Support nested lambdas in BracketTracker

black.py

@@ -647,8 +647,8 @@ class BracketTracker:
     bracket_match: Dict[Tuple[Depth, NodeType], Leaf] = Factory(dict)
     delimiters: Dict[LeafID, Priority] = Factory(dict)
     previous: Optional[Leaf] = None
-    _for_loop_variable: bool = False
-    _lambda_arguments: bool = False
+    _for_loop_variable: int = 0
+    _lambda_arguments: int = 0
 
     def mark(self, leaf: Leaf) -> None:
         """Mark `leaf` with bracket-related metadata. Keep track of delimiters.
@@ -710,7 +710,7 @@ def maybe_increment_for_loop_variable(self, leaf: Leaf) -> bool:
         """
         if leaf.type == token.NAME and leaf.value == "for":
             self.depth += 1
-            self._for_loop_variable = True
+            self._for_loop_variable += 1
             return True
 
         return False
@@ -719,7 +719,7 @@ def maybe_decrement_after_for_loop_variable(self, leaf: Leaf) -> bool:
         """See `maybe_increment_for_loop_variable` above for explanation."""
         if self._for_loop_variable and leaf.type == token.NAME and leaf.value == "in":
             self.depth -= 1
-            self._for_loop_variable = False
+            self._for_loop_variable -= 1
             return True
 
         return False
@@ -732,7 +732,7 @@ def maybe_increment_lambda_arguments(self, leaf: Leaf) -> bool:
         """
         if leaf.type == token.NAME and leaf.value == "lambda":
             self.depth += 1
-            self._lambda_arguments = True
+            self._lambda_arguments += 1
             return True
 
         return False
@@ -741,7 +741,7 @@ def maybe_decrement_after_lambda_arguments(self, leaf: Leaf) -> bool:
         """See `maybe_increment_lambda_arguments` above for explanation."""
         if self._lambda_arguments and leaf.type == token.COLON:
             self.depth -= 1
-            self._lambda_arguments = False
+            self._lambda_arguments -= 1
             return True
 
         return False

tests/expression.diff

@@ -11,7 +11,7 @@
  True
  False
  1
-@@ -29,61 +29,83 @@
+@@ -29,62 +29,84 @@
  ~great
  +value
  -1
@@ -24,9 +24,10 @@
  lambda a, b, c=True: a
 -lambda a, b, c=True, *, d=(1 << v2), e='str': a
 -lambda a, b, c=True, *vararg, d=(v1 << 2), e='str', **kwargs: a + b
--foo = (lambda port_id, ignore_missing: {"port1": port1_resource, "port2": port2_resource}[port_id])
 +lambda a, b, c=True, *, d=(1 << v2), e="str": a
 +lambda a, b, c=True, *vararg, d=(v1 << 2), e="str", **kwargs: a + b
+ manylambdas = lambda x=lambda y=lambda z=1: z: y(): x()
+-foo = (lambda port_id, ignore_missing: {"port1": port1_resource, "port2": port2_resource}[port_id])
 +foo = lambda port_id, ignore_missing: {
 +    "port1": port1_resource, "port2": port2_resource
 +}[
@@ -116,7 +117,7 @@
  call(**self.screen_kwargs)
  call(b, **self.screen_kwargs)
  lukasz.langa.pl
-@@ -92,11 +114,11 @@
+@@ -93,11 +115,11 @@
  1.0 .real
  ....__class__
  list[str]
@@ -129,7 +130,7 @@
  ]
  slice[0]
  slice[0:1]
-@@ -123,103 +145,140 @@
+@@ -124,103 +146,140 @@
  numpy[-(c + 1) :, d]
  numpy[:, l[-2]]
  numpy[:, ::-1]

tests/expression.py

@@ -37,6 +37,7 @@
 lambda a, b, c=True: a
 lambda a, b, c=True, *, d=(1 << v2), e='str': a
 lambda a, b, c=True, *vararg, d=(v1 << 2), e='str', **kwargs: a + b
+manylambdas = lambda x=lambda y=lambda z=1: z: y(): x()
 foo = (lambda port_id, ignore_missing: {"port1": port1_resource, "port2": port2_resource}[port_id])
 1 if True else 2
 str or None if True else str or bytes or None
@@ -266,6 +267,7 @@ async def f():
 lambda a, b, c=True: a
 lambda a, b, c=True, *, d=(1 << v2), e="str": a
 lambda a, b, c=True, *vararg, d=(v1 << 2), e="str", **kwargs: a + b
+manylambdas = lambda x=lambda y=lambda z=1: z: y(): x()
 foo = lambda port_id, ignore_missing: {
     "port1": port1_resource, "port2": port2_resource
 }[