Add a domain to DiagnosticID

This should avoid clashes of diagnostic IDs with the same name from different modules.

Author: ahoppen

Sources/Diagnostics/Message.swift

@@ -18,10 +18,12 @@
 /// same wording. Eg. it’s possible that the message contains more context when
 /// available.
 public struct MessageID: Hashable {
-  private let value: String
+  private let domain: String
+  private let id: String
 
-  public init(_ value: String) {
-    self.value = value
+  public init(domain: String, id: String) {
+    self.domain = domain
+    self.id = id
   }
 }
 

Sources/SwiftParser/Diagnostics/ParserDiagnosticMessages.swift

@@ -13,6 +13,8 @@
 import Diagnostics
 import SwiftSyntax
 
+let diagnosticDomain: String = "SwiftParser"
+
 extension Syntax {
   // FIXME: These should be defined in gyb_syntax_support.
   var nodeTypeNameForDiagnostics: String? {
@@ -43,7 +45,7 @@ public protocol ParserError: DiagnosticMessage {
 
 public extension ParserError {
   static var diagnosticID: MessageID {
-    return MessageID("\(self)")
+    return MessageID(domain: diagnosticDomain, id: "\(self)")
   }
 
   var diagnosticID: MessageID {
@@ -65,7 +67,7 @@ public enum StaticParserError: String, DiagnosticMessage {
   public var message: String { self.rawValue }
 
   public var diagnosticID: MessageID {
-    MessageID("\(type(of: self)).\(self)")
+    MessageID(domain: diagnosticDomain, id: "\(type(of: self)).\(self)")
   }
 
   public var severity: DiagnosticSeverity { .error }

Tests/SwiftParserTest/DiagnosticInfrastructureTests.swift

@@ -9,11 +9,11 @@ public class DiagnosticInfrastructureTests: XCTestCase {
     }
 
     let diag = TestDiagnostic()
-    XCTAssertEqual(diag.diagnosticID, MessageID("TestDiagnostic"))
+    XCTAssertEqual(diag.diagnosticID, MessageID(domain: "SwiftParser", id: "TestDiagnostic"))
     XCTAssertEqual(diag.message, "My test diagnostic")
     XCTAssertEqual(diag.severity, .error)
 
-    XCTAssertEqual(StaticParserError.throwsInReturnPosition.diagnosticID, MessageID("StaticParserDiagnosticMessage.throwsInReturnPosition"))
+    XCTAssertEqual(StaticParserError.throwsInReturnPosition.diagnosticID, MessageID(domain: "SwiftParser", id: "StaticParserDiagnosticMessage.throwsInReturnPosition"))
     XCTAssertEqual(StaticParserError.throwsInReturnPosition.severity, .error)
   }
 }