[Bug c/30794] New: -Wreturn-type acts differently at -O3

["ian at airs dot com" <gcc-bugzilla at gcc dot gnu dot org>]

Compile this simple file with -Wreturn-type -O2:

void *foo () { while (1) ; }

There is no warning.  Then compiler it with -Wreturn-type -O3.  I get

foo.c:1: warning: no return statement in function returning non-void

This happens because the test for -Wreturn-type in finish_function checks for
DECL_INLINE.  At -O3 all functions have DECL_INLINE set.  This applies to the
C++ frontend as well.

It's not obvious to me that this particular warning should change depending on
the optimization level.  And it's really not obvious that we get the warning at
-O3 and not at -O0, -O1, or -O2.

The same issue arises in both the C and the C++ frontends.

One simple fix might be to check DECL_DECLARED_INLINE_P instead of DECL_INLINE.


-- 
           Summary: -Wreturn-type acts differently at -O3
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: ian at airs dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30794