INTERNAL ERROR when formatting a function with a comment

[dcermak]

Describe the bug

Black encounters an internal error when trying to format a function call with a comment before a parameter.

To Reproduce

1. Take this file:

class TestPathToPosition:
    def test_path_after_blank_level(self):
        sls_start = MASTER_DOT_SLS[:position_to_index(MASTER_DOT_SLS, 8, 2)]
        assert construct_path_to_position(
            sls_start,
            # After the last character
            Position(line=8, character=2)
        ) == [
            "saltmaster.packages"
        ]

2. Run Black on it:

$ python -m black fmt_error.py
error: cannot format fmt_error.py: INTERNAL ERROR: Black produced different code on the second pass of the formatter.  Please report a bug on https://github.com/psf/black/issues.  This diff might be helpful: /tmp/blk_l9gcdo5g.log
Oh no! 💥 💔 💥
1 file failed to reformat.

Expected behavior

Formatting should succeed

Environment (please complete the following information):

• Version: latest from pypi
• OS and Python version: Linux (Ubuntu, openSUSE Tumbleweed and Fedora 33), Python 3.8 and 3.9

Does this bug also happen on master?

yes (verified using https://black.now.sh/?version=master)

Additional context

• removing the comment before Position makes the bug dissappear
• contents of the diff:

Mode(target_versions=set(), line_length=88, string_normalization=True, experimental_string_processing=False, is_pyi=False)
--- source
+++ first pass
@@ -1,10 +1,8 @@
 class TestPathToPosition:
     def test_path_after_blank_level(self):
-        sls_start = MASTER_DOT_SLS[:position_to_index(MASTER_DOT_SLS, 8, 2)]
+        sls_start = MASTER_DOT_SLS[: position_to_index(MASTER_DOT_SLS, 8, 2)]
         assert construct_path_to_position(
             sls_start,
             # After the last character
-            Position(line=8, character=2)
-        ) == [
-            "saltmaster.packages"
-        ]
+            Position(line=8, character=2),
+        ) == ["saltmaster.packages"]
--- first pass
+++ second pass
@@ -1,8 +1,11 @@
 class TestPathToPosition:
     def test_path_after_blank_level(self):
         sls_start = MASTER_DOT_SLS[: position_to_index(MASTER_DOT_SLS, 8, 2)]
-        assert construct_path_to_position(
-            sls_start,
-            # After the last character
-            Position(line=8, character=2),
-        ) == ["saltmaster.packages"]
+        assert (
+            construct_path_to_position(
+                sls_start,
+                # After the last character
+                Position(line=8, character=2),
+            )
+            == ["saltmaster.packages"]
+        )

[ichard26]

Hello!

All reproduction cases in this issue format without error on master. The fixing commit was 8672af3 from PR GH-2126. I'll be marking this issue as a duplicate of GH-1629 since that's what GH-2126 aimed to fix and it's highly likely this issue falls under GH-1629.

Since we use the issue tracker as a reflection of what's on master, I'll be closing this issue. If you have any issues, especially with the new (but stable) output, please open a new issue. Oh and the fix should be available in a published release soon, see GH-2125 for more info.

Thank you for reporting!