From e8d899d301346a5591c9d1af06c3c9b3501cf84b Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Fri, 16 Jan 2026 16:26:27 -0700 Subject: [PATCH] compiler-clang.h: require LLVM 19.1.0 or higher for __typeof_unqual__ When building the kernel using a version of LLVM between llvmorg-19-init (the first commit of the LLVM 19 development cycle) and the change in LLVM that actually added __typeof_unqual__ for all C modes [1], which might happen during a bisect of LLVM, there is a build failure: In file included from arch/x86/kernel/asm-offsets.c:9: In file included from include/linux/crypto.h:15: In file included from include/linux/completion.h:12: In file included from include/linux/swait.h:7: In file included from include/linux/spinlock.h:56: In file included from include/linux/preempt.h:79: arch/x86/include/asm/preempt.h:61:2: error: call to undeclared function '__typeof_unqual__'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration] 61 | raw_cpu_and_4(__preempt_count, ~PREEMPT_NEED_RESCHED); | ^ arch/x86/include/asm/percpu.h:478:36: note: expanded from macro 'raw_cpu_and_4' 478 | #define raw_cpu_and_4(pcp, val) percpu_binary_op(4, , "and", (pcp), val) | ^ arch/x86/include/asm/percpu.h:210:3: note: expanded from macro 'percpu_binary_op' 210 | TYPEOF_UNQUAL(_var) pto_tmp__; \ | ^ include/linux/compiler.h:248:29: note: expanded from macro 'TYPEOF_UNQUAL' 248 | # define TYPEOF_UNQUAL(exp) __typeof_unqual__(exp) | ^ The current logic of CC_HAS_TYPEOF_UNQUAL just checks for a major version of 19 but half of the 19 development cycle did not have support for __typeof_unqual__. Harden the logic of CC_HAS_TYPEOF_UNQUAL to avoid this error by only using __typeof_unqual__ with a released version of LLVM 19, which is greater than or equal to 19.1.0 with LLVM's versioning scheme that matches GCC's [2]. Link: https://github.com/llvm/llvm-project/commit/cc308f60d41744b5920ec2e2e5b25e1273c8704b [1] Link: https://github.com/llvm/llvm-project/commit/4532617ae420056bf32f6403dde07fb99d276a49 [2] Link: https://lkml.kernel.org/r/20260116-require-llvm-19-1-for-typeof_unqual-v1-1-3b9a4a4b212b@kernel.org Fixes: ac053946f5c4 ("compiler.h: introduce TYPEOF_UNQUAL() macro") Signed-off-by: Nathan Chancellor Cc: Bill Wendling Cc: Justin Stitt Cc: Uros Bizjak Cc: Signed-off-by: Andrew Morton --- include/linux/compiler-clang.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h index 7edf1a07b5350..e1123dd284862 100644 --- a/include/linux/compiler-clang.h +++ b/include/linux/compiler-clang.h @@ -153,4 +153,4 @@ * Bindgen uses LLVM even if our C compiler is GCC, so we cannot * rely on the auto-detected CONFIG_CC_HAS_TYPEOF_UNQUAL. */ -#define CC_HAS_TYPEOF_UNQUAL (__clang_major__ >= 19) +#define CC_HAS_TYPEOF_UNQUAL (__clang_major__ > 19 || (__clang_major__ == 19 && __clang_minor__ > 0)) -- 2.47.3