Bit-reproduciblity issue for gfortran .mod files

[Alastair McKinstry]

Hi,

gfortran .mod files compressed files, contains a header, which looks like:
(viewed with e.g. zmore /usr/include/cgns.mod ):

GFORTRAN module version '14' created from /build/libcgns-XmhIxt/libcgns-3.3.0/src/cgns_f.F90
(() () () () () () () () () () () () () () () () () () () () () () () ()
() () ())

The full path of the compiled fortran file is included, which can break b=
it-reproducible builds.
(see https://reproducible-builds.org/)

A trivial patch is included, to strip the path.

Best regards
Alastair McKinstry

Index: gcc-7-7.2.0/src/gcc/fortran/module.c
===================================================================
--- gcc-7-7.2.0.orig/src/gcc/fortran/module.c
+++ gcc-7-7.2.0/src/gcc/fortran/module.c
@@ -79,6 +79,10 @@ along with GCC; see the file COPYING3.
 #include "scanner.h"
 #include <zlib.h>
 
+/* for GNU / POSIX basename */
+#define _GNU_SOURCE
+#include <string.h>
+
 #define MODULE_EXTENSION ".mod"
 #define SUBMODULE_EXTENSION ".smod"
 
@@ -6063,8 +6067,9 @@ dump_module (const char *name, int dump_
     gfc_fatal_error ("Can't open module file %qs for writing at %C: %s",
 		     filename_tmp, xstrerror (errno));
 
+  /* Use basename to make builds bit-reproducible */
   gzprintf (module_fp, "GFORTRAN module version '%s' created from %s\n",
-	    MOD_VERSION, gfc_source_file);
+            MOD_VERSION, basename(gfc_source_file));
 
   /* Write the module itself.  */
   iomode = IO_OUTPUT;



-- 
Alastair McKinstry, <alastair@sceal.ie>, <mckinstry@debian.org>, https://diaspora.sceal.ie/u/amckinstry
Misentropy: doubting that the Universe is becoming more disordered. 


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