Tests on travis are failing for several reasons:

1. vardumper tests seem to be broken
2. deps=high tests for the form component install dev-master of intl
3. deps=low tests for the form component install 2.8 version of intl

1 is unrelated and needs to be looked into in separation.
2 will be resolved once this PR is merged to 3.4 and master, but I guess for 3 I need to make the test less reliant on specific data as we won't make it work with 2.8.

3. deps=low

can't we bump some lowest dep in a composer.json?

can't we bump some lowest dep in a composer.json?

We could, but it's not necessary as the failing test just relies on data too much.

I just pushed a change that's hopefully gonna fix it.

Thank you @jakzal.

Looks like this creates merge conflicts with changes made in #30588 (eg und in jv.json)
@ro0NL we're going to need your help to ensure your contribution is not lost. E.g. why does ks.json contain mul in 3.4 but not in 4.2? Looks like the script misses blacklisting und, zxx and mul in 3.4, isn't it? I removed them from 4.2 while merging. See git diff 3.4..4.2 -- src/Symfony/Component/Intl/Resources/data/languages/

@nicolas-grekas #28833 was merged into 4.2 (new feature), since filtering languages could be considered a BC break: https://github.com/symfony/intl/blob/45f4510b4fa85f44ad8c588e238f21e06d602ffe/CHANGELOG.md#420

So Intl data updates are merged into lowest branch, but each branch should be re-comiled to apply these filters.

I'll re-generate data for 4.2 to see if anything needs updating.

The fix here seems to be to check if locale_compose returns false, but at the time of writing, the PHP documentation doesn't say it ever returns false. Maybe there should be an extra check for the empty string there? That way you don't rely on undocumented behavior.

@ToonSpinISAAC regardless of what's documented, locale_compose can return false since ICU 64.1. Not sure what an empty string check would change. Unless you can add a failing test to Symfony I don't think there's anything to fix here.

If there's something to fix here it's probably a documentation bug in PHP. If locale_compose is supposed to return false in these cases then it should be documented, but as it is now it isn't, so strictly speaking nobody can rely on that.

Having said that I don't know what the Symfony team is supposed to do about the above. The reason I'm proposing a check for an empty string is that according to the PHP documentation, the function always returns a string - I don't feel strongly enough about this to be disappointed if the check doesn't happen though. 😄

@ToonSpinISAAC I think it should be fixed in the php docs. Previously locale_compose returned null in scenarios it returns false now. It wasn't documented either.