[Bug c/54113] New: -Wmissing-prototypes cries wolf for C99 inline functions

[Bug c/54113] New: -Wmissing-prototypes cries wolf for C99 inline functions

[eggert at gnu dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54113

             Bug #: 54113
           Summary: -Wmissing-prototypes cries wolf for C99 inline
                    functions
    Classification: Unclassified
           Product: gcc
           Version: 4.7.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: eggert@gnu.org


-Wmissing-prototypes produces false alarms for C99-style
inline functions.  Here's a simple example, taken from
<http://www.drdobbs.com/the-new-c-inline-functions/184401540>.
Suppose foo.h contains this:

  inline float square(float x) {return x*x;}
  inline float cube(float x) {return x*x*x;}

and foo.c contains this:

  #include "foo.h"
  extern float square(float x);
  extern float cube(float x);

Then the command:

  gcc -c -Wmissing-prototypes foo.c

outputs:

  In file included from foo.c:1:0:
  foo.h:1:14: warning: no previous prototype for 'square'
[-Wmissing-prototypes]
  foo.h:2:14: warning: no previous prototype for 'cube' [-Wmissing-prototypes]

The diagnostics should not be output, as this is the normal
way to use inline functions in C.

The simplest way to work around the problem is to avoid
the use of -Wmissing-prototypes, but that disables the
diagnostic for non-inline functions, where it's useful.

To fix this, I suggest that the diagnostic be suppressed
for inline functions, at least for C99 mode.

[Bug c/54113] -Wmissing-prototypes cries wolf for C99 inline functions

[eggert at gnu dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54113

--- Comment #1 from eggert at gnu dot org 2012-08-14 04:08:17 UTC ---
In <http://lists.gnu.org/archive/html/bug-gnulib/2012-08/msg00038.html> Jim
Meyering reports that GCC 4.8.0 20120803 issues a different (but still bogus)
warning for this program.  It reports "error: no previous declaration for 'FOO' 
[-Werror=missing-declarations]" if FOO is an inline function.  This warning
should not be emitted either.

[Bug c/54113] -Wmissing-prototypes produces false alarms for C99 inline functions

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54113

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2013-12-04
                 CC|                            |mpolacek at gcc dot gnu.org
           Assignee|unassigned at gcc dot gnu.org      |mpolacek at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
I have a patch for disabling the diagnostic  for inline functions in C99 mode.

[Bug c/54113] -Wmissing-prototypes produces false alarms for C99 inline functions

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54113

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Author: mpolacek
Date: Wed Dec  4 21:15:31 2013
New Revision: 205680

URL: http://gcc.gnu.org/viewcvs?rev=205680&root=gcc&view=rev
Log:
    PR c/54113
c/
    * c-decl.c (start_function): Don't warn for missing prototype for
    inline functions.
testsuite/
    * gcc.dg/pr54113.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/pr54113.c
Modified:
    trunk/gcc/c/ChangeLog
    trunk/gcc/c/c-decl.c
    trunk/gcc/testsuite/ChangeLog

[Bug c/54113] -Wmissing-prototypes produces false alarms for C99 inline functions

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54113

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Fixed on trunk.