Handle @template constraints correctly

Resolves #2389

CHANGELOG.md

@@ -7,6 +7,7 @@
 
 ### Bug Fixes
 
+-   Fixed conversion of `@template` constraints on JSDoc defined type parameters, #2389.
 -   Invalid link validation is now correctly suppressed before all projects have been converted in packages mode, #2403.
 -   Fixed tsconfig handling for projects using a solution-style tsconfig, #2406.
 -   Fixed broken settings icons caused by icon caching introduced in 0.25.1, #2408.

src/lib/converter/factories/signature.ts

@@ -340,6 +340,54 @@ export function createTypeParamReflection(
     return paramRefl;
 }
 
+export function convertTemplateParameterNodes(
+    context: Context,
+    nodes: readonly ts.JSDocTemplateTag[] | undefined,
+) {
+    return nodes?.flatMap((node) => {
+        return node.typeParameters.map((param, index) => {
+            const paramRefl = new TypeParameterReflection(
+                param.name.text,
+                context.scope,
+                getVariance(param.modifiers),
+            );
+            const paramScope = context.withScope(paramRefl);
+            paramRefl.type =
+                index || !node.constraint
+                    ? void 0
+                    : context.converter.convertType(
+                          paramScope,
+                          node.constraint.type,
+                      );
+            paramRefl.default = param.default
+                ? context.converter.convertType(paramScope, param.default)
+                : void 0;
+            if (
+                param.modifiers?.some(
+                    (m) => m.kind === ts.SyntaxKind.ConstKeyword,
+                )
+            ) {
+                paramRefl.flags.setFlag(ReflectionFlag.Const, true);
+            }
+
+            context.registerReflection(paramRefl, param.symbol);
+
+            if (ts.isJSDocTemplateTag(param.parent)) {
+                paramRefl.comment = context.getJsDocComment(param.parent);
+            }
+
+            context.trigger(
+                ConverterEvents.CREATE_TYPE_PARAMETER,
+                paramRefl,
+                param,
+            );
+            return paramRefl;
+        });
+    });
+    const params = (nodes ?? []).flatMap((tag) => tag.typeParameters);
+    return convertTypeParameterNodes(context, params);
+}
+
 function getVariance(
     modifiers: ts.ModifiersArray | undefined,
 ): VarianceModifier | undefined {

src/lib/converter/jsdoc.ts

@@ -16,7 +16,7 @@ import type { Context } from "./context";
 import { ConverterEvents } from "./converter-events";
 import {
     convertParameterNodes,
-    convertTypeParameterNodes,
+    convertTemplateParameterNodes,
 } from "./factories/signature";
 
 export function convertJsDocAlias(
@@ -163,14 +163,6 @@ function convertTemplateParameters(context: Context, node: ts.JSDoc) {
     );
 }
 
-function convertTemplateParameterNodes(
-    context: Context,
-    nodes: readonly ts.JSDocTemplateTag[] | undefined,
-) {
-    const params = (nodes ?? []).flatMap((tag) => tag.typeParameters);
-    return convertTypeParameterNodes(context, params);
-}
-
 function getTypedefReExportTarget(
     context: Context,
     declaration: ts.JSDocTypedefTag | ts.JSDocEnumTag,

src/test/converter2/issues/gh2389.js

@@ -0,0 +1,6 @@
+/**
+ * @template {string} T, U
+ * @param {T} x
+ * @param {U} y
+ */
+export function foo(x, y) {}

src/test/issues.c2.test.ts

@@ -1163,6 +1163,17 @@ describe("Issue Tests", () => {
         );
     });
 
+    it("Handles @template parameter constraints correctly, #2389", () => {
+        const project = convert();
+        const foo = query(project, "foo");
+        equal(foo.signatures?.length, 1);
+        equal(foo.signatures[0].typeParameters?.length, 2);
+
+        const [T, U] = foo.signatures[0].typeParameters;
+        equal(T.type?.toString(), "string");
+        equal(U.type?.toString(), undefined);
+    });
+
     // This is rather unfortunate, we need to do this so that files which include only
     // a single declare module can still have a comment on them, but it looks really
     // weird and wrong if there are multiple declare module statements in a file...