From 048c9bb05e1c3011332c158d0198f0c79da06ca3 Mon Sep 17 00:00:00 2001
From: Eddie Darling <darling@berkeley.edu>
Date: Sun, 1 Oct 2023 11:33:02 -0700
Subject: [PATCH 1/4] Add regression test

---
 tests/data/preview/comments7.py | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/tests/data/preview/comments7.py b/tests/data/preview/comments7.py
index 8b1224017e5..5b8896b8f64 100644
--- a/tests/data/preview/comments7.py
+++ b/tests/data/preview/comments7.py
@@ -131,6 +131,13 @@ def test_fails_invalid_post_data(
 
 square = Square(4) # type: Optional[Square]
 
+# Regression test for https://github.com/psf/black/issues/3756.
+[
+    (
+        "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"  # aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+    ),
+]
+
 # output
 
 from .config import (
@@ -282,3 +289,11 @@ def test_fails_invalid_post_data(
 
 
 square = Square(4)  # type: Optional[Square]
+
+# Regression test for https://github.com/psf/black/issues/3756.
+[
+    (  # aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+        "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+    ),
+]
+

From c1284a93be94d6d38a5cb594fe23d0a0d5a63bad Mon Sep 17 00:00:00 2001
From: Eddie Darling <darling@berkeley.edu>
Date: Sun, 1 Oct 2023 11:35:03 -0700
Subject: [PATCH 2/4] Adopt parentless comments

Since the id of the old leaf may be
the key to comments, the new leaf
must adopt the old comments
---
 src/black/trans.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/black/trans.py b/src/black/trans.py
index daed26427d7..c0cc92613ac 100644
--- a/src/black/trans.py
+++ b/src/black/trans.py
@@ -942,6 +942,9 @@ def _transform_to_new_line(
                 LL[lpar_or_rpar_idx].remove()  # Remove lpar.
                 replace_child(LL[idx], string_leaf)
                 new_line.append(string_leaf)
+                # replace comments
+                old_comments = new_line.comments.pop(id(LL[idx]), [])
+                new_line.comments.setdefault(id(string_leaf), []).extend(old_comments)
             else:
                 LL[lpar_or_rpar_idx].remove()  # This is a rpar.
 

From aa26b02d04ca5fc2d32aad1f21898537736a3b8a Mon Sep 17 00:00:00 2001
From: Eddie Darling <darling@berkeley.edu>
Date: Sun, 1 Oct 2023 11:36:19 -0700
Subject: [PATCH 3/4] Add test variant

---
 tests/data/preview/comments7.py | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/tests/data/preview/comments7.py b/tests/data/preview/comments7.py
index 5b8896b8f64..0655de999ec 100644
--- a/tests/data/preview/comments7.py
+++ b/tests/data/preview/comments7.py
@@ -137,6 +137,11 @@ def test_fails_invalid_post_data(
         "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"  # aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
     ),
 ]
+[
+    (  # aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+        "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"  # aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+    ),
+]
 
 # output
 
@@ -296,4 +301,8 @@ def test_fails_invalid_post_data(
         "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
     ),
 ]
-
+[
+    (  # aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+        "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"  # aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+    ),
+]

From 59e02d3aa711730d0e5fc14666db018fa51c3de1 Mon Sep 17 00:00:00 2001
From: Eddie Darling <darling@berkeley.edu>
Date: Sun, 1 Oct 2023 12:04:25 -0700
Subject: [PATCH 4/4] Add 3909 to CHANGES.md

---
 CHANGES.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/CHANGES.md b/CHANGES.md
index a879ab3e8da..028a01acd62 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -17,6 +17,8 @@
 
 <!-- Changes that affect Black's preview style -->
 
+- Fix comments getting removed from inside parenthesized strings (#3909)
+
 ### Configuration
 
 <!-- Changes to how Black can be configured -->