Refactor const parse tests (gpuweb#3752)

Refs gpuweb#3741

* Move parse/const tests into decl/const

src/webgpu/listing_meta.json

@@ -1903,6 +1903,7 @@
   "webgpu:shader,validation,decl,const:no_indirect_recursion:*": { "subcaseMS": 0.950 },
   "webgpu:shader,validation,decl,const:no_indirect_recursion_via_array_size:*": { "subcaseMS": 2.601 },
   "webgpu:shader,validation,decl,const:no_indirect_recursion_via_struct_attribute:*": { "subcaseMS": 1.034 },
+  "webgpu:shader,validation,decl,const:placement:*": { "subcaseMS": 1.167 },
   "webgpu:shader,validation,decl,const:type:*": { "subcaseMS": 10.651 },
   "webgpu:shader,validation,decl,context_dependent_resolution:attribute_names:*": { "subcaseMS": 533.132 },
   "webgpu:shader,validation,decl,context_dependent_resolution:builtin_value_names:*": { "subcaseMS": 25.538 },
@@ -2502,7 +2503,6 @@
   "webgpu:shader,validation,parse,comments:line_comment_eof:*": { "subcaseMS": 4.500 },
   "webgpu:shader,validation,parse,comments:line_comment_terminators:*": { "subcaseMS": 1.021 },
   "webgpu:shader,validation,parse,comments:unterminated_block_comment:*": { "subcaseMS": 8.950 },
-  "webgpu:shader,validation,parse,const:placement:*": { "subcaseMS": 1.167 },
   "webgpu:shader,validation,parse,diagnostic:after_other_directives:*": { "subcaseMS": 1.000 },
   "webgpu:shader,validation,parse,diagnostic:conflicting_attribute_different_location:*": { "subcaseMS": 2.257 },
   "webgpu:shader,validation,parse,diagnostic:conflicting_directive:*": { "subcaseMS": 1.244 },

src/webgpu/shader/validation/decl/const.spec.ts

@@ -250,3 +250,54 @@ g.test('assert')
     const_assert x == 0;`;
     t.expectCompileResult(true, code);
   });
+
+g.test('placement')
+  .desc('Tests @const is not allowed to appear')
+  .params(u =>
+    u.combine('scope', [
+      'private-var',
+      'storage-var',
+      'struct-member',
+      'fn-decl',
+      'fn-param',
+      'fn-var',
+      'fn-return',
+      'while-stmt',
+      undefined,
+    ] as const)
+  )
+  .fn(t => {
+    const scope = t.params.scope;
+
+    const attr = '@const';
+    const code = `
+      ${scope === 'private-var' ? attr : ''}
+      var<private> priv_var : i32;
+
+      ${scope === 'storage-var' ? attr : ''}
+      @group(0) @binding(0)
+      var<storage> stor_var : i32;
+
+      struct A {
+        ${scope === 'struct-member' ? attr : ''}
+        a : i32,
+      }
+
+      @vertex
+      ${scope === 'fn-decl' ? attr : ''}
+      fn f(
+        ${scope === 'fn-param' ? attr : ''}
+        @location(0) b : i32,
+      ) -> ${scope === 'fn-return' ? attr : ''} @builtin(position) vec4f {
+        ${scope === 'fn-var' ? attr : ''}
+        var<function> func_v : i32;
+
+        ${scope === 'while-stmt' ? attr : ''}
+        while false {}
+
+        return vec4(1, 1, 1, 1);
+      }
+    `;
+
+    t.expectCompileResult(scope === undefined, code);
+  });