Highlight OPAQUE pragma

[Bodigrim]

https://ghc.gitlab.haskell.org/ghc/doc/users_guide/exts/pragmas.html#opaque-pragma

For changes related to the grammar

• Please add a test case.

  • For changes to regular Haskell code simply add a new section to test/syntax-examples/test.hs.
    Make sure your case has a descriptive comment about what it is covering.

  • When adding foreign definitions, i.e. embeddings, add a new test file for the embedding in
    question.

• Add your changes to the CHANGELOG.md file, ideally with a reference to the issue the PR is
  fixing. Also feel free to credit yourself there.

[sheaf]

Ah sorry, that documentation is completely outdated. I'll update it.

The procedure these days is to add a test to test/tests, in this case test/tests/Opaque.hs would do. You should be able to follow the format of other tests, it's self-explanatory enough I hope.

[Bodigrim]

Sorry, I'm afraid I cannot use test.sh. It says

./test.sh: line 35: local: -n: invalid option
local: usage: local name[=value] ...

That's because Bash on macOS is quite old:

$ /bin/bash --version
GNU bash, version 3.2.57(1)-release (arm64-apple-darwin24)
Copyright (C) 2007 Free Software Foundation, Inc.

[sheaf]

Thank you for your contribution!