[Bug c/50997] New: ARM: No warnings for unreachable code for ARM cross compiler

["fredrik dot hederstierna at securitas-direct dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50997

             Bug #: 50997
           Summary: ARM: No warnings for unreachable code for ARM cross
                    compiler
    Classification: Unclassified
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: fredrik.hederstierna@securitas-direct.com


Created attachment 25729
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25729
Example file with warnings for unreachable code

When I compile for x86 the -Wunreachable-code works as intended, but when using
ARM cross compiler I do not get any warnings.

Attached is example C-file, compiled with (tested -O0,-O1,-O2,-O3):

  gcc -c -O2 unreachable.c -W -Wall -Wextra -Wunreachable-code

For x86 GCC I get output:

unreachable.c: In function âunreachableâ:
unreachable.c:7: warning: ignoring return value of âscanfâ, declared with
attribute warn_unused_result
unreachable.c:41: warning: will never be executed
unreachable.c:46: warning: will never be executed
unreachable.c: In function âmainâ:
unreachable.c:22: warning: will never be executed
unreachable.c:33: warning: will never be executed
unreachable.c:37: warning: will never be executed

Which is correct

For ARM-cross compiler (4.5.1 and 4.6.0 tested) I do not get any warnings at
all.

ARM-cross compiler was compiled with

configure --enable-languages=c,c++ --target="$TARGET" --prefix="$DEST"
--with-gnu-as --with-gnu-ld --disable-nls --with-newlib --disable-__cxa_atexit
--with-ecos

make LDFLAGS=-s all all-gcc all-target-libstdc++-v3 install install-gcc
install-target-libstdc++-v3

Fredrik Hederstierna
Securitas Direct AB
Malmoe Sweden