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