[pydocstyle] Escaped docstring in docstring (D301 ) (#12192)

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## Summary

<!-- What's the purpose of the change? What does it do, and why? -->
This PR updates D301 rule to allow inclduing escaped docstring, e.g.
`\"""Foo.\"""` or `\"\"\"Bar.\"\"\"`, within a docstring.

Related issue: #12152 

## Test Plan

Add more test cases to D301.py and update the snapshot file.

<!-- How was it tested? -->

crates/ruff_linter/resources/test/fixtures/pydocstyle/D301.py

@@ -35,3 +35,67 @@ def make_unique_pod_id(pod_id: str) -> str | None:
 
 def shouldnt_add_raw_here2():
     u"Sum\\mary."
+
+
+def shouldnt_add_raw_for_double_quote_docstring_contains_docstring():
+    """
+    This docstring contains another double-quote docstring.
+
+        def foo():
+            \"\"\"Foo.\"\"\"
+    """
+
+
+def shouldnt_add_raw_for_double_quote_docstring_contains_docstring2():
+    """
+    This docstring contains another double-quote docstring.
+
+        def bar():
+            \"""Bar.\"""
+    
+    More content here.
+    """
+
+
+def shouldnt_add_raw_for_single_quote_docstring_contains_docstring():
+    '''
+    This docstring contains another single-quote docstring.
+
+        def foo():
+            \'\'\'Foo.\'\'\'
+    
+    More content here.
+    '''
+
+
+def shouldnt_add_raw_for_single_quote_docstring_contains_docstring2():
+    '''
+    This docstring contains another single-quote docstring.
+
+        def bar():
+            \'''Bar.\'''
+    
+    More content here.
+    '''
+
+def shouldnt_add_raw_for_docstring_contains_escaped_double_triple_quotes():
+    """
+    Escaped triple quote \""" or \"\"\".
+    """
+
+def shouldnt_add_raw_for_docstring_contains_escaped_single_triple_quotes():
+    '''
+    Escaped triple quote \''' or \'\'\'.
+    '''
+
+
+def should_add_raw_for_single_double_quote_escape():
+    """
+    This is single quote escape \".
+    """
+
+
+def should_add_raw_for_single_single_quote_escape():
+    '''
+    This is single quote escape \'.
+    '''

crates/ruff_linter/src/rules/pydocstyle/rules/backslashes.rs

@@ -1,5 +1,3 @@
-use memchr::memchr_iter;
-
 use ruff_diagnostics::{Diagnostic, Edit, Fix, FixAvailability, Violation};
 use ruff_macros::{derive_message_formats, violation};
 use ruff_text_size::Ranged;
@@ -69,20 +67,47 @@ pub(crate) fn backslashes(checker: &mut Checker, docstring: &Docstring) {
     // Docstring contains at least one backslash.
     let body = docstring.body();
     let bytes = body.as_bytes();
-    if memchr_iter(b'\\', bytes).any(|position| {
+    let mut offset = 0;
-        let escaped_char = bytes.get(position.saturating_add(1));
+    while let Some(position) = memchr::memchr(b'\\', &bytes[offset..]) {
-        // Allow continuations (backslashes followed by newlines) and Unicode escapes.
+        if position + offset + 1 >= body.len() {
-        !matches!(escaped_char, Some(b'\r' | b'\n' | b'u' | b'U' | b'N'))
+            break;
-    }) {
-        let mut diagnostic = Diagnostic::new(EscapeSequenceInDocstring, docstring.range());
-
-        if !docstring.leading_quote().contains(['u', 'U']) {
-            diagnostic.set_fix(Fix::unsafe_edit(Edit::range_replacement(
-                "r".to_owned() + docstring.contents,
-                docstring.range(),
-            )));
         }
 
-        checker.diagnostics.push(diagnostic);
+        let after_escape = &body[position + offset + 1..];
+
+        // End of Docstring.
+        let Some(escaped_char) = &after_escape.chars().next() else {
+            break;
+        };
+
+        if matches!(escaped_char, '"' | '\'') {
+            // If the next three characters are equal to """, it indicates an escaped docstring pattern.
+            if after_escape.starts_with("\"\"\"") || after_escape.starts_with("\'\'\'") {
+                offset += position + 3;
+                continue;
+            }
+            // If the next three characters are equal to "\"\", it indicates an escaped docstring pattern.
+            if after_escape.starts_with("\"\\\"\\\"") || after_escape.starts_with("\'\\\'\\\'") {
+                offset += position + 5;
+                continue;
+            }
+        }
+
+        offset += position + escaped_char.len_utf8();
+
+        // Only allow continuations (backslashes followed by newlines) and Unicode escapes.
+        if !matches!(*escaped_char, '\r' | '\n' | 'u' | 'U' | 'N') {
+            let mut diagnostic = Diagnostic::new(EscapeSequenceInDocstring, docstring.range());
+
+            if !docstring.leading_quote().contains(['u', 'U']) {
+                diagnostic.set_fix(Fix::unsafe_edit(Edit::range_replacement(
+                    "r".to_owned() + docstring.contents,
+                    docstring.range(),
+                )));
+            }
+
+            checker.diagnostics.push(diagnostic);
+            break;
+        }
     }
 }

crates/ruff_linter/src/rules/pydocstyle/snapshots/ruff_linter__rules__pydocstyle__tests__D301_D301.py.snap

@@ -25,4 +25,43 @@ D301.py:37:5: D301 Use `r"""` if any backslashes in a docstring
    |
    = help: Add `r` prefix
 
+D301.py:93:5: D301 [*] Use `r"""` if any backslashes in a docstring
+   |
+92 |   def should_add_raw_for_single_double_quote_escape():
+93 |       """
+   |  _____^
+94 | |     This is single quote escape \".
+95 | |     """
+   | |_______^ D301
+   |
+   = help: Add `r` prefix
 
+ℹ Unsafe fix
+90 90 | 
+91 91 | 
+92 92 | def should_add_raw_for_single_double_quote_escape():
+93    |-    """
+   93 |+    r"""
+94 94 |     This is single quote escape \".
+95 95 |     """
+96 96 | 
+
+D301.py:99:5: D301 [*] Use `r"""` if any backslashes in a docstring
+    |
+ 98 |   def should_add_raw_for_single_single_quote_escape():
+ 99 |       '''
+    |  _____^
+100 | |     This is single quote escape \'.
+101 | |     '''
+    | |_______^ D301
+    |
+    = help: Add `r` prefix
+
+ℹ Unsafe fix
+96  96  | 
+97  97  | 
+98  98  | def should_add_raw_for_single_single_quote_escape():
+99      |-    '''
+    99  |+    r'''
+100 100 |     This is single quote escape \'.
+101 101 |     '''