wehub-resource-sync
30 lines
1.4 KiB
Markdown
30 lines
1.4 KiB
Markdown
# Copybara quirks
|
|
|
|
The purpose of this document is to describe oddities you might see while
|
|
contributing due to the tool that manages copying source back and forth from
|
|
Google's internal repository. This tool is called [Copybara](https://github.com/google/copybara).
|
|
|
|
## Internal source of truth
|
|
|
|
Because the source of truth for the code in this repository is Google's internal
|
|
repo, Copybara does transformations to the code whenever the code is imported
|
|
and exported. This means that sometimes seemingly normal changes can break
|
|
internally in surprising ways.
|
|
|
|
## PR merge status and diff inconsistencies
|
|
|
|
Since the source of truth is internal, PRs are not merged directly, they are
|
|
imported to the Google internal repo where they undergo additional testing,
|
|
and then that internal change is submitted, and attributed to the PR author.
|
|
Because of the transformations that Copybara applies, there's no guarantee that
|
|
the diff will be identical (for example, Copybara applies formatting on import).
|
|
|
|
For this reason, Copybara won't mark the PR as merged, it will close the PR and
|
|
separately apply a commit that should map very closely to the PR.
|
|
|
|
## Dependency on TSL by copy
|
|
|
|
As implemented currently, to prevent any temporary broken commits, XLA
|
|
depends on TSL not by downloading a copy by using Bazel's `http_archive`, but by
|
|
having Copybara copy TSL into XLA's `third_party` directory.
|