Add a subcommand to swift-syntax-dev-utils to verify that .spi.yml is up-to-date

.spi.yml at one point got out of sync of the libraries we added to Package.swift. Add a verification script to make sure that they match. The idea is that for every library that every library that is exposed by SwiftSyntax should be documentated on swiftpackageindex.com.

rdar://108901461

Author: ahoppen

SwiftSyntaxDevUtils/Package.swift

@@ -6,7 +6,7 @@ import PackageDescription
 let package = Package(
   name: "swift-syntax-dev-utils",
   platforms: [
-    .macOS(.v10_15)
+    .macOS(.v13)
   ],
   products: [
     .executable(name: "swift-syntax-dev-utils", targets: ["swift-syntax-dev-utils"])

SwiftSyntaxDevUtils/Sources/swift-syntax-dev-utils/SwiftSyntaxDevUtils.swift

@@ -30,6 +30,7 @@ struct SwiftSyntaxDevUtils: ParsableCommand {
       GenerateSourceCode.self,
       Test.self,
       VerifySourceCode.self,
+      VerifySpiYml.self,
     ]
   )
 

SwiftSyntaxDevUtils/Sources/swift-syntax-dev-utils/commands/VerifySpiYml.swift

@@ -0,0 +1,80 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+import ArgumentParser
+import Foundation
+import RegexBuilder
+
+struct VerifySpiYml: ParsableCommand {
+  static let configuration = CommandConfiguration(
+    abstract: "Verify that the .spi.yml file contains all libraries from Package.swift"
+  )
+
+  /// Returns all libraries declared in `Package.swift`.
+  ///
+  /// Note: It would be nice if we could compile Package.swift with this file and reallly
+  /// inspect the package targets instead of doing regex scraping, but this is good enough
+  /// for now.
+  private func librariesInPackageManifest() throws -> [String] {
+    let extractNameRegex = Regex {
+      #/^.*/#
+      #".library(name: ""#
+      Capture(ZeroOrMore(.word))
+      #"""#
+      #/.*$/#
+    }
+    let packageFile = Paths.packageDir.appending(component: "Package.swift")
+    let packageFileContents = try String(contentsOf: packageFile)
+    return
+      packageFileContents
+      .components(separatedBy: "\n")
+      .filter({ !$0.matches(of: extractNameRegex).isEmpty })
+      .map { $0.replacing(extractNameRegex) { $0.1 } }
+      .sorted()
+  }
+  /// Returns all targets listed in `.spi.yml`.
+  ///
+  /// Note: It would be nice to actually parse the .yml file but then we would need to add
+  /// a dependency from this script on a YAML parser and that just doesn’t seem worth it.
+  private func targetsInSwiftPackageIndexManifest() throws -> [String] {
+    let extractTargetRegex = Regex {
+      #/^      - /#
+      Capture(ZeroOrMore(.word))
+      #/$/#
+    }
+    let spiYmlFile = Paths.packageDir.appending(component: ".spi.yml")
+    let spiYmlFileContents = try String(contentsOf: spiYmlFile)
+    return
+      spiYmlFileContents
+      .components(separatedBy: "\n")
+      .filter({ !$0.matches(of: extractTargetRegex).isEmpty })
+      .map { $0.replacing(extractTargetRegex) { $0.1 } }
+      .sorted()
+  }
+
+  func run() throws {
+    let difference = try targetsInSwiftPackageIndexManifest().difference(from: librariesInPackageManifest())
+
+    if !difference.isEmpty {
+      var message = ".spi.yml did not contain the same libraries as Package.swift:\n"
+      for change in difference {
+        switch change {
+        case .insert(_, let element, _):
+          message += " - Unexpected in .spi.yml: \(element)\n"
+        case .remove(_, let element, _):
+          message += " - Missing in .spi.yml: \(element)"
+        }
+      }
+      throw ScriptExectutionError(message: message)
+    }
+  }
+}