[Bug fortran/66459] New: bogus warning 'w.offset' may be used uninitialized in this function [-Wmaybe-uninitialized]

["mario-baumann at web dot de" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66459

            Bug ID: 66459
           Summary: bogus warning 'w.offset' may be used uninitialized in
                    this function [-Wmaybe-uninitialized]
           Product: gcc
           Version: 5.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mario-baumann at web dot de
  Target Milestone: ---

Created attachment 35716
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=35716&action=edit
Fortran Fixed Form File

Hi All,

The attached file generates bogus warnings if compiled with -Wall AND -O1(or
higher optimizations).


> gfortran -c -Wall -O1 foo.F
foo.F:14:0:

                W(J,I) = 0
 ^
Warning: 'w.offset' may be used uninitialized in this function
[-Wmaybe-uninitialized]
foo.F:14:0: Warning: 'w.dim[1].stride' may be used uninitialized in this
function [-Wmaybe-uninitialized]


> gfortran -v
Using built-in specs.
COLLECT_GCC=./gfortran
COLLECT_LTO_WRAPPER=/Build/gcc/5.1.0/install/libexec/gcc/x86_64-apple-darwin13/5.1.0/lto-wrapper
Target: x86_64-apple-darwin13
Configured with: /Source/gcc/5.1.0/configure --prefix=/Build/gcc/5.1.0/install
--build=x86_64-apple-darwin13 --enable-languages=c,c++,fortran,lto
--enable-cloog-backend=isl --enable-stage1-checking --enable-lto
--enable-libstdcxx-time --with-system-zlib --disable-cloog-version-check
--disable-nls --disable-libquadmath-support
Thread model: posix
gcc version 5.1.0 (GCC)


NOTEs:
- -O0 works fine
- same behaviour with gcc-4.9.2