Remove last trace of TSCUtility

Replace use of `Diagnostic.fatalError` with a
`SwiftDriver.Diagnostics.errorsEmitted` type which removes the final
reference to `TSCUtility` in the actual shipping code.  References
within the test suite may remain for now.

Author: compnerd

Sources/SwiftDriver/Driver/Driver.swift

@@ -26,7 +26,23 @@ import struct TSCBasic.RelativePath
 import var TSCBasic.localFileSystem
 import var TSCBasic.stderrStream
 import var TSCBasic.stdoutStream
-import enum TSCUtility.Diagnostics
+
+extension Driver {
+  /// Stub Error for terminating the process.
+  public enum ErrorDiagnostics: Swift.Error {
+    case emitted
+  }
+}
+
+extension Driver.ErrorDiagnostics: CustomStringConvertible {
+  public var description: String {
+    switch self {
+    case .emitted:
+      return "errors were encountered"
+    }
+  }
+}
+
 
 /// The Swift driver.
 public struct Driver {
@@ -1839,7 +1855,7 @@ extension Driver {
         if let originalPath = swiftFiles[basename] {
           diagnosticsEngine.emit(.error_two_files_same_name(basename: basename, firstPath: originalPath, secondPath: input))
           diagnosticsEngine.emit(.note_explain_two_files_same_name)
-          throw Diagnostics.fatalError
+          throw ErrorDiagnostics.emitted
         } else {
           swiftFiles[basename] = input
         }
@@ -1852,7 +1868,7 @@ extension Driver {
       if let mainPath = swiftFiles["main.swift"] {
         diagnosticsEngine.emit(.error_two_files_same_name(basename: "main.swift", firstPath: mainPath, secondPath: "-e"))
         diagnosticsEngine.emit(.note_explain_two_files_same_name)
-        throw Diagnostics.fatalError
+        throw ErrorDiagnostics.emitted
       }
 
       try withTemporaryDirectory(dir: fileSystem.tempDirectory, removeTreeOnDeinit: false) { absPath in
@@ -2878,7 +2894,7 @@ extension Triple {
       return WindowsToolchain.self
     default:
       diagnosticsEngine.emit(.error_unknown_target(triple))
-      throw Diagnostics.fatalError
+      throw Driver.ErrorDiagnostics.emitted
     }
   }
 }

Sources/SwiftDriver/Jobs/FrontendJobHelpers.swift

@@ -14,7 +14,6 @@ import class TSCBasic.LocalFileOutputByteStream
 import class TSCBasic.TerminalController
 import struct TSCBasic.RelativePath
 import var TSCBasic.stderrStream
-import enum TSCUtility.Diagnostics
 
 /// Whether we should produce color diagnostics by default.
 fileprivate func shouldColorDiagnostics() -> Bool {
@@ -474,7 +473,7 @@ extension Driver {
     if parsedOptions.hasArgument(.updateCode) {
       guard compilerMode == .standardCompile else {
         diagnosticEngine.emit(.error_update_code_not_supported(in: compilerMode))
-        throw Diagnostics.fatalError
+        throw ErrorDiagnostics.emitted
       }
       assert(primaryInputs.count == 1, "Standard compile job had more than one primary input")
       let input = primaryInputs[0]

Sources/swift-driver/main.swift

@@ -32,7 +32,6 @@ import class TSCBasic.Process
 import class TSCBasic.ProcessSet
 import protocol TSCBasic.DiagnosticData
 import var TSCBasic.localFileSystem
-import enum TSCUtility.Diagnostics
 
 let interruptSignalSource = DispatchSource.makeSignalSource(signal: SIGINT)
 let diagnosticsEngine = DiagnosticsEngine(handlers: [Driver.stderrDiagnosticsHandler])
@@ -100,20 +99,23 @@ do {
 
   // FIXME: The following check should be at the end of Driver.init, but current
   // usage of the DiagnosticVerifier in tests makes this difficult.
-  guard !driver.diagnosticEngine.hasErrors else { throw Diagnostics.fatalError }
+  guard !driver.diagnosticEngine.hasErrors else {
+    throw Driver.ErrorDiagnostics.emitted
+  }
 
   let jobs = try driver.planBuild()
   try driver.run(jobs: jobs)
 
   if driver.diagnosticEngine.hasErrors {
     exit(getExitCode(EXIT_FAILURE))
   }
+
   exit(getExitCode(0))
-} catch Diagnostics.fatalError {
-  exit(getExitCode(EXIT_FAILURE))
 } catch let diagnosticData as DiagnosticData {
   diagnosticsEngine.emit(.error(diagnosticData))
   exit(getExitCode(EXIT_FAILURE))
+} catch Driver.ErrorDiagnostics.emitted {
+  exit(getExitCode(EXIT_FAILURE))
 } catch {
   print("error: \(error)")
   exit(getExitCode(EXIT_FAILURE))