kconfig/lxdialog: fix check() with GCC14

GCC14 now treats implicit int types as error so when check() from
check-lxdialog.sh is called to check whether we can link against ncurses
it will fail silently and the help text indicating to install ncurses is
printed.

However, this is not due to missing ncurses but once the stderr redirect
to /dev/null is removed we can see the root cause:
<stdin>:2:1: error: return type defaults to ‘int’ [-Wimplicit-int]

So, in order for menuconfig to work with GCC14 lets just specify the
return type of main() as int.

Npte that the upstream kconfig in the linux kernel source tree no longer
carries or uses the check-lxdialog.sh script since commit 1c5af5cf9308
(kconfig: refactor ncurses package checks for building mconf and nconf),
so there is no commit we can backport to our kconfig copy.

Signed-off-by: Robert Marko <robimarko@gmail.com>
Reviewed-by: Petr Vorel <petr.vorel@gmail.com>
Tested-by: Petr Vorel <petr.vorel@gmail.com>
[yann.morin.1998@free.fr: add note about upstream kernel]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
(cherry picked from commit a6210d28db)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

support/kconfig/lxdialog/check-lxdialog.sh

@@ -48,7 +48,7 @@ trap "rm -f $tmp" 0 1 2 3 15
 check() {
         $cc -x c - -o $tmp 2>/dev/null <<'EOF'
 #include CURSES_LOC
-main() {}
+int main() {}
 EOF
 	if [ $? != 0 ]; then
 	    echo " *** Unable to find the ncurses libraries or the"       1>&2

support/kconfig/patches/22-kconfig-lxdialog-fix-check-with-GCC14.patch

@@ -0,0 +1,43 @@
+From 3ae91337b53fa3ccf0bad7f181fcaf483fab22ee Mon Sep 17 00:00:00 2001
+From: Robert Marko <robimarko@gmail.com>
+Date: Wed, 3 Apr 2024 14:18:07 +0200
+Subject: [PATCH] kconfig/lxdialog: fix check() with GCC14
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+GCC14 now treats implicit int types as error so when check() from
+check-lxdialog.sh is called to check whether we can link against ncurses
+it will fail silently and the help text indicating to install ncurses is
+printed.
+
+However, this is not due to missing ncurses but once the stderr redirect
+to /dev/null is removed we can see the root cause:
+<stdin>:2:1: error: return type defaults to ‘int’ [-Wimplicit-int]
+
+So, in order for menuconfig to work with GCC14 lets just specify the
+return type of main() as int.
+
+Signed-off-by: Robert Marko <robimarko@gmail.com>
+Reviewed-by: Petr Vorel <petr.vorel@gmail.com>
+Tested-by: Petr Vorel <petr.vorel@gmail.com>
+---
+ kconfig/lxdialog/check-lxdialog.sh | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/kconfig/lxdialog/check-lxdialog.sh b/kconfig/lxdialog/check-lxdialog.sh
+index 16cd9a3186..27d6c30a57 100755
+--- a/kconfig/lxdialog/check-lxdialog.sh
++++ b/kconfig/lxdialog/check-lxdialog.sh
+@@ -48,7 +48,7 @@ trap "rm -f $tmp" 0 1 2 3 15
+ check() {
+         $cc -x c - -o $tmp 2>/dev/null <<'EOF'
+ #include CURSES_LOC
+-main() {}
++int main() {}
+ EOF
+ 	if [ $? != 0 ]; then
+ 	    echo " *** Unable to find the ncurses libraries or the"       1>&2
+-- 
+2.44.0
+

support/kconfig/patches/series

@@ -10,3 +10,4 @@
 19-merge_config.sh-add-br2-external-support.patch
 20-merge_config.sh-Allow-to-define-config-prefix.patch
 21-Avoid-false-positive-matches-from-comment-lines.patch
+22-kconfig-lxdialog-fix-check-with-GCC14.patch