Cannot specify version v3.10.0-rc1 in prototool.yaml

[alisonbelow]

Prototool is unable to support version 3.10.0-rc1 specified in prototool.yaml file.

If the prototool.yaml file looks like:

protoc:
  version: 3.10.0-rc1

then the URL https://github.com/protocolbuffers/protobuf/releases/download/v3.10.0-rc1/protoc-3.10.0-rc1-osx-x86_64.zip is attempted to be used to download the appropriate zip file.

If the prototool.yaml file looks like:

protoc:
  version: 3.10.0-rc-1

then the URL https://github.com/protocolbuffers/protobuf/releases/download/v3.10.0-rc-1/protoc-3.10.0-rc-1-osx-x86_64.zip is attempted to be used to download the appropriate zip file.

The URL to download protoc version is https://github.com/protocolbuffers/protobuf/releases/download/v3.10.0-rc1/protoc-3.10.0-rc-1-osx-x86_32.zip. Notice the difference in .../v3.10.0-rc1/... and .../protoc-3.10.0-rc-1-osx-x86_32.zip. The hyphen location differs in the URL snippet and the zip file name, making it impossible to specify this protoc version in the prototool.yaml file.

[smaye81]

Yeah this is due to an anomaly in how the protoc download URL is formed. We can add additional parsing for release candidates to remove the - for the subdomain portion of the URL.

In the meantime, 3.10.0 is out so hopefully you are no longer blocked on this.

[smaye81]

This should be fixed by #515

[alisonbelow]

Thank you!