Support parsing of key path subscripts on metatypes

This is needed to support parsing eg. https://github.com/swiftlang/swift/pull/73242/files#diff-a94f38549dc87ce27c438b255ae2f29c69cc1c2c5e5069f327c5c7fae7bc553dR667
swiftlang · Oct 2, 2024 · 1dc6bad · 1dc6bad
1 parent f4acb89
commit 1dc6bad
Show file tree

Hide file tree

Showing 3 changed files with 26 additions and 4 deletions.
diff --git a/Sources/SwiftParser/Expressions.swift b/Sources/SwiftParser/Expressions.swift
@@ -997,7 +997,7 @@ extension Parser {
     // the token is an operator starts with '.', or the following token is '['.
     let rootType: RawTypeSyntax?
     if !self.at(prefix: ".") {
-      rootType = self.parseSimpleType(stopAtFirstPeriod: true)
+      rootType = self.parseSimpleType(allowMemberTypes: false)
     } else {
       rootType = nil
     }

diff --git a/Sources/SwiftParser/Types.swift b/Sources/SwiftParser/Types.swift
@@ -190,9 +190,8 @@ extension Parser {
     return parseSimpleType(forAttributeName: true)
   }
 
-  /// Parse a "simple" type
   mutating func parseSimpleType(
-    stopAtFirstPeriod: Bool = false,
+    allowMemberTypes: Bool = true,
     forAttributeName: Bool = false
   ) -> RawTypeSyntax {
     enum TypeBaseStart: TokenSpecSet {
@@ -260,7 +259,9 @@ extension Parser {
 
     var loopProgress = LoopProgressCondition()
     while self.hasProgressed(&loopProgress) {
-      if !stopAtFirstPeriod, self.at(.period) {
+      if allowMemberTypes || (self.at(.period) && self.peek(isAt: .keyword(.Type), .keyword(.Protocol))),
+        self.at(.period)
+      {
         let (unexpectedPeriod, period, skipMemberName) = self.consumeMemberPeriod(previousNode: base)
         if skipMemberName {
           let missingIdentifier = missingToken(.identifier)

diff --git a/Tests/SwiftParserTest/ExpressionTests.swift b/Tests/SwiftParserTest/ExpressionTests.swift
@@ -254,6 +254,27 @@ final class ExpressionTests: ParserTestCase {
     )
   }
 
+  func testKeyPathSubscriptOnType() {
+    assertParse(
+      #"\Foo.Type.[2]"#,
+      substructure: KeyPathExprSyntax(
+        root: TypeSyntax(
+          MetatypeTypeSyntax(baseType: TypeSyntax("Foo"), metatypeSpecifier: .keyword(.Type))
+        ),
+        components: KeyPathComponentListSyntax([
+          KeyPathComponentSyntax(
+            period: .periodToken(),
+            component: KeyPathComponentSyntax.Component(
+              KeyPathSubscriptComponentSyntax(
+                arguments: LabeledExprListSyntax([LabeledExprSyntax(expression: ExprSyntax("2"))])
+              )
+            )
+          )
+        ])
+      )
+    )
+  }
+
   func testKeypathExpressionWithSugaredRoot() {
     let cases: [UInt: String] = [
       // Identifiers