stdioext: Avoid compilation errors on UnixWare 7.

Reported by Tim Rice <tim@multitalents.net> in
<https://lists.gnu.org/archive/html/bug-gnulib/2020-09/msg00127.html>.

* lib/fbufmode.c: Don't include <stdio_ext.h> if it does not exist.
* lib/fpurge.c: Likewise.
* lib/freadable.h: Likewise.
* lib/freading.h: Likewise.
* lib/fwritable.h: Likewise.
* lib/fwriting.h: Likewise.
* m4/fbufmode.m4 (gl_FUNC_FBUFMODE): Test whether <stdio_ext.h> exists.
* m4/fpurge.m4 (gl_FUNC_FPURGE): Likewise.
* m4/freadable.m4 (gl_FUNC_FREADABLE): Likewise.
* m4/freading.m4 (gl_FUNC_FREADING): Likewise.
* m4/fwritable.m4 (gl_FUNC_FWRITABLE): Likewise.
* m4/fwriting.m4 (gl_FUNC_FWRITING): Likewise.

6 files changed, 12 insertions, 6 deletions

diff --git a/m4/fbufmode.m4 b/m4/fbufmode.m4
index 87e76e0d7b..e2a146fa29 100644
--- a/m4/fbufmode.m4
+++ b/m4/fbufmode.m4
@@ -1,4 +1,4 @@
-# fbufmode.m4 serial 2
+# fbufmode.m4 serial 3
 dnl Copyright (C) 2007, 2009-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -7,5 +7,6 @@ dnl with or without modifications, as long as this notice is preserved.
 AC_DEFUN([gl_FUNC_FBUFMODE],
 [
   dnl Prerequisites of lib/fbufmode.c.
+  AC_CHECK_HEADERS_ONCE([stdio_ext.h])
   AC_CHECK_FUNCS_ONCE([__flbf __fbufsize])
 ])
diff --git a/m4/fpurge.m4 b/m4/fpurge.m4
index 0796a6f0ed..9a486e00a4 100644
--- a/m4/fpurge.m4
+++ b/m4/fpurge.m4
@@ -1,4 +1,4 @@
-# fpurge.m4 serial 11
+# fpurge.m4 serial 12
 dnl Copyright (C) 2007, 2009-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -8,6 +8,7 @@ AC_DEFUN([gl_FUNC_FPURGE],
 [
   AC_REQUIRE([gl_STDIO_H_DEFAULTS])
   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CHECK_HEADERS_ONCE([stdio_ext.h])
   AC_CHECK_FUNCS_ONCE([fpurge])
   AC_CHECK_FUNCS_ONCE([__fpurge])
   AC_CHECK_DECLS([fpurge], , , [[#include <stdio.h>]])
diff --git a/m4/freadable.m4 b/m4/freadable.m4
index 3237effe02..e988054374 100644
--- a/m4/freadable.m4
+++ b/m4/freadable.m4
@@ -1,4 +1,4 @@
-# freadable.m4 serial 2
+# freadable.m4 serial 3
 dnl Copyright (C) 2007, 2009-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -6,5 +6,6 @@ dnl with or without modifications, as long as this notice is preserved.
 
 AC_DEFUN([gl_FUNC_FREADABLE],
 [
+  AC_CHECK_HEADERS_ONCE([stdio_ext.h])
   AC_CHECK_FUNCS_ONCE([__freadable])
 ])
diff --git a/m4/freading.m4 b/m4/freading.m4
index 440c241e47..6eb25abfa2 100644
--- a/m4/freading.m4
+++ b/m4/freading.m4
@@ -1,4 +1,4 @@
-# freading.m4 serial 1
+# freading.m4 serial 2
 dnl Copyright (C) 2007, 2009-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -6,5 +6,6 @@ dnl with or without modifications, as long as this notice is preserved.
 
 AC_DEFUN([gl_FUNC_FREADING],
 [
+  AC_CHECK_HEADERS_ONCE([stdio_ext.h])
   AC_CHECK_FUNCS_ONCE([__freading])
 ])
diff --git a/m4/fwritable.m4 b/m4/fwritable.m4
index dbe887e886..55db08f87e 100644
--- a/m4/fwritable.m4
+++ b/m4/fwritable.m4
@@ -1,4 +1,4 @@
-# fwritable.m4 serial 2
+# fwritable.m4 serial 3
 dnl Copyright (C) 2007, 2009-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -6,5 +6,6 @@ dnl with or without modifications, as long as this notice is preserved.
 
 AC_DEFUN([gl_FUNC_FWRITABLE],
 [
+  AC_CHECK_HEADERS_ONCE([stdio_ext.h])
   AC_CHECK_FUNCS_ONCE([__fwritable])
 ])
diff --git a/m4/fwriting.m4 b/m4/fwriting.m4
index 4d7cd3ede1..fe2f10ea27 100644
--- a/m4/fwriting.m4
+++ b/m4/fwriting.m4
@@ -1,4 +1,4 @@
-# fwriting.m4 serial 2
+# fwriting.m4 serial 3
 dnl Copyright (C) 2007, 2009-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -6,5 +6,6 @@ dnl with or without modifications, as long as this notice is preserved.
 
 AC_DEFUN([gl_FUNC_FWRITING],
 [
+  AC_CHECK_HEADERS_ONCE([stdio_ext.h])
   AC_CHECK_FUNCS_ONCE([__fwriting])
 ])