Validate that structs must not contain [[block]] decorated struct members

Bug: tint:320
Change-Id: Ia330d194fc343d5cd5dec8fb7a5b126f8f002bc5
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/55280
Reviewed-by: Ben Clayton <bclayton@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>

src/resolver/decoration_validation_test.cc

@@ -617,6 +617,22 @@ TEST_F(StructBlockTest, StructUsedAsArrayElement) {
             "used as an element of an array");
 }
 
+TEST_F(StructBlockTest, StructWithNestedBlockMember_Invalid) {
+  auto* inner =
+      Structure("Inner", {Member("x", ty.i32())},
+                {create<ast::StructBlockDecoration>(Source{{56, 78}})});
+
+  auto* outer =
+      Structure("Outer", {Member(Source{{12, 34}}, "y", ty.Of(inner))});
+
+  Global("G", ty.Of(outer), ast::StorageClass::kPrivate);
+
+  EXPECT_FALSE(r()->Resolve());
+  EXPECT_EQ(
+      r()->error(),
+      R"(12:34 error: structs must not contain [[block]] decorated struct members
+56:78 note: see member's struct decoration here)");
+}
 }  // namespace
 }  // namespace StructBlockTests
 

src/resolver/resolver.cc

@@ -3188,6 +3188,19 @@ bool Resolver::ValidateStructure(const sem::Struct* str) {
         }
       }
     }
+
+    if (auto* member_struct_type = member->Type()->As<sem::Struct>()) {
+      if (auto* member_struct_type_block_decoration =
+              ast::GetDecoration<ast::StructBlockDecoration>(
+                  member_struct_type->Declaration()->decorations())) {
+        diagnostics_.add_error(
+            "structs must not contain [[block]] decorated struct members",
+            member->Declaration()->source());
+        diagnostics_.add_note("see member's struct decoration here",
+                              member_struct_type_block_decoration->source());
+        return false;
+      }
+    }
   }
 
   for (auto* deco : str->Declaration()->decorations()) {