From 16aa78d41867b2d545109f9129bca4f895c0ef7b Mon Sep 17 00:00:00 2001
From: Devdatta Talele <bonde.sagar@gmail.com>
Date: Mon, 6 Jul 2026 19:07:50 +0530
Subject: [PATCH] [Tests] Cover @derivative module selector in
 ModuleSelectorTests

Add a substructure assertion inside testModuleSelectorCorrectCode for
@derivative(of: Module::name). The argument list flows through
parseQualifiedDeclarationName -> parseDeclReferenceExpr and therefore
already accepts module selectors; the new test locks that behavior in
for the simple decl-reference form.

The existing @derivative test in testModuleSelectorAttrs covers the
complex qualified form (@derivative with member access + wrt clause).
This new test covers the simpler decl-reference form in
testModuleSelectorCorrectCode alongside the neighbouring @_implements
and @_dynamicReplacement module-selector coverage.

Drop the pre-existing FIXME. The @_differentiable(jvp:vjp:) legacy
argument form referenced by that FIXME has been removed from the
language, and the underscore-prefixed @_derivative spelling is no
longer parsed as a derivative-registration attribute (only the modern
@derivative spelling is recognised - see
DeclarationAttributeWithSpecialSyntax in
Sources/SwiftParser/Attributes.swift).
---
 .../translated/ModuleSelectorTests.swift      | 32 +++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/Tests/SwiftParserTest/translated/ModuleSelectorTests.swift b/Tests/SwiftParserTest/translated/ModuleSelectorTests.swift
index 1f2114b0ca8..2dddc8c892d 100644
--- a/Tests/SwiftParserTest/translated/ModuleSelectorTests.swift
+++ b/Tests/SwiftParserTest/translated/ModuleSelectorTests.swift
@@ -179,8 +179,36 @@ final class ModuleSelectorTests: ParserTestCase {
       )
     )
 
-    // FIXME: Add tests with autodiff @_differentiable(jvp:vjp:) and
-    // @_derivative(of:)
+    assertParse(
+      """
+      @derivative(of: ModuleSelectorTestingKit::negate)
+      func negateDerivative() {}
+      """,
+      substructure: FunctionDeclSyntax(
+        attributes: [
+          .attribute(
+            AttributeSyntax(
+              attributeName: makeType(name: "derivative"),
+              leftParen: .leftParenToken(),
+              arguments: .derivativeRegistrationArguments(
+                DerivativeAttributeArgumentsSyntax(
+                  originalDeclName: makeDeclRef(
+                    moduleSelector: "ModuleSelectorTestingKit",
+                    baseName: "negate"
+                  )
+                )
+              ),
+              rightParen: .rightParenToken()
+            )
+          )
+        ],
+        name: .identifier("negateDerivative"),
+        signature: FunctionSignatureSyntax(
+          parameterClause: FunctionParameterClauseSyntax {}
+        ),
+        body: CodeBlockSyntax {}
+      )
+    )
 
     assertParse(
       """