Do not create empty file filters

The xdg-desktop-portal file chooser implementation (that can be forced
with `GTK_USE_PORTAL=1`) doesn't allow those and fails to create the
dialog if there are any such filter.

This seems like a potential xdg-desktop-portal bug, but it's easy
enough to workaround, and there's no guarantee yet it will change.

It's also unlikely to actually happen that we create such an empty
filter, but it is possible if a filetype doesn't have a corresponding
filetype_extensions.conf entry.

src/dialogs.c

@@ -372,6 +372,7 @@ static GtkWidget *add_file_open_extra_widget(GtkWidget *dialog)
 static GtkFileChooser *create_open_file_dialog(void)
 {
 	GtkFileChooser *dialog;
+	GtkFileFilter *filter;
 	GtkWidget *viewbtn;
 	GSList *node;
 
@@ -408,18 +409,19 @@ static GtkFileChooser *create_open_file_dialog(void)
 	}
 
 	/* add FileFilters(start with "All Files") */
-	gtk_file_chooser_add_filter(dialog,
-				filetypes_create_file_filter(filetypes[GEANY_FILETYPES_NONE]));
+	if ((filter = filetypes_create_file_filter(filetypes[GEANY_FILETYPES_NONE])))
+		gtk_file_chooser_add_filter(dialog, filter);
 	/* now create meta filter "All Source" */
-	gtk_file_chooser_add_filter(dialog,
-				filetypes_create_file_filter_all_source());
+	if ((filter = filetypes_create_file_filter_all_source()))
+		gtk_file_chooser_add_filter(dialog, filter);
 	foreach_slist(node, filetypes_by_title)
 	{
 		GeanyFiletype *ft = node->data;
 
 		if (G_UNLIKELY(ft->id == GEANY_FILETYPES_NONE))
 			continue;
-		gtk_file_chooser_add_filter(dialog, filetypes_create_file_filter(ft));
+		if ((filter = filetypes_create_file_filter(ft)))
+			gtk_file_chooser_add_filter(dialog, filter);
 	}
 
 	gtk_file_chooser_set_select_multiple(GTK_FILE_CHOOSER(dialog), TRUE);

src/filetypes.c

@@ -1187,6 +1187,7 @@ GtkFileFilter *filetypes_create_file_filter_all_source(void)
 {
 	GtkFileFilter *new_filter;
 	guint i, j;
+	guint n_patterns = 0;
 
 	new_filter = gtk_file_filter_new();
 	gtk_file_filter_set_name(new_filter, _("All Source"));
@@ -1200,7 +1201,16 @@ GtkFileFilter *filetypes_create_file_filter_all_source(void)
 		{
 			gtk_file_filter_add_pattern(new_filter, filetypes[i]->pattern[j]);
 		}
+		n_patterns += j;
 	}
+
+	/* very unlikely case where there is *no* patterns at all */
+	if (n_patterns == 0)
+	{
+		g_object_unref(new_filter);
+		new_filter = NULL;
+	}
+
 	return new_filter;
 }
 
@@ -1213,6 +1223,13 @@ GtkFileFilter *filetypes_create_file_filter(const GeanyFiletype *ft)
 
 	g_return_val_if_fail(ft != NULL, NULL);
 
+	/* unlikely case where the ft has no patterns */
+	if (! ft->pattern[0])
+	{
+		g_debug("Not creating filter for filetype %s that has no pattern", ft->name);
+		return NULL;
+	}
+
 	new_filter = gtk_file_filter_new();
 	title = ft->id == GEANY_FILETYPES_NONE ? _("All files") : ft->title;
 	gtk_file_filter_set_name(new_filter, title);