[spirv-reader] Drop NonWritable NonReadable for now

Pending WGSL issue https://github.com/gpuweb/gpuweb/issues/935

Bug: tint:3, tint:99
Change-Id: I90771e6e0c6a2f109fd6e361d79adea273ca7bc6
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/25261
Reviewed-by: dan sinclair <dsinclair@chromium.org>

src/reader/spirv/parser_impl.cc

@@ -375,6 +375,11 @@ ParserImpl::ConvertMemberDecoration(const Decoration& decoration) {
         return nullptr;
       }
       return std::make_unique<ast::StructMemberOffsetDecoration>(decoration[1]);
+    case SpvDecorationNonReadable:
+    case SpvDecorationNonWritable:
+      // TODO(dneto): Drop these for now.
+      // https://github.com/gpuweb/gpuweb/issues/935
+      return nullptr;
     default:
       // TODO(dneto): Support the remaining member decorations.
       break;
@@ -744,13 +749,14 @@ ast::type::Type* ParserImpl::ConvertType(
         return nullptr;
       } else {
         auto ast_member_decoration = ConvertMemberDecoration(decoration);
-        if (ast_member_decoration == nullptr) {
+        if (!success_) {
-          // Already emitted diagnostics.
           return nullptr;
         }
+        if (ast_member_decoration) {
           ast_member_decorations.push_back(std::move(ast_member_decoration));
         }
       }
+    }
     const auto member_name = namer_.GetMemberName(type_id, member_index);
     auto ast_struct_member = std::make_unique<ast::StructMember>(
         member_name, ast_member_ty, std::move(ast_member_decorations));

src/reader/spirv/parser_impl.h

@@ -182,8 +182,9 @@ class ParserImpl : Reader {
   DecorationList GetDecorationsForMember(uint32_t id,
                                          uint32_t member_index) const;
 
-  /// Converts a SPIR-V decoration.  On failure, emits a diagnostic and returns
+  /// Converts a SPIR-V decoration. If the decoration is recognized but
-  /// nullptr.
+  /// deliberately dropped, then returns nullptr without a diagnostic.
+  /// On failure, emits a diagnostic and returns nullptr.
   /// @param decoration an encoded SPIR-V Decoration
   /// @returns the corresponding ast::StructuMemberDecoration
   std::unique_ptr<ast::StructMemberDecoration> ConvertMemberDecoration(

src/reader/spirv/parser_impl_module_var_test.cc

@@ -1292,6 +1292,50 @@ TEST_F(SpvParserTest,
          "instruction, found '4'."));
 }
 
+TEST_F(SpvParserTest, ModuleScopeVar_NonReadableDecoration_DroppedForNow) {
+  auto* p = parser(test::Assemble(R"(
+     OpName %myvar "myvar"
+     OpDecorate %strct Block
+     OpMemberDecorate %strct 0 NonReadable
+)" + CommonTypes() + R"(
+     %ptr_sb_strct = OpTypePointer StorageBuffer %strct
+     %myvar = OpVariable %ptr_sb_strct StorageBuffer
+  )"));
+  ASSERT_TRUE(p->BuildAndParseInternalModuleExceptFunctions()) << p->error();
+  EXPECT_TRUE(p->error().empty());
+  const auto module_str = p->module().to_str();
+  EXPECT_THAT(module_str, HasSubstr(R"(
+  Variable{
+    myvar
+    storage_buffer
+    __alias_S__struct_S
+  }
+S -> __struct_S
+})")) << module_str;
+}
+
+TEST_F(SpvParserTest, ModuleScopeVar_NonWritableDecoration_DroppedForNow) {
+  auto* p = parser(test::Assemble(R"(
+     OpName %myvar "myvar"
+     OpDecorate %strct Block
+     OpMemberDecorate %strct 0 NonWritable
+)" + CommonTypes() + R"(
+     %ptr_sb_strct = OpTypePointer StorageBuffer %strct
+     %myvar = OpVariable %ptr_sb_strct StorageBuffer
+  )"));
+  ASSERT_TRUE(p->BuildAndParseInternalModuleExceptFunctions()) << p->error();
+  EXPECT_TRUE(p->error().empty());
+  const auto module_str = p->module().to_str();
+  EXPECT_THAT(module_str, HasSubstr(R"(
+  Variable{
+    myvar
+    storage_buffer
+    __alias_S__struct_S
+  }
+S -> __struct_S
+})")) << module_str;
+}
+
 }  // namespace
 }  // namespace spirv
 }  // namespace reader