message: Fix compilations for older compilers that can't deal with sparse initializers.
diff: @@ -140,7 +140,9 @@ TEST(SymbolTableNodeFullPathTest, Print) {
  TEST(ReferenceComponentTest, MatchesMetatypeTest) {
  { // kUnspecified matches all metatypes
  - const ReferenceComponent component{.metatype = SymbolType::kUnspecified};
  + const ReferenceComponent component{.identifier = "",
  + .ref_type = ReferenceType::kUnqualified,
  + .metatype = SymbolType::kUnspecified};
  for (const auto& other : {SymbolType::kUnspecified, SymbolType::kParameter,
  SymbolType::kFunction, SymbolType::kTask}) {
  const auto status = component.MatchesMetatype(other);
  @@ -148,7 +150,10 @@ TEST(ReferenceComponentTest, MatchesMetatypeTest) {
  }
  }
  { // all other types must be matched exactly
  - const ReferenceComponent component{.metatype = SymbolType::kFunction};
  + const ReferenceComponent component{.identifier = "",
  + .ref_type = ReferenceType::kUnqualified,
  + .metatype = SymbolType::kFunction};
  +
  for (const auto& other :
  {SymbolType::kUnspecified, SymbolType::kParameter, SymbolType::kModule,
  SymbolType::kTask, SymbolType::kClass}) {
  @@ -197,6 +202,7 @@ TEST(DependentReferencesTest, PrintOnlyRootNodeUnresolved) {
  .components = absl::make_unique<ReferenceComponentNode>(
  ReferenceComponent{.identifier = "foo",
  .ref_type = ReferenceType::kUnqualified,
  + .metatype = SymbolType::kUnspecified,
  .resolved_symbol = nullptr})};
  std::ostringstream stream;
  stream << dep_refs;
  