Add batch files to execute Dotty commands on Windows

[michelou]

1. Batch files present in directory dist\bin\ will be copied unchanged to the gz/zip archives (see sbt dist-bootstrapped/packArchive).
2. Batch files added to project\scripts\ (ie. build.bat, cmdTests.bat and bootstrapCmdTests.bat) are adapted from .drone.yml (executed on the Dotty CI server) and can generate the documentation and the gz/zip archives (depending on bootstrap and tests results).

NB. Point 1 is ready to be tested on a Windows machine, but point 2 requires my changes in compiler\src\*.scala and compiler\test\*.scala to be committed in a new branch (and submitted as a separate PR). Points 1 and 2 have been tested on a Windows machine and are used in PR #5531.

[liufengyun]

Thanks a lot @michelou !

I created a test here: lampepfl/packtest#18

It seems there is some error when running the batch files. As I've very little experience with batch scripts. Could you please have a look? Thanks a lot.

https://ci.appveyor.com/project/liufengyun/packtest-s6xq2/builds/20551431/job/mdakdmt9m9pp6jlr

[liufengyun]

Thanks @michelou , the CI now is green: lampepfl/packtest#18

[liufengyun]

What is the motivation to have both tests and some utility in the same batch?

[liufengyun]

My only concern with this file is that we need CI for windows. Related issue: #4588

We can try to integrate appveyor and run build.bat, but NOT the whole test set.

[michelou]

I wrote projets/scripts/build.bat to mimic the phases executed on Dotty IC on a Windows workstation, not to be run on an AppVeyor server. For instance I added advanced subcommands - you call them "utility" - to reduce execution times while fixing Windows related issues on my laptop (still 2 issues).

[michelou]

I assume your configuration file .appveyor.yml (adapted from sbt's appveyor.yml) will be added to this repo in the same way as .drone.yml. So yes project/scripts/build.bat needs to be removed and the logic in .drone.yml has to be ported to .appveyor.yml using sbt calls, PowerShell code or (as last choice) calls to batch files (see AppVeyor guide).

[liufengyun]

@michelou Thanks for the clarification. My only concern is about maintainability -- if we don't run project/scripts/build.bat in some CI, then it's highly likely it will break unnoticed in the long run. If we can run some check on windows, it's always a win regardless of the coverage (no need to be the same as .drone.yml).

[smarter]

@liufengyun Note that apparently the latest version of drone supports Windows, and we'd like to add Windows to our CI eventually.

[michelou]

Batch files are still available from my project michelou/dotty-examples (see file BUILD.md).