windows: write arguments to protoc to a file

[pieter-bos]

A colleague on windows noticed an error in our build to this effect:

java.io.IOException: Cannot run program "C:\Users\Pieter\AppData\Local\protocbridge\protocbridge\cache\v1\protoc-windows-x86_64-3.19.2.exe": CreateProcess error=206, The filename or extension is too long

This occurs on windows when the whole process invocation exceeds 32767 bytes. Since protobuf v3.5.0 you can pass arguments via a file instead, by specifying an argument @<filename>, so this PR proposes to just always do that when running protoc on windows.

[pieter-bos]

@thesamet any chance you could have a look?

[thesamet]

I committed 20c99d1 that adds a method to transform a ProtocRunner to one that writes the args to a file, based on the code you provided. Then users, can using this runner from build.sbt like this:

Compile / PB.runProtoc := protocbridge.ProtocRunner.withParametersAsFile((Compile / PB.runProtoc).value)

Can we test that it works for you? Add to your project/plugins.sbt a dependency on the snapshot version of protoc-bridge:

libraryDependency += "com.thesamet.scalapb" %% "protoc-bridge" % "0.9.7+12-20c99d1d-SNAPSHOT"

and then implement the runProtoc setting describe above in build.sbt. I realize it's not as automated as the original PR, however with Windows I've been getting multiple environment-specific hard to reproduce issues over time that I wouldn't like to materially change how it works for everyone.

[pieter-bos]

Thanks! I can't test it out immediately in our build because we use mill, which has a different entry point for scalapbc here. I'll try to hack in a solution to see if it works, which I think is sufficient insofar it concerns protoc-bridge, but I think a proper solution includes making mill-contrib-scalapblib call scalapbc more like the sbt plugin does.