From 33f5ce80d69ae06878da0b9161c4ee93d5bb0861 Mon Sep 17 00:00:00 2001 From: fakuivan Date: Tue, 18 Jun 2024 01:53:41 -0300 Subject: [PATCH] Fix NIM_STATIC_ASSERT_AUX being redefined on different lines (#23729) fixes #17247 This generates a new NIM_STATIC_ASSERT_AUX variable for each line that NIM_STATIC_ASSERT is called from. While this can solve all existing issues in the current code base, this method is not effective for multiple asserts on a single line. --- lib/nimbase.h | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/lib/nimbase.h b/lib/nimbase.h index 2204987db0..c66be40c24 100644 --- a/lib/nimbase.h +++ b/lib/nimbase.h @@ -272,11 +272,15 @@ __EMSCRIPTEN__ #elif defined(__cplusplus) #define NIM_STATIC_ASSERT(x, msg) static_assert((x), msg) #else -#define NIM_STATIC_ASSERT(x, msg) typedef int NIM_STATIC_ASSERT_AUX[(x) ? 1 : -1]; +#define _NIM_STATIC_ASSERT_FINAL(x, append_name) typedef int NIM_STATIC_ASSERT_AUX ## append_name[(x) ? 1 : -1]; +#define _NIM_STATIC_ASSERT_STAGE_3(x, line) _NIM_STATIC_ASSERT_FINAL(x, _AT_LINE_##line) +#define _NIM_STATIC_ASSERT_STAGE_2(x, line) _NIM_STATIC_ASSERT_STAGE_3(x, line) +#define NIM_STATIC_ASSERT(x, msg) _NIM_STATIC_ASSERT_STAGE_2(x,__LINE__) // On failure, your C compiler will say something like: -// "error: 'NIM_STATIC_ASSERT_AUX' declared as an array with a negative size" -// we could use a better fallback to also show line number, using: -// http://www.pixelbeat.org/programming/gcc/static_assert.html +// "error: 'NIM_STATIC_ASSERT_AUX_AT_LINE_XXX' declared as an array with a negative size" +// Adding the line number helps to avoid redefinitions which are not allowed in +// old GCC versions, however the order of evaluation for __LINE__ is a little tricky, +// hence all the helper macros. See https://stackoverflow.com/a/3385694 for more info. #endif /* C99 compiler? */