https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71544
--- Comment #4 from noamb <noamb at bollweevil dot gdbg.org> --- (In reply to noamb from comment #3) > However, presence of options that are invalid for > 4.9.3 in that list makes me think that perhaps the correct list of options > in that (moderately old) version is just different. The same behavior (incorrect with -O1, correct with full list of specific options) is also present on linux gfortran 4.9.3 when the list of options turned on by -O1 is automatically generated by "-O1 -Q --help=optimizers": tin 1035 : gfortran -v Using built-in specs. COLLECT_GCC=gfortran COLLECT_LTO_WRAPPER=/usr/local/gnu/4.9.3/libexec/gcc/x86_64-unknown-linux-gnu/4.9.3/lto-wrapper Target: x86_64-unknown-linux-gnu Configured with: ./configure --prefix=/usr/local/gnu/4.9.3 --enable-languages=c,c++,fortran Thread model: posix gcc version 4.9.3 (GCC) tin 1036 : gfortran -O1 orig_example.F90 ; ./a.out The following line should print 100 589837704 tin 1037 : gfortran `gfortran -O1 -Q --help=optimizers | grep enabled | awk '{print $1}'` orig_example.F90 ; ./a.out f951: warning: command line option ‘-frtti’ is valid for C++/ObjC++ but not for Fortran f951: warning: command line option ‘-fno-threadsafe-statics’ is valid for C++/ObjC++ but not for Fortran f951: warning: variable tracking requested, but useless unless producing debug info The following line should print 100 100