From 2084e7ca4d344c39eb39e53848b51b5d84444414 Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Wed, 10 Dec 2014 00:41:19 +0000 Subject: Add macros for diagnostic control, use for scanf %a tests. In , 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 . (do_test): Disable -Wformat around call to sscanf. * stdio-common/scanf14.c: Include . (main): Disable -Wformat around some calls to scanf functions. --- stdio-common/bug21.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'stdio-common/bug21.c') diff --git a/stdio-common/bug21.c b/stdio-common/bug21.c index d22b9c1a97..ca27272ba1 100644 --- a/stdio-common/bug21.c +++ b/stdio-common/bug21.c @@ -1,4 +1,5 @@ #include +#include static int do_test (void) @@ -6,7 +7,15 @@ do_test (void) static const char buf[] = " "; char *str; + /* 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"); int r = sscanf (buf, "%as", &str); + DIAG_POP_NEEDS_COMMENT; printf ("%d %p\n", r, str); return r != -1 || str != NULL; -- cgit v1.2.1