Make detection of not supported languages more robust

[nvdaes]

Link to issue number:

None. Fixup of PR #20100

Summary of the issue:

Synthesizers may return None for normalized languages, and this is not addressed in #20100.

Description of user facing changes:

None known.

Description of developer facing changes:

None.

Description of development approach:

Considered the situation where the normalized language is None, improved the function to check if a language is supported, and added unit tests for this function.

Testing strategy:

Tested Reading text of the following Codepen pages, based on tests proposed by @CyrilleB79:

• Webpage with multiple languages
  -webpage with English, French an Italian

Also, run unit tests.

Known issues with pull request:

None.

Code Review Checklist:

• Documentation:
  • Change log entry
  • User Documentation
  • Developer / Technical Documentation
  • Context sensitive help for GUI changes
• Testing:
  • Unit tests
  • System (end to end) tests
  • Manual testing
• UX of all users considered:
  • Speech
  • Braille
  • Low Vision
  • Different web browsers
  • Localization in other languages / culture than English
• API is compatible with existing add-ons.
• Security precautions taken.

[Copilot]

Pull request overview

This PR hardens NVDA’s “is this language supported by the current synthesizer?” check by safely handling language codes that can’t be normalized (e.g. meta languages like x-*) and adds unit tests to prevent regressions.

Changes:

• Update SynthDriver.languageIsSupported to normalize input/available languages once, ignore invalid/None entries, and avoid crashes when normalization returns None.
• Add focused unit tests covering None, exact matches, root-language matches, unsupported languages, and meta languages.
• Update the 2026.2 changelog entry wording to reflect the underlying failure mode more accurately.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
user_docs/en/changes.md	Adjusts the release note wording for the bug fix.
tests/unit/test_synthDriverHandler.py	Adds unit tests for SynthDriver.languageIsSupported.
source/synthDriverHandler.py	Makes language support detection robust against unnormalizable language codes.

[SaschaCowley]

Please retarget this at beta

[LeonarddeR]

Could we also consider binding the reporting of not supported languages to reportLanguage as well? I enabled auto language switching for a moment and got overwhelmed by the amount of "not supported warnings". I think the current base level is too verbose.is to

[nvdaes]

@leonard wrote:

Could we also consider binding the reporting of not supported languages to reportLanguage as well?

I find the option very verbose too. This is targeted to beta, and this was requested by @seanbudd . So I think we should wait for feedback from NV Access, in case we should open a new issue.
I'm happy to change this to the current PR, though, so that not supported languages are reported just when report language is checked.