Copy type param descriptions to constructors

Resolves #3031

Author: Gerrit0

CHANGELOG.md

@@ -13,13 +13,16 @@ title: Changelog
   API: Introduced `typeAnnotation` on `CommentTag`
 - Added `excludePrivateClassFields` option to hide `#private` members while allowing `private` members, #3017.
 - Added support for TypeScript's `@this` tag for JS files which describe `this` parameters, #3026.
-- Remove the `@jsx` tag from the list of additional block tags. TSDoc now directly supports this tag, #3035.
+- API: Re-introduced `relevanceBoost` on `DeclarationReflection` for plugin use, #3036.
 
 ## Bug Fixes
 
 - Fixed conversion of auto-accessor types on properties with the `accessor` keyword, #3019.
 - Improved handling of HTML tags within headers for anchor generation, #3023.
 - Improved support for detecting destructured parameters and renaming them to the name used in the doc comment, #3026.
+- Constructor type parameters will now inherit their class's type parameter descriptions if not otherwise specified, #3031.
+- Fixed compatibility with `@microsoft/tsdoc-config` version 0.18.0, #3035.
+- Custom theme icons will now be used in the "On This Page" sidebar, #3039.
 
 ## v0.28.13 (2025-09-14)
 

src/lib/converter/plugins/CommentPlugin.ts

@@ -267,6 +267,8 @@ export class CommentPlugin extends ConverterComponent {
         _context: Context,
         reflection: TypeParameterReflection,
     ) {
+        if (reflection.comment) return;
+
         const comment = reflection.parent?.comment;
         if (comment) {
             let tag = comment.getIdentifiedTag(reflection.name, "@typeParam");
@@ -286,6 +288,20 @@ export class CommentPlugin extends ConverterComponent {
                 reflection.comment = new Comment(tag.content);
                 reflection.comment.sourcePath = comment.sourcePath;
                 removeIfPresent(comment.blockTags, tag);
+                return;
+            }
+        }
+
+        // #3031 if this is a class constructor, also check for type parameters
+        // that live on the class itself and potentially copy their comment.
+        if (
+            reflection.parent?.kindOf(ReflectionKind.ConstructorSignature) &&
+            reflection.parent.parent?.kindOf(ReflectionKind.Constructor)
+        ) {
+            const cls = reflection.parent.parent.parent as DeclarationReflection;
+            const typeParam = cls.typeParameters?.find(param => param.name === reflection.name);
+            if (typeParam?.comment) {
+                reflection.comment = typeParam.comment.clone();
             }
         }
     }

src/lib/converter/symbols.ts

@@ -658,6 +658,15 @@ function convertClassOrInterface(
 
     context.finalizeDeclarationReflection(reflection);
 
+    // Convert type parameters early so that we get access them when converting the constructors if any
+    if (instanceType.typeParameters) {
+        reflection.typeParameters = instanceType.typeParameters.map((param) => {
+            const declaration = param.symbol.declarations?.[0];
+            assert(declaration && ts.isTypeParameterDeclaration(declaration));
+            return createTypeParamReflection(declaration, reflectionContext);
+        });
+    }
+
     if (classDeclaration && reflection.kind === ReflectionKind.Class) {
         // Classes can have static props
         const staticType = context.checker.getTypeOfSymbolAtLocation(
@@ -712,15 +721,6 @@ function convertClassOrInterface(
         context.checker.getPropertiesOfType(instanceType),
     );
 
-    // And type arguments
-    if (instanceType.typeParameters) {
-        reflection.typeParameters = instanceType.typeParameters.map((param) => {
-            const declaration = param.symbol.declarations?.[0];
-            assert(declaration && ts.isTypeParameterDeclaration(declaration));
-            return createTypeParamReflection(declaration, reflectionContext);
-        });
-    }
-
     // Interfaces might also have call signatures
     // Classes might too, because of declaration merging
     context.checker

src/lib/models/DeclarationReflection.ts

@@ -50,6 +50,8 @@ export class DeclarationReflection extends ContainerReflection {
     /**
      * Precomputed boost for search results, may be less than 1 to de-emphasize this member in search results.
      * Does NOT include group/category values as they are computed when building the JS index.
+     *
+     * This is exposed purely for plugin use, see #3036 for details.
      */
     relevanceBoost?: number;
 

src/test/behavior.c2.test.ts

@@ -1509,4 +1509,21 @@ describe("Behavior Tests", () => {
             `warn: Comment for E specifies @sortStrategy with "invalid2", which is an invalid sort strategy*`,
         );
     });
+
+    it("Handles different type parameter comments on class/constructor", () => {
+        const project = convert("ctorTypeParam");
+
+        const ctor = query(project, "Generic.constructor");
+        equal(ctor.signatures?.length, 2);
+
+        // @template on the class gets saved to class type parameters
+        equal(
+            Comment.combineDisplayParts(query(project, "Generic").typeParameters?.[0].comment?.summary),
+            "class docs",
+        );
+        // Custom @template tag for this constructor
+        equal(Comment.combineDisplayParts(ctor.signatures[0].typeParameters?.[0].comment?.summary), "ctor docs");
+        // Inherits description from class's @template
+        equal(Comment.combineDisplayParts(ctor.signatures[1].typeParameters?.[0].comment?.summary), "class docs");
+    });
 });