From 42d4216fd7f621f0eb724a4cb92d8a8cf37fd5ce Mon Sep 17 00:00:00 2001
From: Dhruv Manilawala <dhruvmanila@gmail.com>
Date: Wed, 20 Mar 2024 00:16:35 +0530
Subject: [PATCH] Consider raw source code for `W605` (#10480)

## Summary

This PR fixes a panic in the linter for `W605`.

Consider the following f-string:
```python
f"{{}}ab"
```

The `FStringMiddle` token would contain `{}ab`. Notice that the escaped
braces have _reduced_ the string. This means we cannot use the text
value from the token to determine the location of the escape sequence
but need to extract it from the source code.

fixes: #10434

## Test Plan

Add new test cases and update the snapshots.
---
 .../test/fixtures/pycodestyle/W605_1.py       |  5 ++
 .../rules/invalid_escape_sequence.rs          |  7 +--
 ...s__pycodestyle__tests__W605_W605_1.py.snap | 51 +++++++++++++++++++
 3 files changed, 60 insertions(+), 3 deletions(-)

diff --git a/crates/ruff_linter/resources/test/fixtures/pycodestyle/W605_1.py b/crates/ruff_linter/resources/test/fixtures/pycodestyle/W605_1.py
index b34ad587c46d5..7e60a686d228b 100644
--- a/crates/ruff_linter/resources/test/fixtures/pycodestyle/W605_1.py
+++ b/crates/ruff_linter/resources/test/fixtures/pycodestyle/W605_1.py
@@ -52,3 +52,8 @@
 value = rf'\{1}'
 value = rf'{1:\}'
 value = f"{rf"\{1}"}"
+
+# Regression tests for https://github.com/astral-sh/ruff/issues/10434
+f"{{}}+-\d"
+f"\n{{}}+-\d+"
+f"\n{{}}�+-\d+"
diff --git a/crates/ruff_linter/src/rules/pycodestyle/rules/invalid_escape_sequence.rs b/crates/ruff_linter/src/rules/pycodestyle/rules/invalid_escape_sequence.rs
index 1d788daf48bd7..c5b92d3642e18 100644
--- a/crates/ruff_linter/src/rules/pycodestyle/rules/invalid_escape_sequence.rs
+++ b/crates/ruff_linter/src/rules/pycodestyle/rules/invalid_escape_sequence.rs
@@ -67,14 +67,15 @@ pub(crate) fn invalid_escape_sequence(
     token_range: TextRange,
 ) {
     let (token_source_code, string_start_location, kind) = match token {
-        Tok::FStringMiddle { value, kind } => {
+        Tok::FStringMiddle { kind, .. } => {
             if kind.is_raw_string() {
                 return;
             }
-            let Some(range) = indexer.fstring_ranges().innermost(token_range.start()) else {
+            let Some(f_string_range) = indexer.fstring_ranges().innermost(token_range.start())
+            else {
                 return;
             };
-            (&**value, range.start(), kind)
+            (locator.slice(token_range), f_string_range.start(), kind)
         }
         Tok::String { kind, .. } => {
             if kind.is_raw_string() {
diff --git a/crates/ruff_linter/src/rules/pycodestyle/snapshots/ruff_linter__rules__pycodestyle__tests__W605_W605_1.py.snap b/crates/ruff_linter/src/rules/pycodestyle/snapshots/ruff_linter__rules__pycodestyle__tests__W605_W605_1.py.snap
index c47507e0ccc88..ea0ced5b4fbb0 100644
--- a/crates/ruff_linter/src/rules/pycodestyle/snapshots/ruff_linter__rules__pycodestyle__tests__W605_W605_1.py.snap
+++ b/crates/ruff_linter/src/rules/pycodestyle/snapshots/ruff_linter__rules__pycodestyle__tests__W605_W605_1.py.snap
@@ -224,4 +224,55 @@ W605_1.py:48:15: W605 [*] Invalid escape sequence: `\{`
 50 50 | # Okay
 51 51 | value = rf'\{{1}}'
 
+W605_1.py:57:9: W605 [*] Invalid escape sequence: `\d`
+   |
+56 | # Regression tests for https://github.com/astral-sh/ruff/issues/10434
+57 | f"{{}}+-\d"
+   |         ^^ W605
+58 | f"\n{{}}+-\d+"
+59 | f"\n{{}}�+-\d+"
+   |
+   = help: Use a raw string literal
+
+ℹ Safe fix
+54 54 | value = f"{rf"\{1}"}"
+55 55 | 
+56 56 | # Regression tests for https://github.com/astral-sh/ruff/issues/10434
+57    |-f"{{}}+-\d"
+   57 |+rf"{{}}+-\d"
+58 58 | f"\n{{}}+-\d+"
+59 59 | f"\n{{}}�+-\d+"
 
+W605_1.py:58:11: W605 [*] Invalid escape sequence: `\d`
+   |
+56 | # Regression tests for https://github.com/astral-sh/ruff/issues/10434
+57 | f"{{}}+-\d"
+58 | f"\n{{}}+-\d+"
+   |           ^^ W605
+59 | f"\n{{}}�+-\d+"
+   |
+   = help: Add backslash to escape sequence
+
+ℹ Safe fix
+55 55 | 
+56 56 | # Regression tests for https://github.com/astral-sh/ruff/issues/10434
+57 57 | f"{{}}+-\d"
+58    |-f"\n{{}}+-\d+"
+   58 |+f"\n{{}}+-\\d+"
+59 59 | f"\n{{}}�+-\d+"
+
+W605_1.py:59:12: W605 [*] Invalid escape sequence: `\d`
+   |
+57 | f"{{}}+-\d"
+58 | f"\n{{}}+-\d+"
+59 | f"\n{{}}�+-\d+"
+   |            ^^ W605
+   |
+   = help: Add backslash to escape sequence
+
+ℹ Safe fix
+56 56 | # Regression tests for https://github.com/astral-sh/ruff/issues/10434
+57 57 | f"{{}}+-\d"
+58 58 | f"\n{{}}+-\d+"
+59    |-f"\n{{}}�+-\d+"
+   59 |+f"\n{{}}�+-\\d+"