[PATCH] mktime: sync from glibc

[Paul Eggert]

I managed to get all gnulib's important mktime.c changes into glibc,
so I resurrected the mktime.c link between glibc and gnulib in
gnulib/config/srclist.txt and copied the glibc file into gnulib.
Karl, you may want to check the next time that you sync gnulib
sources, as you'll need up-to-date glibc sources again.

The glibc maintainers don't want to use just spaces to indent
so this resurrects the tabs.  I figured that it was more important
to match than to be tab-free.  The following listing omits the
space-tab diffs as they're uninteresting.

diff --git a/ChangeLog b/ChangeLog
index 89ed235..5296ce5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,15 @@
+2012-05-23  Paul Eggert  <address@hidden>
+
+       mktime: sync from glibc
+       * config/srclist.txt: Uncomment mktime.c.
+       * lib/mktime.c: Sync from glibc master.  This incorporates 3 changes.
+       First, indent with tabs, since glibc uses tabs and doesn't want to
+       change and we'd rather be identical to glibc.  Also, two small
+       coding changes:
+       (isdst_differ): Use &&, not &, as && is the usual style.
+       (__mktime_internal): Rename local var from abs_diff to approx_abs_diff
+       for clarity.
+
 2012-05-23  Akim Demaille  <address@hidden>
 
        announce-gen: du -h is more portable than du --human
diff --git a/config/srclist.txt b/config/srclist.txt
index 290f140..e69fcec 100644
--- a/config/srclist.txt
+++ b/config/srclist.txt
@@ -163,7 +163,7 @@ $GNUORG/disclaim.program                    doc/Copyright
 #tab changes $LIBCSRC/stdlib/strtoul.c         lib gpl
 # (no more strtok_r.h) $LIBCSRC/string/strtok_r.c              lib gpl
 # (gnulib needs config.h?) $LIBCSRC/string/memmem.c            lib gpl
-#$LIBCSRC/time/mktime.c                        lib gpl
+$LIBCSRC/time/mktime.c                 lib gpl
 
 #
 # http://sourceware.org/bugzilla/show_bug.cgi?id=1439
diff --git a/lib/mktime.c b/lib/mktime.c
index fc27adf..e1fbf9e 100644
--- a/lib/mktime.c
+++ b/lib/mktime.c
@@ -1,20 +1,21 @@
 /* Convert a 'struct tm' to a time_t value.
-   Copyright (C) 1993-1999, 2002-2007, 2009-2012 Free Software Foundation, Inc.
+   Copyright (C) 1993-2012 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Paul Eggert <address@hidden>.
 
-   This program is free software; you can redistribute it and/or modify
-   it under the terms of the GNU General Public License as published by
-   the Free Software Foundation; either version 2, or (at your option)
-   any later version.
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
 
-   This program is distributed in the hope that it will be useful,
+   The GNU C Library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-   GNU General Public License for more details.
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
 
-   You should have received a copy of the GNU General Public License along
-   with this program; if not, see <http://www.gnu.org/licenses/>.  */
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
 
 /* Define this to have a standalone program to test this implementation of
    mktime.  */
@@ -52,12 +53,14 @@
 
    Define WRAPV to 1 if the assumption is valid and if
      #pragma GCC optimize ("wrapv")
-   does not trigger GCC bug 
<http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51793>.
+   does not trigger GCC bug 51793
+   <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51793>.
    Otherwise, define it to 0; this forces the use of slower code that,
    while not guaranteed by the C Standard, works on all production
    platforms that we know about.  */
 #ifndef WRAPV
-# if ((__GNUC__ == 4 && 4 <= __GNUC_MINOR__) || 4 < __GNUC__) && defined 
__GLIBC__
+# if (((__GNUC__ == 4 && 4 <= __GNUC_MINOR__) || 4 < __GNUC__) \
+      && defined __GLIBC__)
 #  pragma GCC optimize ("wrapv")
 #  define WRAPV 1
 # else
@@ -179,7 +182,7 @@ const unsigned short int __mon_yday[2][13] =
 static int
 isdst_differ (int a, int b)
 {
-  return (!a != !b) & (0 <= a) & (0 <= b);
+  return (!a != !b) && (0 <= a) && (0 <= b);
 }
 
 /* Return an integer value measuring (YEAR1-YDAY1 HOUR1:MIN1:SEC1) -
@@ -442,7 +445,7 @@ __mktime_internal (struct tm *tp,
 
       int approx_biennia = SHR (t0, ALOG2_SECONDS_PER_BIENNIUM);
       int diff = approx_biennia - approx_requested_biennia;
-      int abs_diff = diff < 0 ? -1 - diff : diff;
+      int approx_abs_diff = diff < 0 ? -1 - diff : diff;
 
       /* IRIX 4.0.5 cc miscalculates TIME_T_MIN / 3: it erroneously
          gives a positive value of 715827882.  Setting a variable
@@ -453,15 +456,15 @@ __mktime_internal (struct tm *tp,
       time_t overflow_threshold =
         (time_t_max / 3 - time_t_min / 3) >> ALOG2_SECONDS_PER_BIENNIUM;
 
-      if (overflow_threshold < abs_diff)
+      if (overflow_threshold < approx_abs_diff)
         {
           /* Overflow occurred.  Try repairing it; this might work if
              the time zone offset is enough to undo the overflow.  */
           time_t repaired_t0 = -1 - t0;
           approx_biennia = SHR (repaired_t0, ALOG2_SECONDS_PER_BIENNIUM);
           diff = approx_biennia - approx_requested_biennia;
-          abs_diff = diff < 0 ? -1 - diff : diff;
-          if (overflow_threshold < abs_diff)
+         approx_abs_diff = diff < 0 ? -1 - diff : diff;
+         if (overflow_threshold < approx_abs_diff)
             return -1;
           guessed_offset += repaired_t0 - t0;
           t0 = repaired_t0;