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Add macros for diagnostic control, use for scanf %a tests.

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In <https://sourceware.org/ml/libc-alpha/2014-11/msg00326.html>,
Roland requested internal macros for use of "#pragma GCC diagnostic".

This patch adds such macros and uses them to disable -Wformat warnings
for some code testing GNU scanf %as where GCC expects C99 scanf %a
(several other stdio tests currently use -Wno-format to disable
warnings).  Limitations in GCC's diagnostic pragmas require separate
macros before and after the code generating the warnings, rather than
a single macro taking that code as an argument.

The macros are named DIAG_*_NEEDS_COMMENT to emphasise to reviewers
the need for a comment accompanying any use of them (such comments may
however just appear once for several uses of the macros for the same
issue in the same file).  I put a GCC version in the arguments to
DIAG_IGNORE_NEEDS_COMMENT, as that seems something useful to grep for
when obsoleting support for an old GCC version and needing to decide
if warning-disabling code is still relevant.

These macros should be usable for replacing existing -Wno-* use in
makefiles (as also suggested by Roland), though I have no plans to
work on that (only on use of the macros in cases where warnings are
currently present that need disabling to use -Werror).

Tested for x86_64.

	* include/libc-internal.h (DIAG_PUSH_NEEDS_COMMENT): New macro.
	(DIAG_POP_NEEDS_COMMENT): Likewise.
	(_DIAG_STR1): Likewise.
	(_DIAG_STR): Likewise.
	(DIAG_IGNORE_NEEDS_COMMENT): Likewise.
	* stdio-common/bug21.c: Include <libc-internal.h>.
	(do_test): Disable -Wformat around call to sscanf.
	* stdio-common/scanf14.c: Include <libc-internal.h>.
	(main): Disable -Wformat around some calls to scanf functions.
This commit is contained in:
Joseph Myers
2014-12-10 00:41:19 +00:00
parent df7ecc6bd2
commit 2084e7ca4d
4 changed files with 73 additions and 0 deletions
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21
stdio-common/scanf14.c
View File

@ -2,6 +2,7 @@
#include <stdlib.h>
#include <string.h>
#include <wchar.h>
#include <libc-internal.h>
#define FAIL() \
do { \
@ -23,6 +24,13 @@ main (void)
FAIL ();
else if (f != 0.25 || memcmp (c, "s x", 3) != 0)
FAIL ();
/* GCC in C99 mode treats %a as the C99 format expecting float *,
but glibc with _GNU_SOURCE treats %as as the GNU allocation
extension, so resulting in "warning: format '%a' expects argument
of type 'float *', but argument 3 has type 'char **'". This
applies to the other %as, %aS and %a[] formats below as well. */
DIAG_PUSH_NEEDS_COMMENT;
DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wformat");
if (sscanf (" 1.25s x", "%as%2c", &sp, c) != 2)
FAIL ();
else
@ -32,10 +40,14 @@ main (void)
memset (sp, 'x', sizeof "1.25s");
free (sp);
}
DIAG_POP_NEEDS_COMMENT;
if (sscanf (" 2.25s x", "%las%2c", &d, c) != 2)
FAIL ();
else if (d != 2.25 || memcmp (c, " x", 2) != 0)
FAIL ();
/* See explanation above. */
DIAG_PUSH_NEEDS_COMMENT;
DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wformat");
if (sscanf (" 3.25S x", "%4aS%3c", &lsp, c) != 2)
FAIL ();
else
@ -54,6 +66,7 @@ main (void)
memset (sp, 'x', sizeof "4.25");
free (sp);
}
DIAG_POP_NEEDS_COMMENT;
if (sscanf ("5.25[0-9.] x", "%la[0-9.]%2c", &d, c) != 2)
FAIL ();
else if (d != 5.25 || memcmp (c, " x", 2) != 0)
@ -82,6 +95,9 @@ main (void)
FAIL ();
if (fseek (fp, 0, SEEK_SET) != 0)
FAIL ();
/* See explanation above. */
DIAG_PUSH_NEEDS_COMMENT;
DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wformat");
if (fscanf (fp, "%as%2c", &sp, c) != 2)
FAIL ();
else
@ -91,11 +107,15 @@ main (void)
memset (sp, 'x', sizeof "1.25s");
free (sp);
}
DIAG_POP_NEEDS_COMMENT;
if (freopen (fname, "r", stdin) == NULL)
FAIL ();
else
{
/* See explanation above. */
DIAG_PUSH_NEEDS_COMMENT;
DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wformat");
if (scanf ("%as%2c", &sp, c) != 2)
FAIL ();
else
@ -105,6 +125,7 @@ main (void)
memset (sp, 'x', sizeof "1.25s");
free (sp);
}
DIAG_POP_NEEDS_COMMENT;
}
fclose (fp);