Superfluous semicolons trigger -Wextra-semi-stmt in clang 8.0.0 from C++ compiler on 1.11.0

[wesm]

Version 1.11.0 generates code like

inline void ObjectInfo::UnPackTo(ObjectInfoT *_o, const flatbuffers::resolver_function_t *_resolver) const {
  (void)_o;
  (void)_resolver;
  { auto _e = object_id(); if (_e) _o->object_id = _e->str(); };
  { auto _e = data_size(); _o->data_size = _e; };
  { auto _e = metadata_size(); _o->metadata_size = _e; };
  { auto _e = ref_count(); _o->ref_count = _e; };
  { auto _e = create_time(); _o->create_time = _e; };
  { auto _e = construct_duration(); _o->construct_duration = _e; };
  { auto _e = digest(); if (_e) _o->digest = _e->str(); };
  { auto _e = is_deletion(); _o->is_deletion = _e; };
}

This causes such warnings as

https://travis-ci.org/apache/arrow/jobs/572381802#L2864

Here's the Flatbuffers file that the above generated code originated from

https://github.com/apache/arrow/blob/master/cpp/src/plasma/format/common.fbs

[vglavnyy]

Thank you for the report.
Indeed, the code generator adds the unnecessary ; to the end of each expression.

flatbuffers/src/idl_gen_cpp.cpp

Lines 2607 to 2611 in acc9990

	code_.SetValue("FIELD_NAME", Name(field));
	auto prefix = " { auto _e = {{FIELD_NAME}}(); ";
	auto check = IsScalar(field.value.type.base_type) ? "" : "if (_e) ";
	auto postfix = " };";
	code_ += std::string(prefix) + check + statement + postfix;

Care to make a PR for this?

[wesm]

Thanks for pointing me to the right line of code. Done