From 8700a4761beb219873956666cf91776a2c61e698 Mon Sep 17 00:00:00 2001 From: "Joy H.J. Lee" Date: Thu, 2 Jul 2026 05:06:35 +0900 Subject: [PATCH] tools/compiler: match glibc 2.42 definition of __attribute_const__ glibc 2.42 added __attribute_const__ to sys/cdefs.h: # define __attribute_const__ __attribute__ ((__const__)) GCC 15 warns when a macro is redefined to a different replacement list (-Wbuiltin-macro-redefined). Since host tool Makefiles (resolve_btfids, objtool) pass -Werror, this conflict becomes fatal. The warning is suppressed on standard native builds because GCC treats /usr/include as a system header path (-isystem), and macro-redefinition warnings from system headers are silently suppressed by GCC. It fires when glibc headers are on a regular include path (-I) instead, which is the case in cross-compilation setups such as NixOS, where the sysroot's glibc is passed explicitly via -I rather than -isystem. Per (C11 6.10.3), identical replacement lists are accepted silently. Match the glibc definition exactly, including the space before "((", so the redefinition is accepted without warning regardless of whether glibc headers are treated as system or non-system includes. Link: https://lore.kernel.org/20260701200635.3992767-1-rkr0k0r@gmail.com Signed-off-by: Joy H.J. Lee Cc: Nathan Chancellor Cc: David Laight Cc: Signed-off-by: Andrew Morton --- tools/include/linux/compiler.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h index f40bd2b04c29..f2f54b038168 100644 --- a/tools/include/linux/compiler.h +++ b/tools/include/linux/compiler.h @@ -119,7 +119,7 @@ #define __read_mostly #ifndef __attribute_const__ -# define __attribute_const__ +# define __attribute_const__ __attribute__ ((__const__)) #endif #ifndef __maybe_unused