[PATCH] sys_types: let Autoconf 2.70 do pid_t

[Paul Eggert]

* m4/pid_t.m4 (AC_TYPE_PID_T): Redefine this Autoconf macro
only for Autoconf versions 2.69 and earlier, since 2.70
will be fixed.
---
 ChangeLog   | 7 +++++++
 m4/pid_t.m4 | 7 ++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/ChangeLog b/ChangeLog
index 073f96870..c6b057e68 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2020-08-23  Paul Eggert  <eggert@cs.ucla.edu>
+
+       sys_types: let Autoconf 2.70 do pid_t
+       * m4/pid_t.m4 (AC_TYPE_PID_T): Redefine this Autoconf macro
+       only for Autoconf versions 2.69 and earlier, since 2.70
+       will be fixed.
+
 2020-08-23  Bruno Haible  <bruno@clisp.org>
 
        tests: Don't assume that pid_t fits in an 'int'.
diff --git a/m4/pid_t.m4 b/m4/pid_t.m4
index 321082d00..4fb9c7aef 100644
--- a/m4/pid_t.m4
+++ b/m4/pid_t.m4
@@ -1,9 +1,12 @@
-# pid_t.m4 serial 1
+# pid_t.m4 serial 2
 dnl Copyright (C) 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.
 
+# 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],
 [
@@ -31,3 +34,5 @@ AC_DEFUN([AC_TYPE_PID_T],
     ],
     [AC_INCLUDES_DEFAULT])
 ])
+
+])# m4_version_prereq 2.70
-- 
2.17.1