Feature Request: Add Support for XLIFF 2.x Files

[Kanti]

Description
Currently, the grumphp-config package (through pluswerk/grumphp-xliff-task) supports linting for XLIFF files — but this appears to target XLIFF 1.2 only.
Modern translation workflows and frameworks (e.g. Symfony 6+, TYPO3 12+, and many CAT tools) increasingly use XLIFF 2.0/2.1, which are not fully compatible with XLIFF 1.x.

Adding support for XLIFF 2.x would ensure that GrumPHP checks remain relevant for current localization pipelines.

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Why this matters

• XLIFF 2.x is the official OASIS standard and is now widely adopted.
• Some projects have fully migrated to .xlf files using version="2.0" or "2.1".
• Without explicit support, valid files may fail validation or be skipped.

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Proposed Implementation

• Detect the XLIFF version via the root attribute (version="2.0" or "2.1").
• Use appropriate XML Schema validation for XLIFF 2.x (available from OASIS).
• Add a configuration flag, e.g.:

parameters:
    tasks:
      xlifflint:
        xliff_version: 2.1

• Fallback to 1.2 if unspecified (to maintain backward compatibility).

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Example

<xliff version="2.0" srcLang="en" trgLang="de">
  <file id="homepage">
    <unit id="welcome">
      <segment>
        <source>Hello world!</source>
        <target>Hallo Welt!</target>
      </segment>
    </unit>
  </file>
</xliff>

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Expected Behavior

• GrumPHP validates XLIFF 2.0/2.1 files correctly.
• No false positives or XML schema errors for valid modern .xlf files.
• Clear validation errors when XLIFF 2.x structure is invalid.

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References

• OASIS XLIFF 2.1 Standard
• pluswerk/grumphp-xliff-task on Packagist

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Environment

• grumphp-config version: latest
• grumphp-xliff-task version: latest
• PHP version: n/a

[Kanti]

https://mastodon.social/@froemken/115967454554170414

Achtet bei euren #TYPO3 xlf Dateien, die diesen 2-letter ISO Code nicht vorne im Namen haben darauf, dass in diesen Dateien das target-language (v1.0/1.2) oder auch trgLng (v2.0) NICHT enthalten ist. Ab TYPO3 14 werden die Labels sonst nicht mehr angezeigt.