From abe57e3d92727f1b26c717fad3978159b987fe79 Mon Sep 17 00:00:00 2001
From: Jelle Zijlstra <jelle.zijlstra@gmail.com>
Date: Mon, 16 Oct 2023 10:51:51 -0700
Subject: [PATCH] Treat raw strings like other docstrings (#3947)

Fixes #3944
---
 CHANGES.md                  |  1 +
 src/black/lines.py          | 15 ++++++++++-----
 src/black/mode.py           |  1 +
 tests/data/raw_docstring.py | 32 ++++++++++++++++++++++++++++++++
 4 files changed, 44 insertions(+), 5 deletions(-)
 create mode 100644 tests/data/raw_docstring.py

diff --git a/CHANGES.md b/CHANGES.md
index d1c4a07..1f6a008 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -21,6 +21,7 @@
   multiple lines (#3899)
 - Magic trailing commas are now respected in return types. (#3916)
 - Require one empty line after module-level docstrings. (#3932)
+- Treat raw triple-quoted strings as docstrings (#3947)
 
 ### Configuration
 
diff --git a/src/black/lines.py b/src/black/lines.py
index 14754d7..48fde88 100644
--- a/src/black/lines.py
+++ b/src/black/lines.py
@@ -193,11 +193,16 @@ class Line:
     @property
     def is_triple_quoted_string(self) -> bool:
         """Is the line a triple quoted string?"""
-        return (
-            bool(self)
-            and self.leaves[0].type == token.STRING
-            and self.leaves[0].value.startswith(('"""', "'''"))
-        )
+        if not self or self.leaves[0].type != token.STRING:
+            return False
+        value = self.leaves[0].value
+        if value.startswith(('"""', "'''")):
+            return True
+        if Preview.accept_raw_docstrings in self.mode and value.startswith(
+            ("r'''", 'r"""', "R'''", 'R"""')
+        ):
+            return True
+        return False
 
     @property
     def opens_block(self) -> bool:
diff --git a/src/black/mode.py b/src/black/mode.py
index a57fa37..309f22d 100644
--- a/src/black/mode.py
+++ b/src/black/mode.py
@@ -188,6 +188,7 @@ class Preview(Enum):
     dummy_implementations = auto()
     walrus_subscript = auto()
     module_docstring_newlines = auto()
+    accept_raw_docstrings = auto()
     fix_power_op_line_length = auto()
 
 
diff --git a/tests/data/raw_docstring.py b/tests/data/raw_docstring.py
new file mode 100644
index 0000000..751fd32
--- /dev/null
+++ b/tests/data/raw_docstring.py
@@ -0,0 +1,32 @@
+# flags: --preview --skip-string-normalization
+class C:
+
+    r"""Raw"""
+
+def f():
+
+    r"""Raw"""
+
+class SingleQuotes:
+
+
+    r'''Raw'''
+
+class UpperCaseR:
+    R"""Raw"""
+
+# output
+class C:
+    r"""Raw"""
+
+
+def f():
+    r"""Raw"""
+
+
+class SingleQuotes:
+    r'''Raw'''
+
+
+class UpperCaseR:
+    R"""Raw"""
-- 
2.39.5