From 285375134473d33df1dcec6390c14f36896e3c6a Mon Sep 17 00:00:00 2001
From: Dhruv Manilawala <dhruvmanila@gmail.com>
Date: Tue, 25 Jun 2024 15:00:31 +0530
Subject: [PATCH] Avoid `E203` for f-string debug expression (#12024)

## Summary

This PR fixes a bug where Ruff would raise `E203` for f-string debug
expression. This isn't valid because whitespaces are important for debug
expressions.

fixes: #12023

## Test Plan

Add test case and make sure there are no snapshot changes.
---
 .../ruff_linter/resources/test/fixtures/pycodestyle/E20.py | 4 ++++
 .../rules/logical_lines/extraneous_whitespace.rs           | 7 +++++++
 ...uff_linter__rules__pycodestyle__tests__E203_E20.py.snap | 5 +++++
 3 files changed, 16 insertions(+)

diff --git a/crates/ruff_linter/resources/test/fixtures/pycodestyle/E20.py b/crates/ruff_linter/resources/test/fixtures/pycodestyle/E20.py
index c22bad56e6..ada032e6dc 100644
--- a/crates/ruff_linter/resources/test/fixtures/pycodestyle/E20.py
+++ b/crates/ruff_linter/resources/test/fixtures/pycodestyle/E20.py
@@ -185,3 +185,7 @@ f"{ham[lower +1 :, "columnname"]}"
 
 #: E203:1:13
 f"{ham[lower + 1  :, "columnname"]}"
+
+#: Okay: https://github.com/astral-sh/ruff/issues/12023
+f"{x = :.2f}"
+f"{(x) = :.2f}"
diff --git a/crates/ruff_linter/src/rules/pycodestyle/rules/logical_lines/extraneous_whitespace.rs b/crates/ruff_linter/src/rules/pycodestyle/rules/logical_lines/extraneous_whitespace.rs
index b99dc634a7..3580c8dad1 100644
--- a/crates/ruff_linter/src/rules/pycodestyle/rules/logical_lines/extraneous_whitespace.rs
+++ b/crates/ruff_linter/src/rules/pycodestyle/rules/logical_lines/extraneous_whitespace.rs
@@ -273,6 +273,13 @@ pub(crate) fn extraneous_whitespace(line: &LogicalLine, context: &mut LogicalLin
                                     }
                                 }
                             } else {
+                                if fstrings > 0
+                                    && symbol == ':'
+                                    && matches!(prev_token, Some(TokenKind::Equal))
+                                {
+                                    // Avoid removing any whitespace for f-string debug expressions.
+                                    continue;
+                                }
                                 let mut diagnostic = Diagnostic::new(
                                     WhitespaceBeforePunctuation { symbol },
                                     TextRange::at(token.start() - offset, offset),
diff --git a/crates/ruff_linter/src/rules/pycodestyle/snapshots/ruff_linter__rules__pycodestyle__tests__E203_E20.py.snap b/crates/ruff_linter/src/rules/pycodestyle/snapshots/ruff_linter__rules__pycodestyle__tests__E203_E20.py.snap
index 5f13020613..7422f4309a 100644
--- a/crates/ruff_linter/src/rules/pycodestyle/snapshots/ruff_linter__rules__pycodestyle__tests__E203_E20.py.snap
+++ b/crates/ruff_linter/src/rules/pycodestyle/snapshots/ruff_linter__rules__pycodestyle__tests__E203_E20.py.snap
@@ -331,6 +331,8 @@ E20.py:187:17: E203 [*] Whitespace before ':'
 186 | #: E203:1:13
 187 | f"{ham[lower + 1  :, "columnname"]}"
     |                 ^^ E203
+188 | 
+189 | #: Okay: https://github.com/astral-sh/ruff/issues/12023
     |
     = help: Remove whitespace before ':'
 
@@ -340,3 +342,6 @@ E20.py:187:17: E203 [*] Whitespace before ':'
 186 186 | #: E203:1:13
 187     |-f"{ham[lower + 1  :, "columnname"]}"
     187 |+f"{ham[lower + 1:, "columnname"]}"
+188 188 | 
+189 189 | #: Okay: https://github.com/astral-sh/ruff/issues/12023
+190 190 | f"{x = :.2f}"