[libcxx-commits] [libcxx] [libcxx] sort `_LIBCPP_INTRODUCED_IN_LLVM_<X>` usages in reverse chronological order (PR #176857)

Mon Jan 19 21:12:36 PST 2026

llvmbot wrote:




@llvm/pr-subscribers-libcxx

Author: None (h-vetinari)

<details>
<summary>Changes</summary>

I noticed that the various `_LIBCPP_INTRODUCED_IN_LLVM_<ver>` usages in `availability.h` were defined a bit all over the place. I think it'd make the most sense to sort them in reverse chronological order (like their definitions).

I've broken this up into separate commits just to show that these are pure moves, as the full diff is a bit busted

---
Full diff: https://github.com/llvm/llvm-project/pull/176857.diff


1 Files Affected:

- (modified) libcxx/include/__configuration/availability.h (+56-56) 


``````````diff

diff --git a/libcxx/include/__configuration/availability.h b/libcxx/include/__configuration/availability.h
index 2c76347090fca..2625177c20c29 100644
--- a/libcxx/include/__configuration/availability.h
+++ b/libcxx/include/__configuration/availability.h
@@ -220,51 +220,20 @@
 #define _LIBCPP_AVAILABILITY_HAS_NEW_SYNC _LIBCPP_INTRODUCED_IN_LLVM_22
 #define _LIBCPP_AVAILABILITY_NEW_SYNC _LIBCPP_INTRODUCED_IN_LLVM_22_ATTRIBUTE
 
-// Enable additional explicit instantiations of iostreams components. This
-// reduces the number of weak definitions generated in programs that use
-// iostreams by providing a single strong definition in the shared library.
-//
-// TODO: Enable additional explicit instantiations on GCC once it supports exclude_from_explicit_instantiation,
-//       or once libc++ doesn't use the attribute anymore.
-// TODO: Enable them on Windows once https://llvm.org/PR41018 has been fixed.
-#if !defined(_LIBCPP_COMPILER_GCC) && !defined(_WIN32)
-#  define _LIBCPP_AVAILABILITY_HAS_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1 _LIBCPP_INTRODUCED_IN_LLVM_12
-#else
-#  define _LIBCPP_AVAILABILITY_HAS_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1 0
-#endif
-
-// This controls the availability of floating-point std::to_chars functions.
-// These overloads were added later than the integer overloads.
-#define _LIBCPP_AVAILABILITY_HAS_TO_CHARS_FLOATING_POINT _LIBCPP_INTRODUCED_IN_LLVM_14
-#define _LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT _LIBCPP_INTRODUCED_IN_LLVM_14_ATTRIBUTE
-
-// This controls whether the library claims to provide a default verbose
-// termination function, and consequently whether the headers will try
-// to use it when the mechanism isn't overriden at compile-time.
-#define _LIBCPP_AVAILABILITY_HAS_VERBOSE_ABORT _LIBCPP_INTRODUCED_IN_LLVM_15
-#define _LIBCPP_AVAILABILITY_VERBOSE_ABORT _LIBCPP_INTRODUCED_IN_LLVM_15_ATTRIBUTE
-
-// This controls the availability of the C++17 std::pmr library,
-// which is implemented in large part in the built library.
-//
-// TODO: Enable std::pmr markup once https://llvm.org/PR40340 has been fixed
-//       Until then, it is possible for folks to try to use `std::pmr` when back-deploying to targets that don't support
-//       it and it'll be a load-time error, but we don't have a good alternative because the library won't compile if we
-//       use availability annotations until that bug has been fixed.
-#define _LIBCPP_AVAILABILITY_HAS_PMR _LIBCPP_INTRODUCED_IN_LLVM_16
-#define _LIBCPP_AVAILABILITY_PMR
+// This controls whether `std::__hash_memory` is available in the dylib, which
+// is used for some `std::hash` specializations.
+#define _LIBCPP_AVAILABILITY_HAS_HASH_MEMORY _LIBCPP_INTRODUCED_IN_LLVM_21
+// No attribute, since we've had hash in the headers before
 
-// These macros controls the availability of __cxa_init_primary_exception
-// in the built library, which std::make_exception_ptr might use
-// (see libcxx/include/__exception/exception_ptr.h).
-#define _LIBCPP_AVAILABILITY_HAS_INIT_PRIMARY_EXCEPTION _LIBCPP_INTRODUCED_IN_LLVM_18
-#define _LIBCPP_AVAILABILITY_INIT_PRIMARY_EXCEPTION _LIBCPP_INTRODUCED_IN_LLVM_18_ATTRIBUTE
+// This controls whether we provide a message for `bad_function_call::what()` that specific to `std::bad_function_call`.
+// See https://wg21.link/LWG2233. This requires `std::bad_function_call::what()` to be available in the dylib.
+#define _LIBCPP_AVAILABILITY_HAS_BAD_FUNCTION_CALL_GOOD_WHAT_MESSAGE _LIBCPP_INTRODUCED_IN_LLVM_21
+// No attribute, since we've had bad_function_call::what() in the headers before
 
-// This controls the availability of C++23 <print>, which
-// has a dependency on the built library (it needs access to
-// the underlying buffer types of std::cout, std::cerr, and std::clog.
-#define _LIBCPP_AVAILABILITY_HAS_PRINT _LIBCPP_INTRODUCED_IN_LLVM_18
-#define _LIBCPP_AVAILABILITY_PRINT _LIBCPP_INTRODUCED_IN_LLVM_18_ATTRIBUTE
+// This controls the availability of floating-point std::from_chars functions.
+// These overloads were added later than the integer overloads.
+#define _LIBCPP_AVAILABILITY_HAS_FROM_CHARS_FLOATING_POINT _LIBCPP_INTRODUCED_IN_LLVM_20
+#define _LIBCPP_AVAILABILITY_FROM_CHARS_FLOATING_POINT _LIBCPP_INTRODUCED_IN_LLVM_20_ATTRIBUTE
 
 // This controls the availability of the C++20 time zone database.
 // The parser code is built in the library.
@@ -280,20 +249,17 @@
 #define _LIBCPP_AVAILABILITY_HAS_BAD_EXPECTED_ACCESS_KEY_FUNCTION _LIBCPP_INTRODUCED_IN_LLVM_19
 #define _LIBCPP_AVAILABILITY_BAD_EXPECTED_ACCESS_KEY_FUNCTION _LIBCPP_INTRODUCED_IN_LLVM_19_ATTRIBUTE
 
-// This controls the availability of floating-point std::from_chars functions.
-// These overloads were added later than the integer overloads.
-#define _LIBCPP_AVAILABILITY_HAS_FROM_CHARS_FLOATING_POINT _LIBCPP_INTRODUCED_IN_LLVM_20
-#define _LIBCPP_AVAILABILITY_FROM_CHARS_FLOATING_POINT _LIBCPP_INTRODUCED_IN_LLVM_20_ATTRIBUTE
-
-// This controls whether `std::__hash_memory` is available in the dylib, which
-// is used for some `std::hash` specializations.
-#define _LIBCPP_AVAILABILITY_HAS_HASH_MEMORY _LIBCPP_INTRODUCED_IN_LLVM_21
-// No attribute, since we've had hash in the headers before
+// These macros controls the availability of __cxa_init_primary_exception
+// in the built library, which std::make_exception_ptr might use
+// (see libcxx/include/__exception/exception_ptr.h).
+#define _LIBCPP_AVAILABILITY_HAS_INIT_PRIMARY_EXCEPTION _LIBCPP_INTRODUCED_IN_LLVM_18
+#define _LIBCPP_AVAILABILITY_INIT_PRIMARY_EXCEPTION _LIBCPP_INTRODUCED_IN_LLVM_18_ATTRIBUTE
 
-// This controls whether we provide a message for `bad_function_call::what()` that specific to `std::bad_function_call`.
-// See https://wg21.link/LWG2233. This requires `std::bad_function_call::what()` to be available in the dylib.
-#define _LIBCPP_AVAILABILITY_HAS_BAD_FUNCTION_CALL_GOOD_WHAT_MESSAGE _LIBCPP_INTRODUCED_IN_LLVM_21
-// No attribute, since we've had bad_function_call::what() in the headers before
+// This controls the availability of C++23 <print>, which
+// has a dependency on the built library (it needs access to
+// the underlying buffer types of std::cout, std::cerr, and std::clog.
+#define _LIBCPP_AVAILABILITY_HAS_PRINT _LIBCPP_INTRODUCED_IN_LLVM_18
+#define _LIBCPP_AVAILABILITY_PRINT _LIBCPP_INTRODUCED_IN_LLVM_18_ATTRIBUTE
 
 // Define availability attributes that depend on both
 // _LIBCPP_HAS_EXCEPTIONS and _LIBCPP_HAS_RTTI.
@@ -304,6 +270,40 @@
 #  define _LIBCPP_AVAILABILITY_INIT_PRIMARY_EXCEPTION
 #endif
 
+// This controls the availability of the C++17 std::pmr library,
+// which is implemented in large part in the built library.
+//
+// TODO: Enable std::pmr markup once https://llvm.org/PR40340 has been fixed
+//       Until then, it is possible for folks to try to use `std::pmr` when back-deploying to targets that don't support
+//       it and it'll be a load-time error, but we don't have a good alternative because the library won't compile if we
+//       use availability annotations until that bug has been fixed.
+#define _LIBCPP_AVAILABILITY_HAS_PMR _LIBCPP_INTRODUCED_IN_LLVM_16
+#define _LIBCPP_AVAILABILITY_PMR
+
+// This controls whether the library claims to provide a default verbose
+// termination function, and consequently whether the headers will try
+// to use it when the mechanism isn't overriden at compile-time.
+#define _LIBCPP_AVAILABILITY_HAS_VERBOSE_ABORT _LIBCPP_INTRODUCED_IN_LLVM_15
+#define _LIBCPP_AVAILABILITY_VERBOSE_ABORT _LIBCPP_INTRODUCED_IN_LLVM_15_ATTRIBUTE
+
+// This controls the availability of floating-point std::to_chars functions.
+// These overloads were added later than the integer overloads.
+#define _LIBCPP_AVAILABILITY_HAS_TO_CHARS_FLOATING_POINT _LIBCPP_INTRODUCED_IN_LLVM_14
+#define _LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT _LIBCPP_INTRODUCED_IN_LLVM_14_ATTRIBUTE
+
+// Enable additional explicit instantiations of iostreams components. This
+// reduces the number of weak definitions generated in programs that use
+// iostreams by providing a single strong definition in the shared library.
+//
+// TODO: Enable additional explicit instantiations on GCC once it supports exclude_from_explicit_instantiation,
+//       or once libc++ doesn't use the attribute anymore.
+// TODO: Enable them on Windows once https://llvm.org/PR41018 has been fixed.
+#if !defined(_LIBCPP_COMPILER_GCC) && !defined(_WIN32)
+#  define _LIBCPP_AVAILABILITY_HAS_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1 _LIBCPP_INTRODUCED_IN_LLVM_12
+#else
+#  define _LIBCPP_AVAILABILITY_HAS_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1 0
+#endif
+
 // Only define a bunch of symbols in the dylib if we need to be compatible with LLVM 7 headers or older
 #  if defined(_LIBCPP_BUILDING_LIBRARY) && _LIBCPP_AVAILABILITY_MINIMUM_HEADER_VERSION < 8
 #    define _LIBCPP_HIDE_FROM_ABI_SINCE_LLVM8

``````````

</details>


https://github.com/llvm/llvm-project/pull/176857
