compat: remove gmtime

ccd469450a (date.c: switch to reentrant {gm,local}time_r, 2019-11-28)
removes the only gmtime() call we had and moves to gmtime_r() which
doesn't have the same portability problems.

Remove the compat gmtime code since it is no longer needed, and confirm
by successfull running t4212 in FreeBSD 9.3 amd64 (the oldest I could
get a hold off).

Further work might be needed to ensure 32bit time_t systems (like FreeBSD
i386) will handle correctly the overflows tested in t4212, but that is
orthogonal to this change, and it doesn't change the current behaviour
as neither gmtime() or gmtime_r() will ever return NULL on those systems
because time_t is unsigned.

Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Makefile

@@ -405,9 +405,6 @@ all::
 # with a different indexfile format version.  If it isn't set the index
 # file format used is index-v[23].
 #
-# Define GMTIME_UNRELIABLE_ERRORS if your gmtime() function does not
-# return NULL when it receives a bogus time_t.
-#
 # Define HAVE_CLOCK_GETTIME if your platform has clock_gettime.
 #
 # Define HAVE_CLOCK_MONOTONIC if your platform has CLOCK_MONOTONIC.
@@ -1801,11 +1798,6 @@ ifndef NO_MSGFMT_EXTENDED_OPTIONS
 	MSGFMT += --check --statistics
 endif
 
-ifdef GMTIME_UNRELIABLE_ERRORS
-	COMPAT_OBJS += compat/gmtime.o
-	BASIC_CFLAGS += -DGMTIME_UNRELIABLE_ERRORS
-endif
-
 ifdef HAVE_CLOCK_GETTIME
 	BASIC_CFLAGS += -DHAVE_CLOCK_GETTIME
 endif

compat/gmtime.c

@@ -1,29 +0,0 @@
-#include "../git-compat-util.h"
-#undef gmtime
-#undef gmtime_r
-
-struct tm *git_gmtime(const time_t *timep)
-{
-	static struct tm result;
-	return git_gmtime_r(timep, &result);
-}
-
-struct tm *git_gmtime_r(const time_t *timep, struct tm *result)
-{
-	struct tm *ret;
-
-	memset(result, 0, sizeof(*result));
-	ret = gmtime_r(timep, result);
-
-	/*
-	 * Rather than NULL, FreeBSD gmtime simply leaves the "struct tm"
-	 * untouched when it encounters overflow. Since "mday" cannot otherwise
-	 * be zero, we can test this very quickly.
-	 */
-	if (ret && !ret->tm_mday) {
-		ret = NULL;
-		errno = EOVERFLOW;
-	}
-
-	return ret;
-}

config.mak.uname

@@ -237,7 +237,6 @@ ifeq ($(uname_S),FreeBSD)
 	PYTHON_PATH = /usr/local/bin/python
 	PERL_PATH = /usr/local/bin/perl
 	HAVE_PATHS_H = YesPlease
-	GMTIME_UNRELIABLE_ERRORS = UnfortunatelyYes
 	HAVE_BSD_SYSCTL = YesPlease
 	HAVE_BSD_KERN_PROC_SYSCTL = YesPlease
 	PAGER_ENV = LESS=FRX LV=-c MORE=FRX

git-compat-util.h

@@ -1208,13 +1208,6 @@ int access_or_die(const char *path, int mode, unsigned flag);
 /* Warn on an inaccessible file if errno indicates this is an error */
 int warn_on_fopen_errors(const char *path);
 
-#ifdef GMTIME_UNRELIABLE_ERRORS
-struct tm *git_gmtime(const time_t *);
-struct tm *git_gmtime_r(const time_t *, struct tm *);
-#define gmtime git_gmtime
-#define gmtime_r git_gmtime_r
-#endif
-
 #if !defined(USE_PARENS_AROUND_GETTEXT_N) && defined(__GNUC__)
 #define USE_PARENS_AROUND_GETTEXT_N 1
 #endif