Basic XLIFF v2.2 support

[matbech]

Description:
When attempting to load an XLIFF file with version 2.2, the process fails completely and throws the following error:
Error while loading XLIFF file: unsupported version (2.2)

Expected behavior:
The system should allow the file to load rather than blocking it entirely. Even though version 2.2 is not fully supported yet, it would be much better if the parser gracefully degraded (perhaps falling back to 2.1/2.0 logic) and simply logged a warning about the unsupported version.

[vslavik]

PRs welcome 😀

Seriously, at least real-world example files would be welcome, can you please attach some? XLIFF 2 is giant and it’s important to know is it used in localization contexts.

The hard error is justified when you don’t know in what ways the new version may break...

For context, 2.2 is a few months old:

• https://docs.oasis-open.org/xliff/xliff-core/v2.2/xliff-core-v2.2-part1.html
• https://docs.oasis-open.org/xliff/xliff-core/v2.2/xliff-extended-v2.2-part2.html#specChangeTracking

The biggest change is some plurals support, which seems simultaneously somewhat over- and under-engineered in a way that makes it hard to use for proper plurals localization.

[matbech]

I am currently migrating away from a CAT tool. As part of this process, I used a custom-built exporter to extract the strings into the XLIFF 2.2 format. The exported data does not yet utilize any features exclusive to version 2.2, such as plurals.

[vslavik]

Ah, I see, so this is just a case of your own script outputting stricter-than-needed version number. I think it’s fair to say that pushes this more into “PRs welcome” territory, but will need fixing as XLIFF 2.2 is adopted in the wild, of course.