Make sure Black doesn't crash when fmt:off is used before a closing paren (#4363)

CHANGES.md

@@ -10,6 +10,8 @@
 
 <!-- Changes that affect Black's stable style -->
 
+- Fix crash when `# fmt: off` is used before a closing parenthesis or bracket. (#4363)
+
 ### Preview style
 
 <!-- Changes that affect Black's preview style -->

src/black/comments.py

@@ -184,24 +184,24 @@ def convert_one_fmt_off_pair(
     for leaf in node.leaves():
         previous_consumed = 0
         for comment in list_comments(leaf.prefix, is_endmarker=False):
-            should_pass_fmt = comment.value in FMT_OFF or _contains_fmt_skip_comment(
-                comment.value, mode
-            )
-            if not should_pass_fmt:
+            is_fmt_off = comment.value in FMT_OFF
+            is_fmt_skip = _contains_fmt_skip_comment(comment.value, mode)
+            if (not is_fmt_off and not is_fmt_skip) or (
+                # Invalid use when `# fmt: off` is applied before a closing bracket.
+                is_fmt_off
+                and leaf.type in CLOSING_BRACKETS
+            ):
                 previous_consumed = comment.consumed
                 continue
             # We only want standalone comments. If there's no previous leaf or
             # the previous leaf is indentation, it's a standalone comment in
             # disguise.
-            if should_pass_fmt and comment.type != STANDALONE_COMMENT:
+            if comment.type != STANDALONE_COMMENT:
                 prev = preceding_leaf(leaf)
                 if prev:
-                    if comment.value in FMT_OFF and prev.type not in WHITESPACE:
+                    if is_fmt_off and prev.type not in WHITESPACE:
                         continue
-                    if (
-                        _contains_fmt_skip_comment(comment.value, mode)
-                        and prev.type in WHITESPACE
-                    ):
+                    if is_fmt_skip and prev.type in WHITESPACE:
                         continue
 
             ignored_nodes = list(generate_ignored_nodes(leaf, comment, mode))
@@ -213,7 +213,7 @@ def convert_one_fmt_off_pair(
             prefix = first.prefix
             if comment.value in FMT_OFF:
                 first.prefix = prefix[comment.consumed :]
-            if _contains_fmt_skip_comment(comment.value, mode):
+            if is_fmt_skip:
                 first.prefix = ""
                 standalone_comment_prefix = prefix
             else:
@@ -233,7 +233,7 @@ def convert_one_fmt_off_pair(
                         fmt_off_prefix = fmt_off_prefix.split("\n")[-1]
                 standalone_comment_prefix += fmt_off_prefix
                 hidden_value = comment.value + "\n" + hidden_value
-            if _contains_fmt_skip_comment(comment.value, mode):
+            if is_fmt_skip:
                 hidden_value += (
                     comment.leading_whitespace
                     if Preview.no_normalize_fmt_skip_whitespace in mode

tests/data/cases/fmtonoff6.py

@@ -0,0 +1,13 @@
+# Regression test for https://github.com/psf/black/issues/2478.
+def foo():
+    arr = (
+        (3833567325051000, 5, 1, 2, 4229.25, 6, 0),
+        # fmt: off
+    )
+
+
+# Regression test for https://github.com/psf/black/issues/3458.
+dependencies = {
+    a: b,
+    # fmt: off
+}