feat: A type alias for no-custom auto inputs

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

@@ -7,7 +7,7 @@ import type { BaseData, v4f } from '../../data/wgslTypes.ts';
 import { getName, setName } from '../../shared/meta.ts';
 import type { InferGPU, InferGPURecord, InferRecord } from '../../shared/repr.ts';
 import { $internal, $resolve } from '../../shared/symbols.ts';
-import type { Assume } from '../../shared/utilityTypes.ts';
+import type { Assume, RemoveIndexSignature } from '../../shared/utilityTypes.ts';
 import type { TgpuVertexAttrib } from '../../shared/vertexFormat.ts';
 import type { ResolutionCtx, SelfResolvable } from '../../types.ts';
 import { shaderStageSlot } from '../slot/internalSlots.ts';
@@ -21,7 +21,8 @@ const builtinVertexIn = {
   $instanceIndex: builtin.instanceIndex,
 } as const;
 
-export type AutoVertexIn<T extends AnyAutoCustoms> = T & InferRecord<typeof builtinVertexIn>;
+export type AutoVertexIn<T extends AnyAutoCustoms> = RemoveIndexSignature<T> &
+  InferRecord<typeof builtinVertexIn>;
 
 export type _AutoVertexIn<T> = AutoVertexIn<{
   [Key in keyof T]: T[Key] extends TgpuVertexAttrib
@@ -47,7 +48,8 @@ const builtinFragmentIn = {
   $subgroupSize: builtin.subgroupSize,
 } as const;
 
-export type AutoFragmentIn<T extends AnyAutoCustoms> = T & InferRecord<typeof builtinFragmentIn>;
+export type AutoFragmentIn<T extends AnyAutoCustoms> = RemoveIndexSignature<T> &
+  InferRecord<typeof builtinFragmentIn>;
 
 const builtinFragmentOut = {
   $fragDepth: builtin.fragDepth,

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

@@ -121,6 +121,8 @@ export declare namespace TgpuFragmentFn {
   type Out = Record<string, BaseData> | BaseData;
   type AutoIn<T extends AnyAutoCustoms> = AutoFragmentIn<T>;
   type AutoOut<T extends AnyAutoCustoms = AnyAutoCustoms> = AutoFragmentOut<T>;
+
+  type AutoInEmpty = AutoFragmentIn<Record<string, never>>;
 }
 
 export function fragmentFn<FragmentOut extends FragmentOutConstrained>(options: {

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

@@ -86,6 +86,8 @@ export declare namespace TgpuVertexFn {
   type Out = Record<string, BaseData>;
   type AutoIn<T> = _AutoVertexIn<T>;
   type AutoOut<T extends AnyAutoCustoms = AnyAutoCustoms> = AutoVertexOut<T>;
+
+  type AutoInEmpty = _AutoVertexIn<Record<string, never>>;
 }
 
 export function vertexFn<VertexOut extends VertexOutConstrained>(options: {

packages/typegpu/src/shared/utilityTypes.ts

@@ -56,7 +56,7 @@ export type Mutable<T> = {
 };
 
 /**
- * Source: https://code.lol/post/programming/higher-kinded-types/
+ * Source: https://code.lol/post/programming/higher-kinded-types
  */
 export type Assume<T, U> = T extends U ? T : U;
 
@@ -74,3 +74,16 @@ export type TypedArray =
 export function assertExhaustive(x: never, location: string): never {
   throw new Error(`Failed to handle ${x} at ${location}`);
 }
+
+/**
+ * Source: https://futurestud.io/tutorials/typescript-how-to-remove-index-signature-from-a-type
+ */
+export type RemoveIndexSignature<T> = {
+  [K in keyof T as string extends K
+    ? never
+    : number extends K
+      ? never
+      : symbol extends K
+        ? never
+        : K]: T[K];
+};

packages/typegpu/tests/renderPipeline.test.ts

@@ -6,8 +6,10 @@ import tgpu, {
   common,
   d,
   MissingBindGroupsError,
+  type TgpuFragmentFn,
   type TgpuFragmentFnShell,
   type TgpuRenderPipeline,
+  type TgpuVertexFn,
   type TgpuVertexFnShell,
 } from '../src/index.js';
 import { $internal } from '../src/shared/symbols.ts';
@@ -1591,7 +1593,7 @@ describe('root.createRenderPipeline', () => {
       attribs: { vertexIndex: vertexLayout.attrib },
       vertex: ({ vertexIndex, $vertexIndex }) => {
         'use gpu';
-        return { $position: d.vec4f() };
+        return { $position: d.vec4f(vertexIndex, $vertexIndex, 0, 1) };
       },
       fragment: () => {
         'use gpu';
@@ -1619,7 +1621,7 @@ describe('root.createRenderPipeline', () => {
       },
       fragment: ({ position }) => {
         'use gpu';
-        return d.vec4f();
+        return position;
       },
       targets: { format: 'rgba8unorm' },
     });
@@ -1641,7 +1643,10 @@ describe('root.createRenderPipeline', () => {
       },
       fragment: ({ $frontFacing, frontFacing }) => {
         'use gpu';
-        return d.vec4f();
+        if ($frontFacing && frontFacing === 1) {
+          return d.vec4f(0, 1, 0, 1);
+        }
+        return d.vec4f(1, 0, 0, 1);
       },
       targets: { format: 'rgba8unorm' },
     });
@@ -1774,6 +1779,54 @@ describe('root.createRenderPipeline', () => {
       ]
     `);
   });
+
+  it('accepts entry functions with no attributes or varyings', ({ root }) => {
+    const positions = tgpu.const(d.arrayOf(d.vec2f, 3), [
+      d.vec2f(0, 0),
+      d.vec2f(1, 0),
+      d.vec2f(0, 1),
+    ]);
+    const vertex = ({ $vertexIndex }: TgpuVertexFn.AutoInEmpty) => {
+      'use gpu';
+      return {
+        $position: d.vec4f(positions.$[$vertexIndex]!, 0, 1),
+      } satisfies TgpuVertexFn.AutoOut;
+    };
+
+    const fragment = ({ $position }: TgpuFragmentFn.AutoInEmpty) => {
+      'use gpu';
+      return $position;
+    };
+
+    const pipeline = root.createRenderPipeline({
+      vertex,
+      fragment,
+    });
+
+    expect(tgpu.resolve([pipeline])).toMatchInlineSnapshot(`
+      "const positions: array<vec2f, 3> = array<vec2f, 3>(vec2f(), vec2f(1, 0), vec2f(0, 1));
+
+      struct VertexOut {
+        @builtin(position) position: vec4f,
+      }
+
+      struct VertexIn {
+        @builtin(vertex_index) vertexIndex: u32,
+      }
+
+      @vertex fn vertex(_arg_0: VertexIn) -> VertexOut {
+        return VertexOut(vec4f(positions[_arg_0.vertexIndex], 0f, 1f));
+      }
+
+      struct FragmentIn {
+        @builtin(position) position: vec4f,
+      }
+
+      @fragment fn fragment(_arg_0: FragmentIn) -> @location(0) vec4f {
+        return _arg_0.position;
+      }"
+    `);
+  });
 });
 
 describe('matchUpVaryingLocations', () => {