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diff --git a/docs/docs/contributing/backend.md b/docs/docs/contributing/backend.md new file mode 100644 index 000000000..e7d98bb7f --- /dev/null +++ b/docs/docs/contributing/backend.md @@ -0,0 +1,65 @@ +--- +layout: doc-page +title: Working with the backend +--- + +The compiler backend is based on a fork of the Scala 2.11 `GenBCode` backend and +lives at https://github.com/lampepfl/scala/tree/sharing-backend. The dotty +source tree contains a git submodule in the directory +[scala-backend](https://github.com/lampepfl/dotty/tree/master/scala-backend) +that points to this fork. We do not compile every file in this submodule, +instead we add the subset of files we need to the dotty-compiler project in the +sbt build. + +The most important thing to know when working with git submodules is that +their content is not automatically updated when you do `git checkout` or `git +pull`, instead everytime you switch branch, you need to do: + +``` shell +git submodule update --init +``` + +## Environment setup + +1. Set the following git configuration options to make working with submodules +easier, see the [Git Book](https://git-scm.com/book/en/v2/Git-Tools-Submodules) +for more information: +``` shell +git config --global diff.submodule log +git config --global status.submodulesummary 1 +git config --global push.recurseSubmodules check +``` + +2. Fork https://github.com/lampepfl/scala (in the following commands, + `dotty-staging/scala` is used as a placeholder for your + own fork). +3. ```shell + cd scala-backend + git remote add scala-staging git@github.com:dotty-staging/scala.git + cd .. + ``` + +## Workflow when changing to the backend + +```shell +cd scala-backend +git checkout -b my-feature-branch +# Make some changes ... + +git push -u scala-backend +# Open a PR against https://github.com/lampepfl/scala/tree/sharing-backend +cd .. +``` + +Once your PR has been merged into the backend, you'll need to make another PR +against dotty itself to update the backend, the following commands should be run +in the root dotty repository, not in the submodule: + +``` shell +# The --remote option will update the submodule to the latest commit in the +# https://github.com/lampepfl/dotty/tree/master/scala-backend branch +git submodule update --init --remote + +git commit -am "Update backend to include ..." +# Then push and make a PR against dotty as usual +``` |