dnl Reentrant time functions: localtime_r, gmtime_r.

dnl Copyright (C) 2003, 2006-2020 Free Software Foundation, Inc.

dnl This file is free software; the Free Software Foundation

dnl gives unlimited permission to copy and/or distribute it,

dnl with or without modifications, as long as this notice is preserved.

dnl Written by Paul Eggert.

AC_DEFUN([gl_TIME_R],

[

  dnl Persuade glibc and Solaris <time.h> to declare localtime_r.

  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])

  AC_REQUIRE([gl_HEADER_TIME_H_DEFAULTS])

  AC_REQUIRE([AC_C_RESTRICT])

  dnl Some systems don't declare localtime_r() and gmtime_r() if _REENTRANT is

  dnl not defined.

  AC_CHECK_DECLS([localtime_r], [], [],

    [[/* mingw's <time.h> provides the functions asctime_r, ctime_r,

         gmtime_r, localtime_r only if <unistd.h> or <pthread.h> has

         been included before.  */

      #if defined __MINGW32__

      # include <unistd.h>

      #endif

      #include <time.h>

    ]])

  if test $ac_cv_have_decl_localtime_r = no; then

    HAVE_DECL_LOCALTIME_R=0

  fi

  AC_CHECK_FUNCS_ONCE([localtime_r])

  if test $ac_cv_func_localtime_r = yes; then

    HAVE_LOCALTIME_R=1

    AC_CACHE_CHECK([whether localtime_r is compatible with its POSIX signature],

      [gl_cv_time_r_posix],

      [AC_COMPILE_IFELSE(

         [AC_LANG_PROGRAM(

            [[/* mingw's <time.h> provides the functions asctime_r, ctime_r,

                 gmtime_r, localtime_r only if <unistd.h> or <pthread.h> has

                 been included before.  */

              #if defined __MINGW32__

              # include <unistd.h>

              #endif

              #include <time.h>

            ]],

            [[/* We don't need to append 'restrict's to the argument types,

                 even though the POSIX signature has the 'restrict's,

                 since C99 says they can't affect type compatibility.  */

              struct tm * (*ptr) (time_t const *, struct tm *) = localtime_r;

              if (ptr) return 0;

              /* Check the return type is a pointer.

                 On HP-UX 10 it is 'int'.  */

              *localtime_r (0, 0);]])

         ],

         [gl_cv_time_r_posix=yes],

         [gl_cv_time_r_posix=no])

      ])

    if test $gl_cv_time_r_posix = yes; then

      REPLACE_LOCALTIME_R=0

    else

      REPLACE_LOCALTIME_R=1

    fi

  else

    HAVE_LOCALTIME_R=0

    dnl On mingw, localtime_r() is defined as an inline function; use through a

    dnl direct function call works but the use as a function pointer leads to a

    dnl link error.

    AC_CACHE_CHECK([whether localtime_r exists as an inline function],

      [gl_cv_func_localtime_r_inline],

      [AC_LINK_IFELSE(

         [AC_LANG_PROGRAM(

            [[/* mingw's <time.h> provides the functions asctime_r, ctime_r,

                 gmtime_r, localtime_r only if <unistd.h> or <pthread.h> has

                 been included before.  */

              #if defined __MINGW32__

              # include <unistd.h>

              #endif

              #include <time.h>

            ]],

            [[time_t a;

              struct tm r;

              localtime_r (&a, &r);

            ]])

         ],

         [gl_cv_func_localtime_r_inline=yes],

         [gl_cv_func_localtime_r_inline=no])

      ])

    if test $gl_cv_func_localtime_r_inline = yes; then

      REPLACE_LOCALTIME_R=1

    fi

  fi

])

# Prerequisites of lib/time_r.c.

AC_DEFUN([gl_PREREQ_TIME_R], [

  :

])