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Message-Id: <c29c3d9b7955d95617350b1f91d97ab8bc23ec48.1685522953.git.Jens.Gustedt@inria.fr>
Date: Wed, 31 May 2023 11:22:59 +0200
From: Jens Gustedt <Jens.Gustedt@...ia.fr>
To: musl@...ts.openwall.com
Subject: [C23 divers headers 12/17] C23: change the assert macro to ... arguments
Macro arguments are ambiguate fellows. A single C expression such as
(struct toto){ 1, 2}.a appears as two macro arguments.
This mandatory change has the macro accept an unlimited number of
macro-parameters, but which then must resolve to a single C
expression. This is achieved by squeezing the argument list through a
trivial function call to a static function. By that we ensure that
lists that represent more than one expression (such as `1, 2`) and
empty lists are diagnosed.
---
include/assert.h | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/include/assert.h b/include/assert.h
index 71007a10..034c4aa7 100644
--- a/include/assert.h
+++ b/include/assert.h
@@ -2,10 +2,17 @@
#undef assert
+// Ensure that this version only accepts arguments that resolve to one
+// C expression after preprocessing.
+#ifndef __ASSERT_EXPRESSION
+#define __ASSERT_EXPRESSION(...) __assert_expression(__VA_ARGS__)
+static inline _Bool __assert_expression(_Bool __x) { return __x; }
+#endif
+
#ifdef NDEBUG
-#define assert(x) (void)0
+#define assert(...) (void)0
#else
-#define assert(x) ((void)((x) || (__assert_fail(#x, __FILE__, __LINE__, __func__),0)))
+#define assert(...) ((void)(__ASSERT_EXPRESSION(__VA_ARGS__) || (__assert_fail(#__VA_ARGS__, __FILE__, __LINE__, __func__),0)))
#endif
#if __STDC_VERSION__ >= 201112L && __STDC_VERSION__ < 202311L && !defined(__cplusplus)
--
2.34.1
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