From b68561dd7925dfee1836f75d3fa8d33fff5c2498 Mon Sep 17 00:00:00 2001
From: Jonathan Wakely <jwakely@redhat.com>
Date: Wed, 28 Aug 2024 12:38:18 +0100
Subject: [PATCH] libstdc++: Fix autoconf check for O_NONBLOCK in <fcntl.h>

I misused the AC_CHECK_DECL macro, assuming that it behaved like
AC_CHECK_DECLS and always defined a HAVE_xxx macro if the decl was
found. Instead, the [action-if-found] shell commands are needed to
defined HAVE_O_NONBLOCK explicitly.

libstdc++-v3/ChangeLog:

	* configure.ac: Fix check for O_NONBLOCK.
	* config.h.in: Regenerate.
	* configure: Regenerate.
---
 libstdc++-v3/config.h.in  | 3 +++
 libstdc++-v3/configure    | 2 ++
 libstdc++-v3/configure.ac | 5 ++++-
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/libstdc++-v3/config.h.in b/libstdc++-v3/config.h.in
index 486ba450749..91e920044ee 100644
--- a/libstdc++-v3/config.h.in
+++ b/libstdc++-v3/config.h.in
@@ -302,6 +302,9 @@
 /* Define if openat is available in <fcntl.h>. */
 #undef HAVE_OPENAT
 
+/* Define if O_NONBLOCK is defined in <fcntl.h> */
+#undef HAVE_O_NONBLOCK
+
 /* Define if poll is available in <poll.h>. */
 #undef HAVE_POLL
 
diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure
index 305675eaa1e..005c4a29fd0 100755
--- a/libstdc++-v3/configure
+++ b/libstdc++-v3/configure
@@ -54132,6 +54132,8 @@ if test "$ac_cv_have_decl_F_GETFL$ac_cv_have_decl_F_SETFL" = yesyes ; then
 "
 if test "x$ac_cv_have_decl_O_NONBLOCK" = xyes; then :
 
+$as_echo "#define HAVE_O_NONBLOCK 1" >>confdefs.h
+
 fi
 
 fi
diff --git a/libstdc++-v3/configure.ac b/libstdc++-v3/configure.ac
index 4049f54bd5a..a3b257fe652 100644
--- a/libstdc++-v3/configure.ac
+++ b/libstdc++-v3/configure.ac
@@ -554,7 +554,10 @@ AC_CHECK_HEADERS([fcntl.h sys/ioctl.h sys/socket.h sys/uio.h poll.h netdb.h arpa
 AC_CHECK_DECL(F_GETFL,,,[#include <fcntl.h>])
 AC_CHECK_DECL(F_SETFL,,,[#include <fcntl.h>])
 if test "$ac_cv_have_decl_F_GETFL$ac_cv_have_decl_F_SETFL" = yesyes ; then
-  AC_CHECK_DECL(O_NONBLOCK,,,[#include <fcntl.h>])
+  AC_CHECK_DECL(O_NONBLOCK,
+    AC_DEFINE(HAVE_O_NONBLOCK,1,[Define if O_NONBLOCK is defined in <fcntl.h>]),
+    [],
+    [#include <fcntl.h>])
 fi
 
 # For Transactional Memory TS