From b12934540f17ba7c22923940e48bfbf02d0ae082 Mon Sep 17 00:00:00 2001 From: John Baldwin Date: Thu, 26 Jan 2023 16:28:22 -0800 Subject: [PATCH] : Decay expression passed to fallback version of __generic() This ensures that __generic() more closely matches _Generic() when using the fallback version when _Generic() is not available (such as GCC). Co-authored by: jrtc27 Reviewed by: jrtc27 Differential Revision: https://reviews.freebsd.org/D38215 --- newlib/libc/include/sys/cdefs.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/newlib/libc/include/sys/cdefs.h b/newlib/libc/include/sys/cdefs.h index 720e70092..808498c50 100644 --- a/newlib/libc/include/sys/cdefs.h +++ b/newlib/libc/include/sys/cdefs.h @@ -328,6 +328,9 @@ * __generic(). Unlike _Generic(), this macro can only distinguish * between a single type, so it requires nested invocations to * distinguish multiple cases. + * + * Note that the comma operator is used to force expr to decay in + * order to match _Generic(). */ #if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L) || \ @@ -337,7 +340,7 @@ #elif __GNUC_PREREQ__(3, 1) && !defined(__cplusplus) #define __generic(expr, t, yes, no) \ __builtin_choose_expr( \ - __builtin_types_compatible_p(__typeof(expr), t), yes, no) + __builtin_types_compatible_p(__typeof((0, (expr))), t), yes, no) #endif /*