Add a script to verify that .spi.yml is up-to-date

.spi.yml 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.

This is also a first stab at writing part of the build infrastructure scripts in Swift.

rdar://108901461

Author: ahoppen

build-script.py

@@ -486,6 +486,18 @@ def verify_source_code_command(args: argparse.Namespace) -> None:
         )
         raise SystemExit(1)
 
+    try:
+        swift = os.path.join(args.toolchain, 'bin', 'swift')
+        verify_spi_yml_script = os.path.join(PACKAGE_DIR, 'utils', 'verifySpiYml.swift')
+        check_call([swift, verify_spi_yml_script], verbose=args.verbose)
+
+    except subprocess.CalledProcessError:
+        printerr(
+            "FAIL: Targets specified in .spi.yml did not match the libraries " +
+            "declared in Package.swift. Please update .spi.yml"
+        )
+        raise SystemExit(1)
+
 
 def build_command(args: argparse.Namespace) -> None:
     try:

utils/verifySpiYml.swift

@@ -0,0 +1,69 @@
+import Foundation
+import RegexBuilder
+
+/// The package root that contains `Package.swift`, `Sources` etc.
+var packageRoot: URL {
+  return URL(fileURLWithPath: #filePath)
+    .deletingLastPathComponent()
+    .deletingLastPathComponent()
+}
+
+/// 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.
+func librariesInPackageManifest() throws -> [String] {
+  let extractNameRegex = Regex {
+    #/^.*/#
+    #".library(name: ""#
+    Capture(ZeroOrMore(.word))
+    #"""#
+    #/.*$/#
+  }
+
+  let packageFile = packageRoot.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) { $0.1 } }
+    .sorted()
+}
+
+/// Returns all targets listed in `.spi.yml`.
+///
+/// Note: It would be nice to actually parse the .yml file but then we would need to add
+/// a dependency from this script on a YAML parser and that just doesn’t seem worth it.
+func targetsInSwiftPackageIndexManifest() throws -> [String] {
+  let extractTargetRegex = Regex {
+    #/^      - /#
+    Capture(ZeroOrMore(.word))
+    #/$/#
+  }
+
+  let spiYmlFile = packageRoot.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()
+}
+
+let difference = try targetsInSwiftPackageIndexManifest().difference(from: librariesInPackageManifest())
+
+for change in difference {
+  switch change {
+  case .insert(_, let element, _):
+    print("Unexpected in .spi.yml: \(element)")
+  case .remove(_, let element, _):
+    print("Missing in .spi.yml: \(element)")
+  }
+}
+
+exit(difference.isEmpty ? 0 : 1)