diff --git a/Package.swift b/Package.swift
index 6d0903660..26cf44f30 100644
--- a/Package.swift
+++ b/Package.swift
@@ -1,9 +1,9 @@
-// swift-tools-version: 5.9
+// swift-tools-version: 6.0
 //===----------------------------------------------------------------------===//
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -47,7 +47,11 @@ var targets: [Target] = [
       + swiftSyntaxDependencies([
         "SwiftOperators", "SwiftParser", "SwiftParserDiagnostics", "SwiftSyntax", "SwiftSyntaxBuilder",
       ]),
-    exclude: ["CMakeLists.txt"]
+    exclude: ["CMakeLists.txt"],
+    swiftSettings: [
+      // TODO: Does not compile with Swift 6 in Swift 6 mode due to Swift concurrency bugs. Remove once swift-tools-version is bumped to 6.1.
+      .swiftLanguageMode(.v5)
+    ]
   ),
   .target(
     name: "_SwiftFormatTestSupport",
@@ -121,6 +125,34 @@ var targets: [Target] = [
   ),
 ]
 
+// Apply global Swift settings to targets.
+do {
+  var globalSwiftSettings: [SwiftSetting] = [
+    // Swift 7 mode upcoming features. These must be compatible with 'swift-tools-version'.
+    .enableUpcomingFeature("ExistentialAny"),
+    .enableUpcomingFeature("InternalImportsByDefault"),
+    .enableUpcomingFeature("MemberImportVisibility"),
+    .enableUpcomingFeature("NonisolatedNonsendingByDefault"),
+  ]
+
+  #if compiler(>=6.1)
+  globalSwiftSettings.append(
+    .unsafeFlags(["-Werror", "ExistentialAny"])
+  )
+  #endif
+
+  globalSwiftSettings += []  // avoid unused warning
+
+  for target in targets where target.type != .plugin {
+    if let swiftSettings = target.swiftSettings {
+      // Target-specific settings should come last.
+      target.swiftSettings = globalSwiftSettings + swiftSettings
+    } else {
+      target.swiftSettings = globalSwiftSettings
+    }
+  }
+}
+
 if buildOnlyTests {
   products = []
   let allowedNames: Set<String> = ["_SwiftFormatTestSupport", "_GenerateSwiftFormat"]
@@ -146,9 +178,11 @@ let package = Package(
   ],
   products: products,
   dependencies: dependencies,
-  targets: targets
+  targets: targets,
+  swiftLanguageModes: [.v5, .v6]
 )
 
+@MainActor
 func swiftSyntaxDependencies(_ names: [String]) -> [Target.Dependency] {
   if buildDynamicSwiftSyntaxLibrary {
     return [.product(name: "_SwiftSyntaxDynamic", package: "swift-syntax")]
diff --git a/Sources/SwiftFormat/API/Configuration.swift b/Sources/SwiftFormat/API/Configuration.swift
index 8fef820c5..e733db61f 100644
--- a/Sources/SwiftFormat/API/Configuration.swift
+++ b/Sources/SwiftFormat/API/Configuration.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import Foundation
+public import Foundation
 
 /// A version number that can be specified in the configuration file, which allows us to change the
 /// format in the future if desired and still support older files.
@@ -22,7 +22,7 @@ import Foundation
 internal let highestSupportedConfigurationVersion = 1
 
 /// Holds the complete set of configured values and defaults.
-public struct Configuration: Codable, Equatable {
+public struct Configuration: Codable, Equatable, Sendable {
 
   private enum CodingKeys: CodingKey {
     case version
@@ -176,7 +176,7 @@ public struct Configuration: Codable, Equatable {
   public var noAssignmentInExpressions: NoAssignmentInExpressionsConfiguration
 
   /// Determines how trailing commas in comma-separated lists should be handled during formatting.
-  public enum MultilineTrailingCommaBehavior: String, Codable {
+  public enum MultilineTrailingCommaBehavior: String, Codable, Sendable {
     case alwaysUsed
     case neverUsed
     case keptAsWritten
@@ -215,7 +215,7 @@ public struct Configuration: Codable, Equatable {
   public var multiElementCollectionTrailingCommas: Bool
 
   /// Determines how multiline string literals should reflow when formatted.
-  public enum MultilineStringReflowBehavior: String, Codable {
+  public enum MultilineStringReflowBehavior: String, Codable, Sendable {
     /// Never reflow multiline string literals.
     case never
     /// Reflow lines in string literal that exceed the maximum line length. For example with a line length of 10:
@@ -320,7 +320,7 @@ public struct Configuration: Codable, Equatable {
     self = try jsonDecoder.decode(Configuration.self, from: data)
   }
 
-  public init(from decoder: Decoder) throws {
+  public init(from decoder: any Decoder) throws {
     let container = try decoder.container(keyedBy: CodingKeys.self)
 
     // If the version number is not present, assume it is 1.
@@ -463,7 +463,7 @@ public struct Configuration: Codable, Equatable {
       ?? defaults.rules
   }
 
-  public func encode(to encoder: Encoder) throws {
+  public func encode(to encoder: any Encoder) throws {
     var container = encoder.container(keyedBy: CodingKeys.self)
 
     try container.encode(version, forKey: .version)
@@ -524,8 +524,8 @@ public struct Configuration: Codable, Equatable {
 }
 
 /// Configuration for the `FileScopedDeclarationPrivacy` rule.
-public struct FileScopedDeclarationPrivacyConfiguration: Codable, Equatable {
-  public enum AccessLevel: String, Codable {
+public struct FileScopedDeclarationPrivacyConfiguration: Codable, Equatable, Sendable {
+  public enum AccessLevel: String, Codable, Sendable {
     /// Private file-scoped declarations should be declared `private`.
     ///
     /// If a file-scoped declaration is declared `fileprivate`, it will be diagnosed (in lint mode)
@@ -547,7 +547,7 @@ public struct FileScopedDeclarationPrivacyConfiguration: Codable, Equatable {
 }
 
 /// Configuration for the `NoAssignmentInExpressions` rule.
-public struct NoAssignmentInExpressionsConfiguration: Codable, Equatable {
+public struct NoAssignmentInExpressionsConfiguration: Codable, Equatable, Sendable {
   /// A list of function names where assignments are allowed to be embedded in expressions that are
   /// passed as parameters to that function.
   public var allowedFunctions: [String] = [
@@ -561,7 +561,7 @@ public struct NoAssignmentInExpressionsConfiguration: Codable, Equatable {
 }
 
 /// Configuration for the `OrderedImports` rule.
-public struct OrderedImportsConfiguration: Codable, Equatable {
+public struct OrderedImportsConfiguration: Codable, Equatable, Sendable {
   /// Determines whether imports within conditional compilation blocks should be ordered.
   public var includeConditionalImports: Bool = false
 
diff --git a/Sources/SwiftFormat/API/DebugOptions.swift b/Sources/SwiftFormat/API/DebugOptions.swift
index e12790df0..074bad198 100644
--- a/Sources/SwiftFormat/API/DebugOptions.swift
+++ b/Sources/SwiftFormat/API/DebugOptions.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -12,7 +12,7 @@
 
 /// Advanced options that are useful when debugging and developing the formatter, but are otherwise
 /// not meant for general use.
-public struct DebugOptions: OptionSet {
+public struct DebugOptions: OptionSet, Sendable {
 
   /// Disables the pretty-printer pass entirely, executing only the syntax-transforming rules in the
   /// pipeline.
diff --git a/Sources/SwiftFormat/API/Finding.swift b/Sources/SwiftFormat/API/Finding.swift
index 7a9399cb9..f29058ef7 100644
--- a/Sources/SwiftFormat/API/Finding.swift
+++ b/Sources/SwiftFormat/API/Finding.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2021 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -39,7 +39,7 @@ public struct Finding {
   /// an `extension` of the `Finding.Message` type and add `static` properties or functions of type
   /// `Finding.Message`; these can be initialized using string literals or string interpolations.
   public struct Message:
-    CustomStringConvertible, ExpressibleByStringLiteral, ExpressibleByStringInterpolation
+    CustomStringConvertible, ExpressibleByStringLiteral, ExpressibleByStringInterpolation, Sendable
   {
     /// The message text of the diagnostic.
     public var text: String
@@ -71,7 +71,7 @@ public struct Finding {
   }
 
   /// The category associated with the finding.
-  public let category: FindingCategorizing
+  public let category: any FindingCategorizing
 
   /// The finding's message.
   public let message: Message
@@ -85,7 +85,7 @@ public struct Finding {
   /// Creates a new finding with the given category, message, optional location, and
   /// notes.
   init(
-    category: FindingCategorizing,
+    category: any FindingCategorizing,
     message: Message,
     location: Location? = nil,
     notes: [Note] = []
diff --git a/Sources/SwiftFormat/API/Indent.swift b/Sources/SwiftFormat/API/Indent.swift
index 5039da135..55c2b0618 100644
--- a/Sources/SwiftFormat/API/Indent.swift
+++ b/Sources/SwiftFormat/API/Indent.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -11,7 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 /// Represents an indentation unit that is applied to lines that are pretty-printed.
-public enum Indent: Hashable, Codable {
+public enum Indent: Hashable, Codable, Sendable {
 
   /// An indentation unit equal to the given number of tab characters.
   ///
@@ -27,7 +27,7 @@ public enum Indent: Hashable, Codable {
     case spaces
   }
 
-  public init(from decoder: Decoder) throws {
+  public init(from decoder: any Decoder) throws {
     let container = try decoder.container(keyedBy: CodingKeys.self)
     let spacesCount = try container.decodeIfPresent(Int.self, forKey: .spaces)
     let tabsCount = try container.decodeIfPresent(Int.self, forKey: .tabs)
@@ -57,7 +57,7 @@ public enum Indent: Hashable, Codable {
     )
   }
 
-  public func encode(to encoder: Encoder) throws {
+  public func encode(to encoder: any Encoder) throws {
     var container = encoder.container(keyedBy: CodingKeys.self)
     switch self {
     case .tabs(let count):
diff --git a/Sources/SwiftFormat/API/Selection.swift b/Sources/SwiftFormat/API/Selection.swift
index 2e7d00109..bb1313ca3 100644
--- a/Sources/SwiftFormat/API/Selection.swift
+++ b/Sources/SwiftFormat/API/Selection.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2024 Apple Inc. and the Swift project authors
+// Copyright (c) 2024 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -11,10 +11,10 @@
 //===----------------------------------------------------------------------===//
 
 import Foundation
-import SwiftSyntax
+public import SwiftSyntax
 
 /// The selection as given on the command line - an array of offets and lengths
-public enum Selection {
+public enum Selection: Sendable {
   case infinite
   case ranges([Range<AbsolutePosition>])
 
diff --git a/Sources/SwiftFormat/API/SwiftFormatError.swift b/Sources/SwiftFormat/API/SwiftFormatError.swift
index 5dd2a6e69..6791dd5d5 100644
--- a/Sources/SwiftFormat/API/SwiftFormatError.swift
+++ b/Sources/SwiftFormat/API/SwiftFormatError.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import Foundation
+public import Foundation
 import SwiftSyntax
 
 /// Errors that can be thrown by the `SwiftFormatter` and `SwiftLinter` APIs.
diff --git a/Sources/SwiftFormat/API/SwiftFormatter.swift b/Sources/SwiftFormat/API/SwiftFormatter.swift
index 6e06015cf..ab73ad891 100644
--- a/Sources/SwiftFormat/API/SwiftFormatter.swift
+++ b/Sources/SwiftFormat/API/SwiftFormatter.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2024 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,10 +10,10 @@
 //
 //===----------------------------------------------------------------------===//
 
-import Foundation
-import SwiftDiagnostics
-import SwiftOperators
-import SwiftSyntax
+public import Foundation
+public import SwiftDiagnostics
+public import SwiftOperators
+public import SwiftSyntax
 
 /// Formats Swift source code or syntax trees according to the Swift style guidelines.
 public final class SwiftFormatter {
diff --git a/Sources/SwiftFormat/API/SwiftLinter.swift b/Sources/SwiftFormat/API/SwiftLinter.swift
index d70f30673..b4263f2ec 100644
--- a/Sources/SwiftFormat/API/SwiftLinter.swift
+++ b/Sources/SwiftFormat/API/SwiftLinter.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,10 +10,10 @@
 //
 //===----------------------------------------------------------------------===//
 
-import Foundation
-import SwiftDiagnostics
-import SwiftOperators
-import SwiftSyntax
+public import Foundation
+public import SwiftDiagnostics
+public import SwiftOperators
+public import SwiftSyntax
 
 /// Diagnoses and reports problems in Swift source code or syntax trees according to the Swift style
 /// guidelines.
diff --git a/Sources/SwiftFormat/Core/Context.swift b/Sources/SwiftFormat/Core/Context.swift
index e00e38b20..5783281c9 100644
--- a/Sources/SwiftFormat/Core/Context.swift
+++ b/Sources/SwiftFormat/Core/Context.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2024 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,10 +10,10 @@
 //
 //===----------------------------------------------------------------------===//
 
-import Foundation
-import SwiftOperators
+public import Foundation
+public import SwiftOperators
 import SwiftParser
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Context contains the bits that each formatter and linter will need access to.
 ///
diff --git a/Sources/SwiftFormat/Core/DocumentationComment.swift b/Sources/SwiftFormat/Core/DocumentationComment.swift
index d89b4c1c6..d47c0607d 100644
--- a/Sources/SwiftFormat/Core/DocumentationComment.swift
+++ b/Sources/SwiftFormat/Core/DocumentationComment.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,8 +10,9 @@
 //
 //===----------------------------------------------------------------------===//
 
-import Markdown
-import SwiftSyntax
+import Foundation
+public import Markdown
+public import SwiftSyntax
 
 /// A structured representation of information extracted from a documentation comment.
 ///
@@ -55,7 +56,7 @@ public struct DocumentationComment {
   ///
   /// If a brief summary paragraph was extracted from the comment, it will not be present in this
   /// collection.
-  public var bodyNodes: [Markup] = []
+  public var bodyNodes: [any Markup] = []
 
   /// The structural layout of the parameter descriptions in the comment.
   public var parameterLayout: ParameterLayout? = nil
@@ -94,7 +95,7 @@ public struct DocumentationComment {
   }
 
   /// Creates a new `DocumentationComment` from the given `Markup` node.
-  private init(markup: Markup) {
+  private init(markup: any Markup) {
     // Extract the first paragraph as the brief summary. It will *not* be included in the body
     // nodes.
     let remainingChildren: DropFirstSequence<MarkupChildren>
@@ -143,7 +144,7 @@ public struct DocumentationComment {
   /// If parameters were successfully extracted, the provided list is mutated to remove them as a
   /// side effect of this function.
   private mutating func extractParameterOutline(from list: inout UnorderedList) {
-    var unprocessedChildren: [Markup] = []
+    var unprocessedChildren: [any Markup] = []
 
     for child in list.children {
       guard
@@ -182,7 +183,7 @@ public struct DocumentationComment {
   /// If parameters were successfully extracted, the provided list is mutated to remove them as a
   /// side effect of this function.
   private mutating func extractSeparatedParameters(from list: inout UnorderedList) {
-    var unprocessedChildren: [Markup] = []
+    var unprocessedChildren: [any Markup] = []
 
     for child in list.children {
       guard
@@ -231,7 +232,7 @@ public struct DocumentationComment {
   ///
   /// If fields were successfully extracted, the provided list is mutated to remove them.
   private mutating func extractSimpleFields(from list: inout UnorderedList) {
-    var unprocessedChildren: [Markup] = []
+    var unprocessedChildren: [any Markup] = []
 
     for child in list.children {
       guard
@@ -271,19 +272,19 @@ private struct ParameterOutlineMarkupRewriter: MarkupRewriter {
   /// Populated if the list item to which this is applied represents a valid parameter field.
   private(set) var parameterName: String? = nil
 
-  mutating func visitListItem(_ listItem: ListItem) -> Markup? {
+  mutating func visitListItem(_ listItem: ListItem) -> (any Markup)? {
     // Only recurse into the exact list item we're applying this to; otherwise, return it unchanged.
     guard listItem.isIdentical(to: origin) else { return listItem }
     return defaultVisit(listItem)
   }
 
-  mutating func visitParagraph(_ paragraph: Paragraph) -> Markup? {
+  mutating func visitParagraph(_ paragraph: Paragraph) -> (any Markup)? {
     // Only recurse into the first paragraph in the list item.
     guard paragraph.indexInParent == 0 else { return paragraph }
     return defaultVisit(paragraph)
   }
 
-  mutating func visitText(_ text: Text) -> Markup? {
+  mutating func visitText(_ text: Text) -> (any Markup)? {
     // Only manipulate the first text node (of the first paragraph).
     guard text.indexInParent == 0 else { return text }
 
@@ -315,13 +316,13 @@ private struct SimpleFieldMarkupRewriter: MarkupRewriter {
   /// Populated if the list item to which this is applied represents a valid simple field.
   private(set) var paragraph: Paragraph? = nil
 
-  mutating func visitListItem(_ listItem: ListItem) -> Markup? {
+  mutating func visitListItem(_ listItem: ListItem) -> (any Markup)? {
     // Only recurse into the exact list item we're applying this to; otherwise, return it unchanged.
     guard listItem.isIdentical(to: origin) else { return listItem }
     return defaultVisit(listItem)
   }
 
-  mutating func visitParagraph(_ paragraph: Paragraph) -> Markup? {
+  mutating func visitParagraph(_ paragraph: Paragraph) -> (any Markup)? {
     // Only recurse into the first paragraph in the list item.
     guard paragraph.indexInParent == 0 else { return paragraph }
     guard let newNode = defaultVisit(paragraph) else { return nil }
@@ -330,7 +331,7 @@ private struct SimpleFieldMarkupRewriter: MarkupRewriter {
     return newParagraph
   }
 
-  mutating func visitText(_ text: Text) -> Markup? {
+  mutating func visitText(_ text: Text) -> (any Markup)? {
     // Only manipulate the first text node (of the first paragraph).
     guard text.indexInParent == 0 else { return text }
 
diff --git a/Sources/SwiftFormat/Core/DocumentationCommentText.swift b/Sources/SwiftFormat/Core/DocumentationCommentText.swift
index 8fbf61873..01a83badc 100644
--- a/Sources/SwiftFormat/Core/DocumentationCommentText.swift
+++ b/Sources/SwiftFormat/Core/DocumentationCommentText.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// The text contents of a documentation comment extracted from trivia.
 ///
diff --git a/Sources/SwiftFormat/Core/FindingEmitter.swift b/Sources/SwiftFormat/Core/FindingEmitter.swift
index 71dd8f83d..f85c54695 100644
--- a/Sources/SwiftFormat/Core/FindingEmitter.swift
+++ b/Sources/SwiftFormat/Core/FindingEmitter.swift
@@ -42,7 +42,7 @@ final class FindingEmitter {
   ///     related locations in the source file.
   public func emit(
     _ message: Finding.Message,
-    category: FindingCategorizing,
+    category: any FindingCategorizing,
     location: Finding.Location? = nil,
     notes: [Finding.Note] = []
   ) {
diff --git a/Sources/SwiftFormat/Core/ImportsXCTestVisitor.swift b/Sources/SwiftFormat/Core/ImportsXCTestVisitor.swift
index ed9e9750f..7718f631c 100644
--- a/Sources/SwiftFormat/Core/ImportsXCTestVisitor.swift
+++ b/Sources/SwiftFormat/Core/ImportsXCTestVisitor.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// A visitor that determines if the target source file imports `XCTest`.
 private class ImportsXCTestVisitor: SyntaxVisitor {
diff --git a/Sources/SwiftFormat/Core/Pipelines+Generated.swift b/Sources/SwiftFormat/Core/Pipelines+Generated.swift
index 54f843549..7f41a1e31 100644
--- a/Sources/SwiftFormat/Core/Pipelines+Generated.swift
+++ b/Sources/SwiftFormat/Core/Pipelines+Generated.swift
@@ -24,11 +24,11 @@ class LintPipeline: SyntaxVisitor {
 
   /// Stores lint and format rule instances, indexed by the `ObjectIdentifier` of a rule's
   /// class type.
-  var ruleCache = [ObjectIdentifier: Rule]()
+  var ruleCache = [ObjectIdentifier: any Rule]()
 
   /// Rules present in this dictionary skip visiting children until they leave the
   /// syntax node stored as their value
-  var shouldSkipChildren = [ObjectIdentifier: SyntaxProtocol]()
+  var shouldSkipChildren = [ObjectIdentifier: any SyntaxProtocol]()
 
   /// Creates a new lint pipeline.
   init(context: Context) {
diff --git a/Sources/SwiftFormat/Core/Rule.swift b/Sources/SwiftFormat/Core/Rule.swift
index 764aa45e3..bfe2ff877 100644
--- a/Sources/SwiftFormat/Core/Rule.swift
+++ b/Sources/SwiftFormat/Core/Rule.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -11,7 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import Foundation
-import SwiftSyntax
+public import SwiftSyntax
 
 /// A Rule is a linting or formatting pass that executes in a given context.
 @_spi(Rules)
diff --git a/Sources/SwiftFormat/Core/RuleBasedFindingCategory.swift b/Sources/SwiftFormat/Core/RuleBasedFindingCategory.swift
index 03a2f4541..52f7ad206 100644
--- a/Sources/SwiftFormat/Core/RuleBasedFindingCategory.swift
+++ b/Sources/SwiftFormat/Core/RuleBasedFindingCategory.swift
@@ -18,12 +18,12 @@
 /// defaults to the rule's type name).
 struct RuleBasedFindingCategory: FindingCategorizing {
   /// The type of the rule associated with this category.
-  private let ruleType: Rule.Type
+  private let ruleType: any Rule.Type
 
   var description: String { ruleType.ruleName }
 
   /// Creates a finding category that wraps the given rule type.
-  init(ruleType: Rule.Type) {
+  init(ruleType: any Rule.Type) {
     self.ruleType = ruleType
   }
 }
diff --git a/Sources/SwiftFormat/Core/RuleMask.swift b/Sources/SwiftFormat/Core/RuleMask.swift
index 976d8ee62..62b47bfef 100644
--- a/Sources/SwiftFormat/Core/RuleMask.swift
+++ b/Sources/SwiftFormat/Core/RuleMask.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -11,7 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import Foundation
-import SwiftSyntax
+public import SwiftSyntax
 
 /// This class takes the raw source text and scans through it searching for comments that instruct
 /// the formatter to change the status of rules for the following node. The comments may include no
@@ -124,6 +124,9 @@ enum IgnoreDirective: CustomStringConvertible {
   }
 }
 
+// This regex is thread-safe.
+extension IgnoreDirective.RegexExpression: @unchecked @retroactive Sendable {}
+
 /// A syntax visitor that finds `SourceRange`s of nodes that have rule status modifying comment
 /// directives. The changes requested in each comment is parsed and collected into a map to support
 /// status lookup per rule name.
diff --git a/Sources/SwiftFormat/Core/SyntaxFormatRule.swift b/Sources/SwiftFormat/Core/SyntaxFormatRule.swift
index 92fc7c835..bbcac0c76 100644
--- a/Sources/SwiftFormat/Core/SyntaxFormatRule.swift
+++ b/Sources/SwiftFormat/Core/SyntaxFormatRule.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// A rule that both formats and lints a given file.
 @_spi(Rules)
diff --git a/Sources/SwiftFormat/Core/SyntaxLintRule.swift b/Sources/SwiftFormat/Core/SyntaxLintRule.swift
index 696cfcb8a..f5e357e0f 100644
--- a/Sources/SwiftFormat/Core/SyntaxLintRule.swift
+++ b/Sources/SwiftFormat/Core/SyntaxLintRule.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -11,7 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import Foundation
-import SwiftSyntax
+public import SwiftSyntax
 
 /// A rule that lints a given file.
 @_spi(Rules)
diff --git a/Sources/SwiftFormat/Core/SyntaxTraits.swift b/Sources/SwiftFormat/Core/SyntaxTraits.swift
index 7c64cca52..6b4801474 100644
--- a/Sources/SwiftFormat/Core/SyntaxTraits.swift
+++ b/Sources/SwiftFormat/Core/SyntaxTraits.swift
@@ -21,20 +21,20 @@ extension FunctionCallExprSyntax: CallingExprSyntaxProtocol {}
 extension SubscriptCallExprSyntax: CallingExprSyntaxProtocol {}
 
 extension Syntax {
-  func asProtocol(_: CallingExprSyntaxProtocol.Protocol) -> CallingExprSyntaxProtocol? {
-    return self.asProtocol(SyntaxProtocol.self) as? CallingExprSyntaxProtocol
+  func asProtocol(_: (any CallingExprSyntaxProtocol).Protocol) -> (any CallingExprSyntaxProtocol)? {
+    return self.asProtocol((any SyntaxProtocol).self) as? (any CallingExprSyntaxProtocol)
   }
-  func isProtocol(_: CallingExprSyntaxProtocol.Protocol) -> Bool {
-    return self.asProtocol(CallingExprSyntaxProtocol.self) != nil
+  func isProtocol(_: (any CallingExprSyntaxProtocol).Protocol) -> Bool {
+    return self.asProtocol((any CallingExprSyntaxProtocol).self) != nil
   }
 }
 
 extension ExprSyntax {
-  func asProtocol(_: CallingExprSyntaxProtocol.Protocol) -> CallingExprSyntaxProtocol? {
-    return Syntax(self).asProtocol(SyntaxProtocol.self) as? CallingExprSyntaxProtocol
+  func asProtocol(_: (any CallingExprSyntaxProtocol).Protocol) -> (any CallingExprSyntaxProtocol)? {
+    return Syntax(self).asProtocol((any SyntaxProtocol).self) as? (any CallingExprSyntaxProtocol)
   }
-  func isProtocol(_: CallingExprSyntaxProtocol.Protocol) -> Bool {
-    return self.asProtocol(CallingExprSyntaxProtocol.self) != nil
+  func isProtocol(_: (any CallingExprSyntaxProtocol).Protocol) -> Bool {
+    return self.asProtocol((any CallingExprSyntaxProtocol).self) != nil
   }
 }
 
@@ -49,20 +49,20 @@ extension TryExprSyntax: KeywordModifiedExprSyntaxProtocol {}
 extension UnsafeExprSyntax: KeywordModifiedExprSyntaxProtocol {}
 
 extension Syntax {
-  func asProtocol(_: KeywordModifiedExprSyntaxProtocol.Protocol) -> KeywordModifiedExprSyntaxProtocol? {
-    return self.asProtocol(SyntaxProtocol.self) as? KeywordModifiedExprSyntaxProtocol
+  func asProtocol(_: (any KeywordModifiedExprSyntaxProtocol).Protocol) -> (any KeywordModifiedExprSyntaxProtocol)? {
+    return self.asProtocol((any SyntaxProtocol).self) as? (any KeywordModifiedExprSyntaxProtocol)
   }
-  func isProtocol(_: KeywordModifiedExprSyntaxProtocol.Protocol) -> Bool {
-    return self.asProtocol(KeywordModifiedExprSyntaxProtocol.self) != nil
+  func isProtocol(_: (any KeywordModifiedExprSyntaxProtocol).Protocol) -> Bool {
+    return self.asProtocol((any KeywordModifiedExprSyntaxProtocol).self) != nil
   }
 }
 
 extension ExprSyntax {
-  func asProtocol(_: KeywordModifiedExprSyntaxProtocol.Protocol) -> KeywordModifiedExprSyntaxProtocol? {
-    return Syntax(self).asProtocol(SyntaxProtocol.self) as? KeywordModifiedExprSyntaxProtocol
+  func asProtocol(_: (any KeywordModifiedExprSyntaxProtocol).Protocol) -> (any KeywordModifiedExprSyntaxProtocol)? {
+    return Syntax(self).asProtocol((any SyntaxProtocol).self) as? (any KeywordModifiedExprSyntaxProtocol)
   }
-  func isProtocol(_: KeywordModifiedExprSyntaxProtocol.Protocol) -> Bool {
-    return self.asProtocol(KeywordModifiedExprSyntaxProtocol.self) != nil
+  func isProtocol(_: (any KeywordModifiedExprSyntaxProtocol).Protocol) -> Bool {
+    return self.asProtocol((any KeywordModifiedExprSyntaxProtocol).self) != nil
   }
 }
 
@@ -70,20 +70,20 @@ extension ExprSyntax {
 /// support a `trailingComma`.
 protocol CommaSeparatedListSyntaxProtocol: SyntaxCollection where Element: WithTrailingCommaSyntax & Equatable {
   /// The node used for trailing comma handling; inserted immediately after this node.
-  var lastNodeForTrailingComma: SyntaxProtocol? { get }
+  var lastNodeForTrailingComma: (any SyntaxProtocol)? { get }
 }
 
 extension ArrayElementListSyntax: CommaSeparatedListSyntaxProtocol {
-  var lastNodeForTrailingComma: SyntaxProtocol? { last?.expression }
+  var lastNodeForTrailingComma: (any SyntaxProtocol)? { last?.expression }
 }
 extension DictionaryElementListSyntax: CommaSeparatedListSyntaxProtocol {
-  var lastNodeForTrailingComma: SyntaxProtocol? { last }
+  var lastNodeForTrailingComma: (any SyntaxProtocol)? { last }
 }
 extension LabeledExprListSyntax: CommaSeparatedListSyntaxProtocol {
-  var lastNodeForTrailingComma: SyntaxProtocol? { last?.expression }
+  var lastNodeForTrailingComma: (any SyntaxProtocol)? { last?.expression }
 }
 extension ClosureCaptureListSyntax: CommaSeparatedListSyntaxProtocol {
-  var lastNodeForTrailingComma: SyntaxProtocol? {
+  var lastNodeForTrailingComma: (any SyntaxProtocol)? {
     if let initializer = last?.initializer {
       return initializer
     } else {
@@ -92,7 +92,7 @@ extension ClosureCaptureListSyntax: CommaSeparatedListSyntaxProtocol {
   }
 }
 extension EnumCaseParameterListSyntax: CommaSeparatedListSyntaxProtocol {
-  var lastNodeForTrailingComma: SyntaxProtocol? {
+  var lastNodeForTrailingComma: (any SyntaxProtocol)? {
     if let defaultValue = last?.defaultValue {
       return defaultValue
     } else {
@@ -101,7 +101,7 @@ extension EnumCaseParameterListSyntax: CommaSeparatedListSyntaxProtocol {
   }
 }
 extension FunctionParameterListSyntax: CommaSeparatedListSyntaxProtocol {
-  var lastNodeForTrailingComma: SyntaxProtocol? {
+  var lastNodeForTrailingComma: (any SyntaxProtocol)? {
     if let defaultValue = last?.defaultValue {
       return defaultValue
     } else if let ellipsis = last?.ellipsis {
@@ -112,7 +112,7 @@ extension FunctionParameterListSyntax: CommaSeparatedListSyntaxProtocol {
   }
 }
 extension GenericParameterListSyntax: CommaSeparatedListSyntaxProtocol {
-  var lastNodeForTrailingComma: SyntaxProtocol? {
+  var lastNodeForTrailingComma: (any SyntaxProtocol)? {
     if let inheritedType = last?.inheritedType {
       return inheritedType
     } else {
@@ -121,12 +121,12 @@ extension GenericParameterListSyntax: CommaSeparatedListSyntaxProtocol {
   }
 }
 extension TuplePatternElementListSyntax: CommaSeparatedListSyntaxProtocol {
-  var lastNodeForTrailingComma: SyntaxProtocol? { last?.pattern }
+  var lastNodeForTrailingComma: (any SyntaxProtocol)? { last?.pattern }
 }
 
 extension SyntaxProtocol {
   func asProtocol(_: (any CommaSeparatedListSyntaxProtocol).Protocol) -> (any CommaSeparatedListSyntaxProtocol)? {
-    return Syntax(self).asProtocol(SyntaxProtocol.self) as? (any CommaSeparatedListSyntaxProtocol)
+    return Syntax(self).asProtocol((any SyntaxProtocol).self) as? (any CommaSeparatedListSyntaxProtocol)
   }
   func isProtocol(_: (any CommaSeparatedListSyntaxProtocol).Protocol) -> Bool {
     return self.asProtocol((any CommaSeparatedListSyntaxProtocol).self) != nil
diff --git a/Sources/SwiftFormat/Core/WithSemicolonSyntax.swift b/Sources/SwiftFormat/Core/WithSemicolonSyntax.swift
index 42ac7ce42..3cf7c90b8 100644
--- a/Sources/SwiftFormat/Core/WithSemicolonSyntax.swift
+++ b/Sources/SwiftFormat/Core/WithSemicolonSyntax.swift
@@ -21,11 +21,11 @@ extension MemberBlockItemSyntax: WithSemicolonSyntax {}
 extension CodeBlockItemSyntax: WithSemicolonSyntax {}
 
 extension SyntaxProtocol {
-  func asProtocol(_: WithSemicolonSyntax.Protocol) -> WithSemicolonSyntax? {
-    return Syntax(self).asProtocol(SyntaxProtocol.self) as? WithSemicolonSyntax
+  func asProtocol(_: (any WithSemicolonSyntax).Protocol) -> (any WithSemicolonSyntax)? {
+    return Syntax(self).asProtocol((any SyntaxProtocol).self) as? (any WithSemicolonSyntax)
   }
 
-  func isProtocol(_: WithSemicolonSyntax.Protocol) -> Bool {
-    return self.asProtocol(WithSemicolonSyntax.self) != nil
+  func isProtocol(_: (any WithSemicolonSyntax).Protocol) -> Bool {
+    return self.asProtocol((any WithSemicolonSyntax).self) != nil
   }
 }
diff --git a/Sources/SwiftFormat/PrettyPrint/PrettyPrint.swift b/Sources/SwiftFormat/PrettyPrint/PrettyPrint.swift
index 69329f3b0..bf5c53b73 100644
--- a/Sources/SwiftFormat/PrettyPrint/PrettyPrint.swift
+++ b/Sources/SwiftFormat/PrettyPrint/PrettyPrint.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -11,7 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import Foundation
-import SwiftSyntax
+public import SwiftSyntax
 
 /// PrettyPrinter takes a Syntax node and outputs a well-formatted, re-indented reproduction of the
 /// code as a String.
diff --git a/Sources/SwiftFormat/PrettyPrint/TokenStreamCreator.swift b/Sources/SwiftFormat/PrettyPrint/TokenStreamCreator.swift
index f56f50e6d..5d17d24ab 100644
--- a/Sources/SwiftFormat/PrettyPrint/TokenStreamCreator.swift
+++ b/Sources/SwiftFormat/PrettyPrint/TokenStreamCreator.swift
@@ -1048,7 +1048,7 @@ private final class TokenStreamCreator: SyntaxVisitor {
         // when visiting that wrapping expression is sufficient. Adding another group here in that
         // case can result in unnecessarily breaking after the modifier keyword.
         if !(base.firstToken(viewMode: .sourceAccurate)?.previousToken(viewMode: .all)?.parent?.isProtocol(
-          KeywordModifiedExprSyntaxProtocol.self
+          (any KeywordModifiedExprSyntaxProtocol).self
         ) ?? false) {
           before(base.firstToken(viewMode: .sourceAccurate), tokens: .open)
           after(calledMemberAccessExpr.declName.baseName.lastToken(viewMode: .sourceAccurate), tokens: .close)
@@ -1789,7 +1789,7 @@ private final class TokenStreamCreator: SyntaxVisitor {
 
     // Check for an anchor token inside of the expression to end a group starting with the `try`
     // keyword.
-    if !(node.parent?.isProtocol(KeywordModifiedExprSyntaxProtocol.self) ?? false),
+    if !(node.parent?.isProtocol((any KeywordModifiedExprSyntaxProtocol).self) ?? false),
       let anchorToken = connectingTokenForKeywordModifiedExpr(inSubExpr: node.expression)
     {
       before(node.tryKeyword, tokens: .open)
@@ -1807,7 +1807,7 @@ private final class TokenStreamCreator: SyntaxVisitor {
 
     // Check for an anchor token inside of the expression to end a group starting with the `await`
     // keyword.
-    if !(node.parent?.isProtocol(KeywordModifiedExprSyntaxProtocol.self) ?? false),
+    if !(node.parent?.isProtocol((any KeywordModifiedExprSyntaxProtocol).self) ?? false),
       let anchorToken = connectingTokenForKeywordModifiedExpr(inSubExpr: node.expression)
     {
       before(node.awaitKeyword, tokens: .open)
@@ -1824,7 +1824,7 @@ private final class TokenStreamCreator: SyntaxVisitor {
 
     // Check for an anchor token inside of the expression to end a group starting with the `unsafe`
     // keyword.
-    if !(node.parent?.isProtocol(KeywordModifiedExprSyntaxProtocol.self) ?? false),
+    if !(node.parent?.isProtocol((any KeywordModifiedExprSyntaxProtocol).self) ?? false),
       let anchorToken = connectingTokenForKeywordModifiedExpr(inSubExpr: node.expression)
     {
       before(node.unsafeKeyword, tokens: .open)
@@ -1841,12 +1841,12 @@ private final class TokenStreamCreator: SyntaxVisitor {
   /// - Returns: The token that should end the group that is started by the modifier keyword, or
   ///   nil if there should be no group.
   func connectingTokenForKeywordModifiedExpr(inSubExpr expr: ExprSyntax) -> TokenSyntax? {
-    if let modifiedExpr = expr.asProtocol(KeywordModifiedExprSyntaxProtocol.self) {
+    if let modifiedExpr = expr.asProtocol((any KeywordModifiedExprSyntaxProtocol).self) {
       // If we were called from a keyword-modified expression like `try`, `await`, or `unsafe`,
       // recursively drill into the child expression.
       return connectingTokenForKeywordModifiedExpr(inSubExpr: modifiedExpr.expression)
     }
-    if let callingExpr = expr.asProtocol(CallingExprSyntaxProtocol.self) {
+    if let callingExpr = expr.asProtocol((any CallingExprSyntaxProtocol).self) {
       return connectingTokenForKeywordModifiedExpr(inSubExpr: callingExpr.calledExpression)
     }
     if let memberAccessExpr = expr.as(MemberAccessExprSyntax.self), let base = memberAccessExpr.base {
@@ -3903,7 +3903,7 @@ private final class TokenStreamCreator: SyntaxVisitor {
   /// that are known to wrap an expression, e.g. try expressions, are handled by checking the
   /// expression that they contain.
   private func isCompoundExpression(_ expr: ExprSyntax) -> Bool {
-    if let modifiedExpr = expr.asProtocol(KeywordModifiedExprSyntaxProtocol.self) {
+    if let modifiedExpr = expr.asProtocol((any KeywordModifiedExprSyntaxProtocol).self) {
       return isCompoundExpression(modifiedExpr.expression)
     }
     switch Syntax(expr).as(SyntaxEnum.self) {
@@ -4262,7 +4262,7 @@ private final class TokenStreamCreator: SyntaxVisitor {
       // When the member access is part of a calling expression, the break before the dot is
       // inserted when visiting the parent node instead so that the break is inserted before any
       // scoping tokens (e.g. `contextualBreakingStart`, `open`).
-      if memberAccessExpr.base != nil && expr.parent?.isProtocol(CallingExprSyntaxProtocol.self) != true {
+      if memberAccessExpr.base != nil && expr.parent?.isProtocol((any CallingExprSyntaxProtocol).self) != true {
         before(memberAccessExpr.period, tokens: .break(.contextual, size: 0))
       }
       var hasCompoundExpression = false
@@ -4292,7 +4292,7 @@ private final class TokenStreamCreator: SyntaxVisitor {
       after(postfixIfExpr.config.poundEndif, tokens: .break(.same, size: 0))
 
       return insertContextualBreaks(base, isTopLevel: false)
-    } else if let callingExpr = expr.asProtocol(CallingExprSyntaxProtocol.self) {
+    } else if let callingExpr = expr.asProtocol((any CallingExprSyntaxProtocol).self) {
       let calledExpression = callingExpr.calledExpression
       let (hasCompoundExpression, hasMemberAccess) =
         insertContextualBreaks(calledExpression, isTopLevel: false)
diff --git a/Sources/SwiftFormat/Rules/AllPublicDeclarationsHaveDocumentation.swift b/Sources/SwiftFormat/Rules/AllPublicDeclarationsHaveDocumentation.swift
index feaa3a550..2cd0c7b4c 100644
--- a/Sources/SwiftFormat/Rules/AllPublicDeclarationsHaveDocumentation.swift
+++ b/Sources/SwiftFormat/Rules/AllPublicDeclarationsHaveDocumentation.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// All public or open declarations must have a top-level documentation comment.
 ///
diff --git a/Sources/SwiftFormat/Rules/AlwaysUseLiteralForEmptyCollectionInit.swift b/Sources/SwiftFormat/Rules/AlwaysUseLiteralForEmptyCollectionInit.swift
index 124ad63f7..4b18540cf 100644
--- a/Sources/SwiftFormat/Rules/AlwaysUseLiteralForEmptyCollectionInit.swift
+++ b/Sources/SwiftFormat/Rules/AlwaysUseLiteralForEmptyCollectionInit.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -12,7 +12,7 @@
 
 import Foundation
 import SwiftParser
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Never use `[<Type>]()` syntax. In call sites that should be replaced with `[]`,
 /// for initializations use explicit type combined with empty array literal `let _: [<Type>] = []`
diff --git a/Sources/SwiftFormat/Rules/AlwaysUseLowerCamelCase.swift b/Sources/SwiftFormat/Rules/AlwaysUseLowerCamelCase.swift
index bbd47d74d..c203b7985 100644
--- a/Sources/SwiftFormat/Rules/AlwaysUseLowerCamelCase.swift
+++ b/Sources/SwiftFormat/Rules/AlwaysUseLowerCamelCase.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// All values should be written in lower camel-case (`lowerCamelCase`).
 /// Underscores (except at the beginning of an identifier) are disallowed.
diff --git a/Sources/SwiftFormat/Rules/AmbiguousTrailingClosureOverload.swift b/Sources/SwiftFormat/Rules/AmbiguousTrailingClosureOverload.swift
index 72eb28cc3..186515659 100644
--- a/Sources/SwiftFormat/Rules/AmbiguousTrailingClosureOverload.swift
+++ b/Sources/SwiftFormat/Rules/AmbiguousTrailingClosureOverload.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Overloads with only a closure argument should not be disambiguated by parameter labels.
 ///
diff --git a/Sources/SwiftFormat/Rules/AvoidRetroactiveConformances.swift b/Sources/SwiftFormat/Rules/AvoidRetroactiveConformances.swift
index 1573d3de2..dd82299d9 100644
--- a/Sources/SwiftFormat/Rules/AvoidRetroactiveConformances.swift
+++ b/Sources/SwiftFormat/Rules/AvoidRetroactiveConformances.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2024 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// `@retroactive` conformances are forbidden.
 ///
diff --git a/Sources/SwiftFormat/Rules/BeginDocumentationCommentWithOneLineSummary.swift b/Sources/SwiftFormat/Rules/BeginDocumentationCommentWithOneLineSummary.swift
index 09fdb92ad..888c64715 100644
--- a/Sources/SwiftFormat/Rules/BeginDocumentationCommentWithOneLineSummary.swift
+++ b/Sources/SwiftFormat/Rules/BeginDocumentationCommentWithOneLineSummary.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -12,7 +12,7 @@
 
 import Foundation
 import Markdown
-import SwiftSyntax
+public import SwiftSyntax
 
 #if os(macOS)
 import NaturalLanguage
@@ -29,7 +29,7 @@ public final class BeginDocumentationCommentWithOneLineSummary: SyntaxLintRule {
   /// even on platforms that support the latter (currently only Apple OSes).
   ///
   /// This allows test runs on those platforms to test both implementations.
-  public static var _forcesFallbackModeForTesting = false
+  nonisolated(unsafe) package static var _forcesFallbackModeForTesting = false
 
   /// Identifies this rule as being opt-in. Well written docs on declarations are important, but
   /// this rule isn't linguistically advanced enough on all platforms to be applied universally.
@@ -240,7 +240,7 @@ extension Finding.Message {
 }
 
 struct InlineCodeRemover: MarkupRewriter {
-  mutating func visitInlineCode(_ inlineCode: InlineCode) -> Markup? {
+  mutating func visitInlineCode(_ inlineCode: InlineCode) -> (any Markup)? {
     nil
   }
 }
diff --git a/Sources/SwiftFormat/Rules/DoNotUseSemicolons.swift b/Sources/SwiftFormat/Rules/DoNotUseSemicolons.swift
index 7559d72ed..693cd5a30 100644
--- a/Sources/SwiftFormat/Rules/DoNotUseSemicolons.swift
+++ b/Sources/SwiftFormat/Rules/DoNotUseSemicolons.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Semicolons should not be present in Swift code.
 ///
@@ -109,7 +109,7 @@ public final class DoNotUseSemicolons: SyntaxFormatRule {
   /// given type.
   private func isCodeBlockItem(
     _ node: some SyntaxProtocol,
-    containingStmtType stmtType: StmtSyntaxProtocol.Type
+    containingStmtType stmtType: any StmtSyntaxProtocol.Type
   ) -> Bool {
     if let codeBlockItem = node.as(CodeBlockItemSyntax.self),
       case .stmt(let stmt) = codeBlockItem.item,
diff --git a/Sources/SwiftFormat/Rules/DontRepeatTypeInStaticProperties.swift b/Sources/SwiftFormat/Rules/DontRepeatTypeInStaticProperties.swift
index b56192cba..0e0f3fe7b 100644
--- a/Sources/SwiftFormat/Rules/DontRepeatTypeInStaticProperties.swift
+++ b/Sources/SwiftFormat/Rules/DontRepeatTypeInStaticProperties.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+import Foundation
+public import SwiftSyntax
 
 /// Static properties of a type that return that type should not include a reference to their type.
 ///
diff --git a/Sources/SwiftFormat/Rules/FileScopedDeclarationPrivacy.swift b/Sources/SwiftFormat/Rules/FileScopedDeclarationPrivacy.swift
index e0f9af4c5..79bd92e3c 100644
--- a/Sources/SwiftFormat/Rules/FileScopedDeclarationPrivacy.swift
+++ b/Sources/SwiftFormat/Rules/FileScopedDeclarationPrivacy.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Declarations at file scope with effective private access should be consistently declared as
 /// either `fileprivate` or `private`, determined by configuration.
diff --git a/Sources/SwiftFormat/Rules/FullyIndirectEnum.swift b/Sources/SwiftFormat/Rules/FullyIndirectEnum.swift
index 53273f676..a0117d7af 100644
--- a/Sources/SwiftFormat/Rules/FullyIndirectEnum.swift
+++ b/Sources/SwiftFormat/Rules/FullyIndirectEnum.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// If all cases of an enum are `indirect`, the entire enum should be marked `indirect`.
 ///
diff --git a/Sources/SwiftFormat/Rules/GroupNumericLiterals.swift b/Sources/SwiftFormat/Rules/GroupNumericLiterals.swift
index b29089efb..b713b20d3 100644
--- a/Sources/SwiftFormat/Rules/GroupNumericLiterals.swift
+++ b/Sources/SwiftFormat/Rules/GroupNumericLiterals.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Numeric literals should be grouped with `_`s to delimit common separators.
 ///
diff --git a/Sources/SwiftFormat/Rules/IdentifiersMustBeASCII.swift b/Sources/SwiftFormat/Rules/IdentifiersMustBeASCII.swift
index 913dc2a06..6c09909c3 100644
--- a/Sources/SwiftFormat/Rules/IdentifiersMustBeASCII.swift
+++ b/Sources/SwiftFormat/Rules/IdentifiersMustBeASCII.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// All identifiers must be ASCII.
 ///
diff --git a/Sources/SwiftFormat/Rules/NeverForceUnwrap.swift b/Sources/SwiftFormat/Rules/NeverForceUnwrap.swift
index f81c9953d..4655b69d9 100644
--- a/Sources/SwiftFormat/Rules/NeverForceUnwrap.swift
+++ b/Sources/SwiftFormat/Rules/NeverForceUnwrap.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Force-unwraps are strongly discouraged and must be documented.
 ///
diff --git a/Sources/SwiftFormat/Rules/NeverUseForceTry.swift b/Sources/SwiftFormat/Rules/NeverUseForceTry.swift
index 2eada1a78..24a2bbbdb 100644
--- a/Sources/SwiftFormat/Rules/NeverUseForceTry.swift
+++ b/Sources/SwiftFormat/Rules/NeverUseForceTry.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Force-try (`try!`) is forbidden.
 ///
diff --git a/Sources/SwiftFormat/Rules/NeverUseImplicitlyUnwrappedOptionals.swift b/Sources/SwiftFormat/Rules/NeverUseImplicitlyUnwrappedOptionals.swift
index 009969ddc..d33b33859 100644
--- a/Sources/SwiftFormat/Rules/NeverUseImplicitlyUnwrappedOptionals.swift
+++ b/Sources/SwiftFormat/Rules/NeverUseImplicitlyUnwrappedOptionals.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Implicitly unwrapped optionals (e.g. `var s: String!`) are forbidden.
 ///
diff --git a/Sources/SwiftFormat/Rules/NoAccessLevelOnExtensionDeclaration.swift b/Sources/SwiftFormat/Rules/NoAccessLevelOnExtensionDeclaration.swift
index 2e9d0631c..5e4491aa6 100644
--- a/Sources/SwiftFormat/Rules/NoAccessLevelOnExtensionDeclaration.swift
+++ b/Sources/SwiftFormat/Rules/NoAccessLevelOnExtensionDeclaration.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Specifying an access level for an extension declaration is forbidden.
 ///
@@ -144,7 +144,7 @@ public final class NoAccessLevelOnExtensionDeclaration: SyntaxFormatRule {
     // allows modifiers but doesn't already have an access level modifier.
     guard
       case .insideExtension(let accessKeyword) = state,
-      let modifiers = decl.asProtocol(WithModifiersSyntax.self)?.modifiers,
+      let modifiers = decl.asProtocol((any WithModifiersSyntax).self)?.modifiers,
       modifiers.accessLevelModifier == nil
     else {
       return DeclSyntax(decl)
diff --git a/Sources/SwiftFormat/Rules/NoAssignmentInExpressions.swift b/Sources/SwiftFormat/Rules/NoAssignmentInExpressions.swift
index 194ed43cb..ba63ea12d 100644
--- a/Sources/SwiftFormat/Rules/NoAssignmentInExpressions.swift
+++ b/Sources/SwiftFormat/Rules/NoAssignmentInExpressions.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+import SwiftOperators
+public import SwiftSyntax
 
 /// Assignment expressions must be their own statements.
 ///
diff --git a/Sources/SwiftFormat/Rules/NoBlockComments.swift b/Sources/SwiftFormat/Rules/NoBlockComments.swift
index 1f5f0647c..b4cdfbbfe 100644
--- a/Sources/SwiftFormat/Rules/NoBlockComments.swift
+++ b/Sources/SwiftFormat/Rules/NoBlockComments.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Block comments should be avoided in favor of line comments.
 ///
diff --git a/Sources/SwiftFormat/Rules/NoCasesWithOnlyFallthrough.swift b/Sources/SwiftFormat/Rules/NoCasesWithOnlyFallthrough.swift
index 486071251..e77bc743c 100644
--- a/Sources/SwiftFormat/Rules/NoCasesWithOnlyFallthrough.swift
+++ b/Sources/SwiftFormat/Rules/NoCasesWithOnlyFallthrough.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Cases that contain only the `fallthrough` statement are forbidden.
 ///
diff --git a/Sources/SwiftFormat/Rules/NoEmptyLineOpeningClosingBraces.swift b/Sources/SwiftFormat/Rules/NoEmptyLineOpeningClosingBraces.swift
index 3251a92b1..45a03da50 100644
--- a/Sources/SwiftFormat/Rules/NoEmptyLineOpeningClosingBraces.swift
+++ b/Sources/SwiftFormat/Rules/NoEmptyLineOpeningClosingBraces.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2024 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Empty lines are forbidden after opening braces and before closing braces.
 ///
diff --git a/Sources/SwiftFormat/Rules/NoEmptyTrailingClosureParentheses.swift b/Sources/SwiftFormat/Rules/NoEmptyTrailingClosureParentheses.swift
index 80dba8bcc..8cd645c3f 100644
--- a/Sources/SwiftFormat/Rules/NoEmptyTrailingClosureParentheses.swift
+++ b/Sources/SwiftFormat/Rules/NoEmptyTrailingClosureParentheses.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Function calls with no arguments and a trailing closure should not have empty parentheses.
 ///
diff --git a/Sources/SwiftFormat/Rules/NoLabelsInCasePatterns.swift b/Sources/SwiftFormat/Rules/NoLabelsInCasePatterns.swift
index aba7cdf1f..1d83443c2 100644
--- a/Sources/SwiftFormat/Rules/NoLabelsInCasePatterns.swift
+++ b/Sources/SwiftFormat/Rules/NoLabelsInCasePatterns.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -11,7 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import Foundation
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Redundant labels are forbidden in case patterns.
 ///
diff --git a/Sources/SwiftFormat/Rules/NoLeadingUnderscores.swift b/Sources/SwiftFormat/Rules/NoLeadingUnderscores.swift
index bc3a7fff5..fed7b2bff 100644
--- a/Sources/SwiftFormat/Rules/NoLeadingUnderscores.swift
+++ b/Sources/SwiftFormat/Rules/NoLeadingUnderscores.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Identifiers in declarations and patterns should not have leading underscores.
 ///
diff --git a/Sources/SwiftFormat/Rules/NoParensAroundConditions.swift b/Sources/SwiftFormat/Rules/NoParensAroundConditions.swift
index 7c9f1dc9d..071eb4b75 100644
--- a/Sources/SwiftFormat/Rules/NoParensAroundConditions.swift
+++ b/Sources/SwiftFormat/Rules/NoParensAroundConditions.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Enforces rules around parentheses in conditions or matched expressions.
 ///
diff --git a/Sources/SwiftFormat/Rules/NoPlaygroundLiterals.swift b/Sources/SwiftFormat/Rules/NoPlaygroundLiterals.swift
index e9d5d653a..24609d9b1 100644
--- a/Sources/SwiftFormat/Rules/NoPlaygroundLiterals.swift
+++ b/Sources/SwiftFormat/Rules/NoPlaygroundLiterals.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -11,7 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import Foundation
-import SwiftSyntax
+public import SwiftSyntax
 
 /// The playground literals (`#colorLiteral`, `#fileLiteral`, and `#imageLiteral`) are forbidden.
 ///
diff --git a/Sources/SwiftFormat/Rules/NoVoidReturnOnFunctionSignature.swift b/Sources/SwiftFormat/Rules/NoVoidReturnOnFunctionSignature.swift
index 3cacd29e0..ffa508393 100644
--- a/Sources/SwiftFormat/Rules/NoVoidReturnOnFunctionSignature.swift
+++ b/Sources/SwiftFormat/Rules/NoVoidReturnOnFunctionSignature.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Functions that return `()` or `Void` should omit the return signature.
 ///
diff --git a/Sources/SwiftFormat/Rules/OmitExplicitReturns.swift b/Sources/SwiftFormat/Rules/OmitExplicitReturns.swift
index 032ef736d..238e48da8 100644
--- a/Sources/SwiftFormat/Rules/OmitExplicitReturns.swift
+++ b/Sources/SwiftFormat/Rules/OmitExplicitReturns.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Single-expression functions, closures, subscripts can omit `return` statement.
 ///
diff --git a/Sources/SwiftFormat/Rules/OneCasePerLine.swift b/Sources/SwiftFormat/Rules/OneCasePerLine.swift
index 08f50e703..3c31e0586 100644
--- a/Sources/SwiftFormat/Rules/OneCasePerLine.swift
+++ b/Sources/SwiftFormat/Rules/OneCasePerLine.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Each enum case with associated values or a raw value should appear in its own case declaration.
 ///
diff --git a/Sources/SwiftFormat/Rules/OneVariableDeclarationPerLine.swift b/Sources/SwiftFormat/Rules/OneVariableDeclarationPerLine.swift
index 0387942fa..253d2f9c8 100644
--- a/Sources/SwiftFormat/Rules/OneVariableDeclarationPerLine.swift
+++ b/Sources/SwiftFormat/Rules/OneVariableDeclarationPerLine.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Each variable declaration, with the exception of tuple destructuring, should
 /// declare 1 variable.
diff --git a/Sources/SwiftFormat/Rules/OnlyOneTrailingClosureArgument.swift b/Sources/SwiftFormat/Rules/OnlyOneTrailingClosureArgument.swift
index ea62a06ff..4ee960891 100644
--- a/Sources/SwiftFormat/Rules/OnlyOneTrailingClosureArgument.swift
+++ b/Sources/SwiftFormat/Rules/OnlyOneTrailingClosureArgument.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Function calls should never mix normal closure arguments and trailing closures.
 ///
diff --git a/Sources/SwiftFormat/Rules/OrderedImports.swift b/Sources/SwiftFormat/Rules/OrderedImports.swift
index bc82bfa8d..3dfe722ad 100644
--- a/Sources/SwiftFormat/Rules/OrderedImports.swift
+++ b/Sources/SwiftFormat/Rules/OrderedImports.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+import Foundation
+public import SwiftSyntax
 
 /// Imports must be lexicographically ordered and logically grouped at the top of each source file.
 /// The order of the import groups is 1) regular imports, 2) declaration imports, 3) @_implementationOnly
diff --git a/Sources/SwiftFormat/Rules/ReplaceForEachWithForLoop.swift b/Sources/SwiftFormat/Rules/ReplaceForEachWithForLoop.swift
index 14e6dcbff..7fa6d6dfa 100644
--- a/Sources/SwiftFormat/Rules/ReplaceForEachWithForLoop.swift
+++ b/Sources/SwiftFormat/Rules/ReplaceForEachWithForLoop.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Replace `forEach` with `for-in` loop unless its argument is a function reference.
 ///
diff --git a/Sources/SwiftFormat/Rules/ReturnVoidInsteadOfEmptyTuple.swift b/Sources/SwiftFormat/Rules/ReturnVoidInsteadOfEmptyTuple.swift
index 977c9bfe0..300478a54 100644
--- a/Sources/SwiftFormat/Rules/ReturnVoidInsteadOfEmptyTuple.swift
+++ b/Sources/SwiftFormat/Rules/ReturnVoidInsteadOfEmptyTuple.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Return `Void`, not `()`, in signatures.
 ///
diff --git a/Sources/SwiftFormat/Rules/TypeNamesShouldBeCapitalized.swift b/Sources/SwiftFormat/Rules/TypeNamesShouldBeCapitalized.swift
index 8a610ed0c..b80d91d39 100644
--- a/Sources/SwiftFormat/Rules/TypeNamesShouldBeCapitalized.swift
+++ b/Sources/SwiftFormat/Rules/TypeNamesShouldBeCapitalized.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// `struct`, `class`, `enum` and `protocol` declarations should have a capitalized name.
 ///
diff --git a/Sources/SwiftFormat/Rules/UseEarlyExits.swift b/Sources/SwiftFormat/Rules/UseEarlyExits.swift
index 3f1e53912..f4faf9994 100644
--- a/Sources/SwiftFormat/Rules/UseEarlyExits.swift
+++ b/Sources/SwiftFormat/Rules/UseEarlyExits.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Early exits should be used whenever possible.
 ///
diff --git a/Sources/SwiftFormat/Rules/UseExplicitNilCheckInConditions.swift b/Sources/SwiftFormat/Rules/UseExplicitNilCheckInConditions.swift
index 5c2f6bdae..2b5830a11 100644
--- a/Sources/SwiftFormat/Rules/UseExplicitNilCheckInConditions.swift
+++ b/Sources/SwiftFormat/Rules/UseExplicitNilCheckInConditions.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 import SwiftSyntaxBuilder
 
 /// When checking an optional value for `nil`-ness, prefer writing an explicit `nil` check rather
diff --git a/Sources/SwiftFormat/Rules/UseLetInEveryBoundCaseVariable.swift b/Sources/SwiftFormat/Rules/UseLetInEveryBoundCaseVariable.swift
index 4d7b41636..54f951123 100644
--- a/Sources/SwiftFormat/Rules/UseLetInEveryBoundCaseVariable.swift
+++ b/Sources/SwiftFormat/Rules/UseLetInEveryBoundCaseVariable.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Every variable bound in a `case` pattern must have its own `let/var`.
 ///
diff --git a/Sources/SwiftFormat/Rules/UseShorthandTypeNames.swift b/Sources/SwiftFormat/Rules/UseShorthandTypeNames.swift
index 28d048fac..edfdd8288 100644
--- a/Sources/SwiftFormat/Rules/UseShorthandTypeNames.swift
+++ b/Sources/SwiftFormat/Rules/UseShorthandTypeNames.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Shorthand type forms must be used wherever possible.
 ///
diff --git a/Sources/SwiftFormat/Rules/UseSingleLinePropertyGetter.swift b/Sources/SwiftFormat/Rules/UseSingleLinePropertyGetter.swift
index 81d4c0a61..e5b889540 100644
--- a/Sources/SwiftFormat/Rules/UseSingleLinePropertyGetter.swift
+++ b/Sources/SwiftFormat/Rules/UseSingleLinePropertyGetter.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Read-only computed properties must use implicit `get` blocks.
 ///
diff --git a/Sources/SwiftFormat/Rules/UseSynthesizedInitializer.swift b/Sources/SwiftFormat/Rules/UseSynthesizedInitializer.swift
index e0081059e..cb4a5f333 100644
--- a/Sources/SwiftFormat/Rules/UseSynthesizedInitializer.swift
+++ b/Sources/SwiftFormat/Rules/UseSynthesizedInitializer.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -11,7 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import Foundation
-import SwiftSyntax
+public import SwiftSyntax
 
 /// When possible, the synthesized `struct` initializer should be used.
 ///
diff --git a/Sources/SwiftFormat/Rules/UseTripleSlashForDocumentationComments.swift b/Sources/SwiftFormat/Rules/UseTripleSlashForDocumentationComments.swift
index 319c478eb..fe20eb057 100644
--- a/Sources/SwiftFormat/Rules/UseTripleSlashForDocumentationComments.swift
+++ b/Sources/SwiftFormat/Rules/UseTripleSlashForDocumentationComments.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -11,7 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import Foundation
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Documentation comments must use the `///` form.
 ///
diff --git a/Sources/SwiftFormat/Rules/UseWhereClausesInForLoops.swift b/Sources/SwiftFormat/Rules/UseWhereClausesInForLoops.swift
index 12e6c3ea9..c7af37ed3 100644
--- a/Sources/SwiftFormat/Rules/UseWhereClausesInForLoops.swift
+++ b/Sources/SwiftFormat/Rules/UseWhereClausesInForLoops.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 /// `for` loops that consist of a single `if` statement must use `where` clauses instead.
 ///
diff --git a/Sources/SwiftFormat/Rules/ValidateDocumentationComments.swift b/Sources/SwiftFormat/Rules/ValidateDocumentationComments.swift
index 05495d207..e606b7e1e 100644
--- a/Sources/SwiftFormat/Rules/ValidateDocumentationComments.swift
+++ b/Sources/SwiftFormat/Rules/ValidateDocumentationComments.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -12,7 +12,7 @@
 
 import Foundation
 import Markdown
-import SwiftSyntax
+public import SwiftSyntax
 
 /// Documentation comments must be complete and valid.
 ///
diff --git a/Sources/SwiftFormat/Utilities/FileIterator.swift b/Sources/SwiftFormat/Utilities/FileIterator.swift
index f6d05776c..b99b5231d 100644
--- a/Sources/SwiftFormat/Utilities/FileIterator.swift
+++ b/Sources/SwiftFormat/Utilities/FileIterator.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import Foundation
+public import Foundation
 
 #if os(Windows)
 import WinSDK
diff --git a/Sources/SwiftFormat/Utilities/URL+isRoot.swift b/Sources/SwiftFormat/Utilities/URL+isRoot.swift
index 6a8522889..6ef990634 100644
--- a/Sources/SwiftFormat/Utilities/URL+isRoot.swift
+++ b/Sources/SwiftFormat/Utilities/URL+isRoot.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import Foundation
+public import Foundation
 
 #if os(Windows)
 import WinSDK
diff --git a/Sources/_GenerateSwiftFormat/FileGenerator.swift b/Sources/_GenerateSwiftFormat/FileGenerator.swift
index 77c82c962..5c6d17cd3 100644
--- a/Sources/_GenerateSwiftFormat/FileGenerator.swift
+++ b/Sources/_GenerateSwiftFormat/FileGenerator.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import Foundation
+public import Foundation
 
 /// Common behavior used to generate source files.
 @_spi(Internal) public protocol FileGenerator {
diff --git a/Sources/_GenerateSwiftFormat/GenerateSwiftFormatPaths.swift b/Sources/_GenerateSwiftFormat/GenerateSwiftFormatPaths.swift
index c36308568..7f6e45bdd 100644
--- a/Sources/_GenerateSwiftFormat/GenerateSwiftFormatPaths.swift
+++ b/Sources/_GenerateSwiftFormat/GenerateSwiftFormatPaths.swift
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import Foundation
+public import Foundation
 
 /// A namespace that provides paths for files generated by the `generate-swift-format` tool.
 @_spi(Internal) public enum GenerateSwiftFormatPaths {
diff --git a/Sources/_GenerateSwiftFormat/RuleCollector.swift b/Sources/_GenerateSwiftFormat/RuleCollector.swift
index 60646d37b..f68f9a37d 100644
--- a/Sources/_GenerateSwiftFormat/RuleCollector.swift
+++ b/Sources/_GenerateSwiftFormat/RuleCollector.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import Foundation
+public import Foundation
 @_spi(Rules) import SwiftFormat
 import SwiftParser
 import SwiftSyntax
@@ -142,7 +142,7 @@ import SwiftSyntax
       /// Ignore it if it doesn't have any; there's no point in putting no-op rules in the pipeline.
       /// Otherwise, return it (we don't need to look at the rest of the inheritances).
       guard !visitedNodes.isEmpty else { return nil }
-      guard let ruleType = _typeByName("SwiftFormat.\(typeName)") as? Rule.Type else {
+      guard let ruleType = _typeByName("SwiftFormat.\(typeName)") as? any Rule.Type else {
         preconditionFailure("Failed to find type for rule named \(typeName)")
       }
       return DetectedRule(
diff --git a/Sources/_GenerateSwiftFormat/Syntax+Convenience.swift b/Sources/_GenerateSwiftFormat/Syntax+Convenience.swift
index 91023b2da..e21f009fd 100644
--- a/Sources/_GenerateSwiftFormat/Syntax+Convenience.swift
+++ b/Sources/_GenerateSwiftFormat/Syntax+Convenience.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftSyntax
+public import SwiftSyntax
 
 extension SyntaxCollection {
   /// The first element in the syntax collection if it is the *only* element, or nil otherwise.
diff --git a/Sources/_SwiftFormatTestSupport/Configuration+Testing.swift b/Sources/_SwiftFormatTestSupport/Configuration+Testing.swift
index 0c8974609..06e3b22ea 100644
--- a/Sources/_SwiftFormatTestSupport/Configuration+Testing.swift
+++ b/Sources/_SwiftFormatTestSupport/Configuration+Testing.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftFormat
+package import SwiftFormat
 
 extension Configuration {
   /// The default configuration to be used during unit tests.
@@ -22,7 +22,7 @@ extension Configuration {
   /// delegate to another initializer first, which defeats the purpose). So, users adding new
   /// configuration settings should be sure to supply a default here for testing, otherwise they
   /// will be implicitly relying on the real default.
-  public static var forTesting: Configuration {
+  package static var forTesting: Configuration {
     var config = Configuration()
     config.rules = Configuration.defaultRuleEnablements
     config.maximumBlankLines = 1
@@ -45,7 +45,7 @@ extension Configuration {
     return config
   }
 
-  public static func forTesting(enabledRule: String) -> Configuration {
+  package static func forTesting(enabledRule: String) -> Configuration {
     var config = Configuration.forTesting
     config.rules = config.rules.mapValues({ _ in false })
     config.rules[enabledRule] = true
diff --git a/Sources/_SwiftFormatTestSupport/DiagnosingTestCase.swift b/Sources/_SwiftFormatTestSupport/DiagnosingTestCase.swift
index b72f7ef95..a1858441a 100644
--- a/Sources/_SwiftFormatTestSupport/DiagnosingTestCase.swift
+++ b/Sources/_SwiftFormatTestSupport/DiagnosingTestCase.swift
@@ -10,10 +10,10 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftFormat
-@_spi(Rules) @_spi(Testing) import SwiftFormat
-import SwiftSyntax
-import XCTest
+@_spi(Rules) @_spi(Testing) public import SwiftFormat
+import SwiftOperators
+public import SwiftSyntax
+public import XCTest
 
 /// DiagnosingTestCase is an XCTestCase subclass meant to inject diagnostic-specific testing
 /// routines into specific formatting test cases.
@@ -48,7 +48,7 @@ open class DiagnosingTestCase: XCTestCase {
     markerLocations: [String: Int],
     emittedFindings: [Finding],
     context: Context,
-    file: StaticString = #file,
+    file: StaticString = #filePath,
     line: UInt = #line
   ) {
     var emittedFindings = emittedFindings
@@ -86,7 +86,7 @@ open class DiagnosingTestCase: XCTestCase {
     markerLocations: [String: Int],
     emittedFindings: inout [Finding],
     context: Context,
-    file: StaticString = #file,
+    file: StaticString = #filePath,
     line: UInt = #line
   ) {
     guard let utf8Offset = markerLocations[findingSpec.marker] else {
@@ -164,7 +164,7 @@ open class DiagnosingTestCase: XCTestCase {
     markerLocations: [String: Int],
     emittedNotes: inout [Finding.Note],
     context: Context,
-    file: StaticString = #file,
+    file: StaticString = #filePath,
     line: UInt = #line
   ) {
     guard let utf8Offset = markerLocations[noteSpec.marker] else {
@@ -218,11 +218,11 @@ open class DiagnosingTestCase: XCTestCase {
   ///     which this function was called.
   ///   - line: The line number on which failure occurred. Defaults to the line number on which this
   ///     function was called.
-  public final func assertStringsEqualWithDiff(
+  package final func assertStringsEqualWithDiff(
     _ actual: String,
     _ expected: String,
     _ message: String = "",
-    file: StaticString = #file,
+    file: StaticString = #filePath,
     line: UInt = #line
   ) {
     let actualLines = actual.components(separatedBy: .newlines)
diff --git a/Sources/_SwiftFormatTestSupport/FindingSpec.swift b/Sources/_SwiftFormatTestSupport/FindingSpec.swift
index e9751ede4..da6af117b 100644
--- a/Sources/_SwiftFormatTestSupport/FindingSpec.swift
+++ b/Sources/_SwiftFormatTestSupport/FindingSpec.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -13,16 +13,16 @@
 /// A description of a `Finding` that can be asserted during tests.
 public struct FindingSpec {
   /// The marker that identifies the finding.
-  public var marker: String
+  package var marker: String
 
   /// The message text associated with the finding.
-  public var message: String
+  package var message: String
 
   /// A description of a `Note` that should be associated with this finding.
-  public var notes: [NoteSpec]
+  package var notes: [NoteSpec]
 
   /// Creates a new `FindingSpec` with the given values.
-  public init(_ marker: String = "1️⃣", message: String, notes: [NoteSpec] = []) {
+  package init(_ marker: String = "1️⃣", message: String, notes: [NoteSpec] = []) {
     self.marker = marker
     self.message = message
     self.notes = notes
@@ -30,15 +30,15 @@ public struct FindingSpec {
 }
 
 /// A description of a `Note` that can be asserted during tests.
-public struct NoteSpec {
+package struct NoteSpec {
   /// The marker that identifies the note.
-  public var marker: String
+  package var marker: String
 
   /// The message text associated with the note.
-  public var message: String
+  package var message: String
 
   /// Creates a new `NoteSpec` with the given values.
-  public init(_ marker: String, message: String) {
+  package init(_ marker: String, message: String) {
     self.marker = marker
     self.message = message
   }
diff --git a/Sources/_SwiftFormatTestSupport/MarkedText.swift b/Sources/_SwiftFormatTestSupport/MarkedText.swift
index 9d63a4812..d2ef34633 100644
--- a/Sources/_SwiftFormatTestSupport/MarkedText.swift
+++ b/Sources/_SwiftFormatTestSupport/MarkedText.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,22 +10,22 @@
 //
 //===----------------------------------------------------------------------===//
 
-import SwiftFormat
+package import SwiftFormat
 import SwiftSyntax
 
 /// Encapsulates the locations of emoji markers extracted from source text.
-public struct MarkedText {
+package struct MarkedText {
   /// A mapping from marker names to the UTF-8 offset where the marker was found in the string.
-  public let markers: [String: Int]
+  package let markers: [String: Int]
 
   /// The text with all markers removed.
-  public let textWithoutMarkers: String
+  package let textWithoutMarkers: String
 
   /// If the marked text contains "⏩" and "⏪", they're used to create a selection
-  public var selection: Selection
+  package var selection: Selection
 
   /// Creates a new `MarkedText` value by extracting emoji markers from the given text.
-  public init(textWithMarkers markedText: String) {
+  package init(textWithMarkers markedText: String) {
     var text = ""
     var markers = [String: Int]()
     var lastIndex = markedText.startIndex
diff --git a/Sources/_SwiftFormatTestSupport/Parsing.swift b/Sources/_SwiftFormatTestSupport/Parsing.swift
index 71f1a64d4..56b9c3e08 100644
--- a/Sources/_SwiftFormatTestSupport/Parsing.swift
+++ b/Sources/_SwiftFormatTestSupport/Parsing.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2024 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -10,8 +10,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-@_spi(ExperimentalLanguageFeatures) import SwiftParser
-import SwiftSyntax
+@_spi(ExperimentalLanguageFeatures) public import SwiftParser
+public import SwiftSyntax
 import XCTest
 
 extension Parser {
diff --git a/Sources/swift-format/Frontend/ConfigurationLoader.swift b/Sources/swift-format/Frontend/ConfigurationLoader.swift
index 57d9bb63b..98b54e53c 100644
--- a/Sources/swift-format/Frontend/ConfigurationLoader.swift
+++ b/Sources/swift-format/Frontend/ConfigurationLoader.swift
@@ -15,7 +15,7 @@ import SwiftFormat
 
 /// Loads formatter configurations, caching them in memory so that multiple operations in the same
 /// directory do not repeatedly hit the file system.
-struct ConfigurationLoader {
+struct ConfigurationLoader: ~Copyable {
   /// The cache of previously loaded configurations.
   private var cache = [String: Configuration]()
 
diff --git a/Sources/swift-format/Frontend/ConfigurationProvider.swift b/Sources/swift-format/Frontend/ConfigurationProvider.swift
new file mode 100644
index 000000000..da9744c27
--- /dev/null
+++ b/Sources/swift-format/Frontend/ConfigurationProvider.swift
@@ -0,0 +1,133 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2025 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+import Foundation
+@_spi(Internal) import SwiftFormat
+
+// FIXME: This needn't be MainActor because we never actually access it concurrently.
+//        It can be made nonisolated if decoupled from the Sendable Frontend.
+/// Provides formatter configurations for given `.swift` source files, configuration files or configuration strings.
+@MainActor
+final class ConfigurationProvider {
+  /// Loads formatter configuration files and caches them in memory.
+  private var configurationLoader: ConfigurationLoader
+
+  /// The diagnostic engine to which warnings and errors will be emitted.
+  private let diagnosticsEngine: DiagnosticsEngine
+
+  /// Creates a new instance with the given options.
+  ///
+  /// - Parameter diagnosticsEngine: The diagnostic engine to which warnings and errors will be emitted.
+  nonisolated init(diagnosticsEngine: DiagnosticsEngine) {
+    self.diagnosticsEngine = diagnosticsEngine
+    self.configurationLoader = ConfigurationLoader()
+  }
+
+  /// Checks if all the rules in the given configuration are supported by the registry.
+  ///
+  /// If there are any rules that are not supported, they are emitted as a warning.
+  private func checkForUnrecognizedRules(in configuration: Configuration) {
+    // If any rules in the decoded configuration are not supported by the registry,
+    // emit them into the diagnosticsEngine as warnings.
+    // That way they will be printed out, but we'll continue execution on the valid rules.
+
+    for (key, _) in configuration.rules {
+      if RuleRegistry.rules.keys.contains(key) {
+        continue
+      }
+      diagnosticsEngine.emitWarning("Configuration contains an unrecognized rule: \(key)", location: nil)
+    }
+  }
+
+  /// Returns the configuration that applies to the given `.swift` source file, when an explicit
+  /// configuration path is also perhaps provided.
+  ///
+  /// This method also checks for unrecognized rules within the configuration.
+  ///
+  /// - Parameters:
+  ///   - pathOrString: A string containing either the path to a configuration file that will be
+  ///     loaded, JSON configuration data directly, or `nil` to try to infer it from
+  ///     `swiftFileURL`.
+  ///   - swiftFileURL: The path to a `.swift` file, which will be used to infer the path to the
+  ///     configuration file if `configurationFilePath` is nil.
+  ///
+  /// - Returns: If successful, the returned configuration is the one loaded from `pathOrString` if
+  ///   it was provided, or by searching in paths inferred by `swiftFileURL` if one exists, or the
+  ///   default configuration otherwise. If an error occurred when reading the configuration, a
+  ///   diagnostic is emitted and `nil` is returned. If neither `pathOrString` nor `swiftFileURL`
+  ///   were provided, a default `Configuration()` will be returned.
+  func provide(
+    forConfigPathOrString pathOrString: String?,
+    orForSwiftFileAt swiftFileURL: URL?
+  ) -> Configuration? {
+    if let pathOrString = pathOrString {
+      // If an explicit configuration file path was given, try to load it and fail if it cannot be
+      // loaded. (Do not try to fall back to a path inferred from the source file path.)
+      let configurationFileURL = URL(fileURLWithPath: pathOrString)
+      do {
+        let configuration = try configurationLoader.configuration(at: configurationFileURL)
+        self.checkForUnrecognizedRules(in: configuration)
+        return configuration
+      } catch {
+        // If we failed to load this from the path, try interpreting the string as configuration
+        // data itself because the user might have written something like `--configuration '{...}'`,
+        let data = pathOrString.data(using: .utf8)!
+        if let configuration = try? Configuration(data: data) {
+          return configuration
+        }
+
+        // Fail if the configuration flag was neither a valid file path nor valid configuration
+        // data.
+        diagnosticsEngine.emitError("Unable to read configuration: \(error.localizedDescription)")
+        return nil
+      }
+    }
+
+    // If no explicit configuration file path was given but a `.swift` source file path was given,
+    // then try to load the configuration by inferring it based on the source file path.
+    if let swiftFileURL = swiftFileURL {
+      do {
+        if let configuration = try configurationLoader.configuration(forPath: swiftFileURL) {
+          self.checkForUnrecognizedRules(in: configuration)
+          return configuration
+        }
+        // Fall through to the default return at the end of the function.
+      } catch {
+        diagnosticsEngine.emitError(
+          "Unable to read configuration for \(swiftFileURL.relativePath): \(error.localizedDescription)"
+        )
+        return nil
+      }
+    } else {
+      // If reading from stdin and no explicit configuration file was given,
+      // walk up the file tree from the cwd to find a config.
+
+      let cwd = URL(fileURLWithPath: FileManager.default.currentDirectoryPath)
+      // Definitely a Swift file. Definitely not a directory. Shhhhhh.
+      do {
+        if let configuration = try configurationLoader.configuration(forPath: cwd) {
+          self.checkForUnrecognizedRules(in: configuration)
+          return configuration
+        }
+      } catch {
+        diagnosticsEngine.emitError(
+          "Unable to read configuration for \(cwd.relativePath): \(error.localizedDescription)"
+        )
+        return nil
+      }
+    }
+
+    // An explicit configuration has not been given, and one cannot be found.
+    // Return the default configuration.
+    return Configuration()
+  }
+}
diff --git a/Sources/swift-format/Frontend/FileToProcess.swift b/Sources/swift-format/Frontend/FileToProcess.swift
new file mode 100644
index 000000000..ea21daa2f
--- /dev/null
+++ b/Sources/swift-format/Frontend/FileToProcess.swift
@@ -0,0 +1,59 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+import Foundation
+import SwiftFormat
+
+/// Represents a file to be processed by the frontend and any file-specific options associated
+/// with it.
+struct FileToProcess: ~Copyable {
+  /// An open file handle to the source code of the file.
+  private let fileHandle: FileHandle
+
+  /// A file URL representing the path to the source file being processed.
+  ///
+  /// It is the responsibility of the specific frontend to make guarantees about the validity of
+  /// this path. For example, the formatting frontend ensures that it is a path to an existing
+  /// file only when doing in-place formatting (so that the file can be replaced). In other
+  /// situations, it may correspond to a different file than the underlying file handle (if
+  /// standard input is used with the `--assume-filename` flag), or it may not be a valid path at
+  /// all (the string `"<stdin>"`).
+  let url: URL
+
+  /// The configuration that should applied for this file.
+  let configuration: Configuration
+
+  /// the selected ranges to process
+  let selection: Selection
+
+  /// Returns the string contents of the file.
+  ///
+  /// The contents of the file are assumed to be UTF-8 encoded. If there is an error decoding the
+  /// contents, `nil` will be returned.
+  func readString() -> String? {
+    let sourceData = fileHandle.readDataToEndOfFile()
+    defer { fileHandle.closeFile() }
+    return String(data: sourceData, encoding: .utf8)
+  }
+
+  init(
+    fileHandle: FileHandle,
+    url: URL,
+    configuration: Configuration,
+    selection: Selection = .infinite
+  ) {
+    self.fileHandle = fileHandle
+    self.url = url
+    self.configuration = configuration
+    self.selection = selection
+  }
+}
diff --git a/Sources/swift-format/Frontend/FormatFrontend.swift b/Sources/swift-format/Frontend/FormatFrontend.swift
index 0e8fca9d2..b6a0aa406 100644
--- a/Sources/swift-format/Frontend/FormatFrontend.swift
+++ b/Sources/swift-format/Frontend/FormatFrontend.swift
@@ -16,16 +16,39 @@ import SwiftFormat
 import SwiftSyntax
 
 /// The frontend for formatting operations.
-class FormatFrontend: Frontend {
+struct FormatFrontend: Frontend {
+  /// The diagnostic engine to which warnings and errors will be emitted.
+  let diagnosticsEngine: DiagnosticsEngine
+
+  /// Options that control the tool's configuration.
+  let configurationOptions: ConfigurationOptions
+
+  /// Options that apply during formatting.
+  let lintFormatOptions: LintFormatOptions
+
+  /// The provider for formatter configurations.
+  let configurationProvider: ConfigurationProvider
+
   /// Whether or not to format the Swift file in-place.
   private let inPlace: Bool
 
-  init(configurationOptions: ConfigurationOptions, lintFormatOptions: LintFormatOptions, inPlace: Bool) {
+  /// Creates a new frontend with the given options.
+  ///
+  /// - Parameter lintFormatOptions: Options that apply during formatting.
+  init(
+    diagnosticEngine: DiagnosticsEngine,
+    configurationOptions: ConfigurationOptions,
+    lintFormatOptions: LintFormatOptions,
+    inPlace: Bool
+  ) {
+    self.diagnosticsEngine = diagnosticEngine
+    self.configurationOptions = configurationOptions
+    self.lintFormatOptions = lintFormatOptions
     self.inPlace = inPlace
-    super.init(configurationOptions: configurationOptions, lintFormatOptions: lintFormatOptions)
+    self.configurationProvider = ConfigurationProvider(diagnosticsEngine: self.diagnosticsEngine)
   }
 
-  override func processFile(_ fileToProcess: FileToProcess) {
+  nonisolated func processFile(_ fileToProcess: borrowing FileToProcess) {
     // In format mode, the diagnostics engine is reserved for fatal messages. Pass nil as the
     // finding consumer to ignore findings emitted while the syntax tree is processed because they
     // will be fixed automatically if they can be, or ignored otherwise.
@@ -33,7 +56,7 @@ class FormatFrontend: Frontend {
     formatter.debugOptions = debugOptions
 
     let url = fileToProcess.url
-    guard let source = fileToProcess.sourceText else {
+    guard let source = fileToProcess.readString() else {
       diagnosticsEngine.emitError(
         "Unable to format \(url.relativePath): file is not readable or does not exist."
       )
diff --git a/Sources/swift-format/Frontend/Frontend.swift b/Sources/swift-format/Frontend/Frontend.swift
index aaa24ad01..a6ff97851 100644
--- a/Sources/swift-format/Frontend/Frontend.swift
+++ b/Sources/swift-format/Frontend/Frontend.swift
@@ -12,216 +12,43 @@
 
 import Foundation
 @_spi(Internal) import SwiftFormat
-import SwiftParser
-import SwiftSyntax
-
-class Frontend {
-  /// Provides formatter configurations for given `.swift` source files, configuration files or configuration strings.
-  struct ConfigurationProvider {
-    /// Loads formatter configuration files and chaches them in memory.
-    private var configurationLoader: ConfigurationLoader = ConfigurationLoader()
-
-    /// The diagnostic engine to which warnings and errors will be emitted.
-    private let diagnosticsEngine: DiagnosticsEngine
-
-    /// Creates a new instance with the given options.
-    ///
-    /// - Parameter diagnosticsEngine: The diagnostic engine to which warnings and errors will be emitted.
-    init(diagnosticsEngine: DiagnosticsEngine) {
-      self.diagnosticsEngine = diagnosticsEngine
-    }
-
-    /// Checks if all the rules in the given configuration are supported by the registry.
-    ///
-    /// If there are any rules that are not supported, they are emitted as a warning.
-    private func checkForUnrecognizedRules(in configuration: Configuration) {
-      // If any rules in the decoded configuration are not supported by the registry,
-      // emit them into the diagnosticsEngine as warnings.
-      // That way they will be printed out, but we'll continue execution on the valid rules.
-      let invalidRules = configuration.rules.filter { !RuleRegistry.rules.keys.contains($0.key) }
-      for rule in invalidRules {
-        diagnosticsEngine.emitWarning("Configuration contains an unrecognized rule: \(rule.key)", location: nil)
-      }
-    }
-
-    /// Returns the configuration that applies to the given `.swift` source file, when an explicit
-    /// configuration path is also perhaps provided.
-    ///
-    /// This method also checks for unrecognized rules within the configuration.
-    ///
-    /// - Parameters:
-    ///   - pathOrString: A string containing either the path to a configuration file that will be
-    ///     loaded, JSON configuration data directly, or `nil` to try to infer it from
-    ///     `swiftFileURL`.
-    ///   - swiftFileURL: The path to a `.swift` file, which will be used to infer the path to the
-    ///     configuration file if `configurationFilePath` is nil.
-    ///
-    /// - Returns: If successful, the returned configuration is the one loaded from `pathOrString` if
-    ///   it was provided, or by searching in paths inferred by `swiftFileURL` if one exists, or the
-    ///   default configuration otherwise. If an error occurred when reading the configuration, a
-    ///   diagnostic is emitted and `nil` is returned. If neither `pathOrString` nor `swiftFileURL`
-    ///   were provided, a default `Configuration()` will be returned.
-    mutating func provide(
-      forConfigPathOrString pathOrString: String?,
-      orForSwiftFileAt swiftFileURL: URL?
-    ) -> Configuration? {
-      if let pathOrString = pathOrString {
-        // If an explicit configuration file path was given, try to load it and fail if it cannot be
-        // loaded. (Do not try to fall back to a path inferred from the source file path.)
-        let configurationFileURL = URL(fileURLWithPath: pathOrString)
-        do {
-          let configuration = try configurationLoader.configuration(at: configurationFileURL)
-          self.checkForUnrecognizedRules(in: configuration)
-          return configuration
-        } catch {
-          // If we failed to load this from the path, try interpreting the string as configuration
-          // data itself because the user might have written something like `--configuration '{...}'`,
-          let data = pathOrString.data(using: .utf8)!
-          if let configuration = try? Configuration(data: data) {
-            return configuration
-          }
-
-          // Fail if the configuration flag was neither a valid file path nor valid configuration
-          // data.
-          diagnosticsEngine.emitError("Unable to read configuration: \(error.localizedDescription)")
-          return nil
-        }
-      }
-
-      // If no explicit configuration file path was given but a `.swift` source file path was given,
-      // then try to load the configuration by inferring it based on the source file path.
-      if let swiftFileURL = swiftFileURL {
-        do {
-          if let configuration = try configurationLoader.configuration(forPath: swiftFileURL) {
-            self.checkForUnrecognizedRules(in: configuration)
-            return configuration
-          }
-          // Fall through to the default return at the end of the function.
-        } catch {
-          diagnosticsEngine.emitError(
-            "Unable to read configuration for \(swiftFileURL.relativePath): \(error.localizedDescription)"
-          )
-          return nil
-        }
-      } else {
-        // If reading from stdin and no explicit configuration file was given,
-        // walk up the file tree from the cwd to find a config.
-
-        let cwd = URL(fileURLWithPath: FileManager.default.currentDirectoryPath)
-        // Definitely a Swift file. Definitely not a directory. Shhhhhh.
-        do {
-          if let configuration = try configurationLoader.configuration(forPath: cwd) {
-            self.checkForUnrecognizedRules(in: configuration)
-            return configuration
-          }
-        } catch {
-          diagnosticsEngine.emitError(
-            "Unable to read configuration for \(cwd.relativePath): \(error.localizedDescription)"
-          )
-          return nil
-        }
-      }
-
-      // An explicit configuration has not been given, and one cannot be found.
-      // Return the default configuration.
-      return Configuration()
-    }
-  }
-
-  /// Represents a file to be processed by the frontend and any file-specific options associated
-  /// with it.
-  final class FileToProcess {
-    /// An open file handle to the source code of the file.
-    private let fileHandle: FileHandle
-
-    /// A file URL representing the path to the source file being processed.
-    ///
-    /// It is the responsibility of the specific frontend to make guarantees about the validity of
-    /// this path. For example, the formatting frontend ensures that it is a path to an existing
-    /// file only when doing in-place formatting (so that the file can be replaced). In other
-    /// situations, it may correspond to a different file than the underlying file handle (if
-    /// standard input is used with the `--assume-filename` flag), or it may not be a valid path at
-    /// all (the string `"<stdin>"`).
-    let url: URL
-
-    /// The configuration that should applied for this file.
-    let configuration: Configuration
-
-    /// the selected ranges to process
-    let selection: Selection
-
-    /// Returns the string contents of the file.
-    ///
-    /// The contents of the file are assumed to be UTF-8 encoded. If there is an error decoding the
-    /// contents, `nil` will be returned.
-    lazy var sourceText: String? = {
-      let sourceData = fileHandle.readDataToEndOfFile()
-      defer { fileHandle.closeFile() }
-      return String(data: sourceData, encoding: .utf8)
-    }()
-
-    init(
-      fileHandle: FileHandle,
-      url: URL,
-      configuration: Configuration,
-      selection: Selection = .infinite
-    ) {
-      self.fileHandle = fileHandle
-      self.url = url
-      self.configuration = configuration
-      self.selection = selection
-    }
-  }
-
-  /// Prints diagnostics to standard error, optionally with color.
-  final let diagnosticPrinter: StderrDiagnosticPrinter
 
+protocol Frontend: Sendable {
   /// The diagnostic engine to which warnings and errors will be emitted.
-  final let diagnosticsEngine: DiagnosticsEngine
+  var diagnosticsEngine: DiagnosticsEngine { get }
 
   /// Options that control the tool's configuration.
-  final let configurationOptions: ConfigurationOptions
+  var configurationOptions: ConfigurationOptions { get }
 
   /// Options that apply during formatting or linting.
-  final let lintFormatOptions: LintFormatOptions
+  var lintFormatOptions: LintFormatOptions { get }
 
   /// The provider for formatter configurations.
-  final var configurationProvider: ConfigurationProvider
+  var configurationProvider: ConfigurationProvider { get }
 
+  /// Called by the frontend to process a single file.
+  ///
+  /// Subclasses must override this method to provide the actual linting or formatting logic.
+  ///
+  /// - Parameter fileToProcess: A `FileToProcess` that contains information about the file to be
+  ///   processed.
+  func processFile(_ fileToProcess: borrowing FileToProcess)
+}
+
+extension Frontend {
   /// Advanced options that are useful for developing/debugging but otherwise not meant for general
   /// use.
-  final var debugOptions: DebugOptions {
+  var debugOptions: DebugOptions {
     [
       lintFormatOptions.debugDisablePrettyPrint ? .disablePrettyPrint : [],
       lintFormatOptions.debugDumpTokenStream ? .dumpTokenStream : [],
     ]
   }
 
-  /// Creates a new frontend with the given options.
-  ///
-  /// - Parameter lintFormatOptions: Options that apply during formatting or linting.
-  init(
-    configurationOptions: ConfigurationOptions,
-    lintFormatOptions: LintFormatOptions,
-    treatWarningsAsErrors: Bool = false
-  ) {
-    self.configurationOptions = configurationOptions
-    self.lintFormatOptions = lintFormatOptions
-
-    self.diagnosticPrinter = StderrDiagnosticPrinter(
-      colorMode: lintFormatOptions.colorDiagnostics.map { $0 ? .on : .off } ?? .auto
-    )
-    self.diagnosticsEngine = DiagnosticsEngine(
-      diagnosticsHandlers: [diagnosticPrinter.printDiagnostic],
-      treatWarningsAsErrors: treatWarningsAsErrors
-    )
-    self.configurationProvider = ConfigurationProvider(diagnosticsEngine: self.diagnosticsEngine)
-  }
-
   /// Runs the linter or formatter over the inputs.
-  final func run() {
+  func run() async {
     if lintFormatOptions.paths == ["-"] {
-      processStandardInput()
+      await processStandardInput()
     } else if lintFormatOptions.paths.isEmpty {
       diagnosticsEngine.emitWarning(
         """
@@ -237,26 +64,17 @@ class Frontend {
         For more information, use the `--help` option.
         """
       )
-      processStandardInput()
+      await processStandardInput()
     } else {
-      processURLs(
+      await processURLs(
         lintFormatOptions.paths.map(URL.init(fileURLWithPath:)),
         parallel: lintFormatOptions.parallel
       )
     }
   }
 
-  /// Called by the frontend to process a single file.
-  ///
-  /// Subclasses must override this method to provide the actual linting or formatting logic.
-  ///
-  /// - Parameter fileToProcess: A `FileToProcess` that contains information about the file to be
-  ///   processed.
-  func processFile(_ fileToProcess: FileToProcess) {
-    fatalError("Must be overridden by subclasses.")
-  }
-
   /// Processes source content from standard input.
+  @MainActor
   private func processStandardInput() {
     let assumedUrl = lintFormatOptions.assumeFilename.map(URL.init(fileURLWithPath:))
 
@@ -280,29 +98,37 @@ class Frontend {
   }
 
   /// Processes source content from a list of files and/or directories provided as file URLs.
-  private func processURLs(_ urls: [URL], parallel: Bool) {
+  @MainActor
+  private func processURLs(_ urls: [URL], parallel: Bool) async {
     precondition(
       !urls.isEmpty,
       "processURLs(_:) should only be called when 'urls' is non-empty."
     )
 
+    let filesToProcess = FileIterator(urls: urls, followSymlinks: lintFormatOptions.followSymlinks)
+
     if parallel {
-      let filesToProcess =
-        FileIterator(urls: urls, followSymlinks: lintFormatOptions.followSymlinks)
-        .compactMap(openAndPrepareFile)
-      DispatchQueue.concurrentPerform(iterations: filesToProcess.count) { index in
-        processFile(filesToProcess[index])
+      await withTaskGroup(of: Void.self) { group in
+        for url in filesToProcess {
+          if let file = self.openAndPrepareFile(at: url) {
+            group.addTask {
+              self.processFile(file)
+            }
+          }
+        }
       }
     } else {
-      FileIterator(urls: urls, followSymlinks: lintFormatOptions.followSymlinks)
-        .lazy
-        .compactMap(openAndPrepareFile)
-        .forEach(processFile)
+      for url in filesToProcess {
+        if let file = self.openAndPrepareFile(at: url) {
+          self.processFile(file)
+        }
+      }
     }
   }
 
   /// Read and prepare the file at the given path for processing, optionally synchronizing
   /// diagnostic output.
+  @MainActor
   private func openAndPrepareFile(at url: URL) -> FileToProcess? {
     guard let sourceFile = try? FileHandle(forReadingFrom: url) else {
       diagnosticsEngine.emitError(
@@ -328,5 +154,4 @@ class Frontend {
       selection: Selection(offsetRanges: lintFormatOptions.offsets)
     )
   }
-
 }
diff --git a/Sources/swift-format/Frontend/LintFrontend.swift b/Sources/swift-format/Frontend/LintFrontend.swift
index c231266a7..ddd59db4b 100644
--- a/Sources/swift-format/Frontend/LintFrontend.swift
+++ b/Sources/swift-format/Frontend/LintFrontend.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -11,13 +11,38 @@
 //===----------------------------------------------------------------------===//
 
 import Foundation
-import SwiftDiagnostics
 import SwiftFormat
 import SwiftSyntax
 
 /// The frontend for linting operations.
-class LintFrontend: Frontend {
-  override func processFile(_ fileToProcess: FileToProcess) {
+struct LintFrontend: Frontend {
+  /// The diagnostic engine to which warnings and errors will be emitted.
+  let diagnosticsEngine: DiagnosticsEngine
+
+  /// Options that control the tool's configuration.
+  let configurationOptions: ConfigurationOptions
+
+  /// Options that apply during linting.
+  let lintFormatOptions: LintFormatOptions
+
+  /// The provider for formatter configurations.
+  let configurationProvider: ConfigurationProvider
+
+  /// Creates a new frontend with the given options.
+  ///
+  /// - Parameter lintFormatOptions: Options that apply during linting.
+  init(
+    diagnosticEngine: DiagnosticsEngine,
+    configurationOptions: ConfigurationOptions,
+    lintFormatOptions: LintFormatOptions
+  ) {
+    self.diagnosticsEngine = diagnosticEngine
+    self.configurationOptions = configurationOptions
+    self.lintFormatOptions = lintFormatOptions
+    self.configurationProvider = ConfigurationProvider(diagnosticsEngine: self.diagnosticsEngine)
+  }
+
+  nonisolated func processFile(_ fileToProcess: borrowing FileToProcess) {
     let linter = SwiftLinter(
       configuration: fileToProcess.configuration,
       findingConsumer: diagnosticsEngine.consumeFinding
@@ -25,7 +50,7 @@ class LintFrontend: Frontend {
     linter.debugOptions = debugOptions
 
     let url = fileToProcess.url
-    guard let source = fileToProcess.sourceText else {
+    guard let source = fileToProcess.readString() else {
       diagnosticsEngine.emitError(
         "Unable to lint \(url.relativePath): file is not readable or does not exist."
       )
diff --git a/Sources/swift-format/Subcommands/DumpConfiguration.swift b/Sources/swift-format/Subcommands/DumpConfiguration.swift
index 3104ed588..c24aef3e9 100644
--- a/Sources/swift-format/Subcommands/DumpConfiguration.swift
+++ b/Sources/swift-format/Subcommands/DumpConfiguration.swift
@@ -16,8 +16,8 @@ import SwiftFormat
 
 extension SwiftFormatCommand {
   /// Dumps the tool's configuration in JSON format to standard output.
-  struct DumpConfiguration: ParsableCommand {
-    static var configuration = CommandConfiguration(
+  struct DumpConfiguration: AsyncParsableCommand {
+    static let configuration = CommandConfiguration(
       abstract: "Dump the configuration in JSON format to standard output",
       discussion: """
         Without any options, dumps the default configuration. When '--effective' is set, dumps the configuration that \
@@ -39,16 +39,16 @@ extension SwiftFormatCommand {
       }
     }
 
-    func run() throws {
+    func run() async throws {
       let diagnosticPrinter = StderrDiagnosticPrinter(colorMode: .auto)
       let diagnosticsEngine = DiagnosticsEngine(diagnosticsHandlers: [diagnosticPrinter.printDiagnostic])
 
       let configuration: Configuration
       if effective {
-        var configurationProvider = Frontend.ConfigurationProvider(diagnosticsEngine: diagnosticsEngine)
+        let configurationProvider = ConfigurationProvider(diagnosticsEngine: diagnosticsEngine)
 
         guard
-          let effectiveConfiguration = configurationProvider.provide(
+          let effectiveConfiguration = await configurationProvider.provide(
             forConfigPathOrString: configurationOptions.configuration,
             orForSwiftFileAt: nil
           )
diff --git a/Sources/swift-format/Subcommands/Format.swift b/Sources/swift-format/Subcommands/Format.swift
index 0aab74d58..cc9702493 100644
--- a/Sources/swift-format/Subcommands/Format.swift
+++ b/Sources/swift-format/Subcommands/Format.swift
@@ -14,8 +14,8 @@ import ArgumentParser
 
 extension SwiftFormatCommand {
   /// Formats one or more files containing Swift code.
-  struct Format: ParsableCommand {
-    static var configuration = CommandConfiguration(
+  struct Format: AsyncParsableCommand {
+    static let configuration = CommandConfiguration(
       abstract: "Format Swift source code",
       discussion: "When no files are specified, it expects the source from standard input."
     )
@@ -44,15 +44,25 @@ extension SwiftFormatCommand {
       }
     }
 
-    func run() throws {
-      try performanceMeasurementOptions.printingInstructionCountIfRequested {
+    func run() async throws {
+      try await self.performanceMeasurementOptions.printingInstructionCountIfRequested {
+        let diagnosticPrinter = StderrDiagnosticPrinter(
+          colorMode: self.formatOptions.diagnosticsColorMode
+        )
+
+        let diagnosticsEngine = DiagnosticsEngine(
+          diagnosticsHandlers: [diagnosticPrinter.printDiagnostic],
+          treatWarningsAsErrors: false
+        )
+
         let frontend = FormatFrontend(
+          diagnosticEngine: diagnosticsEngine,
           configurationOptions: configurationOptions,
           lintFormatOptions: formatOptions,
           inPlace: inPlace
         )
-        frontend.run()
-        if frontend.diagnosticsEngine.hasErrors { throw ExitCode.failure }
+        await frontend.run()
+        if diagnosticsEngine.hasErrors { throw ExitCode.failure }
       }
     }
   }
diff --git a/Sources/swift-format/Subcommands/Lint.swift b/Sources/swift-format/Subcommands/Lint.swift
index 99d088a39..dbfa72560 100644
--- a/Sources/swift-format/Subcommands/Lint.swift
+++ b/Sources/swift-format/Subcommands/Lint.swift
@@ -14,8 +14,8 @@ import ArgumentParser
 
 extension SwiftFormatCommand {
   /// Emits style diagnostics for one or more files containing Swift code.
-  struct Lint: ParsableCommand {
-    static var configuration = CommandConfiguration(
+  struct Lint: AsyncParsableCommand {
+    static let configuration = CommandConfiguration(
       abstract: "Diagnose style issues in Swift source code",
       discussion: "When no files are specified, it expects the source from standard input."
     )
@@ -35,16 +35,25 @@ extension SwiftFormatCommand {
     @OptionGroup(visibility: .hidden)
     var performanceMeasurementOptions: PerformanceMeasurementsOptions
 
-    func run() throws {
-      try performanceMeasurementOptions.printingInstructionCountIfRequested {
+    func run() async throws {
+      try await self.performanceMeasurementOptions.printingInstructionCountIfRequested {
+        let diagnosticPrinter = StderrDiagnosticPrinter(
+          colorMode: self.lintOptions.diagnosticsColorMode
+        )
+
+        let diagnosticsEngine = DiagnosticsEngine(
+          diagnosticsHandlers: [diagnosticPrinter.printDiagnostic],
+          treatWarningsAsErrors: self.strict
+        )
+
         let frontend = LintFrontend(
+          diagnosticEngine: diagnosticsEngine,
           configurationOptions: configurationOptions,
-          lintFormatOptions: lintOptions,
-          treatWarningsAsErrors: strict
+          lintFormatOptions: lintOptions
         )
-        frontend.run()
+        await frontend.run()
 
-        if frontend.diagnosticsEngine.hasErrors {
+        if diagnosticsEngine.hasErrors {
           throw ExitCode.failure
         }
       }
diff --git a/Sources/swift-format/Subcommands/LintFormatOptions.swift b/Sources/swift-format/Subcommands/LintFormatOptions.swift
index 25fdcaf68..c626308f0 100644
--- a/Sources/swift-format/Subcommands/LintFormatOptions.swift
+++ b/Sources/swift-format/Subcommands/LintFormatOptions.swift
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import ArgumentParser
+public import ArgumentParser
 import Foundation
 
 /// Common arguments used by the `lint` and `format` subcommands.
@@ -75,7 +75,15 @@ struct LintFormatOptions: ParsableArguments {
       to not use colors otherwise.
       """
   )
-  var colorDiagnostics: Bool?
+  private var colorDiagnostics: Bool?
+
+  var diagnosticsColorMode: StderrDiagnosticPrinter.ColorMode {
+    switch colorDiagnostics {
+    case .none: .auto
+    case .some(true): .on
+    case .some(false): .off
+    }
+  }
 
   /// Whether symlinks should be followed.
   @Flag(
diff --git a/Sources/swift-format/Subcommands/PerformanceMeasurement.swift b/Sources/swift-format/Subcommands/PerformanceMeasurement.swift
index a230aa052..53edde37a 100644
--- a/Sources/swift-format/Subcommands/PerformanceMeasurement.swift
+++ b/Sources/swift-format/Subcommands/PerformanceMeasurement.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -19,15 +19,17 @@ struct PerformanceMeasurementsOptions: ParsableArguments {
 
   /// If `measureInstructions` is set, execute `body` and print the number of instructions
   /// executed by it. Otherwise, just execute `body`
-  func printingInstructionCountIfRequested<T>(_ body: () throws -> T) rethrows -> T {
+  func printingInstructionCountIfRequested<T>(
+    _ body: () async throws -> T
+  ) async rethrows -> T {
     if !measureInstructions {
-      return try body()
+      return try await body()
     } else {
       let startInstructions = getInstructionsExecuted()
       defer {
         print("Instructions executed: \(getInstructionsExecuted() - startInstructions)")
       }
-      return try body()
+      return try await body()
     }
   }
 }
diff --git a/Sources/swift-format/SwiftFormatCommand.swift b/Sources/swift-format/SwiftFormatCommand.swift
index 5b814a159..1442ab319 100644
--- a/Sources/swift-format/SwiftFormatCommand.swift
+++ b/Sources/swift-format/SwiftFormatCommand.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -15,8 +15,8 @@ import ArgumentParser
 /// Collects the command line options that were passed to `swift-format` and dispatches to the
 /// appropriate subcommand.
 @main
-struct SwiftFormatCommand: ParsableCommand {
-  static var configuration = CommandConfiguration(
+struct SwiftFormatCommand: AsyncParsableCommand {
+  static let configuration = CommandConfiguration(
     commandName: "swift-format",
     abstract: "Format or lint Swift source code",
     subcommands: [
diff --git a/Sources/swift-format/Utilities/DiagnosticsEngine.swift b/Sources/swift-format/Utilities/DiagnosticsEngine.swift
index 5d51bef71..b1d38a652 100644
--- a/Sources/swift-format/Utilities/DiagnosticsEngine.swift
+++ b/Sources/swift-format/Utilities/DiagnosticsEngine.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -16,15 +16,21 @@ import SwiftSyntax
 
 /// Unifies the handling of findings from the linter, parsing errors from the syntax parser, and
 /// generic errors from the frontend so that they are emitted in a uniform fashion.
-final class DiagnosticsEngine {
+final class DiagnosticsEngine: Sendable {
   /// The handler functions that will be called to process diagnostics that are emitted.
-  private let handlers: [(Diagnostic) -> Void]
+  private let handlers: [@Sendable (Diagnostic) -> Void]
 
   /// A Boolean value indicating whether any errors were emitted by the diagnostics engine.
-  private(set) var hasErrors: Bool
+  var hasErrors: Bool {
+    self._hasErrors.value
+  }
+  private let _hasErrors = ThreadSafeBox<Bool>(false)
 
   /// A Boolean value indicating whether any warnings were emitted by the diagnostics engine.
-  private(set) var hasWarnings: Bool
+  var hasWarnings: Bool {
+    self._hasWarnings.value
+  }
+  private let _hasWarnings = ThreadSafeBox<Bool>(false)
 
   /// Whether to upgrade all warnings to errors.
   private let treatWarningsAsErrors: Bool
@@ -34,23 +40,23 @@ final class DiagnosticsEngine {
   /// - Parameter diagnosticsHandlers: An array of functions, each of which takes a `Diagnostic` as
   ///   its sole argument and returns `Void`. The functions are called whenever a diagnostic is
   ///   received by the engine.
-  init(diagnosticsHandlers: [(Diagnostic) -> Void], treatWarningsAsErrors: Bool = false) {
+  init(
+    diagnosticsHandlers: [@Sendable (Diagnostic) -> Void],
+    treatWarningsAsErrors: Bool = false
+  ) {
     self.handlers = diagnosticsHandlers
-    self.hasErrors = false
-    self.hasWarnings = false
     self.treatWarningsAsErrors = treatWarningsAsErrors
   }
 
   /// Emits the diagnostic by passing it to the registered handlers, and tracks whether it was an
   /// error or warning diagnostic.
-  private func emit(_ diagnostic: Diagnostic) {
-    var diagnostic = diagnostic
+  private func emit(_ diagnostic: consuming Diagnostic) {
     if treatWarningsAsErrors, diagnostic.severity == .warning {
       diagnostic.severity = .error
     }
     switch diagnostic.severity {
-    case .error: self.hasErrors = true
-    case .warning: self.hasWarnings = true
+    case .error: self._hasErrors.value = true
+    case .warning: self._hasWarnings.value = true
     default: break
     }
 
@@ -95,7 +101,7 @@ final class DiagnosticsEngine {
   ///
   /// - Parameter finding: The finding that should be emitted.
   func consumeFinding(_ finding: Finding) {
-    emit(diagnosticMessage(for: finding))
+    emit(DiagnosticsEngine.diagnosticMessage(for: finding))
 
     for note in finding.notes {
       emit(
@@ -115,13 +121,13 @@ final class DiagnosticsEngine {
     _ diagnostic: SwiftDiagnostics.Diagnostic,
     _ location: SourceLocation
   ) {
-    emit(diagnosticMessage(for: diagnostic.diagMessage, at: location))
+    emit(DiagnosticsEngine.diagnosticMessage(for: diagnostic.diagMessage, at: location))
   }
 
   /// Converts a diagnostic message from the syntax parser into a diagnostic message that can be
   /// used by the `TSCBasic` diagnostics engine and returns it.
-  private func diagnosticMessage(
-    for message: SwiftDiagnostics.DiagnosticMessage,
+  private static func diagnosticMessage(
+    for message: any SwiftDiagnostics.DiagnosticMessage,
     at location: SourceLocation
   ) -> Diagnostic {
     let severity: Diagnostic.Severity
@@ -141,7 +147,7 @@ final class DiagnosticsEngine {
 
   /// Converts a lint finding into a diagnostic message that can be used by the `TSCBasic`
   /// diagnostics engine and returns it.
-  private func diagnosticMessage(for finding: Finding) -> Diagnostic {
+  private static func diagnosticMessage(for finding: Finding) -> Diagnostic {
     return Diagnostic(
       severity: .warning,
       location: finding.location.map(Diagnostic.Location.init),
diff --git a/Sources/swift-format/Utilities/StderrDiagnosticPrinter.swift b/Sources/swift-format/Utilities/StderrDiagnosticPrinter.swift
index eb4f79c87..31f70da9f 100644
--- a/Sources/swift-format/Utilities/StderrDiagnosticPrinter.swift
+++ b/Sources/swift-format/Utilities/StderrDiagnosticPrinter.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2021 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -14,7 +14,7 @@ import Dispatch
 import Foundation
 
 /// Manages printing of diagnostics to standard error.
-final class StderrDiagnosticPrinter {
+struct StderrDiagnosticPrinter {
   /// Determines how colors are used in printed diagnostics.
   enum ColorMode {
     /// Colors are used if stderr is detected to be connected to a TTY; otherwise, colors will not
@@ -57,6 +57,7 @@ final class StderrDiagnosticPrinter {
   }
 
   /// Prints a diagnostic to standard error.
+  @Sendable
   func printDiagnostic(_ diagnostic: Diagnostic) {
     printQueue.sync {
       let stderr = FileHandleTextOutputStream(FileHandle.standardError)
diff --git a/Sources/swift-format/Utilities/ThreadSafeBox.swift b/Sources/swift-format/Utilities/ThreadSafeBox.swift
new file mode 100644
index 000000000..401248d68
--- /dev/null
+++ b/Sources/swift-format/Utilities/ThreadSafeBox.swift
@@ -0,0 +1,47 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2025 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+import class Foundation.NSLock
+
+/// A thread safe container that contains a mutable value of type `T`.
+///
+/// - Note: Unchecked sendable conformance because value is guarded by a lock.
+// TODO: This can be replaced with Synchronization.Mutex once deployment target >= macOS 15.0
+class ThreadSafeBox<Value: Sendable>: @unchecked Sendable {
+  /// Lock guarding `_value`.
+  private let lock = NSLock()
+
+  private var _value: Value
+
+  init(_ value: Value) {
+    _value = value
+  }
+
+  var value: Value {
+    _read {
+      lock.lock()
+      defer { lock.unlock() }
+      yield _value
+    }
+    _modify {
+      lock.lock()
+      defer { lock.unlock() }
+      yield &_value
+    }
+  }
+
+  func withLock<Result>(_ body: (inout Value) throws -> Result) rethrows -> Result {
+    try self.lock.withLock {
+      try body(&self.value)
+    }
+  }
+}
diff --git a/Tests/SwiftFormatTests/PrettyPrint/AssignmentExprTests.swift b/Tests/SwiftFormatTests/PrettyPrint/AssignmentExprTests.swift
index f6a8604ac..507f19242 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/AssignmentExprTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/AssignmentExprTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class AssignmentExprTests: PrettyPrintTestCase {
   func testBasicAssignmentExprs() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/AttributeTests.swift b/Tests/SwiftFormatTests/PrettyPrint/AttributeTests.swift
index 430656d4e..db979eb30 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/AttributeTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/AttributeTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class AttributeTests: PrettyPrintTestCase {
   func testAttributeParamSpacing() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/BinaryOperatorExprTests.swift b/Tests/SwiftFormatTests/PrettyPrint/BinaryOperatorExprTests.swift
index 9fac440ba..4f42f40c9 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/BinaryOperatorExprTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/BinaryOperatorExprTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class BinaryOperatorExprTests: PrettyPrintTestCase {
   func testNonRangeFormationOperatorsAreSurroundedByBreaks() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/ClassDeclTests.swift b/Tests/SwiftFormatTests/PrettyPrint/ClassDeclTests.swift
index deac2b9e2..55fc8345e 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/ClassDeclTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/ClassDeclTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class ClassDeclTests: PrettyPrintTestCase {
   func testBasicClassDeclarations() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/ClosureExprTests.swift b/Tests/SwiftFormatTests/PrettyPrint/ClosureExprTests.swift
index 76a453c31..e4a30c84f 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/ClosureExprTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/ClosureExprTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class ClosureExprTests: PrettyPrintTestCase {
   func testBasicFunctionClosures_noPackArguments() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/CommaTests.swift b/Tests/SwiftFormatTests/PrettyPrint/CommaTests.swift
index d8dc75da5..cdbac6c4c 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/CommaTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/CommaTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class CommaTests: PrettyPrintTestCase {
   func testArrayCommasAbsentEnabled() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/DeclNameArgumentTests.swift b/Tests/SwiftFormatTests/PrettyPrint/DeclNameArgumentTests.swift
index 37d005e8b..ba9763cd1 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/DeclNameArgumentTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/DeclNameArgumentTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class DeclNameArgumentTests: PrettyPrintTestCase {
   func testSelectors_noPackArguments() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/DoStmtTests.swift b/Tests/SwiftFormatTests/PrettyPrint/DoStmtTests.swift
index 9d013c559..3631db7a0 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/DoStmtTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/DoStmtTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class DoStmtTests: PrettyPrintTestCase {
   func testBasicDoStmt() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/EnumDeclTests.swift b/Tests/SwiftFormatTests/PrettyPrint/EnumDeclTests.swift
index 81e764626..e4dadb05d 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/EnumDeclTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/EnumDeclTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class EnumDeclTests: PrettyPrintTestCase {
   func testBasicEnumDeclarations() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/ExtensionDeclTests.swift b/Tests/SwiftFormatTests/PrettyPrint/ExtensionDeclTests.swift
index 1f27a4a82..284fd5661 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/ExtensionDeclTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/ExtensionDeclTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class ExtensionDeclTests: PrettyPrintTestCase {
   func testBasicExtensionDeclarations() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/FunctionCallTests.swift b/Tests/SwiftFormatTests/PrettyPrint/FunctionCallTests.swift
index 837031317..9329e59da 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/FunctionCallTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/FunctionCallTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class FunctionCallTests: PrettyPrintTestCase {
   func testBasicFunctionCalls_noPackArguments() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/FunctionDeclTests.swift b/Tests/SwiftFormatTests/PrettyPrint/FunctionDeclTests.swift
index 1bfa566f1..cb9757845 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/FunctionDeclTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/FunctionDeclTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class FunctionDeclTests: PrettyPrintTestCase {
   func testBasicFunctionDeclarations_noPackArguments() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/IfConfigTests.swift b/Tests/SwiftFormatTests/PrettyPrint/IfConfigTests.swift
index 1524297bb..2d2d38fbf 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/IfConfigTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/IfConfigTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class IfConfigTests: PrettyPrintTestCase {
   func testBasicIfConfig() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/IfStmtTests.swift b/Tests/SwiftFormatTests/PrettyPrint/IfStmtTests.swift
index 4d2685d0b..6ab85c288 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/IfStmtTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/IfStmtTests.swift
@@ -12,6 +12,7 @@
 
 import SwiftFormat
 import XCTest
+import _SwiftFormatTestSupport
 
 final class IfStmtTests: PrettyPrintTestCase {
   func testIfStatement() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/IndentBlankLinesTests.swift b/Tests/SwiftFormatTests/PrettyPrint/IndentBlankLinesTests.swift
index 0819c2613..5fa8e3689 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/IndentBlankLinesTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/IndentBlankLinesTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class IndentBlankLinesTests: PrettyPrintTestCase {
   func testIndentBlankLinesEnabled() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/InitializerDeclTests.swift b/Tests/SwiftFormatTests/PrettyPrint/InitializerDeclTests.swift
index 4f0edcf91..1e4257f36 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/InitializerDeclTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/InitializerDeclTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class InitializerDeclTests: PrettyPrintTestCase {
   func testBasicInitializerDeclarations_noPackArguments() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/MacroDeclTests.swift b/Tests/SwiftFormatTests/PrettyPrint/MacroDeclTests.swift
index 918e337e5..52a093ce4 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/MacroDeclTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/MacroDeclTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class MacroDeclTests: PrettyPrintTestCase {
   func testBasicMacroDeclarations_noPackArguments() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/MemberAccessExprTests.swift b/Tests/SwiftFormatTests/PrettyPrint/MemberAccessExprTests.swift
index a8f31746f..32fcf1738 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/MemberAccessExprTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/MemberAccessExprTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class MemberAccessExprTests: PrettyPrintTestCase {
   func testMemberAccess() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/ObjectLiteralExprTests.swift b/Tests/SwiftFormatTests/PrettyPrint/ObjectLiteralExprTests.swift
index 499a79d21..e38240171 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/ObjectLiteralExprTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/ObjectLiteralExprTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class ObjectLiteralExprTests: PrettyPrintTestCase {
   func testColorLiteral_noPackArguments() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/PrettyPrintTestCase.swift b/Tests/SwiftFormatTests/PrettyPrint/PrettyPrintTestCase.swift
index eda24f531..2a1837534 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/PrettyPrintTestCase.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/PrettyPrintTestCase.swift
@@ -44,7 +44,7 @@ class PrettyPrintTestCase: DiagnosingTestCase {
     whitespaceOnly: Bool = false,
     findings: [FindingSpec] = [],
     experimentalFeatures: Parser.ExperimentalFeatures = [],
-    file: StaticString = #file,
+    file: StaticString = #filePath,
     line: UInt = #line
   ) {
     var configuration = configuration
diff --git a/Tests/SwiftFormatTests/PrettyPrint/ProtocolDeclTests.swift b/Tests/SwiftFormatTests/PrettyPrint/ProtocolDeclTests.swift
index 9be89469c..1e88cb112 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/ProtocolDeclTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/ProtocolDeclTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class ProtocolDeclTests: PrettyPrintTestCase {
   func testBasicProtocolDeclarations() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/RepeatStmtTests.swift b/Tests/SwiftFormatTests/PrettyPrint/RepeatStmtTests.swift
index 944eb6410..bb5f54f00 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/RepeatStmtTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/RepeatStmtTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class RepeatStmtTests: PrettyPrintTestCase {
   func testBasicRepeatTests_noBreakBeforeWhile() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/RespectsExistingLineBreaksTests.swift b/Tests/SwiftFormatTests/PrettyPrint/RespectsExistingLineBreaksTests.swift
index 09260a679..3c3ba2ffc 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/RespectsExistingLineBreaksTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/RespectsExistingLineBreaksTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 /// Basic checks and regression tests for the `respectsExistingLineBreaks` configuration setting
 /// in both true and false states.
diff --git a/Tests/SwiftFormatTests/PrettyPrint/StringTests.swift b/Tests/SwiftFormatTests/PrettyPrint/StringTests.swift
index 5b5172a28..d6439b93d 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/StringTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/StringTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 @_spi(Rules) @_spi(Testing) import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class StringTests: PrettyPrintTestCase {
   func testStrings() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/StructDeclTests.swift b/Tests/SwiftFormatTests/PrettyPrint/StructDeclTests.swift
index 7d3526226..c7e5a020d 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/StructDeclTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/StructDeclTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class StructDeclTests: PrettyPrintTestCase {
   func testBasicStructDeclarations() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/SubscriptDeclTests.swift b/Tests/SwiftFormatTests/PrettyPrint/SubscriptDeclTests.swift
index 2f3d75a60..fe69bc73c 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/SubscriptDeclTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/SubscriptDeclTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class SubscriptDeclTests: PrettyPrintTestCase {
   func testBasicSubscriptDeclarations() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/SwitchCaseIndentConfigTests.swift b/Tests/SwiftFormatTests/PrettyPrint/SwitchCaseIndentConfigTests.swift
index 02b52d008..f3f8f149a 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/SwitchCaseIndentConfigTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/SwitchCaseIndentConfigTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 /// Tests the `indentSwitchCaseLabels` config option
 final class SwitchCaseIndentConfigTests: PrettyPrintTestCase {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/SwitchStmtTests.swift b/Tests/SwiftFormatTests/PrettyPrint/SwitchStmtTests.swift
index 0aa25e122..f58ef1d00 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/SwitchStmtTests.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/SwitchStmtTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftFormat
+import _SwiftFormatTestSupport
 
 final class SwitchStmtTests: PrettyPrintTestCase {
   func testBasicSwitch() {
diff --git a/Tests/SwiftFormatTests/PrettyPrint/WhitespaceTestCase.swift b/Tests/SwiftFormatTests/PrettyPrint/WhitespaceTestCase.swift
index a638bb7e0..d2189fdef 100644
--- a/Tests/SwiftFormatTests/PrettyPrint/WhitespaceTestCase.swift
+++ b/Tests/SwiftFormatTests/PrettyPrint/WhitespaceTestCase.swift
@@ -34,7 +34,7 @@ class WhitespaceTestCase: DiagnosingTestCase {
     expected: String,
     linelength: Int? = nil,
     findings: [FindingSpec],
-    file: StaticString = #file,
+    file: StaticString = #filePath,
     line: UInt = #line
   ) {
     let markedText = MarkedText(textWithMarkers: input)
diff --git a/Tests/SwiftFormatTests/Rules/BeginDocumentationCommentWithOneLineSummaryTests.swift b/Tests/SwiftFormatTests/Rules/BeginDocumentationCommentWithOneLineSummaryTests.swift
index 1cf33f303..c55c7fee7 100644
--- a/Tests/SwiftFormatTests/Rules/BeginDocumentationCommentWithOneLineSummaryTests.swift
+++ b/Tests/SwiftFormatTests/Rules/BeginDocumentationCommentWithOneLineSummaryTests.swift
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 @_spi(Rules) import SwiftFormat
+import XCTest
 import _SwiftFormatTestSupport
 
 // FIXME: We should place the diagnostic somewhere in the comment, not on the declaration.
diff --git a/Tests/SwiftFormatTests/Rules/FileScopedDeclarationPrivacyTests.swift b/Tests/SwiftFormatTests/Rules/FileScopedDeclarationPrivacyTests.swift
index c0a317f52..460f3d666 100644
--- a/Tests/SwiftFormatTests/Rules/FileScopedDeclarationPrivacyTests.swift
+++ b/Tests/SwiftFormatTests/Rules/FileScopedDeclarationPrivacyTests.swift
@@ -10,6 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+import Foundation
 import SwiftFormat
 @_spi(Rules) import SwiftFormat
 import SwiftSyntax
@@ -174,7 +175,7 @@ final class FileScopedDeclarationPrivacyTests: LintOrFormatRuleTestCase {
   private func runWithMultipleConfigurations(
     source: String,
     testConfigurations: [TestConfiguration],
-    file: StaticString = #file,
+    file: StaticString = #filePath,
     line: UInt = #line,
     findingsProvider: (String, String) -> [FindingSpec]
   ) {
diff --git a/Tests/SwiftFormatTests/Rules/ImportsXCTestVisitorTests.swift b/Tests/SwiftFormatTests/Rules/ImportsXCTestVisitorTests.swift
index 0c4999019..c47f7b658 100644
--- a/Tests/SwiftFormatTests/Rules/ImportsXCTestVisitorTests.swift
+++ b/Tests/SwiftFormatTests/Rules/ImportsXCTestVisitorTests.swift
@@ -12,6 +12,7 @@
 
 import SwiftFormat
 @_spi(Rules) @_spi(Testing) import SwiftFormat
+import SwiftOperators
 import SwiftParser
 import XCTest
 
diff --git a/Tests/SwiftFormatTests/Rules/LintOrFormatRuleTestCase.swift b/Tests/SwiftFormatTests/Rules/LintOrFormatRuleTestCase.swift
index 938d956d8..807b4d571 100644
--- a/Tests/SwiftFormatTests/Rules/LintOrFormatRuleTestCase.swift
+++ b/Tests/SwiftFormatTests/Rules/LintOrFormatRuleTestCase.swift
@@ -37,7 +37,7 @@ class LintOrFormatRuleTestCase: DiagnosingTestCase {
     _ markedSource: String,
     findings: [FindingSpec] = [],
     experimentalFeatures: Parser.ExperimentalFeatures = [],
-    file: StaticString = #file,
+    file: StaticString = #filePath,
     line: UInt = #line
   ) {
     let markedText = MarkedText(textWithMarkers: markedSource)
@@ -103,7 +103,7 @@ class LintOrFormatRuleTestCase: DiagnosingTestCase {
     findings: [FindingSpec] = [],
     configuration: Configuration? = nil,
     experimentalFeatures: Parser.ExperimentalFeatures = [],
-    file: StaticString = #file,
+    file: StaticString = #filePath,
     line: UInt = #line
   ) {
     let markedInput = MarkedText(textWithMarkers: input)