[libcxx-commits] [libcxx] [libc++][test] Fix `msvc_is_lock_free_macro_value()` (PR #105876)

[Stephan T. Lavavej via libcxx-commits]

https://github.com/StephanTLavavej created https://github.com/llvm/llvm-project/pull/105876

Followup to #99570.

* `TEST_COMPILER_MSVC` must be tested for `defined`ness, as it is everywhere else.
  + Definition: https://github.com/llvm/llvm-project/blob/52a7116f5c6ada234f47f7794aaf501a3692b997/libcxx/test/support/test_macros.h#L71-L72
  + Example usage: https://github.com/llvm/llvm-project/blob/52a7116f5c6ada234f47f7794aaf501a3692b997/libcxx/test/std/utilities/function.objects/func.not_fn/not_fn.pass.cpp#L248
  + 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.


>From 31cdf1163d48b51b17b36927fbd96bd8b92a2753 Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl at nuwen.net>
Date: Fri, 23 Aug 2024 12:01:33 -0700
Subject: [PATCH 1/2] Test defined(TEST_COMPILER_MSVC).

Followup to LLVM-99570.

Fixes:
llvm-project\libcxx\test\support\atomic_helpers.h(33): fatal error C1017: invalid integer constant expression
---
 libcxx/test/support/atomic_helpers.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libcxx/test/support/atomic_helpers.h b/libcxx/test/support/atomic_helpers.h
index d2f2b751cb47de..6b1bd55787f926 100644
--- a/libcxx/test/support/atomic_helpers.h
+++ b/libcxx/test/support/atomic_helpers.h
@@ -30,7 +30,7 @@
 #  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.

>From a0a387a43f075a4a4ab1ea3e0201f8416238aa2a Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl at nuwen.net>
Date: Fri, 23 Aug 2024 12:11:46 -0700
Subject: [PATCH 2/2] Fix bogus return type.

Fixes:
llvm-project\libcxx\test\support\atomic_helpers.h(41): warning C4305: 'return': truncation from 'int' to 'bool'

For clarity, also add parens when mixing bitwise with arithmetic operators.
---
 libcxx/test/support/atomic_helpers.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libcxx/test/support/atomic_helpers.h b/libcxx/test/support/atomic_helpers.h
index 6b1bd55787f926..2b3a3caa06a589 100644
--- a/libcxx/test/support/atomic_helpers.h
+++ b/libcxx/test/support/atomic_helpers.h
@@ -37,8 +37,8 @@
 //
 // 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>()