Fix line generation for match match: / case case: (GH-2661)

CHANGES.md

@@ -10,6 +10,8 @@
 - Fixed Python 3.10 support on platforms without ProcessPoolExecutor (#2631)
 - Fixed `match` statements with open sequence subjects, like `match a, b:` or
   `match a, *b:` (#2639) (#2659)
+- Fixed `match`/`case` statements that contain `match`/`case` soft keywords multiple
+  times, like `match re.match()` (#2661)
 - Fixed assignment to environment variables in Jupyter Notebooks (#2642)
 - Add `flake8-simplify` and `flake8-comprehensions` plugins (#2653)
 

src/black/linegen.py

@@ -127,7 +127,7 @@ def visit_stmt(
         """Visit a statement.
 
         This implementation is shared for `if`, `while`, `for`, `try`, `except`,
-        `def`, `with`, `class`, `assert`, `match`, `case` and assignments.
+        `def`, `with`, `class`, `assert`, and assignments.
 
         The relevant Python language `keywords` for a given statement will be
         NAME leaves within it. This methods puts those on a separate line.
@@ -142,6 +142,14 @@ def visit_stmt(
 
             yield from self.visit(child)
 
+    def visit_match_case(self, node: Node) -> Iterator[Line]:
+        """Visit either a match or case statement."""
+        normalize_invisible_parens(node, parens_after=set())
+
+        yield from self.line()
+        for child in node.children:
+            yield from self.visit(child)
+
     def visit_suite(self, node: Node) -> Iterator[Line]:
         """Visit a suite."""
         if self.mode.is_pyi and is_stub_suite(node):
@@ -294,8 +302,8 @@ def __post_init__(self) -> None:
         self.visit_decorated = self.visit_decorators
 
         # PEP 634
-        self.visit_match_stmt = partial(v, keywords={"match"}, parens=Ø)
-        self.visit_case_block = partial(v, keywords={"case"}, parens=Ø)
+        self.visit_match_stmt = self.visit_match_case
+        self.visit_case_block = self.visit_match_case
 
 
 def transform_line(

tests/data/pattern_matching_extras.py

@@ -23,10 +23,10 @@
 
 def func(match: case, case: match) -> case:
     match Something():
-        case another:
-            ...
         case func(match, case):
             ...
+        case another:
+            ...
 
 
 match maybe, multiple:
@@ -47,6 +47,33 @@ def func(match: case, case: match) -> case:
 
 match a, *b, c:
     case [*_]:
-        return "seq"
+        assert "seq" == _
     case {}:
-        return "map"
+        assert "map" == b
+
+
+match match(
+    case,
+    match(
+        match, case, match, looooooooooooooooooooooooooooooooooooong, match, case, match
+    ),
+    case,
+):
+    case case(
+        match=case,
+        case=re.match(
+            loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong
+        ),
+    ):
+        pass
+
+    case [a as match]:
+        pass
+
+    case case:
+        pass
+
+
+match match:
+    case case:
+        pass