From: Paul Pluzhnikov <ppluzhnikov@google.com>
To: libc-alpha@sourceware.org
Cc: Paul Pluzhnikov <ppluzhnikov@google.com>
Subject: [committed][PATCH] Use __builtin_FILE instead of __FILE__ in assert in C++.
Date: Fri, 10 Feb 2023 16:26:28 +0000 [thread overview]
Message-ID: <20230210162626.3097660-1-ppluzhnikov@google.com> (raw)
Likewise use __builtin_LINE instead of __LINE__.
When building C++, inline functions are required to have the exact same
sequence of tokens in every translation unit. But __FILE__ token, when
used in a header file, does not necessarily expand to the exact same
string literal, and that may cause compilation failure when C++ modules
are being used. (It would also cause unpredictable output on assertion
failure at runtime, but this rarely matters in practice.)
For example, given the following sources:
// a.h
#include <assert.h>
inline void fn () { assert (0); }
// a.cc
#include "a.h"
// b.cc
#include "foo/../a.h"
preprocessing a.cc will yield a call to __assert_fail("0", "a.h", ...)
but b.cc will yield __assert_fail("0", "foo/../a.h", ...)
---
assert/assert.h | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/assert/assert.h b/assert/assert.h
index 72209bc5e7..63197b819c 100644
--- a/assert/assert.h
+++ b/assert/assert.h
@@ -86,10 +86,21 @@ __END_DECLS
parentheses around EXPR. Otherwise, those added parentheses would
suppress warnings we'd expect to be detected by gcc's -Wparentheses. */
# if defined __cplusplus
+# if defined __has_builtin
+# if __has_builtin (__builtin_FILE)
+# define __ASSERT_FILE __builtin_FILE ()
+# define __ASSERT_LINE __builtin_LINE ()
+# endif
+# endif
+# if !defined(__ASSERT_FILE)
+# define __ASSERT_FILE __FILE__
+# define __ASSERT_LINE __LINE__
+# endif
# define assert(expr) \
(static_cast <bool> (expr) \
? void (0) \
- : __assert_fail (#expr, __FILE__, __LINE__, __ASSERT_FUNCTION))
+ : __assert_fail (#expr, __ASSERT_FILE, __ASSERT_LINE, \
+ __ASSERT_FUNCTION))
# elif !defined __GNUC__ || defined __STRICT_ANSI__
# define assert(expr) \
((expr) \
--
2.39.1.581.gbfd45094c4-goog
next reply other threads:[~2023-02-10 16:27 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-10 16:26 Paul Pluzhnikov [this message]
2023-02-10 17:01 ` Andreas Schwab
2023-02-10 17:15 ` Paul Pluzhnikov
2023-02-10 21:56 ` Joseph Myers
2023-02-13 14:23 ` Carlos O'Donell
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