[Bug fortran/32147] New: Module files change due to rivial changes in source code

["wdobler at ucalgary dot ca" <gcc-bugzilla at gcc dot gnu dot org>]

With different versions of gfortran, I find that the .mod files often change
even if I just added a debugging print statement somewhere in a subroutine --
i.e. even when the interface to the module (that the .mod file is supposed to
represent) has not changed.

I attach a test file and a Makefile that returns something like `Found 34
differences', but should just find ~2 differences due to differing time stamp
and MD5 sum.


I find this e.g. with (the 64-bit version of) GNU Fortran (GCC) 4.3.0 20070501
(experimental) [SVN version], but also with GNU Fortran 95 (GCC) 4.1.2 (Gentoo
4.1.2).


W o l f g a n g

PS: The same probem occurred with g95, but is fixed now.

PPS: Rationale: I have a tool that backdates .f90 and .o files after
compilation if the module file has not changed. This avoids the `recompilation
cascade', but can only work if the .mod files don't change spuriously.


-- 
           Summary: Module files change due to rivial changes in source code
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: wdobler at ucalgary dot ca


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32147