Improve join performance (#3906)

src/cfnlint/jsonschema/_resolvers_cfn.py

@@ -293,10 +293,12 @@ def _join_expansion(validator: Validator, instances: Any) -> Iterator[Any]:
             yield [value]
         return
 
-    for value, _, _ in validator.resolve_value(instances[0]):
+    for value, instance_validator, errs in validator.resolve_value(instances[0]):
+        if errs:
+            continue
         if not isinstance(value, (str, int, float, bool)):
             raise ValueError(f"Incorrect value type for {value!r}")
-        for values in _join_expansion(validator, instances[1:]):
+        for values in _join_expansion(instance_validator, instances[1:]):
             yield [value] + values
 
 

test/unit/module/jsonschema/test_resolvers_cfn.py

@@ -553,6 +553,20 @@ def test_invalid_functions(name, instance, response):
             {"Fn::Sub": "${MyResource.Arn}"},
             [],
         ),
+        (
+            "Fn::Join uses previous values when doing resolution",
+            {"Fn::Join": ["-", [{"Ref": "Environment"}, {"Ref": "Environment"}]]},
+            [
+                ("dev-dev", deque(), None),
+                ("test-test", deque(), None),
+                ("prod-prod", deque(), None),
+            ],
+        ),
+        (
+            "Fn::Join using a few values with a bad Ref",
+            {"Fn::Join": ["-", [{"Ref": "Environment"}, {"Ref": "DNE"}]]},
+            [],
+        ),
     ],
 )
 def test_valid_functions(name, instance, response):