[PackageLoading] Improve flexibility in formatting Package manifests and correctness in parsing Swift tools version specifications

CHANGELOG.md

@@ -1,28 +1,51 @@
 Note: This is in reverse chronological order, so newer entries are added to the top.
 
+Swift Next
+-----------
+* [#2937]
+
+  * Improvements
+
+    `Package` manifests can now have any combination of leading whitespace characters. This allows more flexibility in formatting the manifests.
+
+    [SR-13566] The Swift tools version specification in each manifest file now accepts any combination of _horizontal_ whitespace characters surrounding `swift-tools-version`, if and only if the specified version ≥ `Next`. For example, `//swift-tools-version:	Next` and `//		 swift-tools-version: Next` are valid.
+
+    All [Unicode line terminators](https://www.unicode.org/reports/tr14/) are now recognised in `Package` manifests. This ensures correctness in parsing manifests that are edited and/or built on many non-Unix-like platforms that use ASCII or Unicode encodings. 
+
+  * API Removal
+
+    `ToolsVersionLoader.Error.malformedToolsVersion(specifier: String, currentToolsVersion: ToolsVersion)` is replaced by `ToolsVersionLoader.Error.malformedToolsVersionSpecification(_ malformation: ToolsVersionSpecificationMalformation)`.
+
+    `ToolsVersionLoader.split(_ bytes: ByteString) -> (versionSpecifier: String?, rest: [UInt8])` and `ToolsVersionLoader.regex` are together replaced by `ToolsVersionLoader.split(_ manifest: String) -> ManifestComponents`.
+
+  * Source Breakages for Swift Packages
+
+    The package manager now throws an error if a manifest file contains invalid UTF-8 byte sequences.
+
+    The package manager no longer silently falls back to using Swift 3.1 as the lowest supported version. Instead, a descriptive error is thrown for each misspelling or malformation in the manifest file.
 
 Swift 4.2
 ---------
 
-* [SE-209](https://github.com/apple/swift-evolution/blob/master/proposals/0209-package-manager-swift-lang-version-update.md)
+* [SE-0209]
 
   The `swiftLanguageVersions` property no longer takes its Swift language versions via
   a freeform Integer array; instead it should be passed as a new `SwiftVersion` enum
   array.
 
-* [SE-208](https://github.com/apple/swift-evolution/blob/master/proposals/0208-package-manager-system-library-targets.md)
+* [SE-0208]
 
   The `Package` manifest now accepts a new type of target, `systemLibrary`. This
   deprecates "system-module packages" which are now to be included in the packages
   that require system-installed dependencies.
 
-* [SE-201](https://github.com/apple/swift-evolution/blob/master/proposals/0201-package-manager-local-dependencies.md)
+* [SE-0201]
 
   Packages can now specify a dependency as `package(path: String)` to point to a
   path on the local filesystem which hosts a package. This will enable interconnected
   projects to be edited in parallel.
 
-* [#1604](https://github.com/apple/swift-package-manager/pull/1604)
+* [#1604]
 
   The `generate-xcodeproj` has a new `--watch` option to automatically regenerate the Xcode project
   if changes are detected. This uses the
@@ -34,21 +57,21 @@ Swift 4.2
   * One scheme per executable target containing the test targets whose dependencies
     intersect with the dependencies of the exectuable target.
 
-* [SR-6978](https://bugs.swift.org/browse/SR-6978)
+* [SR-6978]
   Packages which mix versions of the form `vX.X.X` with `Y.Y.Y` will now be parsed and
   ordered numerically.
 
-* [#1489](https://github.com/apple/swift-package-manager/pull/1489)
+* [#1489]
   A simpler progress bar is now generated for "dumb" terminals.
 
 Swift 4.1
 ---------
 
-* [#1485](https://github.com/apple/swift-package-manager/pull/1485)
+* [#1485]
   Support has been added to automatically generate the `LinuxMain` files for testing on
   Linux systems. On a macOS system, run `swift test --generate-linuxmain`.
 
-* [SR-5918](https://bugs.swift.org/browse/SR-5918)
+* [SR-5918]
   `Package` manifests that include multiple products with the same name will now throw an
   error.
 
@@ -66,14 +89,14 @@ Swift 4.0
 Swift 3.0
 ---------
 
-* [SE-0135](https://github.com/apple/swift-evolution/blob/master/proposals/0135-package-manager-support-for-differentiating-packages-by-swift-version.md)
+* [SE-0135]
 
   The package manager now supports writing Swift 3.0 specific tags and
   manifests, in order to support future evolution of the formats used in both
   cases while still allowing the Swift 3.0 package manager to continue to
   function.
 
-* [SE-0129](https://github.com/apple/swift-evolution/blob/master/proposals/0129-package-manager-test-naming-conventions.md)
+* [SE-0129]
 
   Test modules now *must* be named with a `Tests` suffix (e.g.,
   `Foo/Tests/BarTests/BarTests.swift`). This name also defines the name of the
@@ -85,3 +108,18 @@ Swift 3.0
   `swift build`.
 
 * The `Package` initializer now requires the `name:` parameter.
+
+[SE-0129]: https://github.com/apple/swift-evolution/blob/master/proposals/0129-package-manager-test-naming-conventions.md
+[SE-0135]: https://github.com/apple/swift-evolution/blob/master/proposals/0135-package-manager-support-for-differentiating-packages-by-swift-version.md
+[SE-0201]: https://github.com/apple/swift-evolution/blob/master/proposals/0201-package-manager-local-dependencies.md
+[SE-0208]: https://github.com/apple/swift-evolution/blob/master/proposals/0208-package-manager-system-library-targets.md
+[SE-0209]: https://github.com/apple/swift-evolution/blob/master/proposals/0209-package-manager-swift-lang-version-update.md
+
+[SR-5918]: https://bugs.swift.org/browse/SR-5918
+[SR-6978]: https://bugs.swift.org/browse/SR-6978
+[SR-13566]: https://bugs.swift.org/browse/SR-13566
+
+[#1485]: https://github.com/apple/swift-package-manager/pull/1485
+[#1489]: https://github.com/apple/swift-package-manager/pull/1489
+[#1604]: https://github.com/apple/swift-package-manager/pull/1604
+[#2937]: https://github.com/apple/swift-package-manager/pull/2937

Sources/Commands/SwiftPackageTool.swift

@@ -489,7 +489,7 @@ extension SwiftPackageTool {
             case .set(let value):
                 guard let toolsVersion = ToolsVersion(string: value) else {
                     // FIXME: Probably lift this error defination to ToolsVersion.
-                    throw ToolsVersionLoader.Error.malformedToolsVersion(specifier: value, currentToolsVersion: .currentToolsVersion)
+                    throw ToolsVersionLoader.Error.malformedToolsVersionSpecification(.versionSpecifier(.isMisspelt(value)))
                 }
                 try writeToolsVersion(at: pkg, version: toolsVersion, fs: localFileSystem)