Merge pull request #892 from ahoppen/ahoppen/colon-in-typealias

Add diagnostic if ':' is used in a typealias declaration instead of '='

Author: ahoppen

Sources/SwiftParser/Declarations.swift

@@ -1909,7 +1909,14 @@ extension Parser {
     }
 
     // Parse the binding alias.
-    let (unexpectedBeforeEqual, equal) = self.expect(.equal)
+    let unexpectedBeforeEqual: RawUnexpectedNodesSyntax?
+    let equal: RawTokenSyntax
+    if let colon = self.consume(if: .colon) {
+      unexpectedBeforeEqual = RawUnexpectedNodesSyntax(elements: [RawSyntax(colon)], arena: self.arena)
+      equal = missingToken(.equal, text: nil)
+    } else {
+      (unexpectedBeforeEqual, equal) = self.expect(.equal)
+    }
     let value = self.parseType()
     let initializer = RawTypeInitializerClauseSyntax(
       unexpectedBeforeEqual,

Sources/SwiftParser/Diagnostics/ParseDiagnosticsGenerator.swift

@@ -304,6 +304,22 @@ public class ParseDiagnosticsGenerator: SyntaxAnyVisitor {
     return .visitChildren
   }
 
+  public override func visit(_ node: TypeInitializerClauseSyntax) -> SyntaxVisitorContinueKind {
+    if shouldSkip(node) {
+      return .skipChildren
+    }
+    if node.equal.presence == .missing {
+      exchangeTokens(
+        unexpected: node.unexpectedBeforeEqual,
+        unexpectedTokenCondition: { $0.tokenKind == .colon },
+        correctTokens: [node.equal],
+        message: { _ in MissingNodesError(missingNodes: [Syntax(node.equal)]) },
+        fixIt: { ReplaceTokensFixIt(replaceTokens: $0, replacement: node.equal) }
+      )
+    }
+    return .visitChildren
+  }
+
   public override func visit(_ node: UnresolvedTernaryExprSyntax) -> SyntaxVisitorContinueKind {
     if shouldSkip(node) {
       return .skipChildren

Sources/SwiftParser/Diagnostics/ParserDiagnosticMessages.swift

@@ -169,3 +169,12 @@ public struct MoveTokensInFrontOfFixIt: ParserFixIt {
   }
 }
 
+public struct ReplaceTokensFixIt: ParserFixIt {
+  public let replaceTokens: [TokenSyntax]
+
+  public let replacement: TokenSyntax
+
+  public var message: String {
+    "replace \(missingNodesDescription(missingNodes: replaceTokens.map(Syntax.init), commonParent: nil)) by '\(replacement.text)'"
+  }
+}

Tests/SwiftParserTest/translated/TypealiasTests.swift

@@ -35,17 +35,15 @@ final class TypealiasTests: XCTestCase {
     )
   }
 
+  // <rdar://problem/13339798> QoI: poor diagnostic in malformed typealias
   func testTypealias3a() {
     AssertParse(
       """
-      // <rdar://problem/13339798> QoI: poor diagnostic in malformed typealias
       typealias Foo1 1️⃣: Int
       """,
       diagnostics: [
-        // TODO: Old parser expected error on line 2: expected '=' in type alias declaration, Fix-It replacements: 16 - 17 = '='
-        DiagnosticSpec(message: "expected '=' and value in typealias declaration"),
-        DiagnosticSpec(message: "extraneous ': Int' at top level"),
-      ]
+        DiagnosticSpec(message: "expected '=' in typealias declaration"),
+      ], fixedSource: "typealias Foo1 = Int"
     )
   }
 
@@ -55,10 +53,8 @@ final class TypealiasTests: XCTestCase {
       typealias Foo21️⃣: Int
       """,
       diagnostics: [
-        // TODO: Old parser expected error on line 1: expected '=' in type alias declaration, Fix-It replacements: 15 - 16 = ' ='
-        DiagnosticSpec(message: "expected '=' and value in typealias declaration"),
-        DiagnosticSpec(message: "extraneous ': Int' at top level"),
-      ]
+        DiagnosticSpec(message: "expected '=' in typealias declaration"),
+      ], fixedSource: "typealias Foo2= Int"
     )
   }
 
@@ -68,10 +64,8 @@ final class TypealiasTests: XCTestCase {
       typealias Foo3 1️⃣:Int
       """,
       diagnostics: [
-        // TODO: Old parser expected error on line 1: expected '=' in type alias declaration, Fix-It replacements: 16 - 17 = '= '
-        DiagnosticSpec(message: "expected '=' and value in typealias declaration"),
-        DiagnosticSpec(message: "extraneous ':Int' at top level"),
-      ]
+        DiagnosticSpec(message: "expected '=' in typealias declaration"),
+      ], fixedSource: "typealias Foo3 =Int"
     )
   }
 
@@ -81,10 +75,8 @@ final class TypealiasTests: XCTestCase {
       typealias Foo41️⃣:/*comment*/Int
       """,
       diagnostics: [
-        // TODO: Old parser expected error on line 1: expected '=' in type alias declaration, Fix-It replacements: 15 - 16 = ' = '
-        DiagnosticSpec(message: "expected '=' and value in typealias declaration"),
-        DiagnosticSpec(message: "extraneous ':/*comment*/Int' at top level"),
-      ]
+        DiagnosticSpec(message: "expected '=' in typealias declaration"),
+      ], fixedSource: "typealias Foo4=/*comment*/Int"
     )
   }
 
@@ -94,7 +86,6 @@ final class TypealiasTests: XCTestCase {
       typealias Recovery11️⃣
       """,
       diagnostics: [
-        // TODO: Old parser expected error on line 1: expected '=' in type alias declaration
         DiagnosticSpec(message: "expected '=' and value in typealias declaration"),
       ]
     )
@@ -103,13 +94,11 @@ final class TypealiasTests: XCTestCase {
   func testTypealias6() {
     AssertParse(
       """
-      typealias Recovery2 1️⃣:
+      typealias Recovery2 1️⃣:2️⃣
       """,
       diagnostics: [
-        // TODO: Old parser expected error on line 1: expected '=' in type alias declaration
-        // TODO: Old parser expected error on line 1: expected type in type alias declaration
-        DiagnosticSpec(message: "expected '=' and value in typealias declaration"),
-        DiagnosticSpec(message: "extraneous ':' at top level"),
+        DiagnosticSpec(locationMarker: "1️⃣", message: "expected '=' in typealias declaration", fixIts: ["replace ':' by '='"]),
+        DiagnosticSpec(locationMarker: "2️⃣", message: "expected value in typealias declaration"),
       ]
     )
   }
@@ -120,7 +109,6 @@ final class TypealiasTests: XCTestCase {
       typealias Recovery3 =1️⃣
       """,
       diagnostics: [
-        // TODO: Old parser expected error on line 1: expected type in type alias declaration
         DiagnosticSpec(message: "expected value in typealias declaration"),
       ]
     )
@@ -132,24 +120,19 @@ final class TypealiasTests: XCTestCase {
       typealias Recovery4 1️⃣: Int
       """,
       diagnostics: [
-        // TODO: Old parser expected error on line 1: expected '=' in type alias declaration
-        DiagnosticSpec(message: "expected '=' and value in typealias declaration"),
-        DiagnosticSpec(message: "extraneous ': Int' at top level"),
+        DiagnosticSpec(message: "expected '=' in typealias declaration", fixIts: ["replace ':' by '='"]),
       ]
     )
   }
 
   func testTypealias9() {
     AssertParse(
       """
-      typealias Recovery5 1️⃣: Int, Float
+      typealias Recovery5 1️⃣: Int2️⃣, Float
       """,
       diagnostics: [
-        // TODO: Old parser expected error on line 1: expected '=' in type alias declaration
-        // TODO: Old parser expected error on line 1: consecutive statements on a line must be separated by ';'
-        // TODO: Old parser expected error on line 1: expected expression
-        DiagnosticSpec(message: "expected '=' and value in typealias declaration"),
-        DiagnosticSpec(message: "extraneous ': Int, Float' at top level"),
+        DiagnosticSpec(locationMarker: "1️⃣", message: "expected '=' in typealias declaration", fixIts: ["replace ':' by '='"]),
+        DiagnosticSpec(locationMarker: "2️⃣", message: "extraneous ', Float' at top level"),
       ]
     )
   }
@@ -160,7 +143,6 @@ final class TypealiasTests: XCTestCase {
       typealias Recovery6 = 1️⃣=
       """,
       diagnostics: [
-        // TODO: Old parser expected error on line 1: expected type in type alias declaration
         DiagnosticSpec(message: "expected value in typealias declaration"),
         DiagnosticSpec(message: "extraneous '=' at top level"),
       ]