Add fix and tests for postfix pound ifs (swiftlang#383)

Add fix and tests for postfix pound ifs

Co-authored-by: David Brunow <>

Author: DavidBrunow

Sources/SwiftFormatPrettyPrint/TokenStreamCreator.swift

@@ -1307,7 +1307,15 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
       before(tokenToOpenWith.nextToken, tokens: .break(breakKindClose, newlines: .soft), .close)
     }
 
-    if let condition = node.condition {
+    if isNestedInPostfixIfConfig(node: Syntax(node)) {
+      before(
+        node.firstToken,
+        tokens: [
+          .printerControl(kind: .enableBreaking),
+          .break(.reset),
+        ]
+      )
+    } else if let condition = node.condition {
       before(condition.firstToken, tokens: .printerControl(kind: .disableBreaking))
       after(
         condition.lastToken,
@@ -3459,7 +3467,11 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
 
       if let calledMemberAccessExpr = calledExpression.as(MemberAccessExprSyntax.self) {
         if calledMemberAccessExpr.base != nil {
-          before(calledMemberAccessExpr.dot, tokens: [.break(.contextual, size: 0)])
+          if isNestedInPostfixIfConfig(node: Syntax(calledMemberAccessExpr)) {
+            before(calledMemberAccessExpr.dot, tokens: [.break(.same, size: 0)])
+          } else {
+            before(calledMemberAccessExpr.dot, tokens: [.break(.contextual, size: 0)])
+          }
         }
         before(calledMemberAccessExpr.dot, tokens: beforeTokens)
         after(expr.lastToken, tokens: afterTokens)
@@ -3484,6 +3496,20 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
   }
 }
 
+private func isNestedInPostfixIfConfig(node: Syntax) -> Bool {
+    var this: Syntax? = node
+
+    while this?.parent != nil {
+      if this?.parent?.is(PostfixIfConfigExprSyntax.self) == true {
+        return true
+      }
+
+      this = this?.parent
+    }
+
+    return false
+}
+
 extension Syntax {
   /// Creates a pretty-printable token stream for the provided Syntax node.
   func makeTokenStream(configuration: Configuration, operatorContext: OperatorContext) -> [Token] {

Tests/SwiftFormatPrettyPrintTests/IfConfigTests.swift

@@ -230,4 +230,164 @@ final class IfConfigTests: PrettyPrintTestCase {
 
     assertPrettyPrintEqual(input: input, expected: expected, linelength: 40)
   }
+
+  func testPostfixPoundIfAfterParentheses() {
+    let input =
+      """
+      VStack {
+        Text("something")
+        #if os(iOS)
+        .iOSSpecificModifier()
+        #endif
+        .commonModifier()
+      }
+      """
+
+    let expected =
+      """
+      VStack {
+        Text("something")
+        #if os(iOS)
+          .iOSSpecificModifier()
+        #endif
+        .commonModifier()
+      }
+
+      """
+
+    assertPrettyPrintEqual(input: input, expected: expected, linelength: 45)
+  }
+
+  func testPostfixPoundIfAfterParenthesesMultipleMembers() {
+    let input =
+      """
+      VStack {
+        Text("something")
+        #if os(iOS)
+        .iOSSpecificModifier()
+        .anotherModifier()
+        .anotherAnotherModifier()
+        #endif
+        .commonModifier()
+        .anotherCommonModifier()
+      }
+      """
+
+    let expected =
+      """
+      VStack {
+        Text("something")
+        #if os(iOS)
+          .iOSSpecificModifier()
+          .anotherModifier()
+          .anotherAnotherModifier()
+        #endif
+        .commonModifier()
+        .anotherCommonModifier()
+      }
+
+      """
+
+    assertPrettyPrintEqual(input: input, expected: expected, linelength: 45)
+  }
+
+  func testPostfixPoundIfNested() {
+    let input =
+      """
+      VStack {
+        Text("something")
+        #if os(iOS) || os(watchOS)
+          #if os(iOS)
+          .iOSModifier()
+          #else
+          .watchOSModifier()
+          #endif
+        .iOSAndWatchOSModifier()
+        #endif
+      }
+      """
+
+    let expected =
+      """
+      VStack {
+        Text("something")
+        #if os(iOS) || os(watchOS)
+          #if os(iOS)
+            .iOSModifier()
+          #else
+            .watchOSModifier()
+          #endif
+          .iOSAndWatchOSModifier()
+        #endif
+      }
+
+      """
+
+    assertPrettyPrintEqual(input: input, expected: expected, linelength: 45)
+  }
+
+
+  func testPostfixPoundIfAfterVariables() {
+    let input =
+      """
+      VStack {
+        textView
+        #if os(iOS)
+        .iOSSpecificModifier()
+        #endif
+        .commonModifier()
+      }
+      """
+
+    let expected =
+      """
+      VStack {
+        textView
+        #if os(iOS)
+          .iOSSpecificModifier()
+        #endif
+        .commonModifier()
+      }
+
+      """
+
+    assertPrettyPrintEqual(input: input, expected: expected, linelength: 45)
+  }
+
+  func testPostfixPoundIfAfterClosingBrace() {
+    let input =
+      """
+      HStack {
+          Toggle(isOn: binding) {
+              Text("Some text")
+          }
+          #if !os(tvOS)
+          .toggleStyle(SwitchToggleStyle(tint: Color.blue))
+          #endif
+          .accessibilityValue(
+              binding.wrappedValue == true ? "On" : "Off"
+          )
+      }
+      """
+
+    let expected =
+      """
+      HStack {
+        Toggle(isOn: binding) {
+          Text("Some text")
+        }
+        #if !os(tvOS)
+          .toggleStyle(
+            SwitchToggleStyle(tint: Color.blue))
+        #endif
+        .accessibilityValue(
+          binding.wrappedValue == true
+            ? "On" : "Off"
+        )
+      }
+
+      """
+
+    assertPrettyPrintEqual(input: input, expected: expected, linelength: 45)
+  }
 }