Fix RawExpressionType.accept crash with --cache-fine-grained

Commit 1072c78 (#17148) converted all
quoted types into RawExpressionType, which raised an AssertionError
when accepting a TypeTriggersVisitor.

Fixes #17587.

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

mypy/types.py

@@ -2705,6 +2705,8 @@ def simple_name(self) -> str:
         return self.base_type_name.replace("builtins.", "")
 
     def accept(self, visitor: TypeVisitor[T]) -> T:
+        if self.node is not None:
+            return self.node.accept(visitor)
         assert isinstance(visitor, SyntheticTypeVisitor)
         ret: T = visitor.visit_raw_expression_type(self)
         return ret

test-data/unit/check-typeddict.test

@@ -1442,6 +1442,18 @@ reveal_type(x) # N: Revealed type is "TypedDict('__main__.X', {'a': TypedDict('_
 reveal_type(x['a']['b']) # N: Revealed type is "builtins.int"
 [builtins fixtures/dict.pyi]
 
+[case testTypedDictForwardReferenceCacheFineGrained]
+# flags: --cache-fine-grained
+from mypy_extensions import TypedDict
+class A(TypedDict):
+    b: "B"
+class B(TypedDict):
+    c: "C"
+class C(TypedDict):
+    d: "D"
+class D:
+    pass
+
 [case testSelfRecursiveTypedDictInheriting]
 from mypy_extensions import TypedDict