Modernize package.

Package.swift

@@ -69,3 +69,20 @@ if ProcessInfo.processInfo.environment["OMIT_MACRO_TESTS"] == nil {
     )
   )
 }
+
+for target in package.targets {
+  target.swiftSettings = target.swiftSettings ?? []
+  target.swiftSettings?.append(contentsOf: [
+    .enableUpcomingFeature("ExistentialAny"),
+    .enableUpcomingFeature("ImmutableWeakCaptures"),
+    .enableUpcomingFeature("InferIsolatedConformances"),
+    .enableUpcomingFeature("InternalImportsByDefault"),
+    .enableUpcomingFeature("MemberImportVisibility"),
+    .enableUpcomingFeature("NonisolatedNonsendingByDefault"),
+  ])
+  #if compiler(>=6.4)
+    target.swiftSettings?.append(contentsOf: [
+      .treatAllWarnings(as: .error)
+    ])
+  #endif
+}

Sources/CasePaths/Internal/TypeName.swift

@@ -1,3 +1,5 @@
+import Foundation
+
 // NB: This is adapted from Custom Dump and should ideally be kept in sync.
 package func typeName(_ type: Any.Type) -> String {
   var name = _typeName(type, qualified: true)

Sources/CasePathsMacros/CasePathableMacro.swift

@@ -1,7 +1,7 @@
 import SwiftDiagnostics
-import SwiftSyntax
+public import SwiftSyntax
 import SwiftSyntaxBuilder
-import SwiftSyntaxMacros
+public import SwiftSyntaxMacros
 
 public struct CasePathableMacro {
   static let moduleName = "CasePaths"
@@ -247,7 +247,7 @@ extension CasePathableMacro: MemberMacro {
 }
 
 enum CasePathableMacroDiagnostic {
-  case notAnEnum(DeclGroupSyntax)
+  case notAnEnum(any DeclGroupSyntax)
   case overloadedCaseName(String)
 }
 

Sources/CasePathsMacros/Plugin.swift

@@ -3,7 +3,7 @@ import SwiftSyntaxMacros
 
 @main
 struct CasePathsPlugin: CompilerPlugin {
-  let providingMacros: [Macro.Type] = [
+  let providingMacros: [any Macro.Type] = [
     CasePathableMacro.self
   ]
 }

Tests/CasePathsTests/CasePathsTests.swift

@@ -32,16 +32,16 @@ final class CasePathsTests: XCTestCase {
 
   func testResult() {
     struct SomeError: Error, Equatable {}
-    XCTAssertEqual(Result<Int, Error>.success(42)[case: \.success], 42)
-    XCTAssertNil(Result<Int, Error>.failure(SomeError())[case: \.success])
-    XCTAssertNil(Result<Int, Error>.success(42)[case: \.failure])
-    XCTAssertNotNil(Result<Int, Error>.failure(SomeError())[case: \.failure])
+    XCTAssertEqual(Result<Int, any Error>.success(42)[case: \.success], 42)
+    XCTAssertNil(Result<Int, any Error>.failure(SomeError())[case: \.success])
+    XCTAssertNil(Result<Int, any Error>.success(42)[case: \.failure])
+    XCTAssertNotNil(Result<Int, any Error>.failure(SomeError())[case: \.failure])
     XCTAssertEqual((\Result<Int, SomeError>.Cases.success)(42), .success(42))
     XCTAssertEqual((\Result<Int, SomeError>.Cases.failure)(SomeError()), .failure(SomeError()))
-    XCTAssertEqual(Result.allCasePaths[Result<Int, Error>.success(42)], \.success)
-    XCTAssertNotEqual(Result.allCasePaths[Result<Int, Error>.success(42)], \.failure)
-    XCTAssertEqual(Result.allCasePaths[Result<Int, Error>.failure(SomeError())], \.failure)
-    XCTAssertNotEqual(Result.allCasePaths[Result<Int, Error>.failure(SomeError())], \.success)
+    XCTAssertEqual(Result.allCasePaths[Result<Int, any Error>.success(42)], \.success)
+    XCTAssertNotEqual(Result.allCasePaths[Result<Int, any Error>.success(42)], \.failure)
+    XCTAssertEqual(Result.allCasePaths[Result<Int, any Error>.failure(SomeError())], \.failure)
+    XCTAssertNotEqual(Result.allCasePaths[Result<Int, any Error>.failure(SomeError())], \.success)
   }
 
   func testSelfCaseKeyPathCallAsFunction() {

Tests/CasePathsTests/CaseSetTests.swift

@@ -1,5 +1,5 @@
 #if canImport(Testing) && swift(>=6)
-  import CasePaths
+  public import CasePaths
   import Testing
 
   @dynamicMemberLookup