fixes match statements to work with PositionProvider

libcst/_nodes/statement.py

@@ -2886,6 +2886,9 @@ def _codegen_impl(self, state: CodegenState) -> None:
                 state.add_token("if")
                 self.whitespace_after_if._codegen(state)
                 guard._codegen(state)
+            else:
+                self.whitespace_before_if._codegen(state)
+                self.whitespace_after_if._codegen(state)
 
             self.whitespace_before_colon._codegen(state)
             state.add_token(":")
@@ -3473,6 +3476,13 @@ def _codegen_impl(self, state: CodegenState) -> None:
                     state.add_token(" ")
                 elif isinstance(ws_after, BaseParenthesizableWhitespace):
                     ws_after._codegen(state)
+            else:
+                ws_before = self.whitespace_before_as
+                if isinstance(ws_before, BaseParenthesizableWhitespace):
+                    ws_before._codegen(state)
+                ws_after = self.whitespace_after_as
+                if isinstance(ws_after, BaseParenthesizableWhitespace):
+                    ws_after._codegen(state)
             if name is None:
                 state.add_token("_")
             else:

libcst/metadata/tests/test_position_provider.py

@@ -83,6 +83,53 @@ def visit_Pass(self, node: cst.Pass) -> None:
         wrapper = MetadataWrapper(parse_module("pass"))
         wrapper.visit_batched([ABatchable()])
 
+    def test_match_statement_position_metadata(self) -> None:
+        test = self
+
+        class MatchPositionVisitor(CSTVisitor):
+            METADATA_DEPENDENCIES = (PositionProvider,)
+
+            def visit_Match(self, node: cst.Match) -> None:
+                test.assertEqual(
+                    self.get_metadata(PositionProvider, node),
+                    CodeRange((2, 0), (5, 16)),
+                )
+
+            def visit_MatchCase(self, node: cst.MatchCase) -> None:
+                if (
+                    isinstance(node.pattern, cst.MatchAs)
+                    and node.pattern.name
+                    and node.pattern.name.value == "b"
+                ):
+                    test.assertEqual(
+                        self.get_metadata(PositionProvider, node),
+                        CodeRange((3, 4), (3, 16)),
+                    )
+                elif (
+                    isinstance(node.pattern, cst.MatchAs)
+                    and node.pattern.name
+                    and node.pattern.name.value == "c"
+                ):
+                    test.assertEqual(
+                        self.get_metadata(PositionProvider, node),
+                        CodeRange((4, 4), (4, 16)),
+                    )
+                elif isinstance(node.pattern, cst.MatchAs) and not node.pattern.name:
+                    test.assertEqual(
+                        self.get_metadata(PositionProvider, node),
+                        CodeRange((5, 4), (5, 16)),
+                    )
+
+        code = """
+match status:
+    case b: pass
+    case c: pass
+    case _: pass
+"""
+
+        wrapper = MetadataWrapper(parse_module(code))
+        wrapper.visit(MatchPositionVisitor())
+
 
 class PositionProvidingCodegenStateTest(UnitTest):
     def test_codegen_initial_position(self) -> None: