fix(xml): pass raw # if there's no constant name (#9418)

src/xml/lv_xml.c

@@ -794,6 +794,10 @@ static void resolve_consts(const char ** item_attrs, lv_xml_component_scope_t *
         if(lv_streq(name, "styles")) continue; /*Styles will handle it themselves*/
         if(value[0] == '#') {
             const char * value_clean = &value[1];
+            /* if there's no constant value, we keep `#` as is */
+            if(*value_clean == '\0') {
+                continue;
+            }
 
             const char * const_value = lv_xml_get_const(scope, value_clean);
             if(const_value) {

tests/src/test_cases/xml/test_xml_general.c

@@ -365,4 +365,19 @@ void test_xml_complex(void)
     TEST_ASSERT_EQUAL_SCREENSHOT("xml/complex_1.png");
 }
 
+void test_xml_label_pound_sign_gets_rendered_properly(void)
+{
+    const char * my_screen =
+        "<screen>"
+        "<view>"
+        "<lv_label align=\"center\" text=\"#\"/>"
+        "</view>"
+        "</screen>";
+    lv_xml_register_component_from_data("screen", my_screen);
+    lv_obj_t * scr = lv_xml_create_screen("screen");
+    lv_screen_load(scr);
+    lv_obj_t * label = lv_obj_get_child(scr, 0);
+    TEST_ASSERT(lv_streq("#", lv_label_get_text(label)));
+}
+
 #endif