[libcxx-commits] [libcxx] [libc++][test] Enhance `ADDITIONAL_COMPILE_FLAGS` to work with MSVC (PR #74974)

Sat Dec 9 22:17:51 PST 2023

https://github.com/StephanTLavavej created https://github.com/llvm/llvm-project/pull/74974

Found while running libc++'s tests with MSVC's STL.

The `ADDITIONAL_COMPILE_FLAGS` machinery is very useful, but also very problematic for MSVC, as it speaks Martian and doesn't understand most of Clang's compiler options. (`-Dmeow` is mutually intelligible and that's about it.) We've been dealing with this by simply marking anything that uses `ADDITIONAL_COMPILE_FLAGS` as `FAIL` or `SKIPPED`, but that creates significant gaps in test coverage.

Fortunately, `ADDITIONAL_COMPILE_FLAGS` also supports "features", which can be slightly enhanced to send Clang-compatible and MSVC-compatible options to the right compilers.

* Use the `verify-support` feature.
  + This is already defined by: https://github.com/llvm/llvm-project/blob/b85f1f9b182234ba366d78ae2174a149e44d08c1/libcxx/utils/libcxx/test/features.py#L167-L170
* Add a new feature `any-clang-or-gcc`.
  + The idea is that this should be defined for Apple Clang, vanilla Clang, or GCC, but not MSVC's `cl.exe`. Then this feature should be used when a test wants to compile with `-Wno-meow`. This is the only "ongoing maintenance" request here, which should be minimal and easy to fix if any occurrences are forgotten under `libcxx/test/std`.
* Add `ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-undefined-inline` to `range.lazy.split/constraints.compile.pass.cpp`.
  + As the comment explains, this is compile-only, so the warning is irrelevant.
* Add `ADDITIONAL_COMPILE_FLAGS(msvc-cl-exe)`.
  + The idea is that this should be defined for MSVC's `cl.exe` only. I'm adding such a definition to the MSVC STL test harness, which is why it doesn't appear here.
  + Note that the existing `msvc` feature is completely different - it indicates the presence of the `_MSC_VER` compiler macro, i.e. any compiler pretending to be MSVC. https://github.com/llvm/llvm-project/blob/b85f1f9b182234ba366d78ae2174a149e44d08c1/libcxx/utils/libcxx/test/features.py#L19 https://github.com/llvm/llvm-project/blob/b85f1f9b182234ba366d78ae2174a149e44d08c1/libcxx/utils/libcxx/test/features.py#L117
  + I've named `msvc-cl-exe` to make this distinction clear - it indicates the actual `cl.exe` compiler driver.
    - Fun fact, nobody knows what CL means anymore. I asked our longest-tenured compiler devs (30+ years!) and their best guess was "Compile and Link". :joy_cat:
  + Because MSVC's `/wdNNNN` isn't self-explanatory, I'm commenting every occurrence with what the warning message is.
  + Some warnings being silenced are sign/truncation warnings that were intentional (e.g. caused by calling STL algorithms with types that cause the STL to perform mixed-sign comparisons), or that were relatively innocuous and would be invasive or verbose to physically fix. I tried to fix as much as I could in #74962, #74965, and previous PRs.
  + Other warnings being silenced are counterparts of Clang warnings being silenced (e.g. `-Wno-deprecated-volatile`).
  + "warning C4197: top-level `volatile` in cast is ignored" is emitted for `T();` when `T` is `volatile atomic<Whatever>`, which is innocuous.
  + "warning C4611: interaction between '`_setjmp`' and C++ object destruction is non-portable" is emitted in `setjmp` tests. I didn't see any concerning usage.
  + "warning C4583: '`X::cv_`': destructor is not implicitly called" was emitted in a test that explicitly destroys `x.cv_` so it's fine.
  + There's *no* expectation that as libc++ tests are added, that `ADDITIONAL_COMPILE_FLAGS(msvc-cl-exe)` ought to be added accordingly. In fact, I'd prefer it if you didn't, allowing us to review such warnings as they appear. (Of course, if a test is copy-paste-modified, it would be reasonable to preserve any warning options that are unaffected by the modifications, that would never be a problem for us.)
* Add `ADDITIONAL_COMPILE_FLAGS(msvc-cl-exe)` to silence a blizzard of x86 truncation warnings.


>From e37385902de4323ad6fcc18f4f4d4cfe582a5c02 Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl at nuwen.net>
Date: Tue, 28 Nov 2023 17:37:49 -0800
Subject: [PATCH 1/5] Use the verify-support feature.

---
 .../atomics/atomics.types.generic/trivially_copyable.verify.cpp | 2 +-
 .../std/containers/views/views.span/span.sub/subspan.verify.cpp | 2 +-
 .../any/any.nonmembers/any.cast/const_correctness.verify.cpp    | 2 +-
 .../any.nonmembers/any.cast/not_copy_constructible.verify.cpp   | 2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/libcxx/test/std/atomics/atomics.types.generic/trivially_copyable.verify.cpp b/libcxx/test/std/atomics/atomics.types.generic/trivially_copyable.verify.cpp
index 0955707cdcf38f..80e77048ecd858 100644
--- a/libcxx/test/std/atomics/atomics.types.generic/trivially_copyable.verify.cpp
+++ b/libcxx/test/std/atomics/atomics.types.generic/trivially_copyable.verify.cpp
@@ -15,7 +15,7 @@
 // is not trivially copyable, however Clang will sometimes emit additional
 // errors while trying to instantiate the rest of std::atomic<T>.
 // We silence those to make the test more robust.
-// ADDITIONAL_COMPILE_FLAGS: -Xclang -verify-ignore-unexpected=error
+// ADDITIONAL_COMPILE_FLAGS(verify-support): -Xclang -verify-ignore-unexpected=error
 
 #include <atomic>
 
diff --git a/libcxx/test/std/containers/views/views.span/span.sub/subspan.verify.cpp b/libcxx/test/std/containers/views/views.span/span.sub/subspan.verify.cpp
index d6bc21197098a4..eb881707b1e648 100644
--- a/libcxx/test/std/containers/views/views.span/span.sub/subspan.verify.cpp
+++ b/libcxx/test/std/containers/views/views.span/span.sub/subspan.verify.cpp
@@ -9,7 +9,7 @@
 
 // This test also generates spurious warnings when instantiating std::span
 // with a very large extent (like size_t(-2)) -- silence those.
-// ADDITIONAL_COMPILE_FLAGS: -Xclang -verify-ignore-unexpected=warning
+// ADDITIONAL_COMPILE_FLAGS(verify-support): -Xclang -verify-ignore-unexpected=warning
 
 // <span>
 
diff --git a/libcxx/test/std/utilities/any/any.nonmembers/any.cast/const_correctness.verify.cpp b/libcxx/test/std/utilities/any/any.nonmembers/any.cast/const_correctness.verify.cpp
index 1830626d7f4103..04cae7801c5657 100644
--- a/libcxx/test/std/utilities/any/any.nonmembers/any.cast/const_correctness.verify.cpp
+++ b/libcxx/test/std/utilities/any/any.nonmembers/any.cast/const_correctness.verify.cpp
@@ -20,7 +20,7 @@
 // additional errors while trying to instantiate the rest of any_cast
 // following the static_assert. We ignore unexpected errors in
 // clang-verify to make the test more robust to changes in Clang.
-// ADDITIONAL_COMPILE_FLAGS: -Xclang -verify-ignore-unexpected=error
+// ADDITIONAL_COMPILE_FLAGS(verify-support): -Xclang -verify-ignore-unexpected=error
 
 #include <any>
 
diff --git a/libcxx/test/std/utilities/any/any.nonmembers/any.cast/not_copy_constructible.verify.cpp b/libcxx/test/std/utilities/any/any.nonmembers/any.cast/not_copy_constructible.verify.cpp
index 3b9aac581a083b..5aaca89e9e6794 100644
--- a/libcxx/test/std/utilities/any/any.nonmembers/any.cast/not_copy_constructible.verify.cpp
+++ b/libcxx/test/std/utilities/any/any.nonmembers/any.cast/not_copy_constructible.verify.cpp
@@ -26,7 +26,7 @@
 // additional errors while trying to instantiate the rest of any_cast
 // following the static_assert. We ignore unexpected errors in
 // clang-verify to make the test more robust to changes in Clang.
-// ADDITIONAL_COMPILE_FLAGS: -Xclang -verify-ignore-unexpected=error
+// ADDITIONAL_COMPILE_FLAGS(verify-support): -Xclang -verify-ignore-unexpected=error
 
 #include <any>
 

>From 4cc6dc0d187ae306f95635bbc7b88f3747e2fcfe Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl at nuwen.net>
Date: Wed, 29 Nov 2023 11:48:00 -0800
Subject: [PATCH 2/5] Add a new feature any-clang-or-gcc.

---
 .../std/algorithms/alg.nonmodifying/alg.equal/equal.pass.cpp   | 2 +-
 .../std/algorithms/alg.nonmodifying/alg.find/find.pass.cpp     | 2 +-
 .../algorithms/alg.nonmodifying/alg.find/ranges.find.pass.cpp  | 2 +-
 .../default_initializable.compile.pass.cpp                     | 2 +-
 .../associative/map/map.modifiers/insert_range.pass.cpp        | 2 +-
 .../multimap/multimap.modifiers/insert_range.pass.cpp          | 2 +-
 .../std/containers/associative/multiset/insert_range.pass.cpp  | 2 +-
 .../test/std/containers/associative/set/insert_range.pass.cpp  | 2 +-
 .../std/containers/sequences/array/array.tuple/get.verify.cpp  | 2 +-
 .../unord/unord.map/unord.map.modifiers/insert_range.pass.cpp  | 2 +-
 .../unord.multimap.modifiers/insert_range.pass.cpp             | 2 +-
 .../std/containers/unord/unord.multiset/insert_range.pass.cpp  | 2 +-
 .../test/std/containers/unord/unord.set/insert_range.pass.cpp  | 2 +-
 .../containers/views/mdspan/layout_stride/deduction.pass.cpp   | 2 +-
 .../depr/depr.numeric.limits.has.denorm/deprecated.verify.cpp  | 2 +-
 .../basic.string/string.cons/from_range_deduction.pass.cpp     | 2 +-
 libcxx/test/std/thread/thread.jthread/assign.move.pass.cpp     | 2 +-
 .../meta/meta.unary/dependent_return_type.compile.pass.cpp     | 2 +-
 .../unique.ptr/unique.ptr.class/unique.ptr.asgn/move.pass.cpp  | 2 +-
 .../utilities/variant/variant.variant/implicit_ctad.pass.cpp   | 2 +-
 libcxx/utils/libcxx/test/features.py                           | 3 +++
 21 files changed, 23 insertions(+), 20 deletions(-)

diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.equal/equal.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.equal/equal.pass.cpp
index e28cbe2a08de4a..e79bab5df379e0 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.equal/equal.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.equal/equal.pass.cpp
@@ -19,7 +19,7 @@
 //   equal(Iter1 first1, Iter1 last1, Iter2 first2, Iter2 last2);
 
 // We test the cartesian product, so we sometimes compare differently signed types
-// ADDITIONAL_COMPILE_FLAGS: -Wno-sign-compare
+// ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-sign-compare
 
 #include <algorithm>
 #include <cassert>
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.find/find.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.find/find.pass.cpp
index b55a852c10cafa..7853d7b528453f 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.find/find.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.find/find.pass.cpp
@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-// ADDITIONAL_COMPILE_FLAGS: -Wno-sign-compare
+// ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-sign-compare
 
 // <algorithm>
 
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.find/ranges.find.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.find/ranges.find.pass.cpp
index 22f938f73ae078..e4e2eb7117307f 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.find/ranges.find.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.find/ranges.find.pass.cpp
@@ -10,7 +10,7 @@
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 
-// ADDITIONAL_COMPILE_FLAGS: -Wno-sign-compare
+// ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-sign-compare
 
 // template<input_iterator I, sentinel_for<I> S, class T, class Proj = identity>
 //   requires indirect_binary_predicate<ranges::equal_to, projected<I, Proj>, const T*>
diff --git a/libcxx/test/std/concepts/concepts.lang/concept.default.init/default_initializable.compile.pass.cpp b/libcxx/test/std/concepts/concepts.lang/concept.default.init/default_initializable.compile.pass.cpp
index 4921a48bcccc17..87c3ed0f8803d9 100644
--- a/libcxx/test/std/concepts/concepts.lang/concept.default.init/default_initializable.compile.pass.cpp
+++ b/libcxx/test/std/concepts/concepts.lang/concept.default.init/default_initializable.compile.pass.cpp
@@ -10,7 +10,7 @@
 
 // We voluntarily use std::default_initializable on types that have redundant
 // or ignored cv-qualifiers -- don't warn about it.
-// ADDITIONAL_COMPILE_FLAGS: -Wno-ignored-qualifiers
+// ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-ignored-qualifiers
 
 // template<class T>
 //     concept default_initializable = constructible_from<T> &&
diff --git a/libcxx/test/std/containers/associative/map/map.modifiers/insert_range.pass.cpp b/libcxx/test/std/containers/associative/map/map.modifiers/insert_range.pass.cpp
index 1d7fe7193facf4..6f1c6388408539 100644
--- a/libcxx/test/std/containers/associative/map/map.modifiers/insert_range.pass.cpp
+++ b/libcxx/test/std/containers/associative/map/map.modifiers/insert_range.pass.cpp
@@ -8,7 +8,7 @@
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
 // Some fields in the test case variables are deliberately not explicitly initialized, this silences a warning on GCC.
-// ADDITIONAL_COMPILE_FLAGS: -Wno-missing-field-initializers
+// ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-missing-field-initializers
 
 // <map>
 
diff --git a/libcxx/test/std/containers/associative/multimap/multimap.modifiers/insert_range.pass.cpp b/libcxx/test/std/containers/associative/multimap/multimap.modifiers/insert_range.pass.cpp
index c7c05a896bc9f9..c9d259d03efe88 100644
--- a/libcxx/test/std/containers/associative/multimap/multimap.modifiers/insert_range.pass.cpp
+++ b/libcxx/test/std/containers/associative/multimap/multimap.modifiers/insert_range.pass.cpp
@@ -8,7 +8,7 @@
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
 // Some fields in the test case variables are deliberately not explicitly initialized, this silences a warning on GCC.
-// ADDITIONAL_COMPILE_FLAGS: -Wno-missing-field-initializers
+// ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-missing-field-initializers
 
 // <map>
 
diff --git a/libcxx/test/std/containers/associative/multiset/insert_range.pass.cpp b/libcxx/test/std/containers/associative/multiset/insert_range.pass.cpp
index 9dd85eea47c290..eb125f1520ec1b 100644
--- a/libcxx/test/std/containers/associative/multiset/insert_range.pass.cpp
+++ b/libcxx/test/std/containers/associative/multiset/insert_range.pass.cpp
@@ -8,7 +8,7 @@
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
 // Some fields in the test case variables are deliberately not explicitly initialized, this silences a warning on GCC.
-// ADDITIONAL_COMPILE_FLAGS: -Wno-missing-field-initializers
+// ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-missing-field-initializers
 
 // <set>
 
diff --git a/libcxx/test/std/containers/associative/set/insert_range.pass.cpp b/libcxx/test/std/containers/associative/set/insert_range.pass.cpp
index 1956fc6bd7f3ea..1ae7f7d5cd16e8 100644
--- a/libcxx/test/std/containers/associative/set/insert_range.pass.cpp
+++ b/libcxx/test/std/containers/associative/set/insert_range.pass.cpp
@@ -8,7 +8,7 @@
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
 // Some fields in the test case variables are deliberately not explicitly initialized, this silences a warning on GCC.
-// ADDITIONAL_COMPILE_FLAGS: -Wno-missing-field-initializers
+// ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-missing-field-initializers
 
 // <set>
 
diff --git a/libcxx/test/std/containers/sequences/array/array.tuple/get.verify.cpp b/libcxx/test/std/containers/sequences/array/array.tuple/get.verify.cpp
index 9052b4359f6b0a..c93ea75c221dac 100644
--- a/libcxx/test/std/containers/sequences/array/array.tuple/get.verify.cpp
+++ b/libcxx/test/std/containers/sequences/array/array.tuple/get.verify.cpp
@@ -11,7 +11,7 @@
 // template <size_t I, class T, size_t N> T& get(array<T, N>& a);
 
 // Prevent -Warray-bounds from issuing a diagnostic when testing with clang verify.
-// ADDITIONAL_COMPILE_FLAGS: -Wno-array-bounds
+// ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-array-bounds
 
 #include <array>
 #include <cassert>
diff --git a/libcxx/test/std/containers/unord/unord.map/unord.map.modifiers/insert_range.pass.cpp b/libcxx/test/std/containers/unord/unord.map/unord.map.modifiers/insert_range.pass.cpp
index 8b004336f68cde..f524273bdda03d 100644
--- a/libcxx/test/std/containers/unord/unord.map/unord.map.modifiers/insert_range.pass.cpp
+++ b/libcxx/test/std/containers/unord/unord.map/unord.map.modifiers/insert_range.pass.cpp
@@ -8,7 +8,7 @@
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
 // Some fields in the test case variables are deliberately not explicitly initialized, this silences a warning on GCC.
-// ADDITIONAL_COMPILE_FLAGS: -Wno-missing-field-initializers
+// ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-missing-field-initializers
 
 // <unordered_map>
 
diff --git a/libcxx/test/std/containers/unord/unord.multimap/unord.multimap.modifiers/insert_range.pass.cpp b/libcxx/test/std/containers/unord/unord.multimap/unord.multimap.modifiers/insert_range.pass.cpp
index fcde119f487030..7219225ff16d95 100644
--- a/libcxx/test/std/containers/unord/unord.multimap/unord.multimap.modifiers/insert_range.pass.cpp
+++ b/libcxx/test/std/containers/unord/unord.multimap/unord.multimap.modifiers/insert_range.pass.cpp
@@ -8,7 +8,7 @@
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
 // Some fields in the test case variables are deliberately not explicitly initialized, this silences a warning on GCC.
-// ADDITIONAL_COMPILE_FLAGS: -Wno-missing-field-initializers
+// ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-missing-field-initializers
 
 // <unordered_map>
 
diff --git a/libcxx/test/std/containers/unord/unord.multiset/insert_range.pass.cpp b/libcxx/test/std/containers/unord/unord.multiset/insert_range.pass.cpp
index 73ac4cf071e1bb..119091c007cb03 100644
--- a/libcxx/test/std/containers/unord/unord.multiset/insert_range.pass.cpp
+++ b/libcxx/test/std/containers/unord/unord.multiset/insert_range.pass.cpp
@@ -8,7 +8,7 @@
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
 // Some fields in the test case variables are deliberately not explicitly initialized, this silences a warning on GCC.
-// ADDITIONAL_COMPILE_FLAGS: -Wno-missing-field-initializers
+// ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-missing-field-initializers
 
 // <set>
 
diff --git a/libcxx/test/std/containers/unord/unord.set/insert_range.pass.cpp b/libcxx/test/std/containers/unord/unord.set/insert_range.pass.cpp
index c6306a28b7adb5..d9503808c7f2cb 100644
--- a/libcxx/test/std/containers/unord/unord.set/insert_range.pass.cpp
+++ b/libcxx/test/std/containers/unord/unord.set/insert_range.pass.cpp
@@ -8,7 +8,7 @@
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
 // Some fields in the test case variables are deliberately not explicitly initialized, this silences a warning on GCC.
-// ADDITIONAL_COMPILE_FLAGS: -Wno-missing-field-initializers
+// ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-missing-field-initializers
 
 // <set>
 
diff --git a/libcxx/test/std/containers/views/mdspan/layout_stride/deduction.pass.cpp b/libcxx/test/std/containers/views/mdspan/layout_stride/deduction.pass.cpp
index 0e0a079b598bc0..5384f37fd40c78 100644
--- a/libcxx/test/std/containers/views/mdspan/layout_stride/deduction.pass.cpp
+++ b/libcxx/test/std/containers/views/mdspan/layout_stride/deduction.pass.cpp
@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
-// ADDITIONAL_COMPILE_FLAGS: -Wno-ctad-maybe-unsupported
+// ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-ctad-maybe-unsupported
 
 // <mdspan>
 
diff --git a/libcxx/test/std/depr/depr.numeric.limits.has.denorm/deprecated.verify.cpp b/libcxx/test/std/depr/depr.numeric.limits.has.denorm/deprecated.verify.cpp
index 98d49de80a58cf..9aa0d0b21d1e0a 100644
--- a/libcxx/test/std/depr/depr.numeric.limits.has.denorm/deprecated.verify.cpp
+++ b/libcxx/test/std/depr/depr.numeric.limits.has.denorm/deprecated.verify.cpp
@@ -8,7 +8,7 @@
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
 
-// ADDITIONAL_COMPILE_FLAGS: -Wno-unused-value
+// ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-unused-value
 
 #include <limits>
 
diff --git a/libcxx/test/std/strings/basic.string/string.cons/from_range_deduction.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/from_range_deduction.pass.cpp
index b2dab03506f03a..698f6d834f8607 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/from_range_deduction.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/from_range_deduction.pass.cpp
@@ -10,7 +10,7 @@
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
 // To silence a GCC warning-turned-error re. `BadAlloc::value_type`.
-// ADDITIONAL_COMPILE_FLAGS: -Wno-unused-local-typedefs
+// ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-unused-local-typedefs
 
 // template<ranges::input_range R,
 //          class Allocator = allocator<ranges::range_value_t<R>>>
diff --git a/libcxx/test/std/thread/thread.jthread/assign.move.pass.cpp b/libcxx/test/std/thread/thread.jthread/assign.move.pass.cpp
index 89521ad7660a12..cb92e02faa4f22 100644
--- a/libcxx/test/std/thread/thread.jthread/assign.move.pass.cpp
+++ b/libcxx/test/std/thread/thread.jthread/assign.move.pass.cpp
@@ -10,7 +10,7 @@
 // UNSUPPORTED: libcpp-has-no-experimental-stop_token
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // XFAIL: availability-synchronization_library-missing
-// ADDITIONAL_COMPILE_FLAGS: -Wno-self-move
+// ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-self-move
 
 // jthread& operator=(jthread&&) noexcept;
 
diff --git a/libcxx/test/std/utilities/meta/meta.unary/dependent_return_type.compile.pass.cpp b/libcxx/test/std/utilities/meta/meta.unary/dependent_return_type.compile.pass.cpp
index b382940423e056..390cb1ca6a4351 100644
--- a/libcxx/test/std/utilities/meta/meta.unary/dependent_return_type.compile.pass.cpp
+++ b/libcxx/test/std/utilities/meta/meta.unary/dependent_return_type.compile.pass.cpp
@@ -11,7 +11,7 @@
 // UNSUPPORTED: c++03, c++11
 
 // ignore deprecated volatile return types
-// ADDITIONAL_COMPILE_FLAGS: -Wno-deprecated-volatile
+// ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-deprecated-volatile
 
 #include <type_traits>
 #include <utility>
diff --git a/libcxx/test/std/utilities/smartptr/unique.ptr/unique.ptr.class/unique.ptr.asgn/move.pass.cpp b/libcxx/test/std/utilities/smartptr/unique.ptr/unique.ptr.class/unique.ptr.asgn/move.pass.cpp
index 80d75e721e52e5..1c87019b9ea67a 100644
--- a/libcxx/test/std/utilities/smartptr/unique.ptr/unique.ptr.class/unique.ptr.asgn/move.pass.cpp
+++ b/libcxx/test/std/utilities/smartptr/unique.ptr/unique.ptr.class/unique.ptr.asgn/move.pass.cpp
@@ -9,7 +9,7 @@
 // UNSUPPORTED: c++03
 
 // Self assignment post-conditions are tested.
-// ADDITIONAL_COMPILE_FLAGS: -Wno-self-move
+// ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-self-move
 
 // <memory>
 
diff --git a/libcxx/test/std/utilities/variant/variant.variant/implicit_ctad.pass.cpp b/libcxx/test/std/utilities/variant/variant.variant/implicit_ctad.pass.cpp
index 514c1f87faad06..b090291aeba482 100644
--- a/libcxx/test/std/utilities/variant/variant.variant/implicit_ctad.pass.cpp
+++ b/libcxx/test/std/utilities/variant/variant.variant/implicit_ctad.pass.cpp
@@ -17,7 +17,7 @@
 // We make sure that it is not ill-formed, however we still produce a warning for
 // this one because explicit construction from a variant using CTAD is ambiguous
 // (in the sense that the programer intent is not clear).
-// ADDITIONAL_COMPILE_FLAGS: -Wno-ctad-maybe-unsupported
+// ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-ctad-maybe-unsupported
 
 #include <variant>
 
diff --git a/libcxx/utils/libcxx/test/features.py b/libcxx/utils/libcxx/test/features.py
index 5e854917e6ef45..2e553dc45b6376 100644
--- a/libcxx/utils/libcxx/test/features.py
+++ b/libcxx/utils/libcxx/test/features.py
@@ -61,6 +61,9 @@ def _getAndroidDeviceApi(cfg):
 # Lit features are evaluated in order. Some checks may require the compiler detection to have
 # run first in order to work properly.
 DEFAULT_FEATURES = [
+    # This detects compilers that understand the -Wno-meow family of flags, unlike MSVC's compiler driver cl.exe.
+    Feature(name="any-clang-or-gcc", when=_isAppleClang or _isClang or _isGCC),
+
     Feature(name="apple-clang", when=_isAppleClang),
     Feature(
         name=lambda cfg: "apple-clang-{__clang_major__}".format(**compilerMacros(cfg)),

>From 7f2db6292732214c887eb127c20d75ac356b5b7b Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl at nuwen.net>
Date: Sat, 2 Dec 2023 16:13:46 -0800
Subject: [PATCH 3/5] Add ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc).

---
 .../range.lazy.split/constraints.compile.pass.cpp              | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libcxx/test/std/ranges/range.adaptors/range.lazy.split/constraints.compile.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.lazy.split/constraints.compile.pass.cpp
index a942f439040929..2a772ccb83f811 100644
--- a/libcxx/test/std/ranges/range.adaptors/range.lazy.split/constraints.compile.pass.cpp
+++ b/libcxx/test/std/ranges/range.adaptors/range.lazy.split/constraints.compile.pass.cpp
@@ -8,6 +8,9 @@
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 
+// This is a compile-only test, so "inline function is not defined" warnings are irrelevant.
+// ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-undefined-inline
+
 // template<input_range V, forward_range Pattern>
 //   requires view<V> && view<Pattern> &&
 //            indirectly_comparable<iterator_t<V>, iterator_t<Pattern>, ranges::equal_to> &&

>From ee4b92594c82b8290822562b56834889cccfc9ed Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl at nuwen.net>
Date: Wed, 29 Nov 2023 20:16:10 -0800
Subject: [PATCH 4/5] Add ADDITIONAL_COMPILE_FLAGS(msvc-cl-exe).

---
 .../alg.replace/ranges.replace.pass.cpp                      | 3 +++
 .../std/algorithms/alg.nonmodifying/alg.equal/equal.pass.cpp | 5 +++++
 .../std/algorithms/alg.nonmodifying/alg.find/find.pass.cpp   | 2 ++
 .../alg.nonmodifying/alg.find/ranges.find.pass.cpp           | 3 +++
 .../atomics/atomics.types.generic/general.compile.pass.cpp   | 3 +++
 .../atomics/atomics.types.generic/pointer.compile.pass.cpp   | 3 +++
 .../std/containers/views/mdspan/mdspan/conversion.pass.cpp   | 3 +++
 .../test/std/depr/depr.c.headers/setjmp_h.compile.pass.cpp   | 3 +++
 .../std/language.support/support.runtime/csetjmp.pass.cpp    | 3 +++
 .../std/ranges/range.utility/range.utility.conv/to.pass.cpp  | 3 +++
 .../notify_all_at_thread_exit_lwg3343.pass.cpp               | 3 +++
 .../meta/meta.unary/dependent_return_type.compile.pass.cpp   | 2 ++
 12 files changed, 36 insertions(+)

diff --git a/libcxx/test/std/algorithms/alg.modifying.operations/alg.replace/ranges.replace.pass.cpp b/libcxx/test/std/algorithms/alg.modifying.operations/alg.replace/ranges.replace.pass.cpp
index ab2f705bafe9d0..32da9345c97e15 100644
--- a/libcxx/test/std/algorithms/alg.modifying.operations/alg.replace/ranges.replace.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.modifying.operations/alg.replace/ranges.replace.pass.cpp
@@ -6,6 +6,9 @@
 //
 //===----------------------------------------------------------------------===//
 
+// MSVC warning C4244: 'argument': conversion from 'const _Ty2' to 'T', possible loss of data
+// ADDITIONAL_COMPILE_FLAGS(msvc-cl-exe): /wd4244
+
 // <algorithm>
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.equal/equal.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.equal/equal.pass.cpp
index e79bab5df379e0..93ca4827a6e54d 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.equal/equal.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.equal/equal.pass.cpp
@@ -20,6 +20,11 @@
 
 // We test the cartesian product, so we sometimes compare differently signed types
 // ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-sign-compare
+// MSVC warning C4242: 'argument': conversion from 'int' to 'const _Ty', possible loss of data
+// MSVC warning C4244: 'argument': conversion from 'wchar_t' to 'const _Ty', possible loss of data
+// MSVC warning C4310: cast truncates constant value
+// MSVC warning C4389: '==': signed/unsigned mismatch
+// ADDITIONAL_COMPILE_FLAGS(msvc-cl-exe): /wd4242 /wd4244 /wd4310 /wd4389
 
 #include <algorithm>
 #include <cassert>
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.find/find.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.find/find.pass.cpp
index 7853d7b528453f..64fcf9976f772c 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.find/find.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.find/find.pass.cpp
@@ -7,6 +7,8 @@
 //===----------------------------------------------------------------------===//
 
 // ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-sign-compare
+// MSVC warning C4389: '==': signed/unsigned mismatch
+// ADDITIONAL_COMPILE_FLAGS(msvc-cl-exe): /wd4389
 
 // <algorithm>
 
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.find/ranges.find.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.find/ranges.find.pass.cpp
index e4e2eb7117307f..3b60495b6667d2 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.find/ranges.find.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.find/ranges.find.pass.cpp
@@ -11,6 +11,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 
 // ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-sign-compare
+// MSVC warning C4242: 'argument': conversion from 'const _Ty' to 'ElementT', possible loss of data
+// MSVC warning C4244: 'argument': conversion from 'const _Ty' to 'ElementT', possible loss of data
+// ADDITIONAL_COMPILE_FLAGS(msvc-cl-exe): /wd4242 /wd4244
 
 // template<input_iterator I, sentinel_for<I> S, class T, class Proj = identity>
 //   requires indirect_binary_predicate<ranges::equal_to, projected<I, Proj>, const T*>
diff --git a/libcxx/test/std/atomics/atomics.types.generic/general.compile.pass.cpp b/libcxx/test/std/atomics/atomics.types.generic/general.compile.pass.cpp
index 9f2a28256184ce..c43c2e5ac95372 100644
--- a/libcxx/test/std/atomics/atomics.types.generic/general.compile.pass.cpp
+++ b/libcxx/test/std/atomics/atomics.types.generic/general.compile.pass.cpp
@@ -6,6 +6,9 @@
 //
 //===----------------------------------------------------------------------===//
 
+// MSVC warning C4197: 'volatile std::atomic<operator_hijacker>': top-level volatile in cast is ignored
+// ADDITIONAL_COMPILE_FLAGS(msvc-cl-exe): /wd4197
+
 // UNSUPPORTED: c++03
 
 // XFAIL: availability-synchronization_library-missing
diff --git a/libcxx/test/std/atomics/atomics.types.generic/pointer.compile.pass.cpp b/libcxx/test/std/atomics/atomics.types.generic/pointer.compile.pass.cpp
index 9049beaa9c7897..acc5464e5f690f 100644
--- a/libcxx/test/std/atomics/atomics.types.generic/pointer.compile.pass.cpp
+++ b/libcxx/test/std/atomics/atomics.types.generic/pointer.compile.pass.cpp
@@ -6,6 +6,9 @@
 //
 //===----------------------------------------------------------------------===//
 
+// MSVC warning C4197: 'volatile std::atomic<operator_hijacker *>': top-level volatile in cast is ignored
+// ADDITIONAL_COMPILE_FLAGS(msvc-cl-exe): /wd4197
+
 // UNSUPPORTED: c++03
 
 // XFAIL: availability-synchronization_library-missing
diff --git a/libcxx/test/std/containers/views/mdspan/mdspan/conversion.pass.cpp b/libcxx/test/std/containers/views/mdspan/mdspan/conversion.pass.cpp
index abb647e960c34e..99d786d1d33f5b 100644
--- a/libcxx/test/std/containers/views/mdspan/mdspan/conversion.pass.cpp
+++ b/libcxx/test/std/containers/views/mdspan/mdspan/conversion.pass.cpp
@@ -7,6 +7,9 @@
 //===----------------------------------------------------------------------===//
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
 
+// MSVC warning C4244: 'initializing': conversion from '_Ty' to '_Ty', possible loss of data
+// ADDITIONAL_COMPILE_FLAGS(msvc-cl-exe): /wd4244
+
 // <mdspan>
 
 // template<class OtherElementType, class OtherExtents,
diff --git a/libcxx/test/std/depr/depr.c.headers/setjmp_h.compile.pass.cpp b/libcxx/test/std/depr/depr.c.headers/setjmp_h.compile.pass.cpp
index eaaeecbeb70ec8..feeefc1194e85a 100644
--- a/libcxx/test/std/depr/depr.c.headers/setjmp_h.compile.pass.cpp
+++ b/libcxx/test/std/depr/depr.c.headers/setjmp_h.compile.pass.cpp
@@ -6,6 +6,9 @@
 //
 //===----------------------------------------------------------------------===//
 
+// MSVC warning C4611: interaction between '_setjmp' and C++ object destruction is non-portable
+// ADDITIONAL_COMPILE_FLAGS(msvc-cl-exe): /wd4611
+
 // test <setjmp.h>
 //
 // Even though <setjmp.h> is not provided by libc++, we still test that
diff --git a/libcxx/test/std/language.support/support.runtime/csetjmp.pass.cpp b/libcxx/test/std/language.support/support.runtime/csetjmp.pass.cpp
index d6d32c371b9e5c..c95ebcf8c4b9de 100644
--- a/libcxx/test/std/language.support/support.runtime/csetjmp.pass.cpp
+++ b/libcxx/test/std/language.support/support.runtime/csetjmp.pass.cpp
@@ -6,6 +6,9 @@
 //
 //===----------------------------------------------------------------------===//
 
+// MSVC warning C4611: interaction between '_setjmp' and C++ object destruction is non-portable
+// ADDITIONAL_COMPILE_FLAGS(msvc-cl-exe): /wd4611
+
 // test <csetjmp>
 
 #include <csetjmp>
diff --git a/libcxx/test/std/ranges/range.utility/range.utility.conv/to.pass.cpp b/libcxx/test/std/ranges/range.utility/range.utility.conv/to.pass.cpp
index 03270f25fd92b2..719e6e818b68e0 100644
--- a/libcxx/test/std/ranges/range.utility/range.utility.conv/to.pass.cpp
+++ b/libcxx/test/std/ranges/range.utility/range.utility.conv/to.pass.cpp
@@ -6,6 +6,9 @@
 //
 //===----------------------------------------------------------------------===//
 
+// MSVC warning C4244: 'argument': conversion from '_Ty' to 'int', possible loss of data
+// ADDITIONAL_COMPILE_FLAGS(msvc-cl-exe): /wd4244
+
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
 
 // template<class C, input_range R, class... Args> requires (!view<C>)
diff --git a/libcxx/test/std/thread/thread.condition/notify_all_at_thread_exit_lwg3343.pass.cpp b/libcxx/test/std/thread/thread.condition/notify_all_at_thread_exit_lwg3343.pass.cpp
index ffb632a5149b5e..992ff4a6cfadf3 100644
--- a/libcxx/test/std/thread/thread.condition/notify_all_at_thread_exit_lwg3343.pass.cpp
+++ b/libcxx/test/std/thread/thread.condition/notify_all_at_thread_exit_lwg3343.pass.cpp
@@ -17,6 +17,9 @@
 // UNSUPPORTED: stdlib=apple-libc++ && target={{.+}}-apple-macosx10.{{.+}}
 // UNSUPPORTED: stdlib=apple-libc++ && target={{.+}}-apple-macosx11.{{.+}}
 
+// MSVC warning C4583: 'X::cv_': destructor is not implicitly called
+// ADDITIONAL_COMPILE_FLAGS(msvc-cl-exe): /wd4583
+
 // This is a regression test for LWG3343.
 //
 // <condition_variable>
diff --git a/libcxx/test/std/utilities/meta/meta.unary/dependent_return_type.compile.pass.cpp b/libcxx/test/std/utilities/meta/meta.unary/dependent_return_type.compile.pass.cpp
index 390cb1ca6a4351..22b718bfcadc9b 100644
--- a/libcxx/test/std/utilities/meta/meta.unary/dependent_return_type.compile.pass.cpp
+++ b/libcxx/test/std/utilities/meta/meta.unary/dependent_return_type.compile.pass.cpp
@@ -12,6 +12,8 @@
 
 // ignore deprecated volatile return types
 // ADDITIONAL_COMPILE_FLAGS(any-clang-or-gcc): -Wno-deprecated-volatile
+// MSVC warning C5216: 'volatile int' a volatile qualified return type is deprecated in C++20
+// ADDITIONAL_COMPILE_FLAGS(msvc-cl-exe): /wd5216
 
 #include <type_traits>
 #include <utility>

>From d99d3117dd818618f7af794bf35fdcd3cb06d619 Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl at nuwen.net>
Date: Fri, 8 Dec 2023 14:27:39 -0800
Subject: [PATCH 5/5] Add ADDITIONAL_COMPILE_FLAGS(msvc-cl-exe) to silence a
 blizzard of x86 truncation warnings.

---
 .../fstreams/ifstream.members/buffered_reads.pass.cpp          | 3 +++
 .../fstreams/ofstream.members/buffered_writes.pass.cpp         | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/buffered_reads.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/buffered_reads.pass.cpp
index d57b7c20a2da27..e6a6b650800b6b 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/buffered_reads.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/buffered_reads.pass.cpp
@@ -7,6 +7,9 @@
 //===----------------------------------------------------------------------===//
 
 // ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_DISABLE_DEPRECATION_WARNINGS -D_LIBCPP_ENABLE_CXX26_REMOVED_CODECVT
+// MSVC warning C4242: '+=': conversion from 'const _Ty' to 'size_t', possible loss of data
+// MSVC warning C4244: 'argument': conversion from 'std::streamsize' to 'size_t', possible loss of data
+// ADDITIONAL_COMPILE_FLAGS(msvc-cl-exe): /wd4242 /wd4244
 // UNSUPPORTED: c++03
 
 // <fstream>
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/buffered_writes.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/buffered_writes.pass.cpp
index e7820739505106..697ea7233de494 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/buffered_writes.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/buffered_writes.pass.cpp
@@ -7,6 +7,9 @@
 //===----------------------------------------------------------------------===//
 
 // ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_DISABLE_DEPRECATION_WARNINGS -D_LIBCPP_ENABLE_CXX26_REMOVED_CODECVT
+// MSVC warning C4242: '+=': conversion from 'const _Ty' to 'size_t', possible loss of data
+// MSVC warning C4244: 'argument': conversion from 'std::streamsize' to 'size_t', possible loss of data
+// ADDITIONAL_COMPILE_FLAGS(msvc-cl-exe): /wd4242 /wd4244
 // UNSUPPORTED: c++03
 
 // <fstream>

