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<__msvc_math.hpp>: Restore and test _USE_MATH_DEFINES support #6446

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Stephan T. Lavavej (StephanTLavavej) wants to merge 1 commit into
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<__msvc_math.hpp>: Restore and test _USE_MATH_DEFINES support #6446

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7 changes: 7 additions & 0 deletions stl/inc/__msvc_math.hpp
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Expand Up @@ -23,6 +23,13 @@ _STL_DISABLE_CLANG_WARNINGS
#pragma push_macro("new")
#undef new

// https://learn.microsoft.com/cpp/c-runtime-library/math-constants
// These non-Standard macros (`M_PI` etc.) are widely used, but at least they're opt-in.
// The <numbers> header is a Standard alternative.
#ifdef _USE_MATH_DEFINES
#include <corecrt_math_defines.h>
#endif

extern "C++" {
namespace _Msvc { // duplicate type traits not provided by <yvals_core.h>
template <class _Ty>
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4 changes: 4 additions & 0 deletions tests/std/tests/P0533R9_constexpr_for_cmath_and_cstdlib/env.lst
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Expand Up @@ -24,6 +24,8 @@ PM_CL="/EHsc /Zc:cmath /std:c++latest /MD"
PM_CL="/EHsc /Zc:cmath /std:c++latest /MDd"
PM_CL="/EHsc /Zc:cmath /std:c++latest /MT"
PM_CL="/EHsc /Zc:cmath /std:c++latest /MTd"
# And test the non-Standard macros:
PM_CL="/EHsc /Zc:cmath /std:c++latest /MTd /D_USE_MATH_DEFINES"

# Explicitly disable libc-based math:
PM_CL="/EHsc /Zc:cmath- /std:c++14 /MD"
Expand All @@ -46,3 +48,5 @@ PM_CL="/EHsc /Zc:cmath- /std:c++latest /MD"
PM_CL="/EHsc /Zc:cmath- /std:c++latest /MDd"
PM_CL="/EHsc /Zc:cmath- /std:c++latest /MT"
PM_CL="/EHsc /Zc:cmath- /std:c++latest /MTd"
# And test the non-Standard macros:
PM_CL="/EHsc /Zc:cmath- /std:c++latest /MTd /D_USE_MATH_DEFINES"
6 changes: 6 additions & 0 deletions tests/std/tests/P0533R9_constexpr_for_cmath_and_cstdlib/test.cpp
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Expand Up @@ -690,3 +690,9 @@ int main() {
#endif // ^^^ _HAS_CXX26 && defined(_MSVC_LIBC_MATH) ^^^
#endif // ^^^ defined(__cpp_lib_constexpr_cmath) ^^^
}

#ifdef _USE_MATH_DEFINES
static_assert(static_cast<int>(M_PI * 100.0) == 314, "Unexpected value for M_PI, reboot universe and try again.");
#elif defined(M_PI)
static_assert(false, "When _USE_MATH_DEFINES is not defined, M_PI should not be defined.");
#endif // ^^^ defined(M_PI) ^^^