fix: Check for context instead of comptime mode in comptime

packages/typegpu/src/core/slot/accessor.ts

@@ -2,7 +2,7 @@ import { type AnyData, isData } from '../../data/dataTypes.ts';
 import { schemaCallWrapper } from '../../data/schemaCallWrapper.ts';
 import { isSnippet, type ResolvedSnippet, snip } from '../../data/snippet.ts';
 import type { BaseData } from '../../data/wgslTypes.ts';
-import { getResolutionCtx, inCodegenMode } from '../../execMode.ts';
+import { getResolutionCtx } from '../../execMode.ts';
 import { getName, hasTinyestMetadata, setName } from '../../shared/meta.ts';
 import type { InferGPU } from '../../shared/repr.ts';
 import {
@@ -174,7 +174,7 @@ export class TgpuAccessorImpl<T extends BaseData>
   }
 
   get $(): InferGPU<T> {
-    if (inCodegenMode()) {
+    if (getResolutionCtx()) {
       return this[$gpuValueOf];
     }
 
@@ -198,7 +198,7 @@ export class TgpuMutableAccessorImpl<T extends BaseData>
   }
 
   get $(): InferGPU<T> {
-    if (inCodegenMode()) {
+    if (getResolutionCtx()) {
       return this[$gpuValueOf];
     }
 

packages/typegpu/tests/tgsl/comptime.test.ts

@@ -75,4 +75,69 @@ describe('comptime', () => {
       }"
     `);
   });
+
+  it('can read accessors during shader resolution', () => {
+    const value = tgpu.accessor(d.f32, 1);
+    const readValue = tgpu.comptime(() => value.$);
+
+    const myFn = tgpu.fn(
+      [],
+      d.f32,
+    )(() => {
+      return readValue();
+    });
+
+    expect(tgpu.resolve([myFn])).toMatchInlineSnapshot(`
+      "fn myFn() -> f32 {
+        return 1f;
+      }"
+    `);
+
+    expect(tgpu.resolve([myFn.with(value, 2)])).toMatchInlineSnapshot(`
+      "fn myFn() -> f32 {
+        return 2f;
+      }"
+    `);
+  });
+
+  it('can read and work with accessors in comptime', () => {
+    const valueAccess = tgpu.accessor(d.f32, 1);
+    const doubleValue = tgpu.comptime(() => valueAccess.$ * 2);
+
+    const myFn = tgpu.fn(
+      [],
+      d.f32,
+    )(() => {
+      return doubleValue();
+    });
+
+    expect(tgpu.resolve([myFn])).toMatchInlineSnapshot(`
+      "fn myFn() -> f32 {
+        return NaNf;
+      }"
+    `);
+
+    expect(tgpu.resolve([myFn.with(valueAccess, 2)])).toMatchInlineSnapshot(`
+      "fn myFn() -> f32 {
+        return NaNf;
+      }"
+    `);
+  });
+
+  it('throws when a comptime-read accessor has no value', () => {
+    const value = tgpu.accessor(d.f32);
+    const readValue = tgpu.comptime(() => value.$);
+    const myFn = () => {
+      'use gpu';
+      return readValue();
+    };
+
+    expect(() => tgpu.resolve([myFn])).toThrowErrorMatchingInlineSnapshot(`
+      [Error: Resolution of the following tree failed:
+      - <root>
+      - fn*:myFn
+      - fn*:myFn()
+      - fn:readValue: Missing value for 'slot:value']
+    `);
+  });
 });