Protobuf generation fails when run with front end

[keertip]

Running the dart-protoc-plugin with the VM+FE fails with the message
--dart_out: protoc-gen-dart: Plugin output is unparseable:

The file lib/src/dart_options.pb.dart this line which hides 'void' from dart:core

///
// Generated code. Do not modify.
///
// ignore_for_file: non_constant_identifier_names,library_prefixes
library dart_options_dart_options;

// ignore: UNUSED_SHOWN_NAME
import 'dart:core' show int, bool, double, String, List, override;

which could be the issue.

[kmillikin]

There are two issues in the front end, both of which need to be fixed:

• Treat void as a reserved word (again)

• Add an option to the VM+FE to suppress warnings. (The API for the protoc plugin is to read from stdin and write to stdout. The list of warnings produced on stdout can't be understood by protoc.)

[keertip]

Kevin, could you make this a priority? I can't continue testing in google3 until this is fixed.

[keertip]

Yes, we would want to run the vm with the suppress warnings flag. We have other instances in the internal workflow where the stdout from the cli is used - as in the case of analyzer.

[kmillikin]

@lrhn @peter-ahe-google

This is the issue where void is implicitly hidden from dart:core by not showing it.

[kmillikin]

I have a fix for the first issue, involving the reserved word void, here: https://dart-review.googlesource.com/c/sdk/+/24940

The second issue, involving suppressing warnings, still affects the plugin because there are other warnings besides the bogus ones due to void. Unfortunately, I've run out of time to fix that today (expected fix: tomorrow).

[peter-ahe-google]

Proposed fix for warnings, print them on stderr.

[kmillikin]

I think both of the underlying problems are now fixed. Please reopen this issue if you see the same or related problems.