Merge pull request #1042 from swiftlang/automerge/merge-main-2025-06-30_09-02

Merge `main` into `release/6.2`

Author: bnbarham

.swift-format

@@ -13,6 +13,8 @@
         "NoBlockComments": false,
         "OrderedImports": true,
         "UseLetInEveryBoundCaseVariable": false,
-        "UseSynthesizedInitializer": false
+        "UseSynthesizedInitializer": false,
+        "ReturnVoidInsteadOfEmptyTuple": true,
+        "NoVoidReturnOnFunctionSignature": true,
     }
 }

Sources/SwiftFormat/Core/Trivia+Convenience.swift

@@ -80,13 +80,19 @@ extension Trivia {
       })
   }
 
-  /// Returns `true` if this trivia contains any backslashes (used for multiline string newline
-  /// suppression).
-  var containsBackslashes: Bool {
-    return contains(
-      where: {
-        if case .backslashes = $0 { return true }
-        return false
-      })
+  /// Returns the prefix of this trivia that corresponds to the backslash and pound signs used to
+  /// represent a non-line-break continuation of a multiline string, or nil if the trivia does not
+  /// represent such a continuation.
+  var multilineStringContinuation: String? {
+    var result = ""
+    for piece in pieces {
+      switch piece {
+      case .backslashes, .pounds:
+        piece.write(to: &result)
+      default:
+        break
+      }
+    }
+    return result.isEmpty ? nil : result
   }
 }

Sources/SwiftFormat/PrettyPrint/TokenStreamCreator.swift

@@ -2385,13 +2385,15 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
   }
 
   override func visit(_ node: AttributedTypeSyntax) -> SyntaxVisitorContinueKind {
+    before(node.firstToken(viewMode: .sourceAccurate), tokens: .open)
     arrangeAttributeList(node.attributes)
     for specifier in node.specifiers {
       after(
         specifier.firstToken(viewMode: .sourceAccurate),
         tokens: .break(.continue, newlines: .elective(ignoresDiscretionary: true))
       )
     }
+    after(node.lastToken(viewMode: .sourceAccurate), tokens: .close)
     return .visitChildren
   }
 
@@ -2635,11 +2637,13 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
       emitSegmentTextTokens(segmentText[...])
     }
 
-    if node.trailingTrivia.containsBackslashes && !config.reflowMultilineStringLiterals.isAlways {
-      // Segments with trailing backslashes won't end with a literal newline; the backslash is
-      // considered trivia. To preserve the original text and wrapping, we need to manually render
-      // the backslash and a break into the token stream.
-      appendToken(.syntax("\\"))
+    if !config.reflowMultilineStringLiterals.isAlways,
+      let continuation = node.trailingTrivia.multilineStringContinuation
+    {
+      // Segments with trailing backslashes won't end with a literal newline; the backslash and any
+      // `#` delimiters for raw strings are considered trivia. To preserve the original text and
+      // wrapping, we need to manually render them break into the token stream.
+      appendToken(.syntax(continuation))
       appendToken(.break(breakKind, newlines: .hard(count: 1)))
     }
     return .skipChildren

Sources/swift-format/Frontend/FormatFrontend.swift

@@ -40,7 +40,7 @@ class FormatFrontend: Frontend {
       return
     }
 
-    let diagnosticHandler: (SwiftDiagnostics.Diagnostic, SourceLocation) -> () = {
+    let diagnosticHandler: (SwiftDiagnostics.Diagnostic, SourceLocation) -> Void = {
       (diagnostic, location) in
       guard !self.lintFormatOptions.ignoreUnparsableFiles else {
         // No diagnostics should be emitted in this mode.

Tests/SwiftFormatTests/PrettyPrint/AttributeTests.swift

@@ -623,4 +623,25 @@ final class AttributeTests: PrettyPrintTestCase {
 
     assertPrettyPrintEqual(input: input, expected: expected, linelength: 45)
   }
+
+  func testAttributeLineBreakInInheritanceClause() {
+    let input =
+      """
+      public class MyClass: Foo, @unchecked Sendable, Bar {
+        // …
+      }
+
+      """
+    let expected =
+      """
+      public class MyClass: Foo,
+        @unchecked Sendable, Bar
+      {
+        // …
+      }
+
+      """
+
+    assertPrettyPrintEqual(input: input, expected: expected, linelength: 45)
+  }
 }

Tests/SwiftFormatTests/PrettyPrint/FunctionDeclTests.swift

@@ -1129,8 +1129,8 @@ final class FunctionDeclTests: PrettyPrintTestCase {
           .InnerMember,
       ) {}
       func foo(
-        cmp: @escaping (R) ->
-          ()
+        cmp:
+          @escaping (R) -> ()
       ) {}
       func foo(
         cmp:

Tests/SwiftFormatTests/PrettyPrint/StringTests.swift

@@ -739,4 +739,41 @@ final class StringTests: PrettyPrintTestCase {
 
     assertPrettyPrintEqual(input: input, expected: input + "\n", linelength: 20)
   }
+
+  func testMultilineStringWithContinuations() {
+    let input =
+      ##"""
+      let someString =
+        """
+        lines \
+        \nare \
+        short.
+        """
+      let someString =
+        #"""
+        lines \#
+        \#nare \#
+        short.
+        """#
+      """##
+
+    let expected =
+      ##"""
+      let someString =
+        """
+        lines \
+        \nare \
+        short.
+        """
+      let someString =
+        #"""
+        lines \#
+        \#nare \#
+        short.
+        """#
+
+      """##
+
+    assertPrettyPrintEqual(input: input, expected: expected, linelength: 30)
+  }
 }