From eca6d64195a05282ea9d4a9166406e47f6fbe4c0 Mon Sep 17 00:00:00 2001
From: Jookia <contact@jookia.org>
Date: Fri, 9 Sep 2022 10:33:08 +1000
Subject: [PATCH] configure: Check if iconv uses const char**

---
 configure.ac        | 8 ++++++++
 include/iconvpp.hpp | 8 +++++++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index 409531c4e..19b2137e1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -653,6 +653,14 @@ case "$host" in
     ;;
 esac
 
+dnl TEST: check if iconv uses const char
+AC_MSG_CHECKING([whether iconv uses const char**])
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([
+#include <iconv.h>
+size_t iconv(iconv_t, const char **restrict, size_t *restrict, char **restrict, size_t *restrict);
+])], AC_DEFINE(ICONV_CONST_CHAR, 1) AC_MSG_RESULT(yes), AC_MSG_RESULT(no))
+AH_TEMPLATE(ICONV_CONST_CHAR,[Whether iconv uses const char**])
+
 dnl LIBRARY TEST: SDLnet
 AC_CHECK_HEADER(SDL_net.h,have_sdl_net_h=yes,)
 AC_CHECK_LIB(SDL2_net, SDLNet_Init, have_sdl2_net_lib=yes, , )
diff --git a/include/iconvpp.hpp b/include/iconvpp.hpp
index 25804bc52..85fa1515d 100644
--- a/include/iconvpp.hpp
+++ b/include/iconvpp.hpp
@@ -31,6 +31,12 @@
 # define ICONV_BIG_ENDIAN BIG_ENDIAN
 #endif
 
+#ifdef ICONV_CONST_CHAR
+# define ICONV_IN_TYPE const char**
+#else
+# define ICONV_IN_TYPE char**
+#endif
+
 #include <errno.h>
 #include <stdio.h>
 #include <string.h>
@@ -247,7 +253,7 @@ public:
             iconv(context,NULL,NULL,NULL,NULL);
 
             /* Ref: [http://man7.org/linux/man-pages/man3/iconv.3.html] */
-            int ret = iconv(context,(char**)(&(pclass::src_ptr)),&src_left,(char**)(&(pclass::dst_ptr)),&dst_left);
+            int ret = iconv(context,(ICONV_IN_TYPE)(&(pclass::src_ptr)),&src_left,(char**)(&(pclass::dst_ptr)),&dst_left);
 
             pclass::src_adv = (size_t)(pclass::src_ptr - i_src);
             pclass::dst_adv = (size_t)(pclass::dst_ptr - i_dst);