[libc++][test] Fix msvc_is_lock_free_macro_value()

[StephanTLavavej]

Followup to #99570.

• TEST_COMPILER_MSVC must be tested for definedness, as it is everywhere else.
  • Definition:

    llvm-project/libcxx/test/support/test_macros.h

    Lines 71 to 72 in 52a7116

    	#elif defined(_MSC_VER)
    	# define TEST_COMPILER_MSVC

  • Example usage:

    llvm-project/libcxx/test/std/utilities/function.objects/func.not_fn/not_fn.pass.cpp

    Line 248 in 52a7116

    #ifdef TEST_COMPILER_MSVC

  • Fixes: llvm-project\libcxx\test\support\atomic_helpers.h(33): fatal error C1017: invalid integer constant expression
• Fix bogus return type: msvc_is_lock_free_macro_value() returns 2 or 0, so it needs to return int.
  • Fixes: llvm-project\libcxx\test\support\atomic_helpers.h(41): warning C4305: 'return': truncation from 'int' to 'bool'
• Clarity improvement: also add parens when mixing bitwise with arithmetic operators.

[llvmbot]

@llvm/pr-subscribers-libcxx

Author: Stephan T. Lavavej (StephanTLavavej)

Changes

Followup to #99570.

• TEST_COMPILER_MSVC must be tested for definedness, as it is everywhere else.
  • Definition:

    llvm-project/libcxx/test/support/test_macros.h

    Lines 71 to 72 in 52a7116

    	#elif defined(_MSC_VER)
    	# define TEST_COMPILER_MSVC

  • Example usage:

    llvm-project/libcxx/test/std/utilities/function.objects/func.not_fn/not_fn.pass.cpp

    Line 248 in 52a7116

    #ifdef TEST_COMPILER_MSVC

  • Fixes: llvm-project\libcxx\test\support\atomic_helpers.h(33): fatal error C1017: invalid integer constant expression
• Fix bogus return type: msvc_is_lock_free_macro_value() returns 2 or 0, so it needs to return int.
  • Fixes: llvm-project\libcxx\test\support\atomic_helpers.h(41): warning C4305: 'return': truncation from 'int' to 'bool'
• Clarity improvement: also add parens when mixing bitwise with arithmetic operators.

---

Full diff: https://github.com/llvm/llvm-project/pull/105876.diff

1 Files Affected:

• (modified) libcxx/test/support/atomic_helpers.h (+3-3)

diff --git a/libcxx/test/support/atomic_helpers.h b/libcxx/test/support/atomic_helpers.h
index d2f2b751cb47de..2b3a3caa06a589 100644
--- a/libcxx/test/support/atomic_helpers.h
+++ b/libcxx/test/support/atomic_helpers.h
@@ -30,15 +30,15 @@
 #  define TEST_ATOMIC_LONG_LOCK_FREE __GCC_ATOMIC_LONG_LOCK_FREE
 #  define TEST_ATOMIC_LLONG_LOCK_FREE __GCC_ATOMIC_LLONG_LOCK_FREE
 #  define TEST_ATOMIC_POINTER_LOCK_FREE __GCC_ATOMIC_POINTER_LOCK_FREE
-#elif TEST_COMPILER_MSVC
+#elif defined(TEST_COMPILER_MSVC)
 // This is lifted from STL/stl/inc/atomic on github for the purposes of
 // keeping the tests compiling for MSVC's STL. It's not a perfect solution
 // but at least the tests will keep running.
 //
 // Note MSVC's STL never produces a type that is sometimes lock free, but not always lock free.
 template <class T, size_t Size = sizeof(T)>
-constexpr bool msvc_is_lock_free_macro_value() {
-  return (Size <= 8 && (Size & Size - 1) == 0) ? 2 : 0;
+constexpr int msvc_is_lock_free_macro_value() {
+  return (Size <= 8 && (Size & (Size - 1)) == 0) ? 2 : 0;
 }
 #  define TEST_ATOMIC_CHAR_LOCK_FREE ::msvc_is_lock_free_macro_value<char>()
 #  define TEST_ATOMIC_SHORT_LOCK_FREE ::msvc_is_lock_free_macro_value<short>()

[StephanTLavavej]

Thanks! I'll go ahead and merge this as all of the GH checks have passed, and all of the BuildKite checks except that 4 Apple configurations have been waiting for agents for 21 hours - my changes are very clearly limited to MSVC so there should be no concern there.