Fixed AnnotationTransformer removing quotes from Literals

This bug was a side effect of 4c04b12.

Fixes #399.

docs/versionhistory.rst

@@ -9,6 +9,9 @@ This library adheres to
 - Fixed ``Callable`` erroneously rejecting a callable that has the requested amount of
   positional arguments but they have defaults
   (`#400 <https://github.com/agronholm/typeguard/issues/400>`_)
+- Fixed a regression introduced in v4.1.4 where the elements of ``Literal`` got quotes
+  removed from them by the AST transformer
+  (`#399 <https://github.com/agronholm/typeguard/issues/399>`_)
 
 **4.1.4** (2023-09-10)
 

src/typeguard/_transformer.py

@@ -348,6 +348,10 @@ def __init__(self, transformer: TypeguardTransformer):
         self._level = 0
 
     def visit(self, node: AST) -> Any:
+        # Don't process Literals
+        if isinstance(node, expr) and self._memo.name_matches(node, *literal_names):
+            return node
+
         self._level += 1
         new_node = super().visit(node)
         self._level -= 1
@@ -365,12 +369,6 @@ def visit(self, node: AST) -> Any:
 
         return new_node
 
-    def generic_visit(self, node: AST) -> AST:
-        if isinstance(node, expr) and self._memo.name_matches(node, *literal_names):
-            return node
-
-        return super().generic_visit(node)
-
     def visit_BinOp(self, node: BinOp) -> Any:
         self.generic_visit(node)
 

tests/test_transformer.py

@@ -1805,3 +1805,32 @@ def foo() -> int:
             '''
         ).strip()
     )
+
+
+def test_literal() -> None:
+    # Regression test for #399
+    node = parse(
+        dedent(
+            """
+            from typing import Literal
+
+            def foo(x: Literal['a', 'b']) -> None:
+                pass
+            """
+        )
+    )
+    TypeguardTransformer().visit(node)
+    assert (
+        unparse(node)
+        == dedent(
+            """
+            from typeguard import TypeCheckMemo
+            from typeguard._functions import check_argument_types
+            from typing import Literal
+
+            def foo(x: Literal['a', 'b']) -> None:
+                memo = TypeCheckMemo(globals(), locals())
+                check_argument_types('foo', {'x': (x, Literal['a', 'b'])}, memo)
+            """
+        ).strip()
+    )