https://github.com/python/cpython/commit/587388ff22dc7cfa4b66722daf0d33cd804... commit: 587388ff22dc7cfa4b66722daf0d33cd804af9f2 branch: main author: Victor Stinner <vstinner@python.org> committer: vstinner <vstinner@python.org> date: 2024-04-30T22:29:48+02:00 summary: gh-118124: Use static_assert() in Py_BUILD_ASSERT() on C11 (#118398) Use static_assert() in Py_BUILD_ASSERT() and Py_BUILD_ASSERT_EXPR() on C11 and newer and C++11 and newer. Add tests to test_cext and test_cppext. files: A Misc/NEWS.d/next/C API/2024-04-29-17-44-15.gh-issue-118124.czQQ9G.rst M Include/pymacro.h M Lib/test/test_cext/extension.c M Lib/test/test_cppext/extension.cpp diff --git a/Include/pymacro.h b/Include/pymacro.h index cd6fc4eba9c2ed..b388c2a4a663ce 100644 --- a/Include/pymacro.h +++ b/Include/pymacro.h @@ -46,24 +46,41 @@ /* Argument must be a char or an int in [-128, 127] or [0, 255]. */ #define Py_CHARMASK(c) ((unsigned char)((c) & 0xff)) -/* Assert a build-time dependency, as an expression. - - Your compile will fail if the condition isn't true, or can't be evaluated - by the compiler. This can be used in an expression: its value is 0. - - Example: - - #define foo_to_char(foo) \ - ((char *)(foo) \ - + Py_BUILD_ASSERT_EXPR(offsetof(struct foo, string) == 0)) - - Written by Rusty Russell, public domain, http://ccodearchive.net/ */ -#define Py_BUILD_ASSERT_EXPR(cond) \ +#if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L +# define Py_BUILD_ASSERT_EXPR(cond) \ + ((void)sizeof(struct { int dummy; _Static_assert(cond, #cond); }), \ + 0) +#else + /* Assert a build-time dependency, as an expression. + * + * Your compile will fail if the condition isn't true, or can't be evaluated + * by the compiler. This can be used in an expression: its value is 0. + * + * Example: + * + * #define foo_to_char(foo) \ + * ((char *)(foo) \ + * + Py_BUILD_ASSERT_EXPR(offsetof(struct foo, string) == 0)) + * + * Written by Rusty Russell, public domain, http://ccodearchive.net/ + */ +# define Py_BUILD_ASSERT_EXPR(cond) \ (sizeof(char [1 - 2*!(cond)]) - 1) +#endif -#define Py_BUILD_ASSERT(cond) do { \ - (void)Py_BUILD_ASSERT_EXPR(cond); \ - } while(0) +#if ((defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L) \ + || (defined(__cplusplus) && __cplusplus >= 201103L)) + // Use static_assert() on C11 and newer +# define Py_BUILD_ASSERT(cond) \ + do { \ + static_assert((cond), #cond); \ + } while (0) +#else +# define Py_BUILD_ASSERT(cond) \ + do { \ + (void)Py_BUILD_ASSERT_EXPR(cond); \ + } while(0) +#endif /* Get the number of elements in a visible array diff --git a/Lib/test/test_cext/extension.c b/Lib/test/test_cext/extension.c index 662abd4005e8d2..eb23dbe20353ba 100644 --- a/Lib/test/test_cext/extension.c +++ b/Lib/test/test_cext/extension.c @@ -44,6 +44,11 @@ _testcext_exec(PyObject *module) return -1; } #endif + + // test Py_BUILD_ASSERT() and Py_BUILD_ASSERT_EXPR() + Py_BUILD_ASSERT(sizeof(int) == sizeof(unsigned int)); + assert(Py_BUILD_ASSERT_EXPR(sizeof(int) == sizeof(unsigned int)) == 0); + return 0; } diff --git a/Lib/test/test_cppext/extension.cpp b/Lib/test/test_cppext/extension.cpp index a569c2251d1ad7..ab485b629b7788 100644 --- a/Lib/test/test_cppext/extension.cpp +++ b/Lib/test/test_cppext/extension.cpp @@ -225,6 +225,10 @@ _testcppext_exec(PyObject *module) if (!result) return -1; Py_DECREF(result); + // test Py_BUILD_ASSERT() and Py_BUILD_ASSERT_EXPR() + Py_BUILD_ASSERT(sizeof(int) == sizeof(unsigned int)); + assert(Py_BUILD_ASSERT_EXPR(sizeof(int) == sizeof(unsigned int)) == 0); + return 0; } diff --git a/Misc/NEWS.d/next/C API/2024-04-29-17-44-15.gh-issue-118124.czQQ9G.rst b/Misc/NEWS.d/next/C API/2024-04-29-17-44-15.gh-issue-118124.czQQ9G.rst new file mode 100644 index 00000000000000..3deeb517eb9fce --- /dev/null +++ b/Misc/NEWS.d/next/C API/2024-04-29-17-44-15.gh-issue-118124.czQQ9G.rst @@ -0,0 +1,3 @@ +Fix :c:macro:`Py_BUILD_ASSERT` and :c:macro:`Py_BUILD_ASSERT_EXPR` for +non-constant expressions: use ``static_assert()`` on C11 and newer. +Patch by Victor Stinner.