[BEAM-9301] Check in beam-linkage-check.sh

[suztomo]

#10769 (comment)

This is a script to compare linkage errors (checkJavaLinkage task in the root gradle project) between PR's branch and master branch.

This is a temporary solution before Linkage Checker implements exclusion rules (BEAM-9206).

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Post-Commit Tests Status (on master branch)

Lang	SDK	Apex	Dataflow	Flink	Gearpump	Samza	Spark
Go		---	---		---	---
Java
Python		---			---	---
XLang	---	---	---		---	---	---

Pre-Commit Tests Status (on master branch)

---	Java	Python	Go	Website
Non-portable
Portable	---		---	---

See .test-infra/jenkins/README for trigger phrase, status and link of all Jenkins jobs.

[suztomo]

R: @iemejia
CC: @lukecwik

[suztomo]

@iemejia I tried with zsh compatible shell script, but it's not trivial. Therefore this relies on bash.

[iemejia]

No issues, the shebang should cover it so ok for me

[iemejia]

LGTM Nice!

[iemejia]

Thanks it will be really useful to have this here so we can evolve it together if needed.

[iemejia]

Oups first suggestion of improvement detect if master is checked eagerly to not waste time before failing

[suztomo]

master is checked eagerly

What is it?

[iemejia]

In the last part of the script we do git checkout master just to compare, however if master is already checked out in a different which can happen if you use git worktrees the script breaks losing all the previous work.
I think we can avoid the validation and make the script more robust by not checking master but the hash that corresponds to master. I opened #10865 to tackle this, PTAL @suztomo

[suztomo]

Thank you for explanation.