Do not add trailing commas to return type annotations using PEP 604 unions (#3735)

[etc/vim.git] / src / black / linegen.py

diff --git a/src/black/linegen.py b/src/black/linegen.py
index 0091cbb3bd1d3195d3bc06fed11aeac280b987bf..ad21307c311b83b0e0eb964b34ae6149cfcb0cee 100644 (file)
--- a/src/black/linegen.py
+++ b/src/black/linegen.py
@@ -918,6 +918,13 @@ def bracket_split_build_line(
                     )
                     if isinstance(node, Node) and isinstance(node.prev_sibling, Leaf)
                 )
+                # Except the false negatives above for PEP 604 unions where we
+                # can't add the comma.
+                and not (
+                    leaves[0].parent
+                    and leaves[0].parent.next_sibling
+                    and leaves[0].parent.next_sibling.type == token.VBAR
+                )
             )
 
             if original.is_import or no_commas: