Patchwork [google] Omit date from Fortran .mod files for reproducible builds

Omit date from Fortran .mod files for reproducible builds.

Strict build environments do binary comparisons of files across gcc builds.
Writing the current timestamp into a Fortran .mod file leads to false
positives from such environments.  Omitting the timestamp removes these
false positives.

Targeted for the google/integration branch.

gcc/fortran/ChangeLog.google:
2011-01-27  Simon Baldwin  <simonb@google.com>

	* module.c (gfc_dump_module): Omit timestamp from output.

Google ref: 39202, 25691, 13445, 13307

On Thu, Jan 27, 2011 at 09:00, Simon Baldwin <simonb@google.com> wrote:

> 2011-01-27  Simon Baldwin  <simonb@google.com>
>
>        * module.c (gfc_dump_module): Omit timestamp from output.

OK.

Diego.

We (Janne and I) think this patch can also be applied to the GCC 4.6 
trunk; as the date is never read there is also no .mod ABI issue.

I assume that there are no copyright issues.

Cf. also short "discussion"
    at http://gcc.gnu.org/ml/fortran/2011-01/msg00270.html

Tobias

On 01/27/2011 03:00 PM, Simon Baldwin wrote:
> Omit date from Fortran .mod files for reproducible builds.
>
> Strict build environments do binary comparisons of files across gcc builds.
> Writing the current timestamp into a Fortran .mod file leads to false
> positives from such environments.  Omitting the timestamp removes these
> false positives.
>
> Targeted for the google/integration branch.
>
> gcc/fortran/ChangeLog.google:
> 2011-01-27  Simon Baldwin<simonb@google.com>
>
> 	* module.c (gfc_dump_module): Omit timestamp from output.
>
> Google ref: 39202, 25691, 13445, 13307
>
>
> Index: gcc/fortran/module.c
> ===================================================================
> --- gcc/fortran/module.c	(revision 169330)
> +++ gcc/fortran/module.c	(working copy)
> @@ -5116,8 +5116,7 @@ void
>   gfc_dump_module (const char *name, int dump_flag)
>   {
>     int n;
> -  char *filename, *filename_tmp, *p;
> -  time_t now;
> +  char *filename, *filename_tmp;
>     fpos_t md5_pos;
>     unsigned char md5_new[16], md5_old[16];
>
> @@ -5159,13 +5158,8 @@ gfc_dump_module (const char *name, int d
>   		     filename_tmp, xstrerror (errno));
>
>     /* Write the header, including space reserved for the MD5 sum.  */
> -  now = time (NULL);
> -  p = ctime (&now);
> -
> -  *strchr (p, '\n') = '\0';
> -
> -  fprintf (module_fp, "GFORTRAN module version '%s' created from %s on %s\n"
> -	   "MD5:", MOD_VERSION, gfc_source_file, p);
> +  fprintf (module_fp, "GFORTRAN module version '%s' created from %s\n"
> +	   "MD5:", MOD_VERSION, gfc_source_file);
>     fgetpos (module_fp,&md5_pos);
>     fputs ("00000000000000000000000000000000 -- "
>   	"If you edit this, you'll get what you deserve.\n\n", module_fp);
>

On Fri, Jan 28, 2011 at 06:19, Tobias Burnus <burnus@net-b.de> wrote:
> We (Janne and I) think this patch can also be applied to the GCC 4.6 trunk;
> as the date is never read there is also no .mod ABI issue.
>
> I assume that there are no copyright issues.

There aren't.  Google has signed a blanket copyright assignment with
the FSF.  Any patch coming from a google.com address is covered.

I'll mark this patch for trunk.  Thanks.


Diego.