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. --- include/libc-internal.h | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) (limited to 'include') diff --git a/include/libc-internal.h b/include/libc-internal.h index 2ced1c1..bca59a4 100644 --- a/include/libc-internal.h +++ b/include/libc-internal.h @@ -76,4 +76,35 @@ extern void __init_misc (int, char **, char **); #define ignore_value(x) \ ({ __typeof__ (x) __ignored_value = (x); (void) __ignored_value; }) +/* The macros to control diagnostics are structured like this, rather + than a single macro that both pushes and pops diagnostic state and + takes the affected code as an argument, because the GCC pragmas + work by disabling the diagnostic for a range of source locations + and do not work when all the pragmas and the affected code are in a + single macro expansion. */ + +/* Push diagnostic state. */ +#define DIAG_PUSH_NEEDS_COMMENT _Pragma ("GCC diagnostic push") + +/* Pop diagnostic state. */ +#define DIAG_POP_NEEDS_COMMENT _Pragma ("GCC diagnostic pop") + +#define _DIAG_STR1(s) #s +#define _DIAG_STR(s) _DIAG_STR1(s) + +/* Ignore the diagnostic OPTION. VERSION is the most recent GCC + version for which the diagnostic has been confirmed to appear in + the absence of the pragma (in the form MAJOR.MINOR for GCC 4.x, + just MAJOR for GCC 5 and later). Uses of this pragma should be + reviewed when the GCC version given is no longer supported for + building glibc; the version number should always be on the same + source line as the macro name, so such uses can be found with grep. + Uses should come with a comment giving more details of the + diagnostic, and an architecture on which it is seen if possibly + optimization-related and not in architecture-specific code. This + macro should only be used if the diagnostic seems hard to fix (for + example, optimization-related false positives). */ +#define DIAG_IGNORE_NEEDS_COMMENT(version, option) \ + _Pragma (_DIAG_STR (GCC diagnostic ignored option)) + #endif /* _LIBC_INTERNAL */ -- cgit v1.1