Migrate (somewhat) to Swift 5.0

I am unable to perform automatic migration using Xcode 10.2, since my macbook doesn't support that version of Xcode, so I installed Swift 5.0 toolchain and performed most of the steps manually.

.swift-version

@@ -1 +1 @@
-4.2
+5.0

.travis.yml

@@ -6,7 +6,7 @@ jobs:
     - stage: test
       language: swift
       os: osx
-      osx_image: xcode10.1
+      osx_image: xcode10.2
       before_install:
       - brew update
       install:
@@ -26,7 +26,7 @@ jobs:
       if: tag IS present
       language: generic
       os: osx
-      osx_image: xcode10.1
+      osx_image: xcode10.2
       env:
         secure: 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
       addons:

Package.swift

@@ -1,4 +1,4 @@
-// swift-tools-version:4.0
+// swift-tools-version:5.0
 import PackageDescription
 
 let package = Package(
@@ -28,5 +28,5 @@ let package = Package(
             path: "Sources",
             sources: ["Common", "7-Zip", "BZip2", "Deflate", "GZip", "LZMA", "LZMA2", "TAR", "XZ", "ZIP", "Zlib"]),
     ],
-    swiftLanguageVersions: [4]
+    swiftLanguageVersions: [.v5]
 )

SWCompression.podspec

@@ -20,7 +20,7 @@ Pod::Spec.new do |s|
   s.tvos.deployment_target = "9.0"
   s.watchos.deployment_target = "2.0"
 
-  s.swift_version = "4.2"
+  s.swift_version = "5.0"
 
   s.dependency "BitByteData", "~> 1.4.1"
 

SWCompression.xcodeproj/project.pbxproj

@@ -1265,6 +1265,7 @@
 				SDKROOT = macosx;
 				SUPPORTED_PLATFORMS = "macosx watchsimulator iphonesimulator appletvsimulator watchos appletvos iphoneos";
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
+				SWIFT_VERSION = 5.0;
 				TVOS_DEPLOYMENT_TARGET = 9.0;
 				VERSIONING_SYSTEM = "apple-generic";
 				WATCHOS_DEPLOYMENT_TARGET = 2.0;
@@ -1319,6 +1320,7 @@
 				SDKROOT = macosx;
 				SUPPORTED_PLATFORMS = "macosx iphoneos iphonesimulator appletvos appletvsimulator watchos watchsimulator";
 				SWIFT_COMPILATION_MODE = wholemodule;
+				SWIFT_VERSION = 5.0;
 				TVOS_DEPLOYMENT_TARGET = 9.0;
 				VERSIONING_SYSTEM = "apple-generic";
 				WATCHOS_DEPLOYMENT_TARGET = 2.0;
@@ -1349,7 +1351,6 @@
 				PRODUCT_BUNDLE_IDENTIFIER = me.tsolomko.SWCompression;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SKIP_INSTALL = YES;
-				SWIFT_VERSION = 4.2;
 			};
 			name = Debug;
 		};
@@ -1377,7 +1378,6 @@
 				PRODUCT_BUNDLE_IDENTIFIER = me.tsolomko.SWCompression;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SKIP_INSTALL = YES;
-				SWIFT_VERSION = 4.2;
 			};
 			name = Release;
 		};
@@ -1395,7 +1395,6 @@
 				);
 				PRODUCT_BUNDLE_IDENTIFIER = me.tsolomko.TestSWCompression;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 4.2;
 			};
 			name = Debug;
 		};
@@ -1413,7 +1412,6 @@
 				);
 				PRODUCT_BUNDLE_IDENTIFIER = me.tsolomko.TestSWCompression;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 4.2;
 			};
 			name = Release;
 		};