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authorJim Meyering <meyering@fb.com>2014-06-05 10:42:05 -0700
committerJim Meyering <meyering@fb.com>2016-12-18 01:30:51 -0800
commite077349ce589466eecd47213db4fae6b80ec18c4 (patch)
tree3f8dc06410c398f69426bf115e643284a133436b /assert
parent009ba649b4999ea269de8d0b301e659f075df495 (diff)
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assert.h: allow gcc to detect assert(a = 1) errors
* assert/assert.h (assert): Rewrite assert's definition so that a s/==/=/ typo, e.g., assert(errno = ENOENT) is not hidden from gcc's -Wparentheses by assert-added parentheses. The new definition uses "if (expr) /* empty */; else __assert_fail...", so gcc -Wall will now detect that type of error in an assert, too. The __STRICT_ANSI__ disjunct is to make this work also with both -ansi and -pedantic, which would reject the use of ({...}). I would have preferred to use __extension__ to mark that, but doing so would mistakenly suppress warnings about any extension in the user-supplied "expr". E.g., "assert ( ({1;}) )" must continue to evoke a warning.
Diffstat (limited to 'assert')
-rw-r--r--assert/assert.h21
1 files changed, 17 insertions, 4 deletions
diff --git a/assert/assert.h b/assert/assert.h
index 729edeb..0f25131 100644
--- a/assert/assert.h
+++ b/assert/assert.h
@@ -82,10 +82,23 @@ extern void __assert (const char *__assertion, const char *__file, int __line)
__END_DECLS
-# define assert(expr) \
- ((expr) \
- ? __ASSERT_VOID_CAST (0) \
- : __assert_fail (#expr, __FILE__, __LINE__, __ASSERT_FUNCTION))
+/* When possible, define assert so that it does not add extra
+ parentheses around EXPR. Otherwise, those added parentheses would
+ suppress warnings we'd expect to be detected by gcc's -Wparentheses. */
+# if !defined __GNUC__ || defined __STRICT_ANSI__
+# define assert(expr) \
+ ((expr) \
+ ? __ASSERT_VOID_CAST (0) \
+ : __assert_fail (#expr, __FILE__, __LINE__, __ASSERT_FUNCTION))
+# else
+# define assert(expr) \
+ ({ \
+ if (expr) \
+ ; /* empty */ \
+ else \
+ __assert_fail (#expr, __FILE__, __LINE__, __ASSERT_FUNCTION); \
+ })
+# endif
# ifdef __USE_GNU
# define assert_perror(errnum) \