From 0bcba4fba2f751861cbd21ee3983e1ee2f8a53c1 Mon Sep 17 00:00:00 2001
From: Cameron <cameron.clark@hey.com>
Date: Mon, 30 Oct 2023 01:51:04 +0000
Subject: [PATCH] fix(linter) Fix panic on no useless escape (#1092)

Closes #1041
---
 .../src/rules/eslint/no_useless_escape.rs     | 24 ++++++++++++-------
 .../src/snapshots/no_useless_escape.snap      | 12 ++++++++++
 2 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/crates/oxc_linter/src/rules/eslint/no_useless_escape.rs b/crates/oxc_linter/src/rules/eslint/no_useless_escape.rs
index 278441f33..4eedc4654 100644
--- a/crates/oxc_linter/src/rules/eslint/no_useless_escape.rs
+++ b/crates/oxc_linter/src/rules/eslint/no_useless_escape.rs
@@ -19,6 +19,7 @@ pub struct NoUselessEscape;
 declare_oxc_lint!(
     /// ### What it does
     ///
+    /// Disallow unnecessary escape characters
     ///
     /// ### Why is this bad?
     ///
@@ -135,15 +136,16 @@ fn check_string(string: &str) -> Vec<usize> {
     let mut offsets = vec![];
     let quote_string = string.chars().next();
     let mut in_escape = false;
-    let mut offset = 0;
-    for c in string[1..].chars() {
-        offset += c.len_utf8();
+    let mut byte_offset = 0;
+
+    for c in string.chars() {
+        byte_offset += c.len_utf8();
         if in_escape {
             in_escape = false;
             match c {
                 c if c.is_ascii_digit() || quote_string == Some(c) => { /* noop */ }
                 c if !VALID_STRING_ESCAPES.contains(c) => {
-                    offsets.push(offset);
+                    offsets.push(byte_offset - c.len_utf8());
                 }
                 _ => {}
             }
@@ -162,27 +164,29 @@ fn check_template(string: &str) -> Vec<usize> {
     let mut offsets = vec![];
     let mut in_escape = false;
     let mut prev_char = '`';
-    let mut offset = 0;
+    let mut byte_offset = 1;
 
     let mut chars = string.chars().peekable();
+
     while let Some(c) = chars.next() {
-        offset += c.len_utf8();
+        byte_offset += c.len_utf8();
+
         if in_escape {
             in_escape = false;
             match c {
                 c if c.is_ascii_digit() || c == '`' => { /* noop */ }
                 '{' => {
                     if prev_char != '$' {
-                        offsets.push(offset);
+                        offsets.push(byte_offset - c.len_utf8());
                     }
                 }
                 '$' => {
                     if chars.peek().is_some_and(|c| *c != '{') {
-                        offsets.push(offset);
+                        offsets.push(byte_offset - c.len_utf8());
                     }
                 }
                 c if !VALID_STRING_ESCAPES.contains(c) => {
-                    offsets.push(offset);
+                    offsets.push(byte_offset - c.len_utf8());
                 }
                 _ => {}
             }
@@ -356,6 +360,8 @@ fn test() {
         "`template literal with mixed linebreaks in line continuations \\\n\\\r\\\r\n\\and useless escape`",
         "`\\a```",
         r"var foo = /\（([^\）\（]+)\）$|\(([^\)\)]+)\)$/;",
+        r#"var stringLiteralWithNextLine = "line 1\…line 2";"#,
+        r"var stringLiteralWithNextLine = `line 1\…line 2`;",
     ];
 
     Tester::new_without_config(NoUselessEscape::NAME, pass, fail).test_and_snapshot();
diff --git a/crates/oxc_linter/src/snapshots/no_useless_escape.snap b/crates/oxc_linter/src/snapshots/no_useless_escape.snap
index ecb235b59..0c27346c5 100644
--- a/crates/oxc_linter/src/snapshots/no_useless_escape.snap
+++ b/crates/oxc_linter/src/snapshots/no_useless_escape.snap
@@ -374,4 +374,16 @@ expression: no_useless_escape
    ·                                       ──
    ╰────
 
+  ⚠ eslint(no-useless-escape): Unnecessary escape character '\u{85}'
+   ╭─[no_useless_escape.tsx:1:1]
+ 1 │ var stringLiteralWithNextLine = "line 1\…line 2";
+   ·                                        ─
+   ╰────
+
+  ⚠ eslint(no-useless-escape): Unnecessary escape character '\u{85}'
+   ╭─[no_useless_escape.tsx:1:1]
+ 1 │ var stringLiteralWithNextLine = `line 1\…line 2`;
+   ·                                        ─
+   ╰────
+