[pango/avoid-script-lang-crash] Don't assert in pango_language_get_scripts

[Matthias Clasen <matthiasc src gnome org>]

commit 7db68865b7560ca5d74aa6cd15656b3656ea7f42
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Sep 8 16:49:43 2020 -0400

    Don't assert in pango_language_get_scripts
    
    The assertion in pango_language_get_scripts can
    actually be triggered since we last regenerated
    the pango_script_for_lang table. It now includes
    an entry for und-zsye which has no scripts.
    
    Handle this case without asserting.
    
    This commit includes a test.

 pango/pango-language.c |  2 +-
 tests/testmisc.c       | 15 +++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)
---
diff --git a/pango/pango-language.c b/pango/pango-language.c
index 575d4652..bb5ed470 100644
--- a/pango/pango-language.c
+++ b/pango/pango-language.c
@@ -662,7 +662,7 @@ pango_language_get_scripts (PangoLanguage *language,
                                                 script_for_lang,
                                                 pango_script_for_lang);
 
-  if (!script_for_lang)
+  if (!script_for_lang || script_for_lang->scripts[0] == 0)
     {
       if (num_scripts)
        *num_scripts = 0;
diff --git a/tests/testmisc.c b/tests/testmisc.c
index 9f1f24da..2f6c148b 100644
--- a/tests/testmisc.c
+++ b/tests/testmisc.c
@@ -73,6 +73,20 @@ test_short_string_crash (void)
   g_object_unref (context);
 }
 
+static void
+test_language_emoji_crash (void)
+{
+  PangoLanguage *lang;
+  const PangoScript *scripts;
+  int num;
+
+  lang = pango_language_from_string ("und-zsye");
+  scripts = pango_language_get_scripts (lang, &num);
+
+  g_assert (num >= 0);
+  g_assert (scripts == NULL || num > 0);
+}
+
 int
 main (int argc, char *argv[])
 {
@@ -81,6 +95,7 @@ main (int argc, char *argv[])
   g_test_add_func ("/layout/shape-tab-crash", test_shape_tab_crash);
   g_test_add_func ("/layout/itemize-empty-crash", test_itemize_empty_crash);
   g_test_add_func ("/layout/short-string-crash", test_short_string_crash);
+  g_test_add_func ("/language/emoji-crash", test_language_emoji_crash);
 
   return g_test_run ();
 }