Allow comments on signature parents to count for docs

This is necessary because TypeDoc 0.26 allows function reflections to
have documentation comments, not just signature reflections. This edge
case was missed when adding support for that.

Resolves #2644

src/lib/validation/documentation.ts

@@ -100,7 +100,13 @@ export function validateDocumentation(
 
         const symbolId = project.getSymbolIdFromReflection(ref);
 
-        if (!ref.hasComment() && symbolId) {
+        // #2644, signatures may be documented by their parent reflection.
+        const hasComment =
+            ref.hasComment() ||
+            (ref.kindOf(ReflectionKind.SomeSignature) &&
+                ref.parent?.hasComment());
+
+        if (!hasComment && symbolId) {
             if (symbolId.fileName.includes("node_modules")) {
                 continue;
             }

src/test/converter2/issues/gh2644.ts

@@ -0,0 +1,7 @@
+/**
+ * Lambda docs
+ * @param value - Value.
+ */
+export const voidLambda = (value: unknown): void => {
+    // ...
+};

src/test/issues.c2.test.ts

@@ -1663,4 +1663,11 @@ describe("Issue Tests", () => {
             [[]],
         );
     });
+
+    it("#2644 allows comments on signature parents to count for being documented", () => {
+        app.options.setValue("validation", { notDocumented: true });
+        const project = convert();
+        app.validate(project);
+        logger.expectNoOtherMessages();
+    });
 });