Support --experimental_allow_proto3_optional option

[2is10]

Since protoc version 3.12.0, this option enables the use of optional in proto3 for explicit field presence.

https://github.com/protocolbuffers/protobuf/blob/master/docs/field_presence.md

When I try to use this option, it’s unrecognized in IntelliJ, and the optional keyword is still forbidden.

[2is10]

I looked for a way to configure protoc gradle tasks with --experimental_allow_proto3_optional, but GenerateProtoTask.groovy doesn’t seem to support it.

[okorz001]

I think I have a PR that adds this but I confess I cannot get tests working (even on master)

edit: tests are passing in CI

[ejona86]

The experimental flag is intended to allow time for plugin implementors to support optional. We explicitly want to discourage users going off and adding the flag. Implementors generally can run protoc manually without too much heart-ache, or they can use the test_proto3_optional file name approach. The flag will become default-enabled soon enough.

In general, passing flags to protoc yields ecosystem issues, as everyone really needs to agree on one set of options. For example, that was one of the issues with javanano. We understand you're excited about optional fields in proto, but they are still not supported at this time.

[doctorpangloss]

Please reconsider, this is such a valuable feature, I promise I'll be responsible and move to whatever new syntax you want when it's officially supported.

[tobq]

+1

[hkoosha]

As now this is impossible to build google ads protos with gradle and this plugin :|
I used this workaround.

protobuf {
    def versionOverride = '3.12.0'

    Map<String, String> notation = [
            group     : 'com.google.protobuf',
            name      : 'protoc',
            version   : versionOverride,
            classifier: project.osdetector.classifier,
            ext       : 'exe',
    ]
    Dependency dep = project.dependencies.add('protobuf', notation)
    File protocFile = configurations['protobuf'].fileCollection(dep).singleFile
    if (!protocFile.canExecute() && !protocFile.setExecutable(true))
        throw new GradleException("Cannot set ${protocFile} as executable")
    println "Using protoc: ${protocFile}"

    def myProtoc = new File("$projectDir/my-protoc.sh");
    myProtoc.delete();
    if(myProtoc.exists())
        throw new GradleException("Cannot set delete ${myProtoc}")
    myProtoc << "#!/bin/bash\n"
    myProtoc << "$protocFile " + '--experimental_allow_proto3_optional $@'
    myProtoc << "\n"
    if(!myProtoc.setExecutable(true))
        throw new GradleException("Cannot set ${myProtoc} as executable")

    protoc {
        path = "${protocFile}"
    }
}

Just add "$projectDir/my-protoc.sh" to your .gitignore and you have a self-contained solution.

[ejona86]

It is no longer experimental. https://github.com/protocolbuffers/protobuf/releases/tag/v3.15.0