From e57bccd500d1a816ed929c5449b73bc763675681 Mon Sep 17 00:00:00 2001
From: Micha Reiser <micha@reiser.io>
Date: Sun, 5 Nov 2023 23:35:23 +0900
Subject: [PATCH] Fix multiline lambda expression statement formating (#8466)

## Summary

This PR fixes a bug in our formatter where a multiline lambda expression
statement was formatted over multiple lines without adding parentheses.

The PR "fixes" the problem by not splitting the lambda parameters if it
is not parenthesized

## Test Plan

Added test
---
 .../test/fixtures/ruff/expression/lambda.py   | 25 ++++++++
 .../src/other/parameters.rs                   | 14 ++++-
 .../format@expression__lambda.py.snap         | 59 +++++++++++++++++++
 3 files changed, 95 insertions(+), 3 deletions(-)

diff --git a/crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/lambda.py b/crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/lambda.py
index 3677fedb70..4a7090ff13 100644
--- a/crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/lambda.py
+++ b/crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/lambda.py
@@ -203,3 +203,28 @@ lambda: ( # comment
     y:
     z
 )
+
+lambda self, araa, kkkwargs=aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(*args, **kwargs), e=1, f=2, g=2: d
+
+# Regression tests for https://github.com/astral-sh/ruff/issues/8179
+def a():
+    return b(
+        c,
+        d,
+        e,
+        f=lambda self, *args, **kwargs: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(
+            *args, **kwargs
+        ),
+    )
+
+def a():
+    return b(
+        c,
+        d,
+        e,
+        f=lambda self, araa, kkkwargs,aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa,
+                 args,kwargs,
+                 e=1, f=2, g=2: d,
+        g = 10
+    )
+
diff --git a/crates/ruff_python_formatter/src/other/parameters.rs b/crates/ruff_python_formatter/src/other/parameters.rs
index 5e67e579de..86cad5869b 100644
--- a/crates/ruff_python_formatter/src/other/parameters.rs
+++ b/crates/ruff_python_formatter/src/other/parameters.rs
@@ -102,7 +102,15 @@ impl FormatNodeRule<Parameters> for FormatParameters {
             dangling.split_at(parenthesis_comments_end);
 
         let format_inner = format_with(|f: &mut PyFormatter| {
-            let separator = format_with(|f| write!(f, [token(","), soft_line_break_or_space()]));
+            let separator = format_with(|f: &mut PyFormatter| {
+                token(",").fmt(f)?;
+
+                if f.context().node_level().is_parenthesized() {
+                    soft_line_break_or_space().fmt(f)
+                } else {
+                    space().fmt(f)
+                }
+            });
             let mut joiner = f.join_with(separator);
             let mut last_node: Option<AnyNodeRef> = None;
 
@@ -232,8 +240,6 @@ impl FormatNodeRule<Parameters> for FormatParameters {
             Ok(())
         });
 
-        let mut f = WithNodeLevel::new(NodeLevel::ParenthesizedExpression, f);
-
         let num_parameters = posonlyargs.len()
             + args.len()
             + usize::from(vararg.is_some())
@@ -243,12 +249,14 @@ impl FormatNodeRule<Parameters> for FormatParameters {
         if self.parentheses == ParametersParentheses::Never {
             write!(f, [group(&format_inner), dangling_comments(dangling)])
         } else if num_parameters == 0 {
+            let mut f = WithNodeLevel::new(NodeLevel::ParenthesizedExpression, f);
             // No parameters, format any dangling comments between `()`
             write!(f, [empty_parenthesized("(", dangling, ")")])
         } else {
             // Intentionally avoid `parenthesized`, which groups the entire formatted contents.
             // We want parameters to be grouped alongside return types, one level up, so we
             // format them "inline" here.
+            let mut f = WithNodeLevel::new(NodeLevel::ParenthesizedExpression, f);
             write!(
                 f,
                 [
diff --git a/crates/ruff_python_formatter/tests/snapshots/format@expression__lambda.py.snap b/crates/ruff_python_formatter/tests/snapshots/format@expression__lambda.py.snap
index 8f615a6511..241f61a481 100644
--- a/crates/ruff_python_formatter/tests/snapshots/format@expression__lambda.py.snap
+++ b/crates/ruff_python_formatter/tests/snapshots/format@expression__lambda.py.snap
@@ -209,6 +209,31 @@ lambda: ( # comment
     y:
     z
 )
+
+lambda self, araa, kkkwargs=aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(*args, **kwargs), e=1, f=2, g=2: d
+
+# Regression tests for https://github.com/astral-sh/ruff/issues/8179
+def a():
+    return b(
+        c,
+        d,
+        e,
+        f=lambda self, *args, **kwargs: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(
+            *args, **kwargs
+        ),
+    )
+
+def a():
+    return b(
+        c,
+        d,
+        e,
+        f=lambda self, araa, kkkwargs,aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa,
+                 args,kwargs,
+                 e=1, f=2, g=2: d,
+        g = 10
+    )
+
 ```
 
 ## Output
@@ -413,6 +438,40 @@ lambda: (  # comment
     # comment
     y: z
 )
+
+lambda self, araa, kkkwargs=aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(
+    *args, **kwargs
+), e=1, f=2, g=2: d
+
+
+# Regression tests for https://github.com/astral-sh/ruff/issues/8179
+def a():
+    return b(
+        c,
+        d,
+        e,
+        f=lambda self,
+        *args,
+        **kwargs: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(*args, **kwargs),
+    )
+
+
+def a():
+    return b(
+        c,
+        d,
+        e,
+        f=lambda self,
+        araa,
+        kkkwargs,
+        aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa,
+        args,
+        kwargs,
+        e=1,
+        f=2,
+        g=2: d,
+        g=10,
+    )
 ```