2 dnl Copyright (C) 2017 Free Software Foundation, Inc.
3 dnl This file is free software; the Free Software Foundation
4 dnl gives unlimited permission to copy and/or distribute it,
5 dnl with or without modifications, as long as this notice is preserved.
7 dnl Attempt to ensure that 'time_t' is a 64-bit type
8 dnl and that the functions time(), stat(), etc. return 64-bit times.
10 AC_DEFUN([gl_YEAR2038_EARLY],
12 AC_REQUIRE([AC_CANONICAL_HOST])
15 AC_DEFINE([__MINGW_USE_VC2005_COMPAT], [1],
16 [For 64-bit time_t on 32-bit mingw.])
21 AC_DEFUN([gl_YEAR2038],
23 AC_REQUIRE([AC_CANONICAL_HOST])
26 dnl On native Windows, the system include files define types __time32_t
27 dnl and __time64_t. By default, time_t is an alias of
28 dnl - __time32_t on 32-bit mingw,
29 dnl - __time64_t on 64-bit mingw and on MSVC (since MSVC 8).
30 dnl But when compiling with -D__MINGW_USE_VC2005_COMPAT, time_t is an
31 dnl alias of __time64_t.
32 dnl And when compiling with -D_USE_32BIT_TIME_T, time_t is an alias of
34 AC_CACHE_CHECK([for 64-bit time_t], [gl_cv_type_time_t_64],
38 int verify_time_t_size[sizeof (time_t) >= 8 ? 1 : -1];
41 [gl_cv_type_time_t_64=yes], [gl_cv_type_time_t_64=no])
43 if test $gl_cv_type_time_t_64 = no; then
44 dnl Just bail out if 'time_t' is not 64-bit, and let the user fix the
46 AC_EGREP_CPP([booboo], [
47 #ifdef _USE_32BIT_TIME_T
51 [AC_MSG_FAILURE([This package requires a 64-bit 'time_t' type. Remove _USE_32BIT_TIME_T from the compiler flags.])],
52 [AC_MSG_FAILURE([This package requires a 64-bit 'time_t' type. Your system include files surely provide a way to make 'time_t' an alias of '__time64_t'.])])
56 dnl On many systems, time_t is already a 64-bit type.
57 dnl On those systems where time_t is still 32-bit, it requires kernel
58 dnl and libc support to make it 64-bit. For glibc on Linux/x86, this
59 dnl is work in progress; see
60 dnl <https://sourceware.org/glibc/wiki/Y2038ProofnessDesign>.