gnulib/import/m4/time_r.m4

   1 dnl Reentrant time functions: localtime_r, gmtime_r.
   2
   3 dnl Copyright (C) 2003, 2006-2019 Free Software Foundation, Inc.
   4 dnl This file is free software; the Free Software Foundation
   5 dnl gives unlimited permission to copy and/or distribute it,
   6 dnl with or without modifications, as long as this notice is preserved.
   7
   8 dnl Written by Paul Eggert.
   9
  10 AC_DEFUN([gl_TIME_R],
  11 [
  12   dnl Persuade glibc and Solaris <time.h> to declare localtime_r.
  13   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
  14
  15   AC_REQUIRE([gl_HEADER_TIME_H_DEFAULTS])
  16   AC_REQUIRE([AC_C_RESTRICT])
  17
  18   dnl Some systems don't declare localtime_r() and gmtime_r() if _REENTRANT is
  19   dnl not defined.
  20   AC_CHECK_DECLS([localtime_r], [], [],
  21     [[/* mingw's <time.h> provides the functions asctime_r, ctime_r,
  22          gmtime_r, localtime_r only if <unistd.h> or <pthread.h> has
  23          been included before.  */
  24       #if defined __MINGW32__
  25       # include <unistd.h>
  26       #endif
  27       #include <time.h>
  28     ]])
  29   if test $ac_cv_have_decl_localtime_r = no; then
  30     HAVE_DECL_LOCALTIME_R=0
  31   fi
  32
  33   AC_CHECK_FUNCS_ONCE([localtime_r])
  34   if test $ac_cv_func_localtime_r = yes; then
  35     HAVE_LOCALTIME_R=1
  36     AC_CACHE_CHECK([whether localtime_r is compatible with its POSIX signature],
  37       [gl_cv_time_r_posix],
  38       [AC_COMPILE_IFELSE(
  39          [AC_LANG_PROGRAM(
  40             [[/* mingw's <time.h> provides the functions asctime_r, ctime_r,
  41                  gmtime_r, localtime_r only if <unistd.h> or <pthread.h> has
  42                  been included before.  */
  43               #if defined __MINGW32__
  44               # include <unistd.h>
  45               #endif
  46               #include <time.h>
  47             ]],
  48             [[/* We don't need to append 'restrict's to the argument types,
  49                  even though the POSIX signature has the 'restrict's,
  50                  since C99 says they can't affect type compatibility.  */
  51               struct tm * (*ptr) (time_t const *, struct tm *) = localtime_r;
  52               if (ptr) return 0;
  53               /* Check the return type is a pointer.
  54                  On HP-UX 10 it is 'int'.  */
  55               *localtime_r (0, 0);]])
  56          ],
  57          [gl_cv_time_r_posix=yes],
  58          [gl_cv_time_r_posix=no])
  59       ])
  60     if test $gl_cv_time_r_posix = yes; then
  61       REPLACE_LOCALTIME_R=0
  62     else
  63       REPLACE_LOCALTIME_R=1
  64     fi
  65   else
  66     HAVE_LOCALTIME_R=0
  67     dnl On mingw, localtime_r() is defined as an inline function; use through a
  68     dnl direct function call works but the use as a function pointer leads to a
  69     dnl link error.
  70     AC_CACHE_CHECK([whether localtime_r exists as an inline function],
  71       [gl_cv_func_localtime_r_inline],
  72       [AC_LINK_IFELSE(
  73          [AC_LANG_PROGRAM(
  74             [[/* mingw's <time.h> provides the functions asctime_r, ctime_r,
  75                  gmtime_r, localtime_r only if <unistd.h> or <pthread.h> has
  76                  been included before.  */
  77               #if defined __MINGW32__
  78               # include <unistd.h>
  79               #endif
  80               #include <time.h>
  81             ]],
  82             [[time_t a;
  83               struct tm r;
  84               localtime_r (&a, &r);
  85             ]])
  86          ],
  87          [gl_cv_func_localtime_r_inline=yes],
  88          [gl_cv_func_localtime_r_inline=no])
  89       ])
  90     if test $gl_cv_func_localtime_r_inline = yes; then
  91       REPLACE_LOCALTIME_R=1
  92     fi
  93   fi
  94 ])
  95
  96 # Prerequisites of lib/time_r.c.
  97 AC_DEFUN([gl_PREREQ_TIME_R], [
  98   :
  99 ])