From 32e369e8082f1a9f008f54b5f4365e0386d1ad05 Mon Sep 17 00:00:00 2001
From: stackotter <stackotter@stackotter.dev>
Date: Tue, 4 Apr 2023 21:23:40 +1000
Subject: [PATCH] Avoid disambiguating parentheses being removed from called
 closures in conditions (#298)

A bit of a mouthfull to fit into a reasonably sized commit message. The
NoParensAroundConditions rule removed parens around immediately called closures
and in doing so introduced ambiguities into code that was correct to begin with.
---
 .../NoParensAroundConditions.swift                 | 14 ++++++++++----
 .../NoParensAroundConditionsTests.swift            | 13 +++++++++++++
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/Sources/SwiftFormatRules/NoParensAroundConditions.swift b/Sources/SwiftFormatRules/NoParensAroundConditions.swift
index 162715254..1ee8678a7 100644
--- a/Sources/SwiftFormatRules/NoParensAroundConditions.swift
+++ b/Sources/SwiftFormatRules/NoParensAroundConditions.swift
@@ -30,10 +30,16 @@ public final class NoParensAroundConditions: SyntaxFormatRule {
     assert(tuple.elementList.count == 1)
     let expr = tuple.elementList.first!.expression
 
-    // If the condition is a function with a trailing closure, removing the
-    // outer set of parentheses introduces a parse ambiguity.
-    if let fnCall = expr.as(FunctionCallExprSyntax.self), fnCall.trailingClosure != nil {
-      return ExprSyntax(tuple)
+    // If the condition is a function with a trailing closure or if it's an immediately called
+    // closure, removing the outer set of parentheses introduces a parse ambiguity.
+    if let fnCall = expr.as(FunctionCallExprSyntax.self) {
+      if fnCall.trailingClosure != nil {
+        // Leave parentheses around call with trailing closure.
+        return ExprSyntax(tuple)
+      } else if fnCall.calledExpression.as(ClosureExprSyntax.self) != nil {
+        // Leave parentheses around immediately called closure.
+        return ExprSyntax(tuple)
+      }
     }
 
     diagnose(.removeParensAroundExpression, on: expr)
diff --git a/Tests/SwiftFormatRulesTests/NoParensAroundConditionsTests.swift b/Tests/SwiftFormatRulesTests/NoParensAroundConditionsTests.swift
index 865082ed3..9dbe9d244 100644
--- a/Tests/SwiftFormatRulesTests/NoParensAroundConditionsTests.swift
+++ b/Tests/SwiftFormatRulesTests/NoParensAroundConditionsTests.swift
@@ -160,4 +160,17 @@ final class NoParensAroundConditionsTests: LintOrFormatRuleTestCase {
                 }
                 """)
   }
+
+  func testParensAroundAmbiguousConditions() {
+    XCTAssertFormatting(
+      NoParensAroundConditions.self,
+      input: """
+             if ({ true }()) {}
+             if (functionWithTrailingClosure { 5 }) {}
+             """,
+      expected: """
+                if ({ true }()) {}
+                if (functionWithTrailingClosure { 5 }) {}
+                """)
+  }
 }