Stability fixup: address stability issues relating to interaction between magic commas and invisible parentheses

src/black/__init__.py

@@ -6606,7 +6606,7 @@ def can_omit_invisible_parens(
     last = line.leaves[-1]
     if line.should_explode:
         try:
-            penultimate, last = last_two_except(line.leaves, omit=omit_on_explode)
+            penultimate, last = last_two_except(line.leaves)
         except LookupError:
             # Turns out we'd omit everything.  We cannot skip the optional parentheses.
             return False
@@ -6683,7 +6683,7 @@ def _can_omit_closing_paren(line: Line, *, last: Leaf, line_length: int) -> bool
     return False
 
 
-def last_two_except(leaves: List[Leaf], omit: Collection[LeafID]) -> Tuple[Leaf, Leaf]:
+def last_two_except(leaves: List[Leaf]) -> Tuple[Leaf, Leaf]:
     """Return (penultimate, last) leaves skipping brackets in `omit` and contents."""
     stop_after = None
     last = None
@@ -6696,10 +6696,7 @@ def last_two_except(leaves: List[Leaf], omit: Collection[LeafID]) -> Tuple[Leaf,
         if last:
             return leaf, last
 
-        if id(leaf) in omit:
-            stop_after = leaf.opening_bracket
-        else:
-            last = leaf
+        last = leaf
     else:
         raise LookupError("Last two leaves were also skipped")
 

tests/data/function_trailing_comma.py

@@ -23,6 +23,7 @@ def xxxxxxxxxxxxxxxxxxxxxxxxxxxx() -> Set[
 
 # output
 
+
 def f(
     a,
 ):
@@ -61,16 +62,19 @@ def f(
         "a": 1,
         "b": 2,
     }["a"]
-    if a == {
-        "a": 1,
-        "b": 2,
-        "c": 3,
-        "d": 4,
-        "e": 5,
-        "f": 6,
-        "g": 7,
-        "h": 8,
-    }["a"]:
+    if (
+        a
+        == {
+            "a": 1,
+            "b": 2,
+            "c": 3,
+            "d": 4,
+            "e": 5,
+            "f": 6,
+            "g": 7,
+            "h": 8,
+        }["a"]
+    ):
         pass
 
 

tests/data/invisible_parens_instability.py

@@ -0,0 +1 @@
+assert function(arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8, arg9, arg10, arg11, arg12, arg13, arg14, arg15) != [None]

tests/test_black.py

@@ -233,21 +233,24 @@ def _test_wip(self) -> None:
         black.assert_equivalent(source, actual)
         black.assert_stable(source, actual, black.FileMode())
 
-    @unittest.expectedFailure
+    @patch("black.dump_to_file", dump_to_stderr)
+    def test_invisible_parens_instability(self) -> None:
+        source, _expected = read_data("invisible_parens_instability")
+        actual = fs(source)
+        black.assert_stable(source, actual, DEFAULT_MODE)
+
     @patch("black.dump_to_file", dump_to_stderr)
     def test_trailing_comma_optional_parens_stability1(self) -> None:
         source, _expected = read_data("trailing_comma_optional_parens1")
         actual = fs(source)
         black.assert_stable(source, actual, DEFAULT_MODE)
 
-    @unittest.expectedFailure
     @patch("black.dump_to_file", dump_to_stderr)
     def test_trailing_comma_optional_parens_stability2(self) -> None:
         source, _expected = read_data("trailing_comma_optional_parens2")
         actual = fs(source)
         black.assert_stable(source, actual, DEFAULT_MODE)
 
-    @unittest.expectedFailure
     @patch("black.dump_to_file", dump_to_stderr)
     def test_trailing_comma_optional_parens_stability3(self) -> None:
         source, _expected = read_data("trailing_comma_optional_parens3")