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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.
26 lines
730 B
C
26 lines
730 B
C
#include <stdio.h>
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#include <libc-internal.h>
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static int
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do_test (void)
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{
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static const char buf[] = " ";
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char *str;
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/* GCC in C99 mode treats %a as the C99 format expecting float *,
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but glibc with _GNU_SOURCE treats %as as the GNU allocation
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extension, so resulting in "warning: format '%a' expects argument
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of type 'float *', but argument 3 has type 'char **'". This
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applies to the other %as, %aS and %a[] formats below as well. */
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DIAG_PUSH_NEEDS_COMMENT;
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DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wformat");
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int r = sscanf (buf, "%as", &str);
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DIAG_POP_NEEDS_COMMENT;
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printf ("%d %p\n", r, str);
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return r != -1 || str != NULL;
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}
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#define TEST_FUNCTION do_test ()
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#include "../test-skeleton.c"
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