When multiple target labels are applied to a PR, it should be considered
invalid as our tooling does not support a single PR targetting multiple
trains/versions.
PR Close#40156
Previously, each Angular repository had its own strategy/configuration
for merging pull requests and cherry-picking. We worked out a new
strategy for labeling/branching/versioning that should be the canonical
strategy for all actively maintained projects in the Angular organization.
This PR provides a `ng-dev` merge configuration that implements the
labeling/branching/merging as per the approved proposal.
See the following document for the proposal this commit is based on
for the merge script labeling/branching: https://docs.google.com/document/d/197kVillDwx-RZtSVOBtPb4BBIAw0E9RT3q3v6DZkykU
The merge tool label configuration can be conveniently accesed
within each `.ng-dev` configuration, and can also be extended
if there are special labels on individual projects. This is one
of the reasons why the labels are not directly built into the
merge script. The script should remain unopinionated and flexible.
The configuration is conceptually powerful enough to achieve the
procedures as outlined in the versioning/branching/labeling proposal.
PR Close#38223
The merge tool provides a way for configurations to determine the branches
for a label lazily. This is supported because it allows labels to respect
the currently selected base branch through the Github UI. e.g. if `target: label`
is applied on a PR and the PR is based on the patch branch, then the change
could only go into the selected target branch, while if it would be based on
`master`, the change would be cherry-picked to `master` too. This allows for
convenient back-porting of changes if they did not apply cleanly to the primary
development branch (`master`).
We want to expand this function so that it is possible to report failures if an
invalid target label is appplied (e.g. `target: major` not allowed in
some situations), or if the Github base branch is not valid for the given target
label (e.g. if `target: lts` is used, but it's not based on a LTS branch).
PR Close#38223
Moves the merge script from the components repository over
to the shared dev-infra package. The merge script has been
orginally built for all Angular repositories, but we just
kept it in the components repo temporarily to test it.
Since everything went well on the components side, we now
move the script over and integrate it into the dev-infra package.
PR Close#37138
Joey Perrott
Paul Gschwendtner