[gjs] Silence a warning with JSLocaleToUnicode

[Colin Walters <walters src gnome org>]

commit bd15bc75b9f4cbd60443b973eb582ebb7df69915
Author: Marc-Antoine Perennou <Marc-Antoine Perennou com>
Date:   Tue Feb 15 17:58:53 2011 +0100

    Silence a warning with JSLocaleToUnicode
    
    Since upstream commit http://hg.mozilla.org/mozilla-central/rev/f971ad6ed5a5
    JSLocaleToUnicode takes a const char*, not a char* for its src.
    Conditionally handle this to silent a warning.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=642186

 configure.ac  |   22 +++++++++++++++++++++-
 gjs/context.c |   10 +++++++---
 2 files changed, 28 insertions(+), 4 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 5ff896b..aa819a2 100644
--- a/configure.ac
+++ b/configure.ac
@@ -164,7 +164,7 @@ if `$PKG_CONFIG --exists $JS_PACKAGE '>=' 2`; then
               , [$JS_LIBS])
   AC_CHECK_LIB([mozjs], [JS_EndPC], AC_DEFINE([HAVE_JS_ENDPC], [1], [Define if we have JS_EndPC]),
               , [$JS_LIBS])
-  AC_CHECK_LIB([mozjs], [JS_NewCompartmentAndGlobalObject], 
+  AC_CHECK_LIB([mozjs], [JS_NewCompartmentAndGlobalObject],
               AC_DEFINE([HAVE_JS_NEWCOMPARTMENTANDGLOBALOBJECT], [1], [Define if we have JS_NewCompartmentAndGlobalObject]),
               , [$JS_LIBS])
 
@@ -201,6 +201,26 @@ if test "$js_extra_cflags_needed" = yes; then
 fi
 AC_SUBST([JS_EXTRA_CFLAGS])
 
+AC_MSG_CHECKING([whether JSLocaleToUnicode takes a const char*])
+save_CFLAGS="$CFLAGS"
+CFLAGS="$CFLAGS $JS_CFLAGS -Wno-unused -Werror"
+AC_COMPILE_IFELSE(
+    [AC_LANG_PROGRAM(
+        [[
+            #include <jsapi.h>
+            extern JSBool test_fun (JSContext*, const char*, jsval*);
+        ]],
+        [[JSLocaleToUnicode jsltu = test_fun;]]
+    )],
+    [have_jslocale_to_unicode_const=yes],
+    [have_jslocale_to_unicode_const=no])
+AC_MSG_RESULT([$have_jslocale_to_unicode_const])
+CFLAGS="$save_CFLAGS"
+
+if test "$have_jslocale_to_unicode_const" = yes; then
+     AC_DEFINE([JS_LOCALETOUNICODE_NEEDS_CONST_CHAR], [1], [Define if JSLocaleToUnicode takes a const char* for its src])
+fi
+
 common_packages="gobject-2.0 >= gobject_required_version $JS_PACKAGE"
 gjs_packages="gmodule-2.0 gthread-2.0 $common_packages"
 gjs_gi_packages="gobject-introspection-1.0 >= 0.10.1 $common_packages"
diff --git a/gjs/context.c b/gjs/context.c
index 4d8291c..758a25a 100644
--- a/gjs/context.c
+++ b/gjs/context.c
@@ -483,9 +483,13 @@ out:
 }
 
 static JSBool
-gjs_locale_to_unicode (JSContext *context,
-                       char      *src,
-                       jsval     *retval)
+gjs_locale_to_unicode (JSContext  *context,
+#ifdef JS_LOCALETOUNICODE_NEEDS_CONST_CHAR
+                       const char *src,
+#else
+                       char       *src,
+#endif
+                       jsval      *retval)
 {
     JSBool success;
     char *utf8;