Respect comments before opening braces in opening_brace rule (#5582)

CHANGELOG.md

@@ -28,6 +28,12 @@
   [SimplyDanny](https://github.com/SimplyDanny)
   [#5571](https://github.com/realm/SwiftLint/issues/5571)
 
+* Respect comments before opening brace in `opening_brace` rule when there is
+  one space before the brace after the comment. Everything else is still a
+  violation, yet the rewriter will not remove the comment anymore.  
+  [SimplyDanny](https://github.com/SimplyDanny)
+  [#5578](https://github.com/realm/SwiftLint/issues/5578)
+
 ## 0.55.0: Universal Washing Powder
 
 #### Breaking

Source/SwiftLintBuiltInRules/Rules/Style/OpeningBraceRule.swift

@@ -225,16 +225,32 @@ private extension BracedSyntax {
 
     func violationCorrection(_ locationConverter: SourceLocationConverter) -> ViolationCorrection? {
         if let previousToken = leftBrace.previousToken(viewMode: .sourceAccurate) {
+            let triviaBetween = previousToken.trailingTrivia + leftBrace.leadingTrivia
             let previousLocation = previousToken.endLocation(converter: locationConverter)
             let leftBraceLocation = leftBrace.startLocation(converter: locationConverter)
-            if previousLocation.line != leftBraceLocation.line
-               || previousLocation.column + 1 != leftBraceLocation.column {
+            let violation = ViolationCorrection(
+                start: previousToken.endPositionBeforeTrailingTrivia,
+                end: leftBrace.positionAfterSkippingLeadingTrivia,
+                replacement: " "
+            )
+            if previousLocation.line != leftBraceLocation.line {
+                return violation
+            }
+            if previousLocation.column + 1 == leftBraceLocation.column {
+                return nil
+            }
+            if triviaBetween.containsComments {
+                if triviaBetween.pieces.last == .spaces(1) {
+                    return nil
+                }
+                let comment = triviaBetween.description.trimmingTrailingCharacters(in: .whitespaces)
                 return ViolationCorrection(
-                    start: previousToken.endPositionBeforeTrailingTrivia,
+                    start: previousToken.endPositionBeforeTrailingTrivia + SourceLength(of: comment),
                     end: leftBrace.positionAfterSkippingLeadingTrivia,
                     replacement: " "
                 )
             }
+            return violation
         }
         return nil
     }

Source/SwiftLintBuiltInRules/Rules/Style/OpeningBraceRuleExamples.swift

@@ -52,7 +52,12 @@ struct OpeningBraceRuleExamples {
         Example("""
             if c {}
             else {}
-            """)
+            """),
+        Example("""
+            if c /* comment */ {
+                return
+            }
+        """)
     ]
 
     static let triggeringExamples = [
@@ -210,7 +215,7 @@ struct OpeningBraceRuleExamples {
             """),
         Example("""
             if c  ↓{}
-            else  ↓{}
+            else /* comment */  ↓{}
             """)
     ]
 
@@ -531,6 +536,15 @@ struct OpeningBraceRuleExamples {
                 precedencegroup Group {
                   assignment: true
                 }
-                """)
+                """),
+        Example("""
+            if c /* comment */    {
+                return
+            }
+        """): Example("""
+                if c /* comment */ {
+                    return
+                }
+            """)
     ]
 }

Source/SwiftLintCore/Extensions/SwiftSyntax+SwiftLint.swift

@@ -254,6 +254,12 @@ public extension Trivia {
         }
     }
 
+    var containsComments: Bool {
+        isNotEmpty && contains { piece in
+            !piece.isWhitespace && !piece.isNewline
+        }
+    }
+
     var isSingleSpace: Bool {
         self == .spaces(1)
     }