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| author | Victor Stinner <vstinner@python.org> | 2024-06-27 09:58:44 (GMT) |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2024-06-27 09:58:44 (GMT) |
| commit | 12af8ec864225248c3d2916cb142a5e7ee36cbe2 (patch) | |
| tree | d29a5c87668a1cd1e67ceee0b9074ce7f2c74392 /Include | |
| parent | 4999e0bda091826fcdf303dd439364e1d303a5ce (diff) | |
| download | cpython-12af8ec864225248c3d2916cb142a5e7ee36cbe2.zip cpython-12af8ec864225248c3d2916cb142a5e7ee36cbe2.tar.gz cpython-12af8ec864225248c3d2916cb142a5e7ee36cbe2.tar.bz2 | |
gh-121040: Use __attribute__((fallthrough)) (#121044)
Fix warnings when using -Wimplicit-fallthrough compiler flag.
Annotate explicitly "fall through" switch cases with a new
_Py_FALLTHROUGH macro which uses __attribute__((fallthrough)) if
available. Replace "fall through" comments with _Py_FALLTHROUGH.
Add _Py__has_attribute() macro. No longer define __has_attribute()
macro if it's not defined. Move also _Py__has_builtin() at the top
of pyport.h.
Co-Authored-By: Nikita Sobolev <mail@sobolevn.me>
Diffstat (limited to 'Include')
| -rw-r--r-- | Include/exports.h | 5 | ||||
| -rw-r--r-- | Include/pyport.h | 45 |
2 files changed, 36 insertions, 14 deletions
diff --git a/Include/exports.h b/Include/exports.h index ce60121..0c646d5 100644 --- a/Include/exports.h +++ b/Include/exports.h @@ -41,11 +41,8 @@ * we may still need to support gcc >= 4, as some Ubuntu LTS and Centos versions * have 4 < gcc < 5. */ - #ifndef __has_attribute - #define __has_attribute(x) 0 // Compatibility with non-clang compilers. - #endif #if (defined(__GNUC__) && (__GNUC__ >= 4)) ||\ - (defined(__clang__) && __has_attribute(visibility)) + (defined(__clang__) && _Py__has_attribute(visibility)) #define Py_IMPORTED_SYMBOL __attribute__ ((visibility ("default"))) #define Py_EXPORTED_SYMBOL __attribute__ ((visibility ("default"))) #define Py_LOCAL_SYMBOL __attribute__ ((visibility ("hidden"))) diff --git a/Include/pyport.h b/Include/pyport.h index 1f7a9b4..2b6bd4c 100644 --- a/Include/pyport.h +++ b/Include/pyport.h @@ -9,6 +9,24 @@ #endif +// Preprocessor check for a builtin preprocessor function. Always return 0 +// if __has_builtin() macro is not defined. +// +// __has_builtin() is available on clang and GCC 10. +#ifdef __has_builtin +# define _Py__has_builtin(x) __has_builtin(x) +#else +# define _Py__has_builtin(x) 0 +#endif + +// Preprocessor check for a compiler __attribute__. Always return 0 +// if __has_attribute() macro is not defined. +#ifdef __has_attribute +# define _Py__has_attribute(x) __has_attribute(x) +#else +# define _Py__has_attribute(x) 0 +#endif + // Macro to use C++ static_cast<> in the Python C API. #ifdef __cplusplus # define _Py_STATIC_CAST(type, expr) static_cast<type>(expr) @@ -532,16 +550,6 @@ extern "C" { #endif -// Preprocessor check for a builtin preprocessor function. Always return 0 -// if __has_builtin() macro is not defined. -// -// __has_builtin() is available on clang and GCC 10. -#ifdef __has_builtin -# define _Py__has_builtin(x) __has_builtin(x) -#else -# define _Py__has_builtin(x) 0 -#endif - // _Py_TYPEOF(expr) gets the type of an expression. // // Example: _Py_TYPEOF(x) x_copy = (x); @@ -607,4 +615,21 @@ extern "C" { # define _SGI_MP_SOURCE #endif +// Explicit fallthrough in switch case to avoid warnings +// with compiler flag -Wimplicit-fallthrough. +// +// Usage example: +// +// switch (value) { +// case 1: _Py_FALLTHROUGH; +// case 2: code; break; +// } +// +// __attribute__((fallthrough)) was introduced in GCC 7. +#if _Py__has_attribute(fallthrough) +# define _Py_FALLTHROUGH __attribute__((fallthrough)) +#else +# define _Py_FALLTHROUGH do { } while (0) +#endif + #endif /* Py_PYPORT_H */ |