"
-      export std.string // public data member of type std::string
-      export std.vector // public data members of type std::vector
-    }
-    module utc_clock {
-      header "__chrono/utc_clock.h"
-      export std.chrono.time_point
+    module cxx11 {
+      requires cplusplus11
+      module calendar                   { header "__chrono/calendar.h" }
+      module concepts                   { header "__chrono/concepts.h" }
+      module convert_to_timespec        { header "__chrono/convert_to_timespec.h" }
+      module convert_to_tm              { header "__chrono/convert_to_tm.h" }
+      module day                        { header "__chrono/day.h" }
+      module duration                   { header "__chrono/duration.h" }
+      module exception                  { header "__chrono/exception.h" }
+      module file_clock                 { header "__chrono/file_clock.h" }
+      module formatter                  { header "__chrono/formatter.h" }
+      module gps_clock {
+        header "__chrono/gps_clock.h"
+        export std.chrono.time_point
+      }
+      module hh_mm_ss                   { header "__chrono/hh_mm_ss.h" }
+      module high_resolution_clock {
+        header "__chrono/high_resolution_clock.h"
+        export *
+      }
+      module leap_second {
+        header "__chrono/leap_second.h"
+      }
+      module literals {
+        header "__chrono/literals.h"
+      }
+      module local_info {
+        header "__chrono/local_info.h"
+        export std.chrono.sys_info
+      }
+      module month_weekday              { header "__chrono/month_weekday.h" }
+      module month                      { header "__chrono/month.h" }
+      module monthday                   { header "__chrono/monthday.h" }
+      module ostream                    { header "__chrono/ostream.h" }
+      module parser_std_format_spec     { header "__chrono/parser_std_format_spec.h" }
+      module statically_widen           { header "__chrono/statically_widen.h" }
+      module steady_clock {
+        header "__chrono/steady_clock.h"
+        export std.chrono.time_point
+      }
+      module sys_info {
+        header "__chrono/sys_info.h"
+      }
+      module system_clock {
+        header "__chrono/system_clock.h"
+        export std.chrono.time_point
+      }
+      module tai_clock {
+        header "__chrono/tai_clock.h"
+        export std.chrono.time_point
+      }
+      module time_point                 { header "__chrono/time_point.h" }
+      module time_zone_link             { header "__chrono/time_zone_link.h" }
+      module time_zone                  { header "__chrono/time_zone.h" }
+      module tzdb_list {
+        header "__chrono/tzdb_list.h"
+        export std.forward_list // forward_list iterators are used to implement this API
+        export std.string_view // by-value argument of type std::string_view
+      }
+      module tzdb {
+        header "__chrono/tzdb.h"
+        export std.string // public data member of type std::string
+        export std.vector // public data members of type std::vector
+      }
+      module utc_clock {
+        header "__chrono/utc_clock.h"
+        export std.chrono.time_point
+      }
+      module weekday                    { header "__chrono/weekday.h" }
+      module year_month_day             { header "__chrono/year_month_day.h" }
+      module year_month_weekday         { header "__chrono/year_month_weekday.h" }
+      module year_month                 { header "__chrono/year_month.h" }
+      module year                       { header "__chrono/year.h" }
+      module zoned_time                 { header "__chrono/zoned_time.h" }
     }
-    module weekday                    { header "__chrono/weekday.h" }
-    module year_month_day             { header "__chrono/year_month_day.h" }
-    module year_month_weekday         { header "__chrono/year_month_weekday.h" }
-    module year_month                 { header "__chrono/year_month.h" }
-    module year                       { header "__chrono/year.h" }
-    module zoned_time                 { header "__chrono/zoned_time.h" }
 
     header "chrono"
     export *
@@ -1037,61 +1082,73 @@ module std [system] {
   }
 
   module compare {
-    module common_comparison_category       { header "__compare/common_comparison_category.h" }
-    module compare_partial_order_fallback   { header "__compare/compare_partial_order_fallback.h" }
-    module compare_strong_order_fallback    { header "__compare/compare_strong_order_fallback.h" }
-    module compare_three_way                { header "__compare/compare_three_way.h" }
-    module compare_three_way_result         { header "__compare/compare_three_way_result.h" }
-    module compare_weak_order_fallback      { header "__compare/compare_weak_order_fallback.h" }
-    module is_eq                            { header "__compare/is_eq.h" }
-    module ordering                         { header "__compare/ordering.h" }
-    module partial_order                    { header "__compare/partial_order.h" }
-    module strong_order                     { header "__compare/strong_order.h" }
-    module synth_three_way                  { header "__compare/synth_three_way.h" }
-    module three_way_comparable             { header "__compare/three_way_comparable.h" }
-    module weak_order                       { header "__compare/weak_order.h" }
+    module cxx11 {
+      requires cplusplus11
+      module common_comparison_category       { header "__compare/common_comparison_category.h" }
+      module compare_partial_order_fallback   { header "__compare/compare_partial_order_fallback.h" }
+      module compare_strong_order_fallback    { header "__compare/compare_strong_order_fallback.h" }
+      module compare_three_way                { header "__compare/compare_three_way.h" }
+      module compare_three_way_result         { header "__compare/compare_three_way_result.h" }
+      module compare_weak_order_fallback      { header "__compare/compare_weak_order_fallback.h" }
+      module is_eq                            { header "__compare/is_eq.h" }
+      module ordering                         { header "__compare/ordering.h" }
+      module partial_order                    { header "__compare/partial_order.h" }
+      module strong_order                     { header "__compare/strong_order.h" }
+      module synth_three_way                  { header "__compare/synth_three_way.h" }
+      module three_way_comparable             { header "__compare/three_way_comparable.h" }
+      module weak_order                       { header "__compare/weak_order.h" }
+    }
 
     header "compare"
     export *
   }
 
   module complex {
-    module fwd { header "__fwd/complex.h" }
+    module cxx11 {
+      requires cplusplus11
+      module fwd { header "__fwd/complex.h" }
+    }
 
     header "complex"
     export *
   }
 
   module concepts {
-    module arithmetic               { header "__concepts/arithmetic.h" }
-    module assignable               { header "__concepts/assignable.h" }
-    module boolean_testable         { header "__concepts/boolean_testable.h" }
-    module class_or_enum            { header "__concepts/class_or_enum.h" }
-    module common_reference_with    { header "__concepts/common_reference_with.h" }
-    module common_with              { header "__concepts/common_with.h" }
-    module constructible            { header "__concepts/constructible.h" }
-    module convertible_to           { header "__concepts/convertible_to.h" }
-    module copyable                 { header "__concepts/copyable.h" }
-    module derived_from             { header "__concepts/derived_from.h" }
-    module destructible             { header "__concepts/destructible.h" }
-    module different_from           { header "__concepts/different_from.h" }
-    module equality_comparable      { header "__concepts/equality_comparable.h" }
-    module invocable                { header "__concepts/invocable.h" }
-    module movable                  { header "__concepts/movable.h" }
-    module predicate                { header "__concepts/predicate.h" }
-    module regular                  { header "__concepts/regular.h" }
-    module relation                 { header "__concepts/relation.h" }
-    module same_as                  { header "__concepts/same_as.h" }
-    module semiregular              { header "__concepts/semiregular.h" }
-    module swappable                { header "__concepts/swappable.h" }
-    module totally_ordered          { header "__concepts/totally_ordered.h" }
+    module cxx11 {
+      requires cplusplus11
+      module arithmetic               { header "__concepts/arithmetic.h" }
+      module assignable               { header "__concepts/assignable.h" }
+      module boolean_testable         { header "__concepts/boolean_testable.h" }
+      module class_or_enum            { header "__concepts/class_or_enum.h" }
+      module common_reference_with    { header "__concepts/common_reference_with.h" }
+      module common_with              { header "__concepts/common_with.h" }
+      module constructible            { header "__concepts/constructible.h" }
+      module convertible_to           { header "__concepts/convertible_to.h" }
+      module copyable                 { header "__concepts/copyable.h" }
+      module derived_from             { header "__concepts/derived_from.h" }
+      module destructible             { header "__concepts/destructible.h" }
+      module different_from           { header "__concepts/different_from.h" }
+      module equality_comparable      { header "__concepts/equality_comparable.h" }
+      module invocable                { header "__concepts/invocable.h" }
+      module movable                  { header "__concepts/movable.h" }
+      module predicate                { header "__concepts/predicate.h" }
+      module regular                  { header "__concepts/regular.h" }
+      module relation                 { header "__concepts/relation.h" }
+      module same_as                  { header "__concepts/same_as.h" }
+      module semiregular              { header "__concepts/semiregular.h" }
+      module swappable                { header "__concepts/swappable.h" }
+      module totally_ordered          { header "__concepts/totally_ordered.h" }
+    }
 
     header "concepts"
     export *
   }
 
   module condition_variable {
-    module condition_variable   { header "__condition_variable/condition_variable.h" }
+    module cxx11 {
+      requires cplusplus11
+      module condition_variable   { header "__condition_variable/condition_variable.h" }
+    }
 
     header "condition_variable"
     export *
@@ -1222,7 +1279,10 @@ module std [system] {
   }
 
   module deque {
-    module fwd { header "__fwd/deque.h" }
+    module cxx11 {
+      requires cplusplus11
+      module fwd { header "__fwd/deque.h" }
+    }
 
     header "deque"
     export *
@@ -1231,11 +1291,14 @@ module std [system] {
   }
 
   module exception {
-    module exception          { header "__exception/exception.h" }
-    module exception_ptr      { header "__exception/exception_ptr.h" }
-    module nested_exception   { header "__exception/nested_exception.h" }
-    module operations         { header "__exception/operations.h" }
-    module terminate          { header "__exception/terminate.h" }
+    module cxx11 {
+      requires cplusplus11
+      module exception          { header "__exception/exception.h" }
+      module exception_ptr      { header "__exception/exception_ptr.h" }
+      module nested_exception   { header "__exception/nested_exception.h" }
+      module operations         { header "__exception/operations.h" }
+      module terminate          { header "__exception/terminate.h" }
+    }
 
     header "exception"
     export *
@@ -1247,59 +1310,68 @@ module std [system] {
   }
 
   module expected {
-    module bad_expected_access    { header "__expected/bad_expected_access.h" }
-    module expected               { header "__expected/expected.h" }
-    module unexpect               { header "__expected/unexpect.h" }
-    module unexpected             { header "__expected/unexpected.h" }
+    module cxx11 {
+      requires cplusplus11
+      module bad_expected_access    { header "__expected/bad_expected_access.h" }
+      module expected               { header "__expected/expected.h" }
+      module unexpect               { header "__expected/unexpect.h" }
+      module unexpected             { header "__expected/unexpected.h" }
+    }
 
     header "expected"
     export *
   }
 
   module filesystem {
-    module copy_options                   { header "__filesystem/copy_options.h" }
-    module directory_entry                { header "__filesystem/directory_entry.h" }
-    module directory_iterator             {
-      header "__filesystem/directory_iterator.h"
-      // This is a workaround for https://llvm.org/PR120108.
-      export *
-    }
-    module directory_options              { header "__filesystem/directory_options.h" }
-    module file_status                    { header "__filesystem/file_status.h" }
-    module file_time_type                 { header "__filesystem/file_time_type.h" }
-    module file_type                      { header "__filesystem/file_type.h" }
-    module filesystem_error               { header "__filesystem/filesystem_error.h" }
-    module operations                     { header "__filesystem/operations.h" }
-    module path_iterator                  { header "__filesystem/path_iterator.h" }
-    module path                           {
-      header "__filesystem/path.h"
-      export std.string // returned by various methods of filesystem::path
+    module cxx11 {
+      requires cplusplus11
+      module copy_options                   { header "__filesystem/copy_options.h" }
+      module directory_entry                { header "__filesystem/directory_entry.h" }
+      module directory_iterator             {
+        header "__filesystem/directory_iterator.h"
+        // This is a workaround for https://llvm.org/PR120108.
+        export *
+      }
+      module directory_options              { header "__filesystem/directory_options.h" }
+      module file_status                    { header "__filesystem/file_status.h" }
+      module file_time_type                 { header "__filesystem/file_time_type.h" }
+      module file_type                      { header "__filesystem/file_type.h" }
+      module filesystem_error               { header "__filesystem/filesystem_error.h" }
+      module operations                     { header "__filesystem/operations.h" }
+      module path_iterator                  { header "__filesystem/path_iterator.h" }
+      module path                           {
+        header "__filesystem/path.h"
+        export std.string // returned by various methods of filesystem::path
+      }
+      module perm_options                   { header "__filesystem/perm_options.h" }
+      module perms                          { header "__filesystem/perms.h" }
+      module recursive_directory_iterator   { header "__filesystem/recursive_directory_iterator.h" }
+      module space_info                     { header "__filesystem/space_info.h" }
+      module u8path                         { header "__filesystem/u8path.h" }
     }
-    module perm_options                   { header "__filesystem/perm_options.h" }
-    module perms                          { header "__filesystem/perms.h" }
-    module recursive_directory_iterator   { header "__filesystem/recursive_directory_iterator.h" }
-    module space_info                     { header "__filesystem/space_info.h" }
-    module u8path                         { header "__filesystem/u8path.h" }
 
     header "filesystem"
     export *
   }
 
   module flat_map {
-    module flat_map                       {
-      header "__flat_map/flat_map.h"
-      export std.vector.vector
-      export std.vector.fwd
-    }
-    module flat_multimap                  {
-      header "__flat_map/flat_multimap.h"
-      export std.vector.vector
-      export std.vector.fwd
+    module cxx11 {
+      requires cplusplus11
+      module flat_map                       {
+        header "__flat_map/flat_map.h"
+        export std.vector.vector
+        export std.vector.fwd
+      }
+      module flat_multimap                  {
+        header "__flat_map/flat_multimap.h"
+        export std.vector.vector
+        export std.vector.fwd
+      }
+      module key_value_iterator             { header "__flat_map/key_value_iterator.h" }
+      module sorted_equivalent              { header "__flat_map/sorted_equivalent.h" }
+      module sorted_unique                  { header "__flat_map/sorted_unique.h" }
+      module utils                          { header "__flat_map/utils.h" }
     }
-    module key_value_iterator             { header "__flat_map/key_value_iterator.h" }
-    module sorted_equivalent              { header "__flat_map/sorted_equivalent.h" }
-    module sorted_unique                  { header "__flat_map/sorted_unique.h" }
-    module utils                          { header "__flat_map/utils.h" }
 
     header "flat_map"
     export *
@@ -1310,14 +1382,17 @@ module std [system] {
   }
 
   module flat_set {
-    module flat_set                       {
-      header "__flat_set/flat_set.h"
-      header "__flat_set/flat_multiset.h"
-      export std.vector.vector
-      export std.vector.fwd
+    module cxx11 {
+      requires cplusplus11
+      module flat_set                       {
+        header "__flat_set/flat_set.h"
+        header "__flat_set/flat_multiset.h"
+        export std.vector.vector
+        export std.vector.fwd
+      }
+      module ra_iterator                    { header "__flat_set/ra_iterator.h" }
+      module utils                          { header "__flat_set/utils.h" }
     }
-    module ra_iterator                    { header "__flat_set/ra_iterator.h" }
-    module utils                          { header "__flat_set/utils.h" }
 
     header "flat_set"
     export std.flat_map.sorted_unique
@@ -1330,52 +1405,55 @@ module std [system] {
   }
 
   module format {
-    module buffer                             {
-      header "__format/buffer.h"
-      export std.iterator.back_insert_iterator
-    }
-    module concepts                           { header "__format/concepts.h" }
-    module container_adaptor                  { header "__format/container_adaptor.h" }
-    module enable_insertable                  { header "__format/enable_insertable.h" }
-    module escaped_output_table               { header "__format/escaped_output_table.h" }
-    module extended_grapheme_cluster_table    { header "__format/extended_grapheme_cluster_table.h" }
-    module fmt_pair_like                      { header "__format/fmt_pair_like.h" }
-    module format_arg                         { header "__format/format_arg.h" }
-    module format_arg_store                   { header "__format/format_arg_store.h" }
-    module format_args                        { header "__format/format_args.h" }
-    module format_context {
-      header "__format/format_context.h"
-      export std.optional // default argument for __format_context_create
-    }
-    module format_error {
-      header "__format/format_error.h"
-    }
-    module format_functions {
-      header "__format/format_functions.h"
-      export std.string // returned by the functions in that header
+    module cxx11 {
+      requires cplusplus11
+      module buffer                             {
+        header "__format/buffer.h"
+        export std.iterator.back_insert_iterator
+      }
+      module concepts                           { header "__format/concepts.h" }
+      module container_adaptor                  { header "__format/container_adaptor.h" }
+      module enable_insertable                  { header "__format/enable_insertable.h" }
+      module escaped_output_table               { header "__format/escaped_output_table.h" }
+      module extended_grapheme_cluster_table    { header "__format/extended_grapheme_cluster_table.h" }
+      module fmt_pair_like                      { header "__format/fmt_pair_like.h" }
+      module format_arg                         { header "__format/format_arg.h" }
+      module format_arg_store                   { header "__format/format_arg_store.h" }
+      module format_args                        { header "__format/format_args.h" }
+      module format_context {
+        header "__format/format_context.h"
+        export std.optional // default argument for __format_context_create
+      }
+      module format_error {
+        header "__format/format_error.h"
+      }
+      module format_functions {
+        header "__format/format_functions.h"
+        export std.string // returned by the functions in that header
+      }
+      module format_parse_context               { header "__format/format_parse_context.h" }
+      module format_string                      { header "__format/format_string.h" }
+      module format_to_n_result                 { header "__format/format_to_n_result.h" }
+      module formatter                          { header "__format/formatter.h" }
+      module formatter_bool                     { header "__format/formatter_bool.h" }
+      module formatter_char                     { header "__format/formatter_char.h" }
+      module formatter_floating_point           { header "__format/formatter_floating_point.h" }
+      module formatter_integer                  { header "__format/formatter_integer.h" }
+      module formatter_integral                 { header "__format/formatter_integral.h" }
+      module formatter_output                   { header "__format/formatter_output.h" }
+      module formatter_pointer                  { header "__format/formatter_pointer.h" }
+      module formatter_string                   { header "__format/formatter_string.h" }
+      module formatter_tuple                    { header "__format/formatter_tuple.h" }
+      module fwd                                { header "__fwd/format.h" }
+      module indic_conjunct_break_table         { header "__format/indic_conjunct_break_table.h" }
+      module parser_std_format_spec             { header "__format/parser_std_format_spec.h" }
+      module range_default_formatter            { header "__format/range_default_formatter.h" }
+      module range_format                       { header "__format/range_format.h" }
+      module range_formatter                    { header "__format/range_formatter.h" }
+      module unicode                            { header "__format/unicode.h" }
+      module width_estimation_table             { header "__format/width_estimation_table.h" }
+      module write_escaped                      { header "__format/write_escaped.h" }
     }
-    module format_parse_context               { header "__format/format_parse_context.h" }
-    module format_string                      { header "__format/format_string.h" }
-    module format_to_n_result                 { header "__format/format_to_n_result.h" }
-    module formatter                          { header "__format/formatter.h" }
-    module formatter_bool                     { header "__format/formatter_bool.h" }
-    module formatter_char                     { header "__format/formatter_char.h" }
-    module formatter_floating_point           { header "__format/formatter_floating_point.h" }
-    module formatter_integer                  { header "__format/formatter_integer.h" }
-    module formatter_integral                 { header "__format/formatter_integral.h" }
-    module formatter_output                   { header "__format/formatter_output.h" }
-    module formatter_pointer                  { header "__format/formatter_pointer.h" }
-    module formatter_string                   { header "__format/formatter_string.h" }
-    module formatter_tuple                    { header "__format/formatter_tuple.h" }
-    module fwd                                { header "__fwd/format.h" }
-    module indic_conjunct_break_table         { header "__format/indic_conjunct_break_table.h" }
-    module parser_std_format_spec             { header "__format/parser_std_format_spec.h" }
-    module range_default_formatter            { header "__format/range_default_formatter.h" }
-    module range_format                       { header "__format/range_format.h" }
-    module range_formatter                    { header "__format/range_formatter.h" }
-    module unicode                            { header "__format/unicode.h" }
-    module width_estimation_table             { header "__format/width_estimation_table.h" }
-    module write_escaped                      { header "__format/write_escaped.h" }
 
     header "format"
     export *
@@ -1388,61 +1466,67 @@ module std [system] {
   }
 
   module fstream {
-    module fwd { header "__fwd/fstream.h" }
+    module cxx11 {
+      requires cplusplus11
+      module fwd { header "__fwd/fstream.h" }
+    }
 
     header "fstream"
     export *
   }
 
   module functional {
-    module binary_function              { header "__functional/binary_function.h" }
-    module binary_negate                { header "__functional/binary_negate.h" }
-    module bind_back {
-      header "__functional/bind_back.h"
-      export std.functional.perfect_forward // inherited from and using its operators
-    }
-    module bind_front {
-      header "__functional/bind_front.h"
-      export std.functional.perfect_forward // inherited from and using its operators
-    }
-    module bind                         { header "__functional/bind.h" }
-    module binder1st                    { header "__functional/binder1st.h" }
-    module binder2nd                    { header "__functional/binder2nd.h" }
-    module boyer_moore_searcher {
-      header "__functional/boyer_moore_searcher.h"
-      export std.memory.shared_ptr
-    }
-    module compose {
-      header "__functional/compose.h"
-      export std.functional.perfect_forward // inherited from and using its operators
-    }
-    module default_searcher             { header "__functional/default_searcher.h" }
-    module function                     { header "__functional/function.h" }
-    module hash                         { header "__functional/hash.h" }
-    module identity                     { header "__functional/identity.h" }
-    module invoke                       { header "__functional/invoke.h" }
-    module is_transparent               { header "__functional/is_transparent.h" }
-    module mem_fn                       { header "__functional/mem_fn.h" }
-    module mem_fun_ref                  { header "__functional/mem_fun_ref.h" }
-    module not_fn {
-      header "__functional/not_fn.h"
-      export std.functional.perfect_forward // inherited from and using its operators
-    }
-    module operations {
-      header "__functional/operations.h"
-      export std_core.fwd.functional
-    }
-    module perfect_forward {
-      header "__functional/perfect_forward.h"
-      export std.tuple
+    module cxx11 {
+      requires cplusplus11
+      module binary_function              { header "__functional/binary_function.h" }
+      module binary_negate                { header "__functional/binary_negate.h" }
+      module bind_back {
+        header "__functional/bind_back.h"
+        export std.functional.perfect_forward // inherited from and using its operators
+      }
+      module bind_front {
+        header "__functional/bind_front.h"
+        export std.functional.perfect_forward // inherited from and using its operators
+      }
+      module bind                         { header "__functional/bind.h" }
+      module binder1st                    { header "__functional/binder1st.h" }
+      module binder2nd                    { header "__functional/binder2nd.h" }
+      module boyer_moore_searcher {
+        header "__functional/boyer_moore_searcher.h"
+        export std.memory.shared_ptr
+      }
+      module compose {
+        header "__functional/compose.h"
+        export std.functional.perfect_forward // inherited from and using its operators
+      }
+      module default_searcher             { header "__functional/default_searcher.h" }
+      module function                     { header "__functional/function.h" }
+      module hash                         { header "__functional/hash.h" }
+      module identity                     { header "__functional/identity.h" }
+      module invoke                       { header "__functional/invoke.h" }
+      module is_transparent               { header "__functional/is_transparent.h" }
+      module mem_fn                       { header "__functional/mem_fn.h" }
+      module mem_fun_ref                  { header "__functional/mem_fun_ref.h" }
+      module not_fn {
+        header "__functional/not_fn.h"
+        export std.functional.perfect_forward // inherited from and using its operators
+      }
+      module operations {
+        header "__functional/operations.h"
+        export std_core.fwd.functional
+      }
+      module perfect_forward {
+        header "__functional/perfect_forward.h"
+        export std.tuple
+      }
+      module pointer_to_binary_function   { header "__functional/pointer_to_binary_function.h" }
+      module pointer_to_unary_function    { header "__functional/pointer_to_unary_function.h" }
+      module ranges_operations            { header "__functional/ranges_operations.h" }
+      module reference_wrapper            { header "__functional/reference_wrapper.h" }
+      module unary_function               { header "__functional/unary_function.h" }
+      module unary_negate                 { header "__functional/unary_negate.h" }
+      module weak_result_type             { header "__functional/weak_result_type.h" }
     }
-    module pointer_to_binary_function   { header "__functional/pointer_to_binary_function.h" }
-    module pointer_to_unary_function    { header "__functional/pointer_to_unary_function.h" }
-    module ranges_operations            { header "__functional/ranges_operations.h" }
-    module reference_wrapper            { header "__functional/reference_wrapper.h" }
-    module unary_function               { header "__functional/unary_function.h" }
-    module unary_negate                 { header "__functional/unary_negate.h" }
-    module weak_result_type             { header "__functional/weak_result_type.h" }
 
     header "functional"
     export *
@@ -1464,8 +1548,11 @@ module std [system] {
   }
 
   module ios {
-    module fwd  { header "__fwd/ios.h" }
-    module fpos { header "__ios/fpos.h" }
+    module cxx11 {
+      requires cplusplus11
+      module fwd  { header "__fwd/ios.h" }
+      module fpos { header "__ios/fpos.h" }
+    }
 
     header "ios"
     export *
@@ -1482,71 +1569,77 @@ module std [system] {
   }
 
   module istream {
-    module fwd { header "__fwd/istream.h" }
+    module cxx11 {
+      requires cplusplus11
+      module fwd { header "__fwd/istream.h" }
+    }
 
     header "istream"
     export std.ios // base class
   }
 
   module iterator {
-    module access                     { header "__iterator/access.h" }
-    module advance                    { header "__iterator/advance.h" }
-    module aliasing_iterator          { header "__iterator/aliasing_iterator.h" }
-    module back_insert_iterator       { header "__iterator/back_insert_iterator.h" }
-    module bounded_iter               { header "__iterator/bounded_iter.h" }
-    module common_iterator            { header "__iterator/common_iterator.h" }
-    module concepts {
-      header "__iterator/concepts.h"
-      export std_core.type_traits.common_reference
-    }
-    module counted_iterator           { header "__iterator/counted_iterator.h" }
-    module cpp17_iterator_concepts    { header "__iterator/cpp17_iterator_concepts.h" }
-    module data                       { header "__iterator/data.h" }
-    module default_sentinel           { header "__iterator/default_sentinel.h" }
-    module distance                   { header "__iterator/distance.h" }
-    module empty                      { header "__iterator/empty.h" }
-    module erase_if_container         { header "__iterator/erase_if_container.h" }
-    module front_insert_iterator      { header "__iterator/front_insert_iterator.h" }
-    module incrementable_traits       { header "__iterator/incrementable_traits.h" }
-    module indirectly_comparable      { header "__iterator/indirectly_comparable.h" }
-    module insert_iterator            { header "__iterator/insert_iterator.h" }
-    module istream_iterator           { header "__iterator/istream_iterator.h" }
-    module istreambuf_iterator        {
-      header "__iterator/istreambuf_iterator.h"
-      export std.string.char_traits
-    }
-    module iter_move                  { header "__iterator/iter_move.h" }
-    module iter_swap                  { header "__iterator/iter_swap.h" }
-    module iterator_traits {
-      header "__iterator/iterator_traits.h"
-      export std_core.type_traits.integral_constant
-      export std_core.type_traits.is_convertible
-    }
-    module iterator_with_data         { header "__iterator/iterator_with_data.h" }
-    module iterator                   { header "__iterator/iterator.h" }
-    module mergeable                  { header "__iterator/mergeable.h" }
-    module move_iterator              { header "__iterator/move_iterator.h" }
-    module move_sentinel              { header "__iterator/move_sentinel.h" }
-    module next                       { header "__iterator/next.h" }
-    module ostream_iterator           { header "__iterator/ostream_iterator.h" }
-    module ostreambuf_iterator {
-      header "__iterator/ostreambuf_iterator.h"
-      export iosfwd // for default template argument of ostreambuf_iterator
+    module cxx11 {
+      requires cplusplus11
+      module access                     { header "__iterator/access.h" }
+      module advance                    { header "__iterator/advance.h" }
+      module aliasing_iterator          { header "__iterator/aliasing_iterator.h" }
+      module back_insert_iterator       { header "__iterator/back_insert_iterator.h" }
+      module bounded_iter               { header "__iterator/bounded_iter.h" }
+      module common_iterator            { header "__iterator/common_iterator.h" }
+      module concepts {
+        header "__iterator/concepts.h"
+        export std_core.type_traits.common_reference
+      }
+      module counted_iterator           { header "__iterator/counted_iterator.h" }
+      module cpp17_iterator_concepts    { header "__iterator/cpp17_iterator_concepts.h" }
+      module data                       { header "__iterator/data.h" }
+      module default_sentinel           { header "__iterator/default_sentinel.h" }
+      module distance                   { header "__iterator/distance.h" }
+      module empty                      { header "__iterator/empty.h" }
+      module erase_if_container         { header "__iterator/erase_if_container.h" }
+      module front_insert_iterator      { header "__iterator/front_insert_iterator.h" }
+      module incrementable_traits       { header "__iterator/incrementable_traits.h" }
+      module indirectly_comparable      { header "__iterator/indirectly_comparable.h" }
+      module insert_iterator            { header "__iterator/insert_iterator.h" }
+      module istream_iterator           { header "__iterator/istream_iterator.h" }
+      module istreambuf_iterator        {
+        header "__iterator/istreambuf_iterator.h"
+        export std.string.char_traits
+      }
+      module iter_move                  { header "__iterator/iter_move.h" }
+      module iter_swap                  { header "__iterator/iter_swap.h" }
+      module iterator_traits {
+        header "__iterator/iterator_traits.h"
+        export std_core.type_traits.integral_constant
+        export std_core.type_traits.is_convertible
+      }
+      module iterator_with_data         { header "__iterator/iterator_with_data.h" }
+      module iterator                   { header "__iterator/iterator.h" }
+      module mergeable                  { header "__iterator/mergeable.h" }
+      module move_iterator              { header "__iterator/move_iterator.h" }
+      module move_sentinel              { header "__iterator/move_sentinel.h" }
+      module next                       { header "__iterator/next.h" }
+      module ostream_iterator           { header "__iterator/ostream_iterator.h" }
+      module ostreambuf_iterator {
+        header "__iterator/ostreambuf_iterator.h"
+        export iosfwd // for default template argument of ostreambuf_iterator
+      }
+      module permutable                 { header "__iterator/permutable.h" }
+      module prev                       { header "__iterator/prev.h" }
+      module product_iterator           { header "__iterator/product_iterator.h" }
+      module projected                  { header "__iterator/projected.h" }
+      module ranges_iterator_traits     { header "__iterator/ranges_iterator_traits.h" }
+      module readable_traits            { header "__iterator/readable_traits.h" }
+      module reverse_access             { header "__iterator/reverse_access.h" }
+      module reverse_iterator           { header "__iterator/reverse_iterator.h" }
+      module segmented_iterator         { header "__iterator/segmented_iterator.h" }
+      module size                       { header "__iterator/size.h" }
+      module sortable                   { header "__iterator/sortable.h" }
+      module static_bounded_iter        { header "__iterator/static_bounded_iter.h" }
+      module unreachable_sentinel       { header "__iterator/unreachable_sentinel.h" }
+      module wrap_iter                  { header "__iterator/wrap_iter.h" }
     }
-    module permutable                 { header "__iterator/permutable.h" }
-    module prev                       { header "__iterator/prev.h" }
-    module product_iterator           { header "__iterator/product_iterator.h" }
-    module projected                  { header "__iterator/projected.h" }
-    module ranges_iterator_traits     { header "__iterator/ranges_iterator_traits.h" }
-    module readable_traits            { header "__iterator/readable_traits.h" }
-    module reverse_access             { header "__iterator/reverse_access.h" }
-    module reverse_iterator           { header "__iterator/reverse_iterator.h" }
-    module segmented_iterator         { header "__iterator/segmented_iterator.h" }
-    module size                       { header "__iterator/size.h" }
-    module sortable                   { header "__iterator/sortable.h" }
-    module static_bounded_iter        { header "__iterator/static_bounded_iter.h" }
-    module unreachable_sentinel       { header "__iterator/unreachable_sentinel.h" }
-    module wrap_iter                  { header "__iterator/wrap_iter.h" }
 
     header "iterator"
     export *
@@ -1564,46 +1657,51 @@ module std [system] {
   }
 
   module locale {
-    header "locale"
-    module check_grouping  { header "__locale_dir/check_grouping.h" }
-    module get_c_locale    { header "__locale_dir/get_c_locale.h" }
-    module messages        { header "__locale_dir/messages.h" }
-    module money           { header "__locale_dir/money.h" }
-    module num             { header "__locale_dir/num.h" }
-    module pad_and_output  { header "__locale_dir/pad_and_output.h" }
-    module scan_keyword    { header "__locale_dir/scan_keyword.h" }
-    module time            { header "__locale_dir/time.h" }
-    module wbuffer_convert { header "__locale_dir/wbuffer_convert.h" }
-    module wstring_convert { header "__locale_dir/wstring_convert.h" }
-
-    module support {
-      header "__locale_dir/locale_base_api.h"
-      export *
-    }
+    module cxx11 {
+      requires cplusplus11
+      module check_grouping  { header "__locale_dir/check_grouping.h" }
+      module get_c_locale    { header "__locale_dir/get_c_locale.h" }
+      module messages        { header "__locale_dir/messages.h" }
+      module money           { header "__locale_dir/money.h" }
+      module num             { header "__locale_dir/num.h" }
+      module pad_and_output  { header "__locale_dir/pad_and_output.h" }
+      module scan_keyword    { header "__locale_dir/scan_keyword.h" }
+      module time            { header "__locale_dir/time.h" }
+      module wbuffer_convert { header "__locale_dir/wbuffer_convert.h" }
+      module wstring_convert { header "__locale_dir/wstring_convert.h" }
+
+      module support {
+        header "__locale_dir/locale_base_api.h"
+        export *
+      }
 
-    module support_impl {
-      textual header "__locale_dir/support/apple.h"
-      textual header "__locale_dir/support/bsd_like.h"
-      textual header "__locale_dir/support/freebsd.h"
-      textual header "__locale_dir/support/fuchsia.h"
-      textual header "__locale_dir/support/linux.h"
-      textual header "__locale_dir/support/netbsd.h"
-      textual header "__locale_dir/support/no_locale/characters.h"
-      textual header "__locale_dir/support/no_locale/strtonum.h"
-      textual header "__locale_dir/support/windows.h"
-    }
+      module support_impl {
+        textual header "__locale_dir/support/apple.h"
+        textual header "__locale_dir/support/bsd_like.h"
+        textual header "__locale_dir/support/freebsd.h"
+        textual header "__locale_dir/support/fuchsia.h"
+        textual header "__locale_dir/support/linux.h"
+        textual header "__locale_dir/support/netbsd.h"
+        textual header "__locale_dir/support/no_locale/characters.h"
+        textual header "__locale_dir/support/no_locale/strtonum.h"
+        textual header "__locale_dir/support/windows.h"
+      }
 
-    module locale_base_api {
-      textual header "__locale_dir/locale_base_api/bsd_locale_fallbacks.h"
-      textual header "__locale_dir/locale_base_api/ibm.h"
-      textual header "__locale_dir/locale_base_api/musl.h"
-      textual header "__locale_dir/locale_base_api/openbsd.h"
+      module locale_base_api {
+        textual header "__locale_dir/locale_base_api/bsd_locale_fallbacks.h"
+        textual header "__locale_dir/locale_base_api/ibm.h"
+        textual header "__locale_dir/locale_base_api/musl.h"
+        textual header "__locale_dir/locale_base_api/openbsd.h"
+      }
     }
+
+    header "locale"
     export *
   }
 
   // TODO: Understand why this needs to live in its own module
   module locale_base [system] {
+    requires cplusplus11
     header "__locale"
     export *
   }
@@ -1615,16 +1713,19 @@ module std [system] {
   }
 
   module mdspan {
-    module aligned_accessor   { header "__mdspan/aligned_accessor.h" }
-    module default_accessor   { header "__mdspan/default_accessor.h" }
-    module extents            { header "__mdspan/extents.h" }
-    module fwd                { header "__fwd/mdspan.h" }
-    module layout_left        { header "__mdspan/layout_left.h" }
-    module layout_right       { header "__mdspan/layout_right.h" }
-    module layout_stride      { header "__mdspan/layout_stride.h" }
-    module mdspan {
-      header "__mdspan/mdspan.h"
-      export std.array // returned by some methods
+    module cxx11 {
+      requires cplusplus11
+      module aligned_accessor   { header "__mdspan/aligned_accessor.h" }
+      module default_accessor   { header "__mdspan/default_accessor.h" }
+      module extents            { header "__mdspan/extents.h" }
+      module fwd                { header "__fwd/mdspan.h" }
+      module layout_left        { header "__mdspan/layout_left.h" }
+      module layout_right       { header "__mdspan/layout_right.h" }
+      module layout_stride      { header "__mdspan/layout_stride.h" }
+      module mdspan {
+        header "__mdspan/mdspan.h"
+        export std.array // returned by some methods
+      }
     }
 
     header "mdspan"
@@ -1632,112 +1733,124 @@ module std [system] {
   }
 
   module memory {
-    module addressof                          { header "__memory/addressof.h" }
-    module align                              { header "__memory/align.h" }
-    module aligned_alloc                      { header "__memory/aligned_alloc.h" }
-    module allocate_at_least                  { header "__memory/allocate_at_least.h" }
-    module allocation_guard                   { header "__memory/allocation_guard.h" }
-    module allocator {
-      header "__memory/allocator.h"
-      export * // TODO: Workaround for https://llvm.org/PR120108
-    }
-    module allocator_arg_t                    { header "__memory/allocator_arg_t.h" }
-    module allocator_destructor               { header "__memory/allocator_destructor.h" }
-    module allocator_traits                   { header "__memory/allocator_traits.h" }
-    module array_cookie                       { header "__memory/array_cookie.h" }
-    module assume_aligned                     { header "__memory/assume_aligned.h" }
-    module auto_ptr                           { header "__memory/auto_ptr.h" }
-    module compressed_pair                    { header "__memory/compressed_pair.h" }
-    module concepts                           { header "__memory/concepts.h" }
-    module construct_at                       { header "__memory/construct_at.h" }
-    module destroy                            { header "__memory/destroy.h" }
-    module destruct_n                         { header "__memory/destruct_n.h" }
-    module fwd                                { header "__fwd/memory.h" }
-    module inout_ptr                          { header "__memory/inout_ptr.h" }
-    module is_sufficiently_aligned            { header "__memory/is_sufficiently_aligned.h" }
-    module noexcept_move_assign_container     { header "__memory/noexcept_move_assign_container.h" }
-    module out_ptr                            { header "__memory/out_ptr.h" }
-    module pointer_traits                     { header "__memory/pointer_traits.h" }
-    module ranges_construct_at                { header "__memory/ranges_construct_at.h" }
-    module ranges_destroy                     { header "__memory/ranges_destroy.h" }
-    module ranges_uninitialized_algorithms {
-      header "__memory/ranges_uninitialized_algorithms.h"
-      export std.algorithm.in_out_result
-    }
-    module raw_storage_iterator               { header "__memory/raw_storage_iterator.h" }
-    module shared_count                       { header "__memory/shared_count.h" }
-    module shared_ptr                         { header "__memory/shared_ptr.h" }
-    module swap_allocator                     { header "__memory/swap_allocator.h" }
-    module temp_value                         { header "__memory/temp_value.h" }
-    module temporary_buffer                   {
-      header "__memory/temporary_buffer.h"
-      export std.utility.pair // return type of std::get_temporary_buffer()
-    }
-    module uninitialized_algorithms {
-      header "__memory/uninitialized_algorithms.h"
-      export std.utility.pair
-    }
-    module unique_ptr {
-      header "__memory/unique_ptr.h"
-    }
-    module unique_temporary_buffer {
-      header "__memory/unique_temporary_buffer.h"
-      export std.memory.unique_ptr
-      export std_core.type_traits.is_constant_evaluated
-      export * // TODO: Workaround for https://llvm.org/PR120108
+    module cxx11 {
+      requires cplusplus11
+      module addressof                          { header "__memory/addressof.h" }
+      module align                              { header "__memory/align.h" }
+      module aligned_alloc                      { header "__memory/aligned_alloc.h" }
+      module allocate_at_least                  { header "__memory/allocate_at_least.h" }
+      module allocation_guard                   { header "__memory/allocation_guard.h" }
+      module allocator {
+        header "__memory/allocator.h"
+        export * // TODO: Workaround for https://llvm.org/PR120108
+      }
+      module allocator_arg_t                    { header "__memory/allocator_arg_t.h" }
+      module allocator_destructor               { header "__memory/allocator_destructor.h" }
+      module allocator_traits                   { header "__memory/allocator_traits.h" }
+      module array_cookie                       { header "__memory/array_cookie.h" }
+      module assume_aligned                     { header "__memory/assume_aligned.h" }
+      module auto_ptr                           { header "__memory/auto_ptr.h" }
+      module compressed_pair                    { header "__memory/compressed_pair.h" }
+      module concepts                           { header "__memory/concepts.h" }
+      module construct_at                       { header "__memory/construct_at.h" }
+      module destroy                            { header "__memory/destroy.h" }
+      module destruct_n                         { header "__memory/destruct_n.h" }
+      module fwd                                { header "__fwd/memory.h" }
+      module inout_ptr                          { header "__memory/inout_ptr.h" }
+      module is_sufficiently_aligned            { header "__memory/is_sufficiently_aligned.h" }
+      module noexcept_move_assign_container     { header "__memory/noexcept_move_assign_container.h" }
+      module out_ptr                            { header "__memory/out_ptr.h" }
+      module pointer_traits                     { header "__memory/pointer_traits.h" }
+      module ranges_construct_at                { header "__memory/ranges_construct_at.h" }
+      module ranges_destroy                     { header "__memory/ranges_destroy.h" }
+      module ranges_uninitialized_algorithms {
+        header "__memory/ranges_uninitialized_algorithms.h"
+        export std.algorithm.in_out_result
+      }
+      module raw_storage_iterator               { header "__memory/raw_storage_iterator.h" }
+      module shared_count                       { header "__memory/shared_count.h" }
+      module shared_ptr                         { header "__memory/shared_ptr.h" }
+      module swap_allocator                     { header "__memory/swap_allocator.h" }
+      module temp_value                         { header "__memory/temp_value.h" }
+      module temporary_buffer                   {
+        header "__memory/temporary_buffer.h"
+        export std.utility.pair // return type of std::get_temporary_buffer()
+      }
+      module uninitialized_algorithms {
+        header "__memory/uninitialized_algorithms.h"
+        export std.utility.pair
+      }
+      module unique_ptr {
+        header "__memory/unique_ptr.h"
+      }
+      module unique_temporary_buffer {
+        header "__memory/unique_temporary_buffer.h"
+        export std.memory.unique_ptr
+        export std_core.type_traits.is_constant_evaluated
+        export * // TODO: Workaround for https://llvm.org/PR120108
+      }
+      module uses_allocator                     { header "__memory/uses_allocator.h" }
+      module uses_allocator_construction        { header "__memory/uses_allocator_construction.h" }
     }
-    module uses_allocator                     { header "__memory/uses_allocator.h" }
-    module uses_allocator_construction        { header "__memory/uses_allocator_construction.h" }
 
     header "memory"
     export *
   }
 
   module memory_resource {
-    module fwd                            { header "__fwd/memory_resource.h" }
-    module memory_resource                { header "__memory_resource/memory_resource.h" }
-    module monotonic_buffer_resource      { header "__memory_resource/monotonic_buffer_resource.h" }
-    module polymorphic_allocator          { header "__memory_resource/polymorphic_allocator.h" }
-    module pool_options                   { header "__memory_resource/pool_options.h" }
-    module synchronized_pool_resource     { header "__memory_resource/synchronized_pool_resource.h" }
-    module unsynchronized_pool_resource   { header "__memory_resource/unsynchronized_pool_resource.h" }
+    module cxx11 {
+      requires cplusplus11
+      module fwd                            { header "__fwd/memory_resource.h" }
+      module memory_resource                { header "__memory_resource/memory_resource.h" }
+      module monotonic_buffer_resource      { header "__memory_resource/monotonic_buffer_resource.h" }
+      module polymorphic_allocator          { header "__memory_resource/polymorphic_allocator.h" }
+      module pool_options                   { header "__memory_resource/pool_options.h" }
+      module synchronized_pool_resource     { header "__memory_resource/synchronized_pool_resource.h" }
+      module unsynchronized_pool_resource   { header "__memory_resource/unsynchronized_pool_resource.h" }
+    }
 
     header "memory_resource"
     export *
   }
 
   module mutex {
-    module lock_guard     { header "__mutex/lock_guard.h" }
-    module mutex          { header "__mutex/mutex.h" }
-    module once_flag      { header "__mutex/once_flag.h" }
-    module tag_types      { header "__mutex/tag_types.h" }
-    module unique_lock    { header "__mutex/unique_lock.h" }
+    module cxx11 {
+      requires cplusplus11
+      module lock_guard     { header "__mutex/lock_guard.h" }
+      module mutex          { header "__mutex/mutex.h" }
+      module once_flag      { header "__mutex/once_flag.h" }
+      module tag_types      { header "__mutex/tag_types.h" }
+      module unique_lock    { header "__mutex/unique_lock.h" }
+    }
 
     header "mutex"
     export *
   }
 
   module new {
-    header "new"
-    module align_val_t          { header "__new/align_val_t.h" }
-    module allocate {
-      header "__new/allocate.h"
-      export std.utility.element_count // used as part of the API
-      export * // TODO: Workaround for https://llvm.org/PR120108
-    }
-    module destroying_delete_t  { header "__new/destroying_delete_t.h" }
-    module exceptions           { header "__new/exceptions.h" }
-    module global_new_delete    {
-      header "__new/global_new_delete.h"
+    module cxx11 {
+      requires cplusplus11
+      module align_val_t          { header "__new/align_val_t.h" }
+      module allocate {
+        header "__new/allocate.h"
+        export std.utility.element_count // used as part of the API
+        export * // TODO: Workaround for https://llvm.org/PR120108
+      }
+      module destroying_delete_t  { header "__new/destroying_delete_t.h" }
+      module exceptions           { header "__new/exceptions.h" }
+      module global_new_delete    {
+        header "__new/global_new_delete.h"
 
-      export std.new.nothrow_t
+        export std.new.nothrow_t
+      }
+      module interference_size    { header "__new/interference_size.h" }
+      module launder              { header "__new/launder.h" }
+      module new_handler          { header "__new/new_handler.h" }
+      module nothrow_t            { header "__new/nothrow_t.h" }
+      module placement_new_delete { header "__new/placement_new_delete.h" }
     }
-    module interference_size    { header "__new/interference_size.h" }
-    module launder              { header "__new/launder.h" }
-    module new_handler          { header "__new/new_handler.h" }
-    module nothrow_t            { header "__new/nothrow_t.h" }
-    module placement_new_delete { header "__new/placement_new_delete.h" }
 
+    header "new"
     export *
   }
 
@@ -1747,22 +1860,25 @@ module std [system] {
   }
 
   module numeric {
-    module accumulate                 { header "__numeric/accumulate.h" }
-    module adjacent_difference        { header "__numeric/adjacent_difference.h" }
-    module exclusive_scan             { header "__numeric/exclusive_scan.h" }
-    module gcd_lcm                    { header "__numeric/gcd_lcm.h" }
-    module inclusive_scan             { header "__numeric/inclusive_scan.h" }
-    module inner_product              { header "__numeric/inner_product.h" }
-    module iota                       { header "__numeric/iota.h" }
-    module midpoint                   { header "__numeric/midpoint.h" }
-    module partial_sum                { header "__numeric/partial_sum.h" }
-    module pstl                       { header "__numeric/pstl.h" }
-    module reduce                     { header "__numeric/reduce.h" }
-    module ranges_iota                { header "__numeric/ranges_iota.h" }
-    module saturation_arithmetic      { header "__numeric/saturation_arithmetic.h" }
-    module transform_exclusive_scan   { header "__numeric/transform_exclusive_scan.h" }
-    module transform_inclusive_scan   { header "__numeric/transform_inclusive_scan.h" }
-    module transform_reduce           { header "__numeric/transform_reduce.h" }
+    module cxx11 {
+      requires cplusplus11
+      module accumulate                 { header "__numeric/accumulate.h" }
+      module adjacent_difference        { header "__numeric/adjacent_difference.h" }
+      module exclusive_scan             { header "__numeric/exclusive_scan.h" }
+      module gcd_lcm                    { header "__numeric/gcd_lcm.h" }
+      module inclusive_scan             { header "__numeric/inclusive_scan.h" }
+      module inner_product              { header "__numeric/inner_product.h" }
+      module iota                       { header "__numeric/iota.h" }
+      module midpoint                   { header "__numeric/midpoint.h" }
+      module partial_sum                { header "__numeric/partial_sum.h" }
+      module pstl                       { header "__numeric/pstl.h" }
+      module reduce                     { header "__numeric/reduce.h" }
+      module ranges_iota                { header "__numeric/ranges_iota.h" }
+      module saturation_arithmetic      { header "__numeric/saturation_arithmetic.h" }
+      module transform_exclusive_scan   { header "__numeric/transform_exclusive_scan.h" }
+      module transform_inclusive_scan   { header "__numeric/transform_inclusive_scan.h" }
+      module transform_reduce           { header "__numeric/transform_reduce.h" }
+    }
 
     header "numeric"
     export *
@@ -1774,18 +1890,21 @@ module std [system] {
   }
 
   module ostream {
-    module basic_ostream {
-      header "__ostream/basic_ostream.h"
-      export std.ios // base class
-    }
-    module fwd {
-      header "__fwd/ostream.h"
-    }
-    module print {
-      header "__ostream/print.h"
-      export *
+    module cxx11 {
+      requires cplusplus11
+      module basic_ostream {
+        header "__ostream/basic_ostream.h"
+        export std.ios // base class
+      }
+      module fwd {
+        header "__fwd/ostream.h"
+      }
+      module print {
+        header "__ostream/print.h"
+        export *
+      }
+      module put_character_sequence { header "__ostream/put_character_sequence.h" }
     }
-    module put_character_sequence { header "__ostream/put_character_sequence.h" }
 
     header "ostream"
     export *
@@ -1797,159 +1916,168 @@ module std [system] {
   }
 
   module queue {
-    module fwd { header "__fwd/queue.h" }
+    module cxx11 {
+      requires cplusplus11
+      module fwd { header "__fwd/queue.h" }
+    }
 
     header "queue"
     export *
   }
 
   module random {
-    module bernoulli_distribution             { header "__random/bernoulli_distribution.h" }
-    module binomial_distribution              { header "__random/binomial_distribution.h" }
-    module cauchy_distribution                { header "__random/cauchy_distribution.h" }
-    module chi_squared_distribution           { header "__random/chi_squared_distribution.h" }
-    module clamp_to_integral                  { header "__random/clamp_to_integral.h" }
-    module default_random_engine              { header "__random/default_random_engine.h" }
-    module discard_block_engine               { header "__random/discard_block_engine.h" }
-    module discrete_distribution              { header "__random/discrete_distribution.h" }
-    module exponential_distribution           { header "__random/exponential_distribution.h" }
-    module extreme_value_distribution         { header "__random/extreme_value_distribution.h" }
-    module fisher_f_distribution              { header "__random/fisher_f_distribution.h" }
-    module gamma_distribution                 { header "__random/gamma_distribution.h" }
-    module generate_canonical                 { header "__random/generate_canonical.h" }
-    module geometric_distribution             { header "__random/geometric_distribution.h" }
-    module independent_bits_engine            { header "__random/independent_bits_engine.h" }
-    module is_seed_sequence                   { header "__random/is_seed_sequence.h" }
-    module is_valid {
-      header "__random/is_valid.h"
-      export std_core.type_traits.integral_constant
+    module cxx11 {
+      requires cplusplus11
+      module bernoulli_distribution             { header "__random/bernoulli_distribution.h" }
+      module binomial_distribution              { header "__random/binomial_distribution.h" }
+      module cauchy_distribution                { header "__random/cauchy_distribution.h" }
+      module chi_squared_distribution           { header "__random/chi_squared_distribution.h" }
+      module clamp_to_integral                  { header "__random/clamp_to_integral.h" }
+      module default_random_engine              { header "__random/default_random_engine.h" }
+      module discard_block_engine               { header "__random/discard_block_engine.h" }
+      module discrete_distribution              { header "__random/discrete_distribution.h" }
+      module exponential_distribution           { header "__random/exponential_distribution.h" }
+      module extreme_value_distribution         { header "__random/extreme_value_distribution.h" }
+      module fisher_f_distribution              { header "__random/fisher_f_distribution.h" }
+      module gamma_distribution                 { header "__random/gamma_distribution.h" }
+      module generate_canonical                 { header "__random/generate_canonical.h" }
+      module geometric_distribution             { header "__random/geometric_distribution.h" }
+      module independent_bits_engine            { header "__random/independent_bits_engine.h" }
+      module is_seed_sequence                   { header "__random/is_seed_sequence.h" }
+      module is_valid {
+        header "__random/is_valid.h"
+        export std_core.type_traits.integral_constant
+      }
+      module knuth_b                            { header "__random/knuth_b.h" }
+      module linear_congruential_engine         { header "__random/linear_congruential_engine.h" }
+      module log2                               { header "__random/log2.h" }
+      module lognormal_distribution             { header "__random/lognormal_distribution.h" }
+      module mersenne_twister_engine            { header "__random/mersenne_twister_engine.h" }
+      module negative_binomial_distribution     { header "__random/negative_binomial_distribution.h" }
+      module normal_distribution                { header "__random/normal_distribution.h" }
+      module piecewise_constant_distribution    { header "__random/piecewise_constant_distribution.h" }
+      module piecewise_linear_distribution      { header "__random/piecewise_linear_distribution.h" }
+      module poisson_distribution               { header "__random/poisson_distribution.h" }
+      module random_device                      { header "__random/random_device.h" }
+      module ranlux                             { header "__random/ranlux.h" }
+      module seed_seq                           { header "__random/seed_seq.h" }
+      module shuffle_order_engine               { header "__random/shuffle_order_engine.h" }
+      module student_t_distribution             { header "__random/student_t_distribution.h" }
+      module subtract_with_carry_engine         { header "__random/subtract_with_carry_engine.h" }
+      module uniform_int_distribution           { header "__random/uniform_int_distribution.h" }
+      module uniform_random_bit_generator       { header "__random/uniform_random_bit_generator.h" }
+      module uniform_real_distribution          { header "__random/uniform_real_distribution.h" }
+      module weibull_distribution               { header "__random/weibull_distribution.h" }
     }
-    module knuth_b                            { header "__random/knuth_b.h" }
-    module linear_congruential_engine         { header "__random/linear_congruential_engine.h" }
-    module log2                               { header "__random/log2.h" }
-    module lognormal_distribution             { header "__random/lognormal_distribution.h" }
-    module mersenne_twister_engine            { header "__random/mersenne_twister_engine.h" }
-    module negative_binomial_distribution     { header "__random/negative_binomial_distribution.h" }
-    module normal_distribution                { header "__random/normal_distribution.h" }
-    module piecewise_constant_distribution    { header "__random/piecewise_constant_distribution.h" }
-    module piecewise_linear_distribution      { header "__random/piecewise_linear_distribution.h" }
-    module poisson_distribution               { header "__random/poisson_distribution.h" }
-    module random_device                      { header "__random/random_device.h" }
-    module ranlux                             { header "__random/ranlux.h" }
-    module seed_seq                           { header "__random/seed_seq.h" }
-    module shuffle_order_engine               { header "__random/shuffle_order_engine.h" }
-    module student_t_distribution             { header "__random/student_t_distribution.h" }
-    module subtract_with_carry_engine         { header "__random/subtract_with_carry_engine.h" }
-    module uniform_int_distribution           { header "__random/uniform_int_distribution.h" }
-    module uniform_random_bit_generator       { header "__random/uniform_random_bit_generator.h" }
-    module uniform_real_distribution          { header "__random/uniform_real_distribution.h" }
-    module weibull_distribution               { header "__random/weibull_distribution.h" }
 
     header "random"
     export *
   }
 
   module ranges {
-    module access                         { header "__ranges/access.h" }
-    module all                            {
-      header "__ranges/all.h"
-      export std.ranges.ref_view
-    }
-    module as_rvalue_view                 { header "__ranges/as_rvalue_view.h" }
-    module chunk_by_view {
-      header "__ranges/chunk_by_view.h"
-      export std.functional.bind_back
-    }
-    module common_view                    { header "__ranges/common_view.h" }
-    module concepts                       { header "__ranges/concepts.h" }
-    module container_compatible_range     { header "__ranges/container_compatible_range.h" }
-    module counted {
-      header "__ranges/counted.h"
-      export std.span            // return type of views::counted
-      export std.ranges.subrange // return type of views::counted
-    }
-    module dangling {
-      header "__ranges/dangling.h"
-    }
-    module data {
-      header "__ranges/data.h"
-    }
-    module drop_view {
-      header "__ranges/drop_view.h"
-      export std.functional.bind_back
-    }
-    module drop_while_view {
-      header "__ranges/drop_while_view.h"
-      export std.functional.bind_back
-    }
-    module elements_view                  { header "__ranges/elements_view.h" }
-    module empty                          { header "__ranges/empty.h" }
-    module empty_view                     { header "__ranges/empty_view.h" }
-    module enable_borrowed_range          { header "__ranges/enable_borrowed_range.h" }
-    module enable_view                    { header "__ranges/enable_view.h" }
-    module filter_view {
-      header "__ranges/filter_view.h"
-      export std.functional.bind_back
-    }
-    module from_range                     { header "__ranges/from_range.h" }
-    module iota_view                      { header "__ranges/iota_view.h" }
-    module istream_view                   { header "__ranges/istream_view.h" }
-    module join_view                      { header "__ranges/join_view.h" }
-    module join_with_view                 { header "__ranges/join_with_view.h" }
-    module lazy_split_view {
-      header "__ranges/lazy_split_view.h"
-      export std.functional.bind_back
-    }
-    module movable_box                    { header "__ranges/movable_box.h" }
-    module non_propagating_cache          { header "__ranges/non_propagating_cache.h" }
-    module owning_view                    { header "__ranges/owning_view.h" }
-    module range_adaptor                  { header "__ranges/range_adaptor.h" }
-    module rbegin                         { header "__ranges/rbegin.h" }
-    module ref_view                       { header "__ranges/ref_view.h" }
-    module rend                           { header "__ranges/rend.h" }
-    module repeat_view                    { header "__ranges/repeat_view.h" }
-    module reverse_view                   { header "__ranges/reverse_view.h" }
-    module single_view                    { header "__ranges/single_view.h" }
-    module size                           { header "__ranges/size.h" }
-    module split_view {
-      header "__ranges/split_view.h"
-      export std.functional.bind_back
-    }
-    module subrange {
-      header "__ranges/subrange.h"
-      export std.ranges.subrange_fwd
-    }
-    module subrange_fwd {
-      header "__fwd/subrange.h"
-    }
-    module take_view {
-      header "__ranges/take_view.h"
-      export std.functional.bind_back
-    }
-    module take_while_view {
-      header "__ranges/take_while_view.h"
-      export std.functional.bind_back
-    }
-    module to {
-      header "__ranges/to.h"
-      export std.functional.bind_back
-    }
-    module transform_view {
-      header "__ranges/transform_view.h"
-      export std.functional.bind_back
-    }
-    module view_interface {
-      header "__ranges/view_interface.h"
-    }
-    module views {
-      header "__ranges/views.h"
-    }
-    module zip_view {
-      header "__ranges/zip_view.h"
-      export std.utility.pair
-    }
-    module zip_transform_view {
-      header "__ranges/zip_transform_view.h"
+    module cxx11 {
+      requires cplusplus11
+      module access                         { header "__ranges/access.h" }
+      module all                            {
+        header "__ranges/all.h"
+        export std.ranges.ref_view
+      }
+      module as_rvalue_view                 { header "__ranges/as_rvalue_view.h" }
+      module chunk_by_view {
+        header "__ranges/chunk_by_view.h"
+        export std.functional.bind_back
+      }
+      module common_view                    { header "__ranges/common_view.h" }
+      module concepts                       { header "__ranges/concepts.h" }
+      module container_compatible_range     { header "__ranges/container_compatible_range.h" }
+      module counted {
+        header "__ranges/counted.h"
+        export std.span            // return type of views::counted
+        export std.ranges.subrange // return type of views::counted
+      }
+      module dangling {
+        header "__ranges/dangling.h"
+      }
+      module data {
+        header "__ranges/data.h"
+      }
+      module drop_view {
+        header "__ranges/drop_view.h"
+        export std.functional.bind_back
+      }
+      module drop_while_view {
+        header "__ranges/drop_while_view.h"
+        export std.functional.bind_back
+      }
+      module elements_view                  { header "__ranges/elements_view.h" }
+      module empty                          { header "__ranges/empty.h" }
+      module empty_view                     { header "__ranges/empty_view.h" }
+      module enable_borrowed_range          { header "__ranges/enable_borrowed_range.h" }
+      module enable_view                    { header "__ranges/enable_view.h" }
+      module filter_view {
+        header "__ranges/filter_view.h"
+        export std.functional.bind_back
+      }
+      module from_range                     { header "__ranges/from_range.h" }
+      module iota_view                      { header "__ranges/iota_view.h" }
+      module istream_view                   { header "__ranges/istream_view.h" }
+      module join_view                      { header "__ranges/join_view.h" }
+      module join_with_view                 { header "__ranges/join_with_view.h" }
+      module lazy_split_view {
+        header "__ranges/lazy_split_view.h"
+        export std.functional.bind_back
+      }
+      module movable_box                    { header "__ranges/movable_box.h" }
+      module non_propagating_cache          { header "__ranges/non_propagating_cache.h" }
+      module owning_view                    { header "__ranges/owning_view.h" }
+      module range_adaptor                  { header "__ranges/range_adaptor.h" }
+      module rbegin                         { header "__ranges/rbegin.h" }
+      module ref_view                       { header "__ranges/ref_view.h" }
+      module rend                           { header "__ranges/rend.h" }
+      module repeat_view                    { header "__ranges/repeat_view.h" }
+      module reverse_view                   { header "__ranges/reverse_view.h" }
+      module single_view                    { header "__ranges/single_view.h" }
+      module size                           { header "__ranges/size.h" }
+      module split_view {
+        header "__ranges/split_view.h"
+        export std.functional.bind_back
+      }
+      module subrange {
+        header "__ranges/subrange.h"
+        export std.ranges.subrange_fwd
+      }
+      module subrange_fwd {
+        header "__fwd/subrange.h"
+      }
+      module take_view {
+        header "__ranges/take_view.h"
+        export std.functional.bind_back
+      }
+      module take_while_view {
+        header "__ranges/take_while_view.h"
+        export std.functional.bind_back
+      }
+      module to {
+        header "__ranges/to.h"
+        export std.functional.bind_back
+      }
+      module transform_view {
+        header "__ranges/transform_view.h"
+        export std.functional.bind_back
+      }
+      module view_interface {
+        header "__ranges/view_interface.h"
+      }
+      module views {
+        header "__ranges/views.h"
+      }
+      module zip_view {
+        header "__ranges/zip_view.h"
+        export std.utility.pair
+      }
+      module zip_transform_view {
+        header "__ranges/zip_transform_view.h"
+      }
     }
 
     header "ranges"
@@ -1994,7 +2122,10 @@ module std [system] {
   }
 
   module span {
-    module fwd { header "__fwd/span.h" }
+    module cxx11 {
+      requires cplusplus11
+      module fwd { header "__fwd/span.h" }
+    }
 
     header "span"
     export *
@@ -2002,14 +2133,20 @@ module std [system] {
   }
 
   module sstream {
-    module fwd { header "__fwd/sstream.h" }
+    module cxx11 {
+      requires cplusplus11
+      module fwd { header "__fwd/sstream.h" }
+    }
 
     header "sstream"
     export *
   }
 
   module stack {
-    module fwd { header "__fwd/stack.h" }
+    module cxx11 {
+      requires cplusplus11
+      module fwd { header "__fwd/stack.h" }
+    }
 
     header "stack"
     export *
@@ -2021,33 +2158,42 @@ module std [system] {
   }
 
   module stop_token {
-    module atomic_unique_lock     { header "__stop_token/atomic_unique_lock.h" }
-    module intrusive_list_view    { header "__stop_token/intrusive_list_view.h" }
-    module intrusive_shared_ptr   { header "__stop_token/intrusive_shared_ptr.h" }
-    module stop_callback          { header "__stop_token/stop_callback.h" }
-    module stop_source            { header "__stop_token/stop_source.h" }
-    module stop_state             { header "__stop_token/stop_state.h" }
-    module stop_token             { header "__stop_token/stop_token.h" }
+    module cxx11 {
+      requires cplusplus11
+      module atomic_unique_lock     { header "__stop_token/atomic_unique_lock.h" }
+      module intrusive_list_view    { header "__stop_token/intrusive_list_view.h" }
+      module intrusive_shared_ptr   { header "__stop_token/intrusive_shared_ptr.h" }
+      module stop_callback          { header "__stop_token/stop_callback.h" }
+      module stop_source            { header "__stop_token/stop_source.h" }
+      module stop_state             { header "__stop_token/stop_state.h" }
+      module stop_token             { header "__stop_token/stop_token.h" }
+    }
 
     header "stop_token"
     export *
   }
 
   module streambuf {
-    module fwd { header "__fwd/streambuf.h" }
+    module cxx11 {
+      requires cplusplus11
+      module fwd { header "__fwd/streambuf.h" }
+    }
 
     header "streambuf"
     export *
   }
 
   module string {
-    module char_traits              { header "__string/char_traits.h" }
-    module constexpr_c_functions    {
-      header "__string/constexpr_c_functions.h"
-      export std.utility.element_count // used as part of the constexpr C function's API
+    module cxx11 {
+      requires cplusplus11
+      module char_traits              { header "__string/char_traits.h" }
+      module constexpr_c_functions    {
+        header "__string/constexpr_c_functions.h"
+        export std.utility.element_count // used as part of the constexpr C function's API
+      }
+      module extern_template_lists    { header "__string/extern_template_lists.h" }
+      module fwd                      { header "__fwd/string.h" }
     }
-    module extern_template_lists    { header "__string/extern_template_lists.h" }
-    module fwd                      { header "__fwd/string.h" }
 
     header "string"
     export *
@@ -2055,7 +2201,10 @@ module std [system] {
   }
 
   module string_view {
-    module fwd { header "__fwd/string_view.h" }
+    module cxx11 {
+      requires cplusplus11
+      module fwd { header "__fwd/string_view.h" }
+    }
 
     header "string_view"
     export *
@@ -2073,38 +2222,44 @@ module std [system] {
   }
 
   module system_error {
-    module errc               { header "__system_error/errc.h" }
-    module error_category     { header "__system_error/error_category.h" }
-    module error_code {
-      header "__system_error/error_code.h"
-      export std.system_error.error_category // methods of error_code return that type
+    module cxx11 {
+      requires cplusplus11
+      module errc               { header "__system_error/errc.h" }
+      module error_category     { header "__system_error/error_category.h" }
+      module error_code {
+        header "__system_error/error_code.h"
+        export std.system_error.error_category // methods of error_code return that type
+      }
+      module error_condition    { header "__system_error/error_condition.h" }
+      module system_error       { header "__system_error/system_error.h" }
+      module throw_system_error { header "__system_error/throw_system_error.h" }
     }
-    module error_condition    { header "__system_error/error_condition.h" }
-    module system_error       { header "__system_error/system_error.h" }
-    module throw_system_error { header "__system_error/throw_system_error.h" }
 
     header "system_error"
     export *
   }
 
   module thread {
-    module formatter              { header "__thread/formatter.h" }
-    module id                     { header "__thread/id.h" }
-    module jthread                { header "__thread/jthread.h" }
-    module poll_with_backoff      { header "__thread/poll_with_backoff.h" }
-    module this_thread            { header "__thread/this_thread.h" }
-    module thread                 { header "__thread/thread.h" }
-    module timed_backoff_policy   { header "__thread/timed_backoff_policy.h" }
-
-    module support {
-      header "__thread/support.h"
-      export *
-    }
-    module support_impl {
-      textual header "__thread/support/c11.h"
-      textual header "__thread/support/external.h"
-      textual header "__thread/support/pthread.h"
-      textual header "__thread/support/windows.h"
+    module cxx11 {
+      requires cplusplus11
+      module formatter              { header "__thread/formatter.h" }
+      module id                     { header "__thread/id.h" }
+      module jthread                { header "__thread/jthread.h" }
+      module poll_with_backoff      { header "__thread/poll_with_backoff.h" }
+      module this_thread            { header "__thread/this_thread.h" }
+      module thread                 { header "__thread/thread.h" }
+      module timed_backoff_policy   { header "__thread/timed_backoff_policy.h" }
+
+      module support {
+        header "__thread/support.h"
+        export *
+      }
+      module support_impl {
+        textual header "__thread/support/c11.h"
+        textual header "__thread/support/external.h"
+        textual header "__thread/support/pthread.h"
+        textual header "__thread/support/windows.h"
+      }
     }
 
     header "thread"
@@ -2112,14 +2267,17 @@ module std [system] {
   }
 
   module tuple {
-    module find_index               { header "__tuple/find_index.h" }
-    module ignore                   { header "__tuple/ignore.h" }
-    module sfinae_helpers           { header "__tuple/sfinae_helpers.h" }
-    module tuple_element            { header "__tuple/tuple_element.h" }
-    module tuple_like_no_subrange   { header "__tuple/tuple_like_no_subrange.h" }
-    module tuple_like               { header "__tuple/tuple_like.h" }
-    module tuple_size               { header "__tuple/tuple_size.h" }
-    module tuple_types              { header "__tuple/tuple_types.h" }
+    module cxx11 {
+      requires cplusplus11
+      module find_index               { header "__tuple/find_index.h" }
+      module ignore                   { header "__tuple/ignore.h" }
+      module sfinae_helpers           { header "__tuple/sfinae_helpers.h" }
+      module tuple_element            { header "__tuple/tuple_element.h" }
+      module tuple_like_no_subrange   { header "__tuple/tuple_like_no_subrange.h" }
+      module tuple_like               { header "__tuple/tuple_like.h" }
+      module tuple_size               { header "__tuple/tuple_size.h" }
+      module tuple_types              { header "__tuple/tuple_types.h" }
+    }
 
     header "tuple"
     export *
@@ -2148,43 +2306,46 @@ module std [system] {
   }
 
   module utility {
-    module as_const                        { header "__utility/as_const.h" }
-    module as_lvalue                       { header "__utility/as_lvalue.h" }
-    module auto_cast                       {
-      header "__utility/auto_cast.h"
-      export std_core.type_traits.decay // the macro expansion uses that trait
-    }
-    module cmp                             { header "__utility/cmp.h" }
-    module convert_to_integral             { header "__utility/convert_to_integral.h" }
-    module default_three_way_comparator    { header "__utility/default_three_way_comparator.h" }
-    module element_count                   { header "__utility/element_count.h" }
-    module exception_guard                 { header "__utility/exception_guard.h" }
-    module exchange                        { header "__utility/exchange.h" }
-    module forward_like                    { header "__utility/forward_like.h" }
-    module in_place                        {
-      header "__utility/in_place.h"
-      export std_core.type_traits.integral_constant
-    }
-    module integer_sequence                { header "__utility/integer_sequence.h" }
-    module is_pointer_in_range             { header "__utility/is_pointer_in_range.h" }
-    module is_valid_range                  { header "__utility/is_valid_range.h" }
-    module lazy_synth_three_way_comparator { header "__utility/lazy_synth_three_way_comparator.h" }
-    module move                            { header "__utility/move.h" }
-    module no_destroy                      { header "__utility/no_destroy.h" }
-    module pair                            {
-      header "__utility/pair.h"
-      export std.utility.piecewise_construct
+    module cxx11 {
+      requires cplusplus11
+      module as_const                        { header "__utility/as_const.h" }
+      module as_lvalue                       { header "__utility/as_lvalue.h" }
+      module auto_cast                       {
+        header "__utility/auto_cast.h"
+        export std_core.type_traits.decay // the macro expansion uses that trait
+      }
+      module cmp                             { header "__utility/cmp.h" }
+      module convert_to_integral             { header "__utility/convert_to_integral.h" }
+      module default_three_way_comparator    { header "__utility/default_three_way_comparator.h" }
+      module element_count                   { header "__utility/element_count.h" }
+      module exception_guard                 { header "__utility/exception_guard.h" }
+      module exchange                        { header "__utility/exchange.h" }
+      module forward_like                    { header "__utility/forward_like.h" }
+      module in_place                        {
+        header "__utility/in_place.h"
+        export std_core.type_traits.integral_constant
+      }
+      module integer_sequence                { header "__utility/integer_sequence.h" }
+      module is_pointer_in_range             { header "__utility/is_pointer_in_range.h" }
+      module is_valid_range                  { header "__utility/is_valid_range.h" }
+      module lazy_synth_three_way_comparator { header "__utility/lazy_synth_three_way_comparator.h" }
+      module move                            { header "__utility/move.h" }
+      module no_destroy                      { header "__utility/no_destroy.h" }
+      module pair                            {
+        header "__utility/pair.h"
+        export std.utility.piecewise_construct
+      }
+      module piecewise_construct             { header "__utility/piecewise_construct.h" }
+      module priority_tag                    { header "__utility/priority_tag.h" }
+      module private_constructor_tag         { header "__utility/private_constructor_tag.h" }
+      module rel_ops                         { header "__utility/rel_ops.h" }
+      module scope_guard                     { header "__utility/scope_guard.h" }
+      module small_buffer                    { header "__utility/small_buffer.h" }
+      module swap                            { header "__utility/swap.h" }
+      module to_underlying                   { header "__utility/to_underlying.h" }
+      module try_key_extraction              { header "__utility/try_key_extraction.h" }
+      module unreachable                     { header "__utility/unreachable.h" }
     }
-    module piecewise_construct             { header "__utility/piecewise_construct.h" }
-    module priority_tag                    { header "__utility/priority_tag.h" }
-    module private_constructor_tag         { header "__utility/private_constructor_tag.h" }
-    module rel_ops                         { header "__utility/rel_ops.h" }
-    module scope_guard                     { header "__utility/scope_guard.h" }
-    module small_buffer                    { header "__utility/small_buffer.h" }
-    module swap                            { header "__utility/swap.h" }
-    module to_underlying                   { header "__utility/to_underlying.h" }
-    module try_key_extraction              { header "__utility/try_key_extraction.h" }
-    module unreachable                     { header "__utility/unreachable.h" }
 
     header "utility"
     export *
@@ -2196,46 +2357,52 @@ module std [system] {
   }
 
   module variant {
-    module fwd       { header "__fwd/variant.h" }
-    module monostate { header "__variant/monostate.h" }
+    module cxx11 {
+      requires cplusplus11
+      module fwd       { header "__fwd/variant.h" }
+      module monostate { header "__variant/monostate.h" }
+    }
 
     header "variant"
     export *
   }
 
   module vector {
-    module fwd                   { header "__fwd/vector.h" }
+    module cxx11 {
+      requires cplusplus11
+      module fwd                   { header "__fwd/vector.h" }
 
-    module comparison            { header "__vector/comparison.h" }
-    module container_traits      { header "__vector/container_traits.h" }
-    module erase                 { header "__vector/erase.h" }
-    module vector_bool_formatter {
-      header "__vector/vector_bool_formatter.h"
+      module comparison            { header "__vector/comparison.h" }
+      module container_traits      { header "__vector/container_traits.h" }
+      module erase                 { header "__vector/erase.h" }
+      module vector_bool_formatter {
+        header "__vector/vector_bool_formatter.h"
 
-      export std.format.formatter
-    }
-    module pmr                   {
-      header "__vector/pmr.h"
+        export std.format.formatter
+      }
+      module pmr                   {
+        header "__vector/pmr.h"
 
-      export std.memory_resource.polymorphic_allocator
-    }
-    module swap                  { header "__vector/swap.h" }
-    module vector_bool           {
-      header "__vector/vector_bool.h"
-      export std.bit_reference
-      export std.memory.allocator
-      export std.vector.comparison
-      export std.vector.fwd
-      export std.vector.swap
-    }
-    module vector                {
-      header "__vector/vector.h"
-      export std.iterator.bounded_iter
-      export std.iterator.wrap_iter
-      export std.memory.allocator
-      export std.vector.comparison
-      export std.vector.fwd
-      export std.vector.swap
+        export std.memory_resource.polymorphic_allocator
+      }
+      module swap                  { header "__vector/swap.h" }
+      module vector_bool           {
+        header "__vector/vector_bool.h"
+        export std.bit_reference
+        export std.memory.allocator
+        export std.vector.comparison
+        export std.vector.fwd
+        export std.vector.swap
+      }
+      module vector                {
+        header "__vector/vector.h"
+        export std.iterator.bounded_iter
+        export std.iterator.wrap_iter
+        export std.memory.allocator
+        export std.vector.comparison
+        export std.vector.fwd
+        export std.vector.swap
+      }
     }
 
     header "vector"
@@ -2252,15 +2419,19 @@ module std [system] {
     module type_traits        { header "experimental/type_traits" }
     module utility            { header "experimental/utility" }
     module simd {
-      private header "experimental/__simd/aligned_tag.h"
-      private header "experimental/__simd/declaration.h"
-      private header "experimental/__simd/reference.h"
-      private header "experimental/__simd/scalar.h"
-      private header "experimental/__simd/simd_mask.h"
-      private header "experimental/__simd/simd.h"
-      private header "experimental/__simd/traits.h"
-      private header "experimental/__simd/utility.h"
-      private header "experimental/__simd/vec_ext.h"
+      module cxx11 {
+        requires cplusplus11
+        private header "experimental/__simd/aligned_tag.h"
+        private header "experimental/__simd/declaration.h"
+        private header "experimental/__simd/reference.h"
+        private header "experimental/__simd/scalar.h"
+        private header "experimental/__simd/simd_mask.h"
+        private header "experimental/__simd/simd.h"
+        private header "experimental/__simd/traits.h"
+        private header "experimental/__simd/utility.h"
+        private header "experimental/__simd/vec_ext.h"
+      }
+
       header "experimental/simd"
       export *
     }
@@ -2269,12 +2440,14 @@ module std [system] {
   // Implementation detail headers that are private to libc++. These modules
   // must not be directly imported.
   module debug_utils {
+    requires cplusplus11
     module randomize_range              { header "__debug_utils/randomize_range.h" }
     module sanitizers                   { header "__debug_utils/sanitizers.h" }
     module strict_weak_ordering_check   { header "__debug_utils/strict_weak_ordering_check.h" }
   }
 
   module get_fwd {
+    requires cplusplus11
     header "__fwd/get.h"
     export std_core.fwd.pair
     export std_core.fwd.tuple
@@ -2285,6 +2458,7 @@ module std [system] {
   }
 
   module pstl {
+    requires cplusplus11
     module backend_fwd {
       header "__pstl/backend_fwd.h"
     }
@@ -2350,35 +2524,38 @@ module std [system] {
 
   // Miscellaneous modules for top-level headers
   module bit_reference_fwd {
+    requires cplusplus11
     header "__fwd/bit_reference.h"
   }
   module bit_reference {
+    requires cplusplus11
     header "__bit_reference"
     export std.bit_reference_fwd
   }
-  module hash_table           { header "__hash_table" }
-  module node_handle          { header "__node_handle" }
-  module split_buffer         { header "__split_buffer" }
-  module tree                 { header "__tree" }
-  module std_mbstate_t {
-    header "__std_mbstate_t.h"
-    export *
+  module hash_table           {
+    requires cplusplus11
+    header "__hash_table"
   }
-  module log_hardening_failure {
-    header "__log_hardening_failure"
+  module node_handle          {
+    requires cplusplus11
+    header "__node_handle"
   }
-  module verbose_abort {
-    header "__verbose_abort"
+  module split_buffer         {
+    requires cplusplus11
+    header "__split_buffer"
   }
-  module verbose_trap {
-    header "__verbose_trap"
+  module tree                 {
+    requires cplusplus11
+    header "__tree"
   }
-  module internal_assert {
-    header "__assert"
+  module std_mbstate_t {
+    requires cplusplus11
+    header "__std_mbstate_t.h"
     export *
   }
-  module assertion_handler {
-    header "__assertion_handler" // generated via CMake
+  module internal_assert {
+    requires cplusplus11
+    header "__assert"
     export *
   }
 
@@ -2388,10 +2565,13 @@ module std [system] {
 
   // This module needs to appear after __tree to work around issues with modules in Objective-C++ mode.
   module coroutine {
-    module coroutine_handle         { header "__coroutine/coroutine_handle.h" }
-    module coroutine_traits         { header "__coroutine/coroutine_traits.h" }
-    module noop_coroutine_handle    { header "__coroutine/noop_coroutine_handle.h" }
-    module trivial_awaitables       { header "__coroutine/trivial_awaitables.h" }
+    module cxx11 {
+      requires cplusplus11
+      module coroutine_handle         { header "__coroutine/coroutine_handle.h" }
+      module coroutine_traits         { header "__coroutine/coroutine_traits.h" }
+      module noop_coroutine_handle    { header "__coroutine/noop_coroutine_handle.h" }
+      module trivial_awaitables       { header "__coroutine/trivial_awaitables.h" }
+    }
 
     header "coroutine"
     export *
diff --git a/libcxx/include/string.h b/libcxx/include/string.h
index 6bdcd6a6eecbd..e0c0949086c41 100644
--- a/libcxx/include/string.h
+++ b/libcxx/include/string.h
@@ -51,6 +51,10 @@ size_t strlen(const char* s);
 
 */
 
+#if __has_include_next(<string.h>)
+#  include_next <string.h>
+#endif
+
 #if defined(__cplusplus) && __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
 #  include <__cxx03/string.h>
 #else
@@ -60,10 +64,6 @@ size_t strlen(const char* s);
 #    pragma GCC system_header
 #  endif
 
-#  if __has_include_next(<string.h>)
-#    include_next <string.h>
-#  endif
-
 // MSVCRT, GNU libc and its derivates may already have the correct prototype in
 // <string.h>. This macro can be defined by users if their C library provides
 // the right signature.
diff --git a/libcxx/test/extensions/clang/clang_modules_include.gen.py b/libcxx/test/extensions/clang/clang_modules_include.gen.py
index 28661049d6e85..4bcae5a65baff 100644
--- a/libcxx/test/extensions/clang/clang_modules_include.gen.py
+++ b/libcxx/test/extensions/clang/clang_modules_include.gen.py
@@ -33,8 +33,6 @@
 # TODO: Fix seemingly circular inclusion or <wchar.h> on AIX
 # UNSUPPORTED: LIBCXX-AIX-FIXME
 
-# UNSUPPORTED: FROZEN-CXX03-HEADERS-FIXME
-
 # RUN: %{python} %s %{libcxx-dir}/utils
 # END.
 



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