[Bug c/36651] New: 64-bit enumerator incorrectly demoted to 32 bits

[jjk at acm dot org]

This problem can be reproduced using the attached testcase.

In GCC 3.2.3 (i386-redhat-linux), it works as expected:
> ~ % gcc -v
> Reading specs from /usr/lib/gcc-lib/i386-redhat-linux/3.2.3/specs
> Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --enable-shared --enable-threads=posix --disable-checking --with-system-zlib --enable-__cxa_atexit --host=i386-redhat-linux
> Thread model: posix
> gcc version 3.2.3 20030502 (Red Hat Linux 3.2.3-54)
> ~ % gcc -o foo foo.c
> ~ % ./foo
> 100000002 100000002

In GCC 4.1.2 (x86_64-redhat-linux), apparently the value FOO is interpreted
as a 32-bit integer before the left shift; the bizarre thing is that casting
to Foo (which should be unnecessary) avoids this.
> ~ % gcc -v
> Using built-in specs.
> Target: x86_64-redhat-linux
> Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-libgcj-multifile --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --enable-plugin --with-java-home=/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre --with-cpu=generic --host=x86_64-redhat-linux
> Thread model: posix
> gcc version 4.1.2 20070626 (Red Hat 4.1.2-14)
> ~ % gcc -o foo foo.c
> foo.c: In function 'main':
> foo.c:13: warning: left shift count >= width of type
> ~ % ./foo
> 2 100000002

When I asked about this on gcc-help, Andrew Haley <aph@redhat.com> wrote:
> It's a bug.  C99 says an enumerated type shall be large enough to
> represent all its members, and that when promoting the rank of the
> enumerated type shall equal the rank of the compatible integer type.


-- 
           Summary: 64-bit enumerator incorrectly demoted to 32 bits
           Product: gcc
           Version: 4.1.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jjk at acm dot org
  GCC host triplet: x86_64-redhat-linux
GCC target triplet: x86_64-redhat-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36651