Update ImplementationRequest to match version 3.14 of the LSP spec

Sources/LanguageServerProtocol/DefinitionRequest.swift

@@ -24,7 +24,7 @@
 /// - Returns: The location of the definition(s).
 public struct DefinitionRequest: TextDocumentRequest, Hashable {
   public static let method: String = "textDocument/definition"
-  public typealias Response = DefinitionResponse?
+  public typealias Response = LocationsOrLocationLinksResponse?
 
   /// The document in which to lookup the symbol location.
   public var textDocument: TextDocumentIdentifier
@@ -37,32 +37,3 @@ public struct DefinitionRequest: TextDocumentRequest, Hashable {
     self.position = position
   }
 }
-
-public enum DefinitionResponse: ResponseType, Hashable {
-  case locations([Location])
-  case locationLinks([LocationLink])
-
-  public init(from decoder: Decoder) throws {
-    if let locations = try? [Location](from: decoder) {
-      self = .locations(locations)
-    } else if let locationLinks = try? [LocationLink](from: decoder) {
-      self = .locationLinks(locationLinks)
-    } else if let location = try? Location(from: decoder) {
-      // Fallback: Decode single location as array with one element
-      self = .locations([location])
-    } else {
-      let context = DecodingError.Context(codingPath: decoder.codingPath, debugDescription: "DefinitionResponse could neither be decoded as [Location], nor as [LocationLink], nor as Location")
-      throw DecodingError.dataCorrupted(context)
-    }
-  }
-
-  public func encode(to encoder: Encoder) throws {
-    switch self {
-    case .locations(let locations):
-      try locations.encode(to: encoder)
-    case .locationLinks(let locationLinks):
-      try locationLinks.encode(to: encoder)
-    }
-  }
-}
-

Sources/LanguageServerProtocol/ImplementationRequest.swift

@@ -25,7 +25,7 @@
 ///            protocol conforming types, subclasses, or overrides.
 public struct ImplementationRequest: TextDocumentRequest, Hashable {
   public static let method: String = "textDocument/implementation"
-  public typealias Response = [Location]
+  public typealias Response = LocationsOrLocationLinksResponse?
 
   /// The document in which the given symbol is located.
   public var textDocument: TextDocumentIdentifier

Sources/LanguageServerProtocol/LocationsOrLocationLinksResponse.swift

@@ -0,0 +1,40 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2019 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
+//
+//===----------------------------------------------------------------------===//
+
+public enum LocationsOrLocationLinksResponse: ResponseType, Hashable {
+  case locations([Location])
+  case locationLinks([LocationLink])
+
+  public init(from decoder: Decoder) throws {
+    if let locations = try? [Location](from: decoder) {
+      self = .locations(locations)
+    } else if let locationLinks = try? [LocationLink](from: decoder) {
+      self = .locationLinks(locationLinks)
+    } else if let location = try? Location(from: decoder) {
+      // Fallback: Decode single location as array with one element
+      self = .locations([location])
+    } else {
+      let context = DecodingError.Context(codingPath: decoder.codingPath, debugDescription: "Expected [Location], [LocationLink], or Location")
+      throw DecodingError.dataCorrupted(context)
+    }
+  }
+
+  public func encode(to encoder: Encoder) throws {
+    switch self {
+    case .locations(let locations):
+      try locations.encode(to: encoder)
+    case .locationLinks(let locationLinks):
+      try locationLinks.encode(to: encoder)
+    }
+  }
+}
+

Sources/SourceKit/SourceKitServer.swift

@@ -81,7 +81,7 @@ public final class SourceKitServer: LanguageServer {
                                          CompletionList(isIncomplete: false, items: []))
     registerToolchainTextDocumentRequest(SourceKitServer.hover, nil)
     registerToolchainTextDocumentRequest(SourceKitServer.definition, .locations([]))
-    registerToolchainTextDocumentRequest(SourceKitServer.implementation, [])
+    registerToolchainTextDocumentRequest(SourceKitServer.implementation, .locations([]))
     registerToolchainTextDocumentRequest(SourceKitServer.symbolInfo, [])
     registerToolchainTextDocumentRequest(SourceKitServer.documentSymbolHighlight, nil)
     registerToolchainTextDocumentRequest(SourceKitServer.foldingRange, nil)
@@ -627,13 +627,13 @@ extension SourceKitServer {
         if let error = result.failure {
           req.reply(.failure(error))
         } else {
-          req.reply([])
+          req.reply(.locations([]))
         }
         return
       }
 
       guard let usr = symbol.usr, let index = index else {
-        return req.reply([])
+        return req.reply(.locations([]))
       }
 
       var occurs = index.occurrences(ofUSR: usr, roles: .baseOf)
@@ -655,7 +655,7 @@ extension SourceKitServer {
         )
       }
 
-      req.reply(locations)
+      req.reply(.locations(locations))
     }
     let request = Request(symbolInfo, id: req.id, clientID: ObjectIdentifier(self),
                           cancellation: req.cancellationToken, reply: callback)

Tests/LanguageServerProtocolTests/CodingTests.swift

@@ -298,7 +298,7 @@ final class CodingTests: XCTestCase {
       "Some documentation"
       """)
 
-    checkCoding(DefinitionResponse.locations([Location(uri: uri, range: range)]), json: """
+    checkCoding(LocationsOrLocationLinksResponse.locations([Location(uri: uri, range: range)]), json: """
       [
         {
           "range" : \(rangejson.indented(4, skipFirstLine: true)),
@@ -307,7 +307,7 @@ final class CodingTests: XCTestCase {
       ]
       """)
 
-    checkCoding(DefinitionResponse.locationLinks([LocationLink(targetUri: uri, targetRange: range, targetSelectionRange: range)]), json: """
+    checkCoding(LocationsOrLocationLinksResponse.locationLinks([LocationLink(targetUri: uri, targetRange: range, targetSelectionRange: range)]), json: """
       [
         {
           "targetRange" : \(rangejson.indented(4, skipFirstLine: true)),
@@ -322,7 +322,7 @@ final class CodingTests: XCTestCase {
         "range" : \(rangejson.indented(2, skipFirstLine: true)),
         "uri" : "\(urljson)"
       }
-      """, expected: DefinitionResponse.locations([Location(uri: uri, range: range)]))
+      """, expected: LocationsOrLocationLinksResponse.locations([Location(uri: uri, range: range)]))
 
     checkCoding(DocumentSymbolResponse.documentSymbols([DocumentSymbol(name: "mySymbol", kind: .function, range: range, selectionRange: range)]), json: """
       [

Tests/SourceKitTests/ImplementationTests.swift

@@ -25,7 +25,11 @@ final class ImplementationTests: XCTestCase {
     func impls(at testLoc: TestLocation) throws -> Set<Location> {
       let textDocument = testLoc.docIdentifier
       let request = ImplementationRequest(textDocument: textDocument, position: Position(testLoc))
-      let implementations = try ws.sk.sendSync(request)
+      let response = try ws.sk.sendSync(request)
+      guard case .locations(let implementations) = response else {
+        XCTFail("Response was not locations")
+        return []
+      }
       return Set(implementations)
     }
     func testLoc(_ name: String) -> TestLocation {