Merge pull request #2442 from kimdv/kimdv/2435-bad-diagnostic-if-function-call-is-missing-an-argument-label

Emit diagnostic when missing label in function call

Author: kimdv

Sources/SwiftParser/Expressions.swift

@@ -1861,6 +1861,10 @@ extension Parser {
       if self.atArgumentLabel(allowDollarIdentifier: true) && self.peek(isAt: .colon) {
         (unexpectedBeforeLabel, label) = parseArgumentLabel()
         colon = consumeAnyToken()
+      } else if let _colon = self.consume(if: .colon) {
+        unexpectedBeforeLabel = nil
+        label = RawTokenSyntax(missing: .identifier, arena: self.arena)
+        colon = _colon
       } else {
         unexpectedBeforeLabel = nil
         label = nil

Tests/SwiftParserTest/ExpressionTests.swift

@@ -2977,4 +2977,17 @@ final class StatementExpressionTests: ParserTestCase {
       substructure: AttributeSyntax(attributeName: TypeSyntax("Sendable"))
     )
   }
+
+  func testFunctionWithMissingLabel() {
+    assertParse(
+      "foo(1️⃣: 1)",
+      diagnostics: [
+        DiagnosticSpec(
+          message: "expected label in function call",
+          fixIts: ["insert label"]
+        )
+      ],
+      fixedSource: "foo(<#identifier#>: 1)"
+    )
+  }
 }