Add script that generates commands for our releases

[biboudis]

This small script, currently, it just generates the necessary commands according to our release. For now it gets the latest release from the list of tags not ending in RCXX. In the future it may be used to fully automate our release process.

Sample output for the current release #5907:

cd /dotty
git checkout 0.12.x
sed -i '' 's/^\([[:blank:]]*\)val baseVersion = "0.12.0-RC1".*/\1val baseVersion = "0.12.0"/' project/Build.scala
git commit -am 'Release Dotty 0.12.0'
git tag 0.12.0
git push --follow-tags --set-upstream origin 0.12
git checkout master
git merge 0.12.x
git push
git checkout -b 0.13.x
sed -i '' 's/^\([[:blank:]]*\)val baseVersion = "0.12.0".*/\1val baseVersion = "0.13.0-RC1"/' project/Build.scala
git commit -am 'Release Dotty 0.13.0-RC1'
git tag 0.13.0-RC1
git push --follow-tags --set-upstream origin 0.13.x
git checkout master
sed -i '' 's/^\([[:blank:]]*\)val baseVersion = "0.13.0".*/\1val baseVersion = "0.14.0"/' project/Build.scala
git commit -am 'Set baseVersion to 0.14.0'
git push

[abgruszecki]

@biboudis if you want to write reasonably resilient shellscripts you might be interested in https://github.com/AleksanderBG/bashutil/blob/master/try.sh. It defines a try function that you use like this:

try mkdir "$dir"
try touch "$dir/file"

try first prints the command being run, attempts to run it and exits if the command returns false. It's way easier to understand what when wrong when you use sth like this.

[abgruszecki]

Oh, I forgot to add this: set -e can sometimes be really surprising, that's why it can be preferable to use something like try: https://mywiki.wooledge.org/BashFAQ/105

[allanrenucci]

I am not convinced by this PR. People publishing and pushing directly to master should know what git commands they are running and what they do. This script suggests that you can just run the script, copy paste the output in your terminal and you're good to go.

On the other hand, I think it would be great to document theses step somewhere. Not sure a script that prints the steps is the best format though

[allanrenucci]

What it this RELEASE_DIR. Why not assume this is ran from within the dotty repo

[biboudis]

Because I wanted a fresh cloned copy with default remotes etc.

[allanrenucci]

Why --set-upstream?

[allanrenucci]

Why --set-upstream?

[allanrenucci]

git push origin master. I am wondering if the default pushes all branches. If think it is better to be specific, specially when you're pushing to master

[allanrenucci]

This script should not assume that origin is lampepfl/dotty

[allanrenucci]

We've been releasing 0.x stable and 0.(x + 1)-RC1 at the same time but there is no reason it should always be the case

[biboudis]

@allanrenucci This was meant to be an auto-generated script towards some level of automation instead of the complete manual way now.

@AleksanderBG At this step all commands are echos, for mere manual execution. Not need for resilience at this point.