pkgs/development/compilers/gcc/use-source-date-epoch.patch

   1 https://gcc.gnu.org/ml/gcc-patches/2015-06/msg02210.html
   2
   3 diff --git a/libcpp/macro.c b/libcpp/macro.c
   4 index 1e0a0b5..a52e3cb 100644
   5 --- a/libcpp/macro.c
   6 +++ b/libcpp/macro.c
   7 @@ -349,14 +349,38 @@ _cpp_builtin_macro_text (cpp_reader *pfile, cpp_hashnode *node)
   8              slow on some systems.  */
   9           time_t tt;
  10           struct tm *tb = NULL;
  11 +         char *source_date_epoch;
  12
  13 -         /* (time_t) -1 is a legitimate value for "number of seconds
  14 -            since the Epoch", so we have to do a little dance to
  15 -            distinguish that from a genuine error.  */
  16 -         errno = 0;
  17 -         tt = time(NULL);
  18 -         if (tt != (time_t)-1 || errno == 0)
  19 -           tb = localtime (&tt);
  20 +         /* Allow the date and time to be set externally by an exported
  21 +            environment variable to enable reproducible builds. */
  22 +         source_date_epoch = getenv ("SOURCE_DATE_EPOCH");
  23 +         if (source_date_epoch)
  24 +           {
  25 +             errno = 0;
  26 +             tt = (time_t) strtol (source_date_epoch, NULL, 10);
  27 +             if (errno == 0)
  28 +               {
  29 +                 tb = gmtime (&tt);
  30 +                 if (tb == NULL)
  31 +                   cpp_error (pfile, CPP_DL_ERROR,
  32 +                              "SOURCE_DATE_EPOCH=\"%s\" is not a valid date",
  33 +                              source_date_epoch);
  34 +               }
  35 +             else
  36 +               cpp_error (pfile, CPP_DL_ERROR,
  37 +                          "SOURCE_DATE_EPOCH=\"%s\" is not a valid number",
  38 +                          source_date_epoch);
  39 +           }
  40 +         else
  41 +           {
  42 +           /* (time_t) -1 is a legitimate value for "number of seconds
  43 +              since the Epoch", so we have to do a little dance to
  44 +              distinguish that from a genuine error.  */
  45 +           errno = 0;
  46 +           tt = time(NULL);
  47 +           if (tt != (time_t)-1 || errno == 0)
  48 +             tb = localtime (&tt);
  49 +         }
  50
  51           if (tb)
  52             {