fix: Allow TgpuGenericFn to be resolved (#2245)

Author: iwoplaza

packages/typegpu/src/core/function/tgpuFn.ts

@@ -329,7 +329,11 @@ function createGenericFn<T extends AnyFn>(inner: T, pairs: SlotValuePair[]): Tgp
       if (!getName(inner)) {
         setName(inner, label);
       }
-      return this as TgpuGenericFn<T>;
+      return this as TgpuGenericFn<T> & SelfResolvable;
+    },
+
+    [$resolve](ctx: ResolutionCtx): ResolvedSnippet {
+      return ctx.resolve(inner);
     },
 
     with(

packages/typegpu/tests/tgpuGenericFn.test.ts

@@ -372,4 +372,34 @@ describe('TgpuGenericFn - shellless callback wrapper', () => {
       }"
     `);
   });
+
+  it('can be resolved', () => {
+    const foo = tgpu.fn(() => {
+      'use gpu';
+      return 3;
+    });
+
+    const resolved = tgpu.resolve([foo]);
+    expect(resolved).toMatchInlineSnapshot(`
+      "fn foo() -> i32 {
+        return 3;
+      }"
+    `);
+  });
+
+  it('can be resolved (with provided slots)', () => {
+    const mulSlot = tgpu.slot<number>();
+
+    const foo = tgpu.fn(() => {
+      'use gpu';
+      return 3 * mulSlot.$;
+    });
+
+    const resolved = tgpu.resolve([foo.with(mulSlot, 2)]);
+    expect(resolved).toMatchInlineSnapshot(`
+      "fn foo() -> i32 {
+        return 6;
+      }"
+    `);
+  });
 });