diff --git a/Documentation/Evolution/RegexBuilderDSL.md b/Documentation/Evolution/RegexBuilderDSL.md
index 635112e93..73303cb74 100644
--- a/Documentation/Evolution/RegexBuilderDSL.md
+++ b/Documentation/Evolution/RegexBuilderDSL.md
@@ -329,7 +329,7 @@ public enum RegexComponentBuilder {
   /// recording its source location.
   public static func buildExpression<R: RegexComponent>(
     _ regex: R, 
-    file: String = #file, 
+    file: String = #filePath, 
     function: String = #function, 
     line: Int = #line,
     column: Int = #column
@@ -478,7 +478,7 @@ public enum AlternationBuilder {
   /// recording its source location.
   public static func buildExpression<R: RegexComponent>(
     _ regex: R, 
-    file: String = #file, 
+    file: String = #filePath, 
     function: String = #function, 
     line: Int = #line,
     column: Int = #column
diff --git a/Package.swift b/Package.swift
index e9198908d..5567d18c2 100644
--- a/Package.swift
+++ b/Package.swift
@@ -1,4 +1,4 @@
-// swift-tools-version:5.5
+// swift-tools-version:6.0
 // The swift-tools-version declares the minimum version of Swift required to build this package.
 
 import PackageDescription
@@ -31,6 +31,7 @@ let availabilityDefinition = PackageDescription.SwiftSetting.unsafeFlags([
 let privateStdlibSettings: [PackageDescription.SwiftSetting] = [
     .unsafeFlags(["-Xfrontend", "-disable-implicit-concurrency-module-import"]),
     .unsafeFlags(["-Xfrontend", "-disable-implicit-string-processing-module-import"]),
+    .enableUpcomingFeature("MemberImportVisibility"),
 ]
 
 /// Swift settings for building a user-facing stdlib-like module.
@@ -38,6 +39,7 @@ let publicStdlibSettings: [PackageDescription.SwiftSetting] = [
     .unsafeFlags(["-enable-library-evolution"]),
     .unsafeFlags(["-Xfrontend", "-disable-implicit-concurrency-module-import"]),
     .unsafeFlags(["-Xfrontend", "-disable-implicit-string-processing-module-import"]),
+    .enableUpcomingFeature("MemberImportVisibility"),
     availabilityDefinition
 ]
 
diff --git a/Sources/RegexBenchmark/Utils/Time.swift b/Sources/RegexBenchmark/Utils/Time.swift
index 36d615450..25e1bebfe 100644
--- a/Sources/RegexBenchmark/Utils/Time.swift
+++ b/Sources/RegexBenchmark/Utils/Time.swift
@@ -14,7 +14,7 @@
 import Foundation
 import ArgumentParser
 
-public struct Time {
+public struct Time: Sendable {
   public let seconds: TimeInterval
   
   public init(_ seconds: TimeInterval) {
diff --git a/Sources/RegexBuilder/DSL.swift b/Sources/RegexBuilder/DSL.swift
index 42266466f..7e19caae2 100644
--- a/Sources/RegexBuilder/DSL.swift
+++ b/Sources/RegexBuilder/DSL.swift
@@ -32,21 +32,21 @@ internal protocol _BuiltinRegexComponent: RegexComponent {
 // MARK: - Primitive regex components
 
 @available(SwiftStdlib 5.7, *)
-extension String: @retroactive RegexComponent {
+extension String: RegexComponent {
   public typealias Output = Substring
 
   public var regex: Regex<Output> { .init(verbatim: self) }
 }
 
 @available(SwiftStdlib 5.7, *)
-extension Substring: @retroactive RegexComponent {
+extension Substring: RegexComponent {
   public typealias Output = Substring
 
   public var regex: Regex<Output> { String(self).regex }
 }
 
 @available(SwiftStdlib 5.7, *)
-extension Character: @retroactive RegexComponent {
+extension Character: RegexComponent {
   public typealias Output = Substring
 
   public var regex: Regex<Output> {
@@ -55,7 +55,7 @@ extension Character: @retroactive RegexComponent {
 }
 
 @available(SwiftStdlib 5.7, *)
-extension UnicodeScalar: @retroactive RegexComponent {
+extension UnicodeScalar: RegexComponent {
   public typealias Output = Substring
 
   public var regex: Regex<Output> {
diff --git a/Sources/RegexTester/CompileOnceTest.swift b/Sources/RegexTester/CompileOnceTest.swift
index 56de4afd8..c486603ba 100644
--- a/Sources/RegexTester/CompileOnceTest.swift
+++ b/Sources/RegexTester/CompileOnceTest.swift
@@ -15,14 +15,14 @@ import _StringProcessing
 import Foundation
 
 @available(SwiftStdlib 5.8, *)
-let litPattern = #/a+bcd(?:g*)ab+?c?de(?:(?:(?i:f)))hij|zzz++a|3|2|1/#
+nonisolated(unsafe) let litPattern = #/a+bcd(?:g*)ab+?c?de(?:(?:(?i:f)))hij|zzz++a|3|2|1/#
 @available(SwiftStdlib 5.8, *)
-let strPattern = try! Regex("a+bcd(?:g*)ab+?c?de(?:(?:(?i:f)))hij|zzz++a|3|2|1")
+nonisolated(unsafe) let strPattern = try! Regex("a+bcd(?:g*)ab+?c?de(?:(?:(?i:f)))hij|zzz++a|3|2|1")
 
 @available(SwiftStdlib 5.8, *)
 struct CompileOnceTest: ParsableCommand {
-  static let litPattern = #/a+bcd(?:g*)ab+?c?de(?:(?:(?i:f)))hij|zzz++a|3|2|1/#
-  static let strPattern = try! Regex("a+bcd(?:g*)ab+?c?de(?:(?:(?i:f)))hij|zzz++a|3|2|1")
+  nonisolated(unsafe) static let litPattern = #/a+bcd(?:g*)ab+?c?de(?:(?:(?i:f)))hij|zzz++a|3|2|1/#
+  nonisolated(unsafe) static let strPattern = try! Regex("a+bcd(?:g*)ab+?c?de(?:(?:(?i:f)))hij|zzz++a|3|2|1")
   
   var N: Int { 10_000 }
   var testString = "zzzzzzzzza"
diff --git a/Sources/TestSupport/TestSupport.swift b/Sources/TestSupport/TestSupport.swift
index fc9353f32..65cfd3539 100644
--- a/Sources/TestSupport/TestSupport.swift
+++ b/Sources/TestSupport/TestSupport.swift
@@ -23,7 +23,7 @@ public func XCTExpectFailure(
 
 /// Guards certain tests to make sure we have a new stdlib available.
 public func ensureNewStdlib(
-  file: StaticString = #file, line: UInt = #line
+  file: StaticString = #filePath, line: UInt = #line
 ) -> Bool {
   guard #available(SwiftStdlib 5.7, *) else {
     XCTExpectFailure { XCTFail("Unsupported stdlib", file: file, line: line) }
diff --git a/Sources/VariadicsGenerator/VariadicsGenerator.swift b/Sources/VariadicsGenerator/VariadicsGenerator.swift
index b1953bcd4..fb3b44315 100644
--- a/Sources/VariadicsGenerator/VariadicsGenerator.swift
+++ b/Sources/VariadicsGenerator/VariadicsGenerator.swift
@@ -12,15 +12,7 @@
 // swift run VariadicsGenerator --max-arity 10 > Sources/RegexBuilder/Variadics.swift
 
 import ArgumentParser
-#if os(macOS)
-import Darwin
-#elseif canImport(Glibc)
-import Glibc
-#elseif os(Windows)
-import CRT
-#elseif canImport(Bionic)
-import Bionic
-#endif
+import Foundation
 
 // (T), (T)
 // (T), (T, T)
@@ -100,10 +92,10 @@ func outputForEach<C: Collection>(
 
 struct StandardErrorStream: TextOutputStream {
   func write(_ string: String) {
-    fputs(string, stderr)
+    FileHandle.standardError.write(Data(string.utf8))
   }
 }
-var standardError = StandardErrorStream()
+nonisolated(unsafe) var standardError = StandardErrorStream()
 
 typealias Counter = Int64
 let regexComponentProtocolName = "RegexComponent"
diff --git a/Sources/_RegexParser/Utility/AllScalars.swift b/Sources/_RegexParser/Utility/AllScalars.swift
index ec3bf81ea..805054465 100644
--- a/Sources/_RegexParser/Utility/AllScalars.swift
+++ b/Sources/_RegexParser/Utility/AllScalars.swift
@@ -10,7 +10,7 @@
 //===----------------------------------------------------------------------===//
 
 extension Unicode.Scalar {
-  public struct AllScalars: RandomAccessCollection {
+  public struct AllScalars: RandomAccessCollection, Sendable {
     // Unicode scalar values are in two discontiguous blocks:
     // 0...0xD7FF and 0xE000...0x10FFFF
     internal static var lowerSectionFirstValue: Int { 0 }
diff --git a/Sources/_RegexParser/Utility/Errors.swift b/Sources/_RegexParser/Utility/Errors.swift
index 8dbe67fa0..1ca93c548 100644
--- a/Sources/_RegexParser/Utility/Errors.swift
+++ b/Sources/_RegexParser/Utility/Errors.swift
@@ -22,7 +22,7 @@ public struct Unsupported: Error, CustomStringConvertible {
 
   public init(
     _ s: String,
-    file: StaticString = #file,
+    file: StaticString = #filePath,
     line: UInt = #line
   ) {
     self.message = s
@@ -44,7 +44,7 @@ public struct Unreachable: Error, CustomStringConvertible {
 
   public init(
     _ s: String,
-    file: StaticString = #file,
+    file: StaticString = #filePath,
     line: UInt = #line
   ) {
     self.message = s
diff --git a/Sources/_StringProcessing/Compiler.swift b/Sources/_StringProcessing/Compiler.swift
index 09cdef90d..bcc5677e0 100644
--- a/Sources/_StringProcessing/Compiler.swift
+++ b/Sources/_StringProcessing/Compiler.swift
@@ -115,7 +115,7 @@ func _compileRegex(
 }
 
 @_spi(RegexBenchmark)
-public struct _CompileOptions: OptionSet {
+public struct _CompileOptions: OptionSet, Sendable {
   public let rawValue: Int
   public init(rawValue: Int) {
     self.rawValue = rawValue
diff --git a/Sources/_StringProcessing/ConsumerInterface.swift b/Sources/_StringProcessing/ConsumerInterface.swift
index c842b8ba6..62df83b17 100644
--- a/Sources/_StringProcessing/ConsumerInterface.swift
+++ b/Sources/_StringProcessing/ConsumerInterface.swift
@@ -335,9 +335,11 @@ func consumeCharacterWithSingleScalar(
 func consumeFunction(
   for opts: MatchingOptions
 ) -> (@escaping ScalarPredicate) -> MEProgram.ConsumeFunction {
-  opts.semanticLevel == .graphemeCluster
-    ? consumeCharacterWithLeadingScalar
-    : consumeScalar
+  if opts.semanticLevel == .graphemeCluster {
+    consumeCharacterWithLeadingScalar
+  } else {
+    consumeScalar
+  }
 }
 
 extension AST.Atom.CharacterProperty {
diff --git a/Sources/_StringProcessing/Regex/DSLTree.swift b/Sources/_StringProcessing/Regex/DSLTree.swift
index 62100f148..36c4baf29 100644
--- a/Sources/_StringProcessing/Regex/DSLTree.swift
+++ b/Sources/_StringProcessing/Regex/DSLTree.swift
@@ -416,7 +416,7 @@ extension DSLTree.Node {
 
 @_spi(RegexBuilder)
 public struct ReferenceID: Hashable {
-  private static var counter: Int = 0
+  nonisolated(unsafe) private static var counter: Int = 0
   var base: Int
 
   public var _raw: Int {
diff --git a/Tests/RegexBuilderTests/AlgorithmsTests.swift b/Tests/RegexBuilderTests/AlgorithmsTests.swift
index d9d27e7a1..b51efb067 100644
--- a/Tests/RegexBuilderTests/AlgorithmsTests.swift
+++ b/Tests/RegexBuilderTests/AlgorithmsTests.swift
@@ -27,7 +27,7 @@ class RegexConsumerTests: XCTestCase {
       input: String,
       result: String,
       _ replace: (Regex<R.RegexOutput>.Match) -> String,
-      file: StaticString = #file,
+      file: StaticString = #filePath,
       line: UInt = #line
     ) {
       XCTAssertEqual(input.replacing(regex, with: replace), result)
@@ -67,7 +67,7 @@ class RegexConsumerTests: XCTestCase {
       input: String,
       _ replace: (Regex<R.RegexOutput>.Match) -> String,
       _ tests: (subrange: Range<String.Index>, maxReplacement: Int, result: String)...,
-      file: StaticString = #file,
+      file: StaticString = #filePath,
       line: UInt = #line
     ) {
       for (subrange, maxReplacement, result) in tests {
@@ -125,7 +125,7 @@ class AlgorithmsResultBuilderTests: XCTestCase {
     _ tests: (input: String, expectedCaptures: MatchType?)...,
     matchType: MatchType.Type,
     equivalence: (MatchType, MatchType) -> Bool,
-    file: StaticString = #file,
+    file: StaticString = #filePath,
     line: UInt = #line,
     @RegexComponentBuilder _ content: () -> some RegexComponent<RegexOutputType>
   ) throws {
@@ -152,7 +152,7 @@ class AlgorithmsResultBuilderTests: XCTestCase {
   func expectEqual<Expected: Equatable>(
     _ algo: EquatableAlgo,
     _ tests: (input: String, expected: Expected)...,
-    file: StaticString = #file,
+    file: StaticString = #filePath,
     line: UInt = #line,
     @RegexComponentBuilder _ content: () -> some RegexComponent
   ) throws {
diff --git a/Tests/RegexBuilderTests/CustomTests.swift b/Tests/RegexBuilderTests/CustomTests.swift
index 348a1c290..69339fcfc 100644
--- a/Tests/RegexBuilderTests/CustomTests.swift
+++ b/Tests/RegexBuilderTests/CustomTests.swift
@@ -127,7 +127,7 @@ enum MatchCall {
 fileprivate func customTest<Match: Equatable>(
   _ regex: Regex<Match>,
   _ tests: (input: String, call: MatchCall, match: Match?)...,
-  file: StaticString = #file,
+  file: StaticString = #filePath,
   line: UInt = #line
 ) {
   for (input, call, match) in tests {
@@ -147,7 +147,7 @@ fileprivate func customTest<Match>(
   _ regex: some RegexComponent<Match>,
   _ isEquivalent: (Match, Match) -> Bool,
   _ tests: (input: String, call: MatchCall, match: Match?)...,
-  file: StaticString = #file,
+  file: StaticString = #filePath,
   line: UInt = #line
 ) {
   for (input, call, match) in tests {
@@ -431,7 +431,7 @@ class CustomRegexComponentTests: XCTestCase {
     func customTest<Match: Equatable, E: Error & Equatable>(
       _ regex: Regex<Match>,
       _ tests: (input: String, match: Match?, expectError: E?)...,
-      file: StaticString = #file,
+      file: StaticString = #filePath,
       line: UInt = #line
     ) {
       for (input, match, expectError) in tests {
@@ -449,7 +449,7 @@ class CustomRegexComponentTests: XCTestCase {
     func customTest<Match: Equatable, Error1: Error & Equatable, Error2: Error & Equatable>(
       _ regex: Regex<Match>,
       _ tests: (input: String, match: Match?, expectError1: Error1?, expectError2: Error2?)...,
-      file: StaticString = #file,
+      file: StaticString = #filePath,
       line: UInt = #line
     ) {
       for (input, match, expectError1, expectError2) in tests {
@@ -469,7 +469,7 @@ class CustomRegexComponentTests: XCTestCase {
     func customTest<Capture: Equatable, Error1: Error & Equatable, Error2: Error & Equatable>(
       _ regex: Regex<(Substring, Capture)>,
       _ tests: (input: String, match: (Substring, Capture)?, expectError1: Error1?, expectError2: Error2?)...,
-      file: StaticString = #file,
+      file: StaticString = #filePath,
       line: UInt = #line
     ) {
       for (input, match, expectError1, expectError2) in tests {
@@ -490,7 +490,7 @@ class CustomRegexComponentTests: XCTestCase {
     func customTest<Capture1: Equatable, Capture2: Equatable, Error1: Error & Equatable, Error2: Error & Equatable>(
       _ regex: Regex<(Substring, Capture1, Capture2)>,
       _ tests: (input: String, match: (Substring, Capture1, Capture2)?, expectError1: Error1?, expectError2: Error2?)...,
-      file: StaticString = #file,
+      file: StaticString = #filePath,
       line: UInt = #line
     ) {
       for (input, match, expectError1, expectError2) in tests {
@@ -646,7 +646,7 @@ class CustomRegexComponentTests: XCTestCase {
       _ regex: Regex<Match>,
       _ input: Concat,
       expected: (wholeMatch: Match?, firstMatch: Match?, prefixMatch: Match?),
-      file: StaticString = #file, line: UInt = #line
+      file: StaticString = #filePath, line: UInt = #line
     ) {
       let wholeResult = input.wholeMatch(of: regex)?.output
       let firstResult = input.firstMatch(of: regex)?.output
@@ -661,7 +661,7 @@ class CustomRegexComponentTests: XCTestCase {
       _ regex: Regex<CaptureMatch1>,
       _ input: Concat,
       expected: (wholeMatch: CaptureMatch1?, firstMatch: CaptureMatch1?, prefixMatch: CaptureMatch1?),
-      file: StaticString = #file, line: UInt = #line
+      file: StaticString = #filePath, line: UInt = #line
     ) {
       let wholeResult = input.wholeMatch(of: regex)?.output
       let firstResult = input.firstMatch(of: regex)?.output
diff --git a/Tests/RegexBuilderTests/DSLListCoalescingTests.swift b/Tests/RegexBuilderTests/DSLListCoalescingTests.swift
index 4deb807e6..8afd872c5 100644
--- a/Tests/RegexBuilderTests/DSLListCoalescingTests.swift
+++ b/Tests/RegexBuilderTests/DSLListCoalescingTests.swift
@@ -401,7 +401,7 @@ class DSLListCoalescingTests: XCTestCase {
 }
 
 
-extension DSLTree.Node: @retroactive Equatable {
+extension DSLTree.Node: Equatable {
   public static func == (lhs: DSLTree.Node, rhs: DSLTree.Node) -> Bool {
     switch (lhs, rhs) {
     case (.concatenation(let l), .concatenation(let r)): return l == r
diff --git a/Tests/RegexBuilderTests/RegexDSLTests.swift b/Tests/RegexBuilderTests/RegexDSLTests.swift
index a72a49fc0..9d067596b 100644
--- a/Tests/RegexBuilderTests/RegexDSLTests.swift
+++ b/Tests/RegexBuilderTests/RegexDSLTests.swift
@@ -14,6 +14,10 @@ import XCTest
 import RegexBuilder
 import TestSupport
 
+// Module-local conformances for testing
+extension Regex: @unchecked Sendable {}
+extension Regex.Match: @unchecked Sendable {}
+
 @available(SwiftStdlib 5.7, *)
 class RegexDSLTests: XCTestCase {
   func _testDSLCaptures<MatchType>(
@@ -21,7 +25,7 @@ class RegexDSLTests: XCTestCase {
     matchType: MatchType.Type,
     _ equivalence: (MatchType, MatchType) -> Bool,
     xfail: Bool = false,
-    file: StaticString = #file,
+    file: StaticString = #filePath,
     line: UInt = #line,
     @RegexComponentBuilder _ content: () -> some RegexComponent<MatchType>
   ) throws {
@@ -976,7 +980,7 @@ class RegexDSLTests: XCTestCase {
   func testCanOnlyMatchAtStart() throws {
     func expectCanOnlyMatchAtStart(
       _ expectation: Bool,
-      file: StaticString = #file, line: UInt = #line,
+      file: StaticString = #filePath, line: UInt = #line,
       @RegexComponentBuilder _ content: () -> some RegexComponent
     ) {
       let regex = content().regex
@@ -1643,7 +1647,7 @@ class RegexDSLTests: XCTestCase {
       var label: String
       init(_ label: String) { self.label = label }
       
-      static var traceOutput = ""
+      nonisolated(unsafe) static var traceOutput = ""
       
       func consuming(_ input: String, startingAt index: String.Index, in bounds: Range<String.Index>) throws -> (upperBound: String.Index, output: Void)? {
         print("Matching '\(label)'", to: &Self.traceOutput)
diff --git a/Tests/RegexTests/AlgorithmsTests.swift b/Tests/RegexTests/AlgorithmsTests.swift
index d41917ce3..5807a5d98 100644
--- a/Tests/RegexTests/AlgorithmsTests.swift
+++ b/Tests/RegexTests/AlgorithmsTests.swift
@@ -17,7 +17,7 @@ class RegexConsumerTests: XCTestCase {
 
 }
 
-var enablePrinting = false
+let enablePrinting = false
 func output<T>(_ s: @autoclosure () -> T) {
   if enablePrinting {
     print(s())
@@ -33,12 +33,12 @@ func makeSingleUseSequence<T>(element: T, count: Int) -> UnfoldSequence<T, Void>
 }
 
 struct CountedOptionSet: OptionSet {
-  static var arrayLiteralCreationCount = 0
+  nonisolated(unsafe) static var arrayLiteralCreationCount = 0
   
   var rawValue: Int
   
-  static var one = Self(rawValue: 1)
-  static var two = Self(rawValue: 1)
+  static let one = Self(rawValue: 1)
+  static let two = Self(rawValue: 1)
 }
 
 extension CountedOptionSet {
@@ -120,7 +120,7 @@ class AlgorithmTests: XCTestCase {
       _ string: String,
       _ regex: String,
       _ expected: [Range<Int>],
-      file: StaticString = #file, line: UInt = #line
+      file: StaticString = #filePath, line: UInt = #line
     ) {
       let regex = try! Regex(regex)
       
@@ -164,7 +164,7 @@ class AlgorithmTests: XCTestCase {
       _ input: String,
       _ pattern: String,
       _ expected: [Range<Int>],
-      file: StaticString = #file, line: UInt = #line
+      file: StaticString = #filePath, line: UInt = #line
     ) {
       let actualSeq: [Range<Int>] = input.ranges(of: pattern).map(input.offsets(of:))
       XCTAssertEqual(actualSeq, expected, file: file, line: line)
@@ -222,7 +222,7 @@ class AlgorithmTests: XCTestCase {
       _ string: String,
       _ regex: String,
       _ expected: [Substring],
-      file: StaticString = #file, line: UInt = #line
+      file: StaticString = #filePath, line: UInt = #line
     ) {
       let regex = try! Regex(regex)
       let actual = Array(string.split(separator: regex, omittingEmptySubsequences: false))
@@ -243,7 +243,7 @@ class AlgorithmTests: XCTestCase {
       _ string: String,
       _ separator: String,
       _ expected: [Substring],
-      file: StaticString = #file, line: UInt = #line
+      file: StaticString = #filePath, line: UInt = #line
     ) {
       let actual = Array(string.split(separator: separator, omittingEmptySubsequences: false))
       XCTAssertEqual(actual, expected, file: file, line: line)
@@ -379,7 +379,7 @@ class AlgorithmTests: XCTestCase {
       _ string: String,
       _ regex: String,
       _ expected: Substring,
-      file: StaticString = #file, line: UInt = #line
+      file: StaticString = #filePath, line: UInt = #line
     ) {
       let regex = try! Regex(regex)
       let actual = string.trimmingPrefix(regex)
@@ -403,7 +403,7 @@ class AlgorithmTests: XCTestCase {
       _ string: String,
       _ predicate: (Character) -> Bool,
       _ expected: Substring,
-      file: StaticString = #file, line: UInt = #line
+      file: StaticString = #filePath, line: UInt = #line
     ) {
       let actual = string.trimmingPrefix(while: predicate)
       XCTAssertEqual(actual, expected, file: file, line: line)
@@ -425,7 +425,7 @@ class AlgorithmTests: XCTestCase {
       _ string: String,
       _ pattern: String,
       _ expected: Substring,
-      file: StaticString = #file, line: UInt = #line
+      file: StaticString = #filePath, line: UInt = #line
     ) {
       let actual = string.trimmingPrefix(pattern)
       XCTAssertEqual(actual, expected, file: file, line: line)
@@ -465,7 +465,7 @@ class AlgorithmTests: XCTestCase {
       _ regex: String,
       _ replacement: String,
       _ expected: String,
-      file: StaticString = #file, line: UInt = #line
+      file: StaticString = #filePath, line: UInt = #line
     ) {
       let regex = try! Regex(regex)
       let actual = string.replacing(regex, with: replacement)
@@ -494,7 +494,7 @@ class AlgorithmTests: XCTestCase {
       _ pattern: String,
       _ replacement: String,
       _ expected: String,
-      file: StaticString = #file, line: UInt = #line
+      file: StaticString = #filePath, line: UInt = #line
     ) {
       let actual = string.replacing(pattern, with: replacement)
       XCTAssertEqual(actual, expected, file: file, line: line)
@@ -577,7 +577,7 @@ class AlgorithmTests: XCTestCase {
       _ expected: Bool,
       _ a: some StringProtocol,
       _ b: some StringProtocol,
-      file: StaticString = #file, line: UInt = #line
+      file: StaticString = #filePath, line: UInt = #line
     ) {
       let result = a.firstRange(of: b) != nil
       XCTAssertEqual(expected, result, file: file, line: line)
diff --git a/Tests/RegexTests/CaptureTests.swift b/Tests/RegexTests/CaptureTests.swift
index bbf41d3b3..f17ac1967 100644
--- a/Tests/RegexTests/CaptureTests.swift
+++ b/Tests/RegexTests/CaptureTests.swift
@@ -137,7 +137,7 @@ func captureTest(
   _ expected: CaptureList,
   _ tests: (input: String, output: [StringCapture])...,
   skipEngine: Bool = false,
-  file: StaticString = #file,
+  file: StaticString = #filePath,
   line: UInt = #line
 ) {
   let ast = try! parse(regex, .traditional)
diff --git a/Tests/RegexTests/CompileTests.swift b/Tests/RegexTests/CompileTests.swift
index 1d967c7ed..0879a875e 100644
--- a/Tests/RegexTests/CompileTests.swift
+++ b/Tests/RegexTests/CompileTests.swift
@@ -152,7 +152,7 @@ extension RegexTests {
 
   private func testCompilationEquivalence(
     _ equivs: [String],
-    file: StaticString = #file,
+    file: StaticString = #filePath,
     line: UInt = #line
   ) throws {
     assert(!equivs.isEmpty)
@@ -179,7 +179,7 @@ extension RegexTests {
 
   private func testCompileError(
     _ regex: String, _ error: RegexCompilationError,
-    file: StaticString = #file, line: UInt = #line
+    file: StaticString = #filePath, line: UInt = #line
   ) {
     do {
       _ = try _compileRegex(regex)
@@ -266,7 +266,7 @@ extension RegexTests {
     func expectInitialOptions<T>(
       _ regex: Regex<T>,
       _ optionSequence: AST.MatchingOptionSequence,
-      file: StaticString = #file,
+      file: StaticString = #filePath,
       line: UInt = #line
     ) throws {
       var options = MatchingOptions()
@@ -280,7 +280,7 @@ extension RegexTests {
     func expectInitialOptions(
       _ pattern: String,
       _ optionSequence: AST.MatchingOptionSequence,
-      file: StaticString = #file,
+      file: StaticString = #filePath,
       line: UInt = #line
     ) throws {
       let regex = try Regex(pattern)
@@ -322,7 +322,7 @@ extension RegexTests {
     semanticLevel: RegexSemanticLevel? = nil,
     contains targets: Set<DecodedInstr> = [],
     doesNotContain invalid: Set<DecodedInstr> = [],
-    file: StaticString = #file,
+    file: StaticString = #filePath,
     line: UInt = #line
   ) {
     do {
@@ -562,7 +562,7 @@ extension RegexTests {
     func expectCanOnlyMatchAtStart(
       _ regexStr: String,
       _ expectTrue: Bool,
-      file: StaticString = #file,
+      file: StaticString = #filePath,
       line: UInt = #line
     ) throws {
       let regex = try Regex(regexStr)
diff --git a/Tests/RegexTests/LexTests.swift b/Tests/RegexTests/LexTests.swift
index ccfd18eb8..331292a1e 100644
--- a/Tests/RegexTests/LexTests.swift
+++ b/Tests/RegexTests/LexTests.swift
@@ -19,7 +19,7 @@ func diagnose(
   expecting expected: ParseError,
   _ syntax: SyntaxOptions = .traditional,
   _ f: (inout Parser) -> (),
-  file: StaticString = #file,
+  file: StaticString = #filePath,
   line: UInt = #line
 ) {
   var parser = Parser(Source(input), syntax: syntax)
diff --git a/Tests/RegexTests/MatchTests.swift b/Tests/RegexTests/MatchTests.swift
index 34fff7465..73b0a7b91 100644
--- a/Tests/RegexTests/MatchTests.swift
+++ b/Tests/RegexTests/MatchTests.swift
@@ -14,6 +14,10 @@ import XCTest
 @testable @_spi(RegexBenchmark) @_spi(Foundation) import _StringProcessing
 import TestSupport
 
+// Module-local conformances for testing
+extension Regex: @unchecked Sendable {}
+extension Regex.Match: @unchecked Sendable {}
+
 struct MatchError: Error {
   var message: String
   init(_ message: String) {
@@ -27,7 +31,7 @@ struct MatchError: Error {
 func _roundTripLiteral(
   _ regexStr: String,
   syntax: SyntaxOptions,
-  file: StaticString = #file,
+  file: StaticString = #filePath,
   line: UInt = #line
 ) throws -> Regex<AnyRegexOutput>? {
   guard let pattern = try Regex(regexStr, syntax: syntax)._literalPattern else {
@@ -45,7 +49,7 @@ func _firstMatch(
   validateOptimizations: Bool,
   semanticLevel: RegexSemanticLevel = .graphemeCluster,
   syntax: SyntaxOptions = .traditional,
-  file: StaticString = #file,
+  file: StaticString = #filePath,
   line: UInt = #line
 ) throws -> (String, [String?])? {
   var regex = try Regex(regexStr, syntax: syntax).matchingSemantics(semanticLevel)
@@ -182,7 +186,7 @@ func flatCaptureTest(
   xfail: Bool = false,
   validateOptimizations: Bool = true,
   semanticLevel: RegexSemanticLevel = .graphemeCluster,
-  file: StaticString = #file,
+  file: StaticString = #filePath,
   line: UInt = #line
 ) {
   for (test, expect) in tests {
@@ -244,7 +248,7 @@ func matchTest(
   xfail: Bool = false,
   validateOptimizations: Bool = true,
   semanticLevel: RegexSemanticLevel = .graphemeCluster,
-  file: StaticString = #file,
+  file: StaticString = #filePath,
   line: UInt = #line
 ) {
   for (test, expect) in tests {
@@ -2831,7 +2835,7 @@ extension RegexTests {
   func expectCompletion(
     regex: String,
     in target: String,
-    file: StaticString = #file,
+    file: StaticString = #filePath,
     line: UInt = #line
   ) {
     let expectation = XCTestExpectation(description: "Run the given regex to completion")
diff --git a/Tests/RegexTests/ParseTests.swift b/Tests/RegexTests/ParseTests.swift
index cbb9e6b32..0bb189731 100644
--- a/Tests/RegexTests/ParseTests.swift
+++ b/Tests/RegexTests/ParseTests.swift
@@ -40,7 +40,7 @@ func parseTest(
   throwsError expectedErrors: ParseError..., unsupported: Bool = false,
   uncheckedErrors: Bool = false, syntax: SyntaxOptions = .traditional,
   captures expectedCaptures: CaptureList = [],
-  file: StaticString = #file,
+  file: StaticString = #filePath,
   line: UInt = #line
 ) {
   parseTest(
@@ -57,7 +57,7 @@ func parseTest(
   uncheckedErrors: Bool = false,
   syntax: SyntaxOptions = .traditional,
   captures expectedCaptures: CaptureList = [],
-  file: StaticString = #file,
+  file: StaticString = #filePath,
   line: UInt = #line
 ) {
   let ast = parseWithRecovery(input, syntax)
@@ -143,7 +143,7 @@ func parseTest(
 @discardableResult
 func delimiterLexingTest(
   _ input: String, ignoreTrailing: Bool = false,
-  file: StaticString = #file, line: UInt = #line
+  file: StaticString = #filePath, line: UInt = #line
 ) -> String {
   input.withCString(encodedAs: UTF8.self) { ptr in
     let endPtr = ptr + input.utf8.count
@@ -173,7 +173,7 @@ func parseWithDelimitersTest(
   _ input: String, _ expecting: AST.Node,
   throwsError expectedErrors: ParseError..., unsupported: Bool = false,
   uncheckedErrors: Bool = false, ignoreTrailing: Bool = false,
-  file: StaticString = #file, line: UInt = #line
+  file: StaticString = #filePath, line: UInt = #line
 ) {
   // First try lexing.
   let literal = delimiterLexingTest(
@@ -200,7 +200,7 @@ func parseWithDelimitersTest(
 func parseNotEqualTest(
   _ lhs: String, _ rhs: String,
   syntax: SyntaxOptions = .traditional,
-  file: StaticString = #file, line: UInt = #line
+  file: StaticString = #filePath, line: UInt = #line
 ) {
   let lhsAST = parseWithRecovery(lhs, syntax)
   let rhsAST = parseWithRecovery(rhs, syntax)
@@ -217,7 +217,7 @@ func rangeTest(
   _ input: String, syntax: SyntaxOptions = .traditional,
   _ expectedRange: (String) -> Range<Int>,
   at locFn: (AST.Node) -> SourceLocation = \.location,
-  file: StaticString = #file, line: UInt = #line
+  file: StaticString = #filePath, line: UInt = #line
 ) {
   let ast = parseWithRecovery(input, syntax).root
   let range = input.offsets(of: locFn(ast).range)
@@ -275,7 +275,7 @@ func matchDiagnostics(
 func diagnosticTest(
   _ input: String, _ expectedErrors: ParseError..., unsupported: Bool = false,
   syntax: SyntaxOptions = .traditional,
-  file: StaticString = #file, line: UInt = #line
+  file: StaticString = #filePath, line: UInt = #line
 ) {
   let ast = parseWithRecovery(input, syntax)
   matchDiagnostics(
@@ -286,7 +286,7 @@ func diagnosticTest(
 
 func diagnosticWithDelimitersTest(
   _ input: String, _ expectedErrors: ParseError..., unsupported: Bool = false,
-  ignoreTrailing: Bool = false, file: StaticString = #file, line: UInt = #line
+  ignoreTrailing: Bool = false, file: StaticString = #filePath, line: UInt = #line
 ) {
   // First try lexing.
   let literal = delimiterLexingTest(
@@ -302,7 +302,7 @@ func diagnosticWithDelimitersTest(
 func delimiterLexingDiagnosticTest(
   _ input: String, _ expected: DelimiterLexError.Kind,
   syntax: SyntaxOptions = .traditional,
-  file: StaticString = #file, line: UInt = #line
+  file: StaticString = #filePath, line: UInt = #line
 ) {
   do {
     _ = try input.withCString { ptr in
@@ -328,7 +328,7 @@ func delimiterLexingDiagnosticTest(
 
 func compilerInterfaceDiagnosticMessageTest(
   _ input: String, _ expectedErr: String,
-  file: StaticString = #file, line: UInt = #line
+  file: StaticString = #filePath, line: UInt = #line
 ) {
   do {
     let captureBuffer = UnsafeMutableRawBufferPointer(start: nil, count: 0)
diff --git a/Tests/RegexTests/RenderDSLTests.swift b/Tests/RegexTests/RenderDSLTests.swift
index b6b249242..1d6427d7b 100644
--- a/Tests/RegexTests/RenderDSLTests.swift
+++ b/Tests/RegexTests/RenderDSLTests.swift
@@ -30,7 +30,7 @@ extension BidirectionalCollection {
 func testConversion(
   _ regex: String,
   _ expectedDSL: String,
-  file: StaticString = #file, line: UInt = #line
+  file: StaticString = #filePath, line: UInt = #line
 ) throws {
   let ast = try _RegexParser.parse(regex, .traditional)
   let actualDSL = renderAsBuilderDSL(ast: ast).trimmingSuffix(while: \.isWhitespace)
diff --git a/Tests/RegexTests/SyntaxOptionsTests.swift b/Tests/RegexTests/SyntaxOptionsTests.swift
index 13618488c..11e3969db 100644
--- a/Tests/RegexTests/SyntaxOptionsTests.swift
+++ b/Tests/RegexTests/SyntaxOptionsTests.swift
@@ -14,11 +14,11 @@
 import XCTest
 
 
-private let dplus = oneOrMore(
+nonisolated(unsafe) private let dplus = oneOrMore(
   of: atom(.escaped(.decimalDigit)))
-private let dotAST = concat(
+nonisolated(unsafe) private let dotAST = concat(
   dplus, ".", dplus, ".", dplus, ".", dplus)
-private let dotASTQuoted = concat(
+nonisolated(unsafe) private let dotASTQuoted = concat(
   dplus, quote("."), dplus, quote("."), dplus, quote("."), dplus)
 
 extension RegexTests {
diff --git a/Tests/RegexTests/UTS18Tests.swift b/Tests/RegexTests/UTS18Tests.swift
index ae7aa2aa0..f4c93a222 100644
--- a/Tests/RegexTests/UTS18Tests.swift
+++ b/Tests/RegexTests/UTS18Tests.swift
@@ -56,7 +56,7 @@ fileprivate func expectFirstMatch<Output: Equatable>(
   _ input: String,
   _ r: Regex<Output>,
   _ output: Output,
-  file: StaticString = #file,
+  file: StaticString = #filePath,
   line: UInt = #line)
 {
   XCTAssertEqual(input.firstMatch(of: r)?.output, output, file: file, line: line)