[4.0] Drop Xcode 8.3/Swift 3.1 support

.swift-version

@@ -1 +1 @@
-3.1
+4.0

.travis.yml

@@ -1,3 +1,7 @@
+branches:
+  only:
+    - master
+
 matrix:
   include:
     - script:
@@ -6,34 +10,13 @@ matrix:
         - xcodebuild $XCODE_ACTION -scheme Result-iOS -sdk iphonesimulator -destination "name=iPhone SE" | xcpretty
         - xcodebuild $XCODE_ACTION -scheme Result-tvOS -sdk appletvsimulator -destination "name=Apple TV 1080p" | xcpretty
         - xcodebuild build -scheme Result-watchOS -sdk watchsimulator | xcpretty
-        # - pod lib lint
-      env:
-        - JOB=Xcode
-        - XCODE_ACTION="build-for-testing test-without-building"
-      os: osx
-      osx_image: xcode8.3
-      language: objective-c
-    - script:
-        - set -o pipefail
-        - xcodebuild $XCODE_ACTION -scheme Result-Mac | xcpretty
-        - xcodebuild $XCODE_ACTION -scheme Result-iOS -sdk iphonesimulator -destination "name=iPhone SE" | xcpretty
-        - xcodebuild $XCODE_ACTION -scheme Result-tvOS -sdk appletvsimulator -destination "name=Apple TV 1080p" | xcpretty
-        - xcodebuild build -scheme Result-watchOS -sdk watchsimulator | xcpretty
-        # - pod lib lint
+        - pod lib lint
       env:
         - JOB=Xcode
         - XCODE_ACTION="build-for-testing test-without-building"
       os: osx
       osx_image: xcode9
       language: objective-c
-    - script:
-        - swift --version
-        - swift build
-        - swift test
-      env: JOB=SPM
-      os: osx
-      osx_image: xcode8.3
-      language: objective-c
     - script:
         - swift --version
         - swift build
@@ -46,7 +29,8 @@ matrix:
         - swift --version
         - swift build
         - swift test
-      env: JOB=Linux
+      env:
+        - JOB=Linux
       sudo: required
       dist: trusty
       language: generic
@@ -58,11 +42,12 @@ matrix:
         - swift test
       env:
         - JOB=Linux
-        - SWIFT_VERSION=4.0-DEVELOPMENT-SNAPSHOT-2017-08-04-a
+        - SWIFT_VERSION=4.0-DEVELOPMENT-SNAPSHOT-2017-09-26-a
       sudo: required
       dist: trusty
       language: generic
       install:
         - eval "$(curl -sL https://gist.githubusercontent.com/kylef/5c0475ff02b7c7671d2a/raw/9f442512a46d7a2af7b850d65a7e9bd31edfb09b/swiftenv-install.sh)"
+
 notifications:
   email: false

Result/AnyError.swift

@@ -29,13 +29,6 @@ extension AnyError: CustomStringConvertible {
 
 extension AnyError: LocalizedError {
 	public var errorDescription: String? {
-		#if !(swift(>=4.0) || os(macOS) || os(iOS) || os(tvOS) || os(watchOS))
-			// This workaround below is not needed for Swift 4.0 thanks to
-			// https://github.com/apple/swift-corelibs-foundation/pull/967.
-			if let nsError = error as? NSError {
-				return nsError.localizedDescription
-			}
-		#endif
 		return error.localizedDescription
 	}
 

Tests/ResultTests/ResultTests.swift

@@ -2,11 +2,11 @@
 
 final class ResultTests: XCTestCase {
 	func testMapTransformsSuccesses() {
-		XCTAssertEqual(success.map { $0.characters.count } ?? 0, 7)
+		XCTAssertEqual(success.map { $0.count } ?? 0, 7)
 	}
 
 	func testMapRewrapsFailures() {
-		XCTAssertEqual(failure.map { $0.characters.count } ?? 0, 0)
+		XCTAssertEqual(failure.map { $0.count } ?? 0, 0)
 	}
 
 	func testInitOptionalSuccess() {
@@ -37,7 +37,7 @@ final class ResultTests: XCTestCase {
 
 	func testBimapTransformsSuccesses() {
 		XCTAssertEqual(success.bimap(
-			success: { $0.characters.count },
+			success: { $0.count },
 			failure: { $0 }
 		) ?? 0, 7)
 	}