https://gcc.gnu.org/bugzilla/show_bug.cgi?id=72798
Bug ID: 72798
Summary: Module (.mod) file changes even when interface does
not
Product: gcc
Version: 5.3.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: townsend at astro dot wisc.edu
Target Milestone: ---
Created attachment 39054
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=39054&action=edit
Test case demonstrating problem
In a big project I'm involved in, we take advantage of the fact that gfortran's
.mod files don't change across a recompilation, if the public interface of the
module is unchanged. This allows us to avoid very time-consuming compilation
cascades.
However, I've run into a case where this desirable behavior doesn't seem to
work. If I compile the attached module ('gfortran -c test_mod.f90') with and
without the print statement commented out, I get .mod files which not only
differ in contents, but also in size.
Is this correct behavior? If so, how might I go about judging whether the
public interface of a module has or hasn't changed?
