validation: structure containing a RTA cannot be used as a uniform buffer

Bug: tint:294
Change-Id: I47a87d902c3bc0df6f62712b7461f51a0f292343
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/54860
Auto-Submit: Sarah Mashayekhi <sarahmashay@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>

src/resolver/resolver.cc

@@ -744,6 +744,21 @@ bool Resolver::ValidateGlobalVariable(const VariableInfo* info) {
         }
         return false;
       }
+
+      for (auto* member : str->Members()) {
+        if (auto* arr = member->Type()->As<sem::Array>()) {
+          if (arr->IsRuntimeSized()) {
+            diagnostics_.add_error(
+                "structure containing a runtime sized array "
+                "cannot be used as a uniform buffer",
+                info->declaration->source());
+            diagnostics_.add_note("structure is declared here",
+                                  str->Declaration()->source());
+            return false;
+          }
+        }
+      }
+
       break;
     }
     default:

src/resolver/storage_class_validation_test.cc

@@ -152,7 +152,24 @@ TEST_F(ResolverStorageClassValidationTest, StorageBufferNoError_Aliases) {
   ASSERT_TRUE(r()->Resolve());
 }
 
-///
+TEST_F(ResolverStorageClassValidationTest, UniformBuffer_Struct_Runtime) {
+  // [[block]] struct S { m:  array<f32>; };
+  // [[set(0), binding(0)]] var<uniform, > svar : S;
+
+  auto* s = Structure(Source{{12, 34}}, "S", {Member("m", ty.array<i32>())},
+                      {create<ast::StructBlockDecoration>()});
+
+  Global(Source{{56, 78}}, "svar", ty.Of(s), ast::StorageClass::kUniform,
+         ast::DecorationList{
+             create<ast::BindingDecoration>(0),
+             create<ast::GroupDecoration>(0),
+         });
+
+  ASSERT_FALSE(r()->Resolve());
+  EXPECT_EQ(r()->error(),
+            "56:78 error: structure containing a runtime sized array cannot be "
+            "used as a uniform buffer\n12:34 note: structure is declared here");
+}
 
 TEST_F(ResolverStorageClassValidationTest, UniformBufferBool) {
   // var<uniform> g : bool;