From 8a399018269bebd3ee99d2f4f51656b1b74ed02d Mon Sep 17 00:00:00 2001
From: "Z. Liu" <zhixu.liu@gmail.com>
Date: Thu, 9 Jan 2025 14:19:48 +0800
Subject: [PATCH] autoconf: fix -Wimplicit-function-declaration

With modern C compilers this is a bug and will cause false positives in
feature tests.

Signed-off-by: Z. Liu <zhixu.liu@gmail.com>
---
 autoconf/hercules.m4 | 17 ++++++++++++-----
 configure.ac         |  3 +++
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/autoconf/hercules.m4 b/autoconf/hercules.m4
index edd71d63..08647581 100644
--- a/autoconf/hercules.m4
+++ b/autoconf/hercules.m4
@@ -291,6 +291,7 @@ AC_DEFUN([_HC_CHECK_NEED_GETOPT_WRAPPER],
                    Will the linker complain about duplicate
                    symbols for getopt? We'll soon find out!
                 */
+                extern int getopt(int, char *const[], const char *);
                 extern char *optarg;
                 extern int optind;
 
@@ -315,6 +316,8 @@ DUPGETOPT1
                    needs getopt. Will linker complain about
                    duplicate symbols for getopt? Let's see.
                 */
+                extern int getopt(int, char *const[], const char *);
+                extern int test1();
                 extern char *optarg;
                 extern int optind;
                 extern int test2();
@@ -334,11 +337,11 @@ DUPGETOPT1
                 }
 DUPGETOPT2
 
-            libtool --mode=compile ${CC-cc} conftest1.c -c -o conftest1.lo > /dev/null 2>&1
-            libtool --mode=compile ${CC-cc} conftest2.c -c -o conftest2.lo > /dev/null 2>&1
+            libtool --tag=CC --mode=compile ${CC-cc} conftest1.c -c -o conftest1.lo > /dev/null 2>&1
+            libtool --tag=CC --mode=compile ${CC-cc} conftest2.c -c -o conftest2.lo > /dev/null 2>&1
 
-            libtool --mode=link ${CC-cc} -shared -rpath /lib -no-undefined conftest1.lo                 -o libconftest1.la > /dev/null 2>&1
-            libtool --mode=link ${CC-cc} -shared -rpath /lib -no-undefined conftest2.lo libconftest1.la -o libconftest2.la > /dev/null 2>&1
+            libtool --tag=CC --mode=link ${CC-cc} -shared -rpath /lib -no-undefined conftest1.lo                 -o libconftest1.la > /dev/null 2>&1
+            libtool --tag=CC --mode=link ${CC-cc} -shared -rpath /lib -no-undefined conftest2.lo libconftest1.la -o libconftest2.la > /dev/null 2>&1
 
             if test $? = 0; then
 
@@ -385,7 +388,11 @@ AC_DEFUN([HC_CHECK_NEED_GETOPT_OPTRESET],
         [hc_cv_need_getopt_optreset],
         [
             AC_TRY_LINK(
-                [],
+                [
+                    #ifdef HAVE_UNISTD_H
+                    #include <unistd.h>
+                    #endif
+                ],
                 [
                     extern int optreset;
                     optreset=1;
diff --git a/configure.ac b/configure.ac
index f12d4705..68dae467 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1168,6 +1168,9 @@ if test "$GCC" = "yes"; then
 
                             -g -O2 -fomit-frame-pointer
                     */
+                    #if HAVE_STRING_H
+                    #include <string.h>
+                    #endif
 
                     int foo ()
                     {
-- 
2.45.2