INTERNAL ERROR: Black produced different code on the second pass of the formatter.

[andrewdotn]

When trying to format a file, I got an error message telling me to report the issue here.

To Reproduce

1. Take this file

def x():
    assert y(
        [
            {"blahblah": ["blahblahblahblah"]}
        ],
        [{"blahblah": ["blahblahblahblah"]}],
        [{"blahblah": ["blahblahblahblah"]}]
    ) == {"x": "a", "y":  []}

2. Run Black on it with these arguments: black foo.py
3. See error

Expected behavior

No error message

Environment:

• Version: master @ 20.8b2.dev111+g5446a92f0161
• OS and Python version: macOS 11, Python 3.9.1

Additional context Add any other context about the problem here.

Mode(target_versions={<TargetVersion.PY38: 8>, <TargetVersion.PY36: 6>, <TargetVersion.PY37: 7>}, line_length=88, string_normalization=True, magic_trailing_comma=True, experimental_string_processing=False, is_pyi=False)
--- source
+++ first pass
@@ -1,9 +1,6 @@
 def x():
     assert y(
-        [
-            {"blahblah": ["blahblahblahblah"]}
-        ],
         [{"blahblah": ["blahblahblahblah"]}],
-        [{"blahblah": ["blahblahblahblah"]}]
-    ) == {"x": "a", "y":  []}
-
+        [{"blahblah": ["blahblahblahblah"]}],
+        [{"blahblah": ["blahblahblahblah"]}],
+    ) == {"x": "a", "y": []}
--- first pass
+++ second pass
@@ -1,6 +1,9 @@
 def x():
-    assert y(
-        [{"blahblah": ["blahblahblahblah"]}],
-        [{"blahblah": ["blahblahblahblah"]}],
-        [{"blahblah": ["blahblahblahblah"]}],
-    ) == {"x": "a", "y": []}
+    assert (
+        y(
+            [{"blahblah": ["blahblahblahblah"]}],
+            [{"blahblah": ["blahblahblahblah"]}],
+            [{"blahblah": ["blahblahblahblah"]}],
+        )
+        == {"x": "a", "y": []}
+    )

[klieret]

Hi @andrewdotn : I can confirm this is happening also for other versions.

But for anyone stuck with this issue: You can work around it by simply adding the missing comma that black wanted to add in its first pass.

[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!