1  /* Macros for controlling diagnostic output from the compiler.
       2     Copyright (C) 2014-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #ifndef _LIBC_DIAG_H
      20  #define _LIBC_DIAG_H 1
      21  
      22  /* Ignore the value of an expression when a cast to void does not
      23     suffice (in particular, for a call to a function declared with
      24     attribute warn_unused_result).  */
      25  #define ignore_value(x) \
      26    ({ __typeof__ (x) __ignored_value = (x); (void) __ignored_value; })
      27  
      28  /* The macros to control diagnostics are structured like this, rather
      29     than a single macro that both pushes and pops diagnostic state and
      30     takes the affected code as an argument, because the GCC pragmas
      31     work by disabling the diagnostic for a range of source locations
      32     and do not work when all the pragmas and the affected code are in a
      33     single macro expansion.  */
      34  
      35  /* Push diagnostic state.  */
      36  #define DIAG_PUSH_NEEDS_COMMENT _Pragma ("GCC diagnostic push")
      37  
      38  /* Pop diagnostic state.  */
      39  #define DIAG_POP_NEEDS_COMMENT _Pragma ("GCC diagnostic pop")
      40  
      41  #define _DIAG_STR1(s) #s
      42  #define _DIAG_STR(s) _DIAG_STR1(s)
      43  
      44  /* Ignore the diagnostic OPTION.  VERSION is the most recent GCC
      45     version for which the diagnostic has been confirmed to appear in
      46     the absence of the pragma (in the form MAJOR.MINOR for GCC 4.x,
      47     just MAJOR for GCC 5 and later).  Uses of this pragma should be
      48     reviewed when the GCC version given is no longer supported for
      49     building glibc; the version number should always be on the same
      50     source line as the macro name, so such uses can be found with grep.
      51     Uses should come with a comment giving more details of the
      52     diagnostic, and an architecture on which it is seen if possibly
      53     optimization-related and not in architecture-specific code.  This
      54     macro should only be used if the diagnostic seems hard to fix (for
      55     example, optimization-related false positives).  */
      56  #define DIAG_IGNORE_NEEDS_COMMENT(version, option)     \
      57    _Pragma (_DIAG_STR (GCC diagnostic ignored option))
      58  
      59  /* Similar to DIAG_IGNORE_NEEDS_COMMENT the following macro ignores the
      60     diagnostic OPTION but only if optimizations for size are enabled.
      61     This is required because different warnings may be generated for
      62     different optimization levels.  For example a key piece of code may
      63     only generate a warning when compiled at -Os, but at -O2 you could
      64     still want the warning to be enabled to catch errors.  In this case
      65     you would use DIAG_IGNORE_Os_NEEDS_COMMENT to disable the warning
      66     only for -Os.  */
      67  #ifdef __OPTIMIZE_SIZE__
      68  # define DIAG_IGNORE_Os_NEEDS_COMMENT(version, option) \
      69    _Pragma (_DIAG_STR (GCC diagnostic ignored option))
      70  #else
      71  # define DIAG_IGNORE_Os_NEEDS_COMMENT(version, option)
      72  #endif
      73  
      74  #endif /* libc-diag.h */