Core: Fix operator[] for typed dictionaries

core/variant/dictionary.cpp

@@ -84,16 +84,25 @@ Variant Dictionary::get_value_at_index(int p_index) const {
 }
 
 Variant &Dictionary::operator[](const Variant &p_key) {
-	if (unlikely(_p->read_only)) {
-		if (likely(_p->variant_map.has(p_key))) {
-			*_p->read_only = _p->variant_map[p_key];
+	Variant key = p_key;
+	if (unlikely(!_p->typed_key.validate(key))) {
+		if (_p->typed_fallback == nullptr) {
+			_p->typed_fallback = memnew(Variant);
+		} else {
+			*_p->typed_fallback = Variant();
+		}
+
+		return *_p->typed_fallback;
+	} else if (unlikely(_p->read_only)) {
+		if (likely(_p->variant_map.has(key))) {
+			*_p->read_only = _p->variant_map[key];
 		} else {
 			*_p->read_only = Variant();
 		}
 
 		return *_p->read_only;
 	} else {
-		return _p->variant_map[p_key];
+		return _p->variant_map[key];
 	}
 }
 

modules/gdscript/tests/scripts/analyzer/errors/typed_dictionary_assign_differently_typed_key.gd

@@ -0,0 +1,7 @@
+func get_key():
+	return "key"
+
+func test():
+	var typed: Dictionary[int, int]
+	typed[get_key()] = 0
+	print('not ok')

modules/gdscript/tests/scripts/analyzer/errors/typed_dictionary_assign_differently_typed_key.out

@@ -0,0 +1,2 @@
+GDTEST_ANALYZER_ERROR
+Invalid index type "String" for a base of type "Dictionary[int, int]".

modules/gdscript/tests/scripts/runtime/errors/typed_dictionary_assign_differently_typed_key.gd

@@ -0,0 +1,7 @@
+func get_key() -> Variant:
+	return "key"
+
+func test():
+	var typed: Dictionary[int, int]
+	typed[get_key()] = 0
+	print('not ok')

modules/gdscript/tests/scripts/runtime/errors/typed_dictionary_assign_differently_typed_key.out

@@ -0,0 +1,5 @@
+GDTEST_RUNTIME_ERROR
+>> ERROR
+>> Method/function failed. Returning: false
+>> Attempted to use a variable of type 'String' into a TypedDictionary.Key of type 'int'.
+not ok