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Make MSVC use [[nodiscard]] #2615

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Nov 26, 2021
Merged

Make MSVC use [[nodiscard]] #2615

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Make MSVC use [[nodiscard]]
AlexGuteniev Nov 25, 2021
21eaab9
Merge remote-tracking branch 'upstream/master' into nodiscard
AlexGuteniev Nov 25, 2021
6a13275
It was not me!
AlexGuteniev Nov 25, 2021
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13 changes: 9 additions & 4 deletions include/fmt/core.h
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Original file line number Diff line number Diff line change
Expand Up @@ -82,11 +82,17 @@
# define FMT_HAS_CPP_ATTRIBUTE(x) 0
#endif

#ifdef _MSVC_LANG
# define FMT_CPLUSPLUS _MSVC_LANG
#else
# define FMT_CPLUSPLUS __cplusplus
#endif
Comment on lines +85 to +89
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What is going on here? Doesn't MSVC use the standard __cplusplus macro?

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/Zc:__cplusplus enables updated C++ macro. By default __cplusplus is defined to some ancient value.

As I read in MSVC STL chat, the reason for this default behavior is the compatibility with some open-source code, in which higher __cplusplus values enable not only legitimate C++ features, but also gcc extensions.

You already had _MSVC_LANG for [[fallthrough]], I'm just propagating it a bit further.


#define FMT_HAS_CPP14_ATTRIBUTE(attribute) \
(__cplusplus >= 201402L && FMT_HAS_CPP_ATTRIBUTE(attribute))
(FMT_CPLUSPLUS >= 201402L && FMT_HAS_CPP_ATTRIBUTE(attribute))

#define FMT_HAS_CPP17_ATTRIBUTE(attribute) \
(__cplusplus >= 201703L && FMT_HAS_CPP_ATTRIBUTE(attribute))
(FMT_CPLUSPLUS >= 201703L && FMT_HAS_CPP_ATTRIBUTE(attribute))
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// Check if relaxed C++14 constexpr is supported.
// GCC doesn't allow throw in constexpr until version 6 (bug 67371).
Expand Down Expand Up @@ -180,8 +186,7 @@
# else
# define FMT_FALLTHROUGH
# endif
#elif FMT_HAS_CPP17_ATTRIBUTE(fallthrough) || \
(defined(_MSVC_LANG) && _MSVC_LANG >= 201703L)
#elif FMT_HAS_CPP17_ATTRIBUTE(fallthrough)
# define FMT_FALLTHROUGH [[fallthrough]]
#else
# define FMT_FALLTHROUGH
Expand Down