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emacs/m4/pid_t.m4
2024-05-11 18:46:26 -07:00

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# pid_t.m4
# serial 4
dnl Copyright (C) 2020-2024 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.
# The following implementation works around a problem in autoconf <= 2.69.
m4_version_prereq([2.70], [], [
dnl Define pid_t if the headers don't define it.
AC_DEFUN([AC_TYPE_PID_T],
[
AC_CHECK_TYPE([pid_t],
[],
[dnl On 64-bit native Windows, define it to the equivalent of 'intptr_t'
dnl (= 'long long' = '__int64'), because that is the return type
dnl of the _spawnv* functions
dnl <https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/spawnvp-wspawnvp>
dnl and the argument type of the _cwait function
dnl <https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/cwait>.
dnl Otherwise (on 32-bit Windows and on old Unix platforms), define it
dnl to 'int'.
AC_COMPILE_IFELSE(
[AC_LANG_PROGRAM([[
#if defined _WIN64 && !defined __CYGWIN__
LLP64
#endif
]])
],
[gl_pid_type='int'],
[gl_pid_type='__int64'])
AC_DEFINE_UNQUOTED([pid_t], [$gl_pid_type],
[Define as a signed integer type capable of holding a process identifier.])
],
[AC_INCLUDES_DEFAULT])
])
])# m4_version_prereq 2.70