Date: Sat, 30 May 2026 13:44:28 +0000 From: Robert Clausecker <fuz@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Cc: Faraz Vahedi <kfv@kfv.io> Subject: git: 867b51452ea7 - main - libc: Add variadic assert in accordance with C23 Message-ID: <6a1ae9bc.27dc1.4cecadc6@gitrepo.freebsd.org>
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The branch main has been updated by fuz: URL: https://cgit.FreeBSD.org/src/commit/?id=867b51452ea78ece0b312a387e63fdbc2a11056a commit 867b51452ea78ece0b312a387e63fdbc2a11056a Author: Faraz Vahedi <kfv@kfv.io> AuthorDate: 2026-05-28 07:31:29 +0000 Commit: Robert Clausecker <fuz@FreeBSD.org> CommitDate: 2026-05-30 13:43:51 +0000 libc: Add variadic assert in accordance with C23 Signed-off-by: Faraz Vahedi <kfv@kfv.io> Reviewed by: fuz MFC after: 1 month Pull Request: https://github.com/freebsd/freebsd-src/pull/2203 --- include/assert.h | 42 +++++++++++++++++++++++++++++++++++------- 1 file changed, 35 insertions(+), 7 deletions(-) diff --git a/include/assert.h b/include/assert.h index 7dd48e61c082..159efacfa45b 100644 --- a/include/assert.h +++ b/include/assert.h @@ -46,16 +46,43 @@ #undef __assert_unreachable #ifdef NDEBUG -#define assert(e) ((void)0) -#define _assert(e) ((void)0) +#define assert(...) ((void)0) +#define _assert(...) ((void)0) #if __BSD_VISIBLE #define __assert_unreachable() __unreachable() #endif /* __BSD_VISIBLE */ #else -#define _assert(e) assert(e) - -#define assert(e) ((e) ? (void)0 : __assert(__func__, __FILE__, \ - __LINE__, #e)) +#ifdef __cplusplus +#if __cplusplus < 202002L +/* + * C++ modes prior to C++20 cannot simultaneously satisfy all three + * desirable properties of the sanitiser: + * + * Approach No double-eval Lambda support Arity check + * ----------------------------- -------------- -------------- ----------- + * sizeof(cast(expression)) yes no yes + * static_cast<bool>(expression) no yes no + * (void)bool(expression) no yes no + * + * NOTE: C++20 introduced lambdas in unevaluated contexts; see P0315R4. + * + * Since no approach satisfies all three below C++20, the least harmful + * choice is to forgo the check entirely rather than silently break one + * of the remaining guarantees. + * + */ +#define __assert_sanitize(...) ((void)0) +#else +#define __assert_sanitize(...) (void)sizeof(((bool(*)(bool))0)(__VA_ARGS__)) +#endif /* __cplusplus < 202002L */ +#else +#define __assert_sanitize(...) (void)sizeof(((_Bool(*)(_Bool))0)(__VA_ARGS__)) +#endif /* __cplusplus */ +#define assert(...) (__assert_sanitize(__VA_ARGS__), \ + (__VA_ARGS__) ? (void)0 : \ + __assert(__func__, __FILE__, \ + __LINE__, #__VA_ARGS__)) +#define _assert(...) assert(__VA_ARGS__) #if __BSD_VISIBLE #define __assert_unreachable() assert(0 && "unreachable segment reached") #endif /* __BSD_VISIBLE */ @@ -76,7 +103,8 @@ * C23 defines static_assert and its obsolescent alternative spelling, * _Static_assert, as keywords. */ -#if __ISO_C_VISIBLE >= 2011 && __ISO_C_VISIBLE < 2023 && !defined(__cplusplus) +#if __ISO_C_VISIBLE >= 2011 && !defined(__cplusplus) && \ + __STDC_VERSION__ < 202311L #define static_assert _Static_assert #endifhome | help
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