Invalid characters fix: escape quote triplets in triple-quoted strings

crates/ruff_linter/src/rules/pylint/rules/invalid_string_characters.rs

@@ -265,9 +265,16 @@ pub(crate) fn invalid_string_characters<'a>(
             let replacement: &str = match c {
                 '\\' => "\\\\",
                 '\'' | '"' => {
-                    // Quotes don't have to be escaped in triple-quoted strings,
-                    // *except* at the very end (like """this: \"""").
-                    if string_flags.is_triple_quoted() && column + 1 < string_content.len() {
+                    // Quotes only have to be escaped in triple-quoted strings at the beginning
+                    // of a triplet (like `\"""\"""` within the string, or `\""""` at the end).
+                    // For simplicity, escape all quotes not followed by the same character
+                    // (e.g., `r""" \""" \""""` becomes `""" \\\"\"" \""""`).
+                    if string_flags.is_triple_quoted()
+                        && string_content
+                            .as_bytes()
+                            .get(column + 1)
+                            .is_some_and(|c2| char::from(*c2) != c)
+                    {
                         continue;
                     }
                     match (c, string_flags.quote_style()) {

crates/ruff_linter/src/rules/pylint/snapshots/ruff_linter__rules__pylint__tests__PLE2510_invalid_characters.py.snap

@@ -69,7 +69,7 @@ invalid_characters.py:63:35: PLE2510 [*] Invalid unescaped character backspace,
 63 | raw_single_singlequote = r'\ \' " ␈'
    |                                   ^ PLE2510
 64 | raw_triple_singlequote = r'''\ ' " '''
-65 | raw_triple_singlequote_2 = r'''​\''''
+65 | raw_triple_singlequote_2 = r'''​ \''' \''''
    |
    = help: Replace with escape sequence
 
@@ -80,7 +80,7 @@ invalid_characters.py:63:35: PLE2510 [*] Invalid unescaped character backspace,
 63    |-raw_single_singlequote = r'\ \' " ␈'
    63 |+raw_single_singlequote = '\\ \\\' " \b'
 64 64 | raw_triple_singlequote = r'''\ ' " '''
-65 65 | raw_triple_singlequote_2 = r'''​\''''
+65 65 | raw_triple_singlequote_2 = r'''​ \''' \''''
 66 66 | raw_single_doublequote = r"\ ' \" ␛"
 
 invalid_characters.py:77:1: PLE2510 [*] Invalid unescaped character backspace, use "\b" instead