ICU-22559 Hardcode the macroregions and add a debug assertion

[sffc]

This is the first working prototype. Possible future work (unclear if we should block this PR):

1. Make sure that there is a test that fails when macroregions aren't being loaded (removing them does not seem to cause any test failures in intltest, which is concerning)
2. Convert the data-consistency assertion to a unit test
3. Port this change to Java

Checklist

• Required: Issue filed: https://unicode-org.atlassian.net/browse/ICU-22559
• Required: The PR title must be prefixed with a JIRA Issue number.
• Required: The PR description must include the link to the Jira Issue, for example by completing the URL in the first checklist item
• Required: Each commit message must be prefixed with a JIRA Issue number.
• Issue accepted (done by Technical Committee after discussion)
• Tests included, if applicable
• API docs and/or User Guide docs changed or added, if applicable

[markusicu]

Thanks for working on this!

Unfortunately, there are test failures. For one of them, we will need to cherry-pick PR #2685 from the maint/maint-74 branch to main. Or maybe just include the one-line icu4c/source/test/depstest/dependencies.txt change here as well? FYI @echeran

For the warnings-as-errors failures, see below.

[sffc]

Unfortunately, there are test failures. For one of them, we will need to cherry-pick PR #2685 from the maint/maint-74 branch to main. Or maybe just include the one-line icu4c/source/test/depstest/dependencies.txt change here as well? FYI @echeran

#2689

[markusicu]

lgtm tnx -- pse squash

[jira-pull-request-webhook]

Hooray! The files in the branch are the same across the force-push. 😃

~ Your Friendly Jira-GitHub PR Checker Bot

[sffc]

Can I merge despite the following depstest error which seems unrelated?

Error: in group ustream: io/ustream.o imports std::ios_base_library_init() - is this a new system symbol?

[markusicu]

Can I merge despite the following depstest error which seems unrelated?

I think that's ok. That failure will be fixed by the maintenance branch change that I pointed out, and that you have in your merger back to main.

[FrankYFTang]

Could you add a comment pointing to the
https://github.com/unicode-org/icu/blob/main/icu4c/source/data/misc/supplementalData.txt#L7661
... region:macroregion{