We can't accept tree-sitter grammars, only TextMate compatible grammars as stated in the CONTRIBUTING.md file. The tree-sitter grammars you see referenced are pulled in directly by the syntax highlighting engine and are managed independently by the team that manages the engine. We update that README whenever that team adds a new grammar.

I don't know that team's plans but as C++ is very popular, it's likely to be switching to C++ some time.

I'm not sure I understand what you mean. Why exactly can we not switch to the tree-sitter-cpp grammar for C++ when other languages use tree-sitter?

Why exactly can we not switch to the tree-sitter-cpp grammar for C++ when other languages use tree-sitter?

Because those other languages aren't getting their grammars from Linguist. They're being pulled in directly by the syntax highlighting engine.

That's why we have this line right at the top of the vendor/README.md:

Essentially GitHub has two syntax highlighting engines: the old engine that uses TextMate-compatible grammars and the new engine that uses tree-sitter grammars.

Linguist provides the grammars for the former (in the tarball attached to every release). The latter pulls the tree-sitter grammars in directly.

There is a plan to slowly phase out the old TextMate-compatible engine, in favour of the new tree-sitter engine, and at this point the team involved may extend the ability to add tree-sitter grammars via Linguist or some other means, but we're no where near that point right now as it turns out tree-sitter grammars aren't all created equal and some have severe performance issues.

So adding a tree-sitter grammar to Linguist will have no effect and the script/add-grammar script should have reported various problems and prevented the addition.

Why exactly can we not switch to the tree-sitter-cpp grammar for C++ when other languages use tree-sitter?

Because those other languages aren't getting their grammars from Linguist. They're being pulled in directly by the syntax highlighting engine.

That's why we have this line right at the top of the vendor/README.md:

linguist/vendor/README.md

Line 6 in 964e265

**Note:** grammars marked with 🐌 are not updated when Linguist is so upstream fixes may take longer to appear on GitHub.

Essentially GitHub has two syntax highlighting engines: the old engine that uses TextMate-compatible grammars and the new engine that uses tree-sitter grammars.

Linguist provides the grammars for the former (in the tarball attached to every release). The latter pulls the tree-sitter grammars in directly.

There is a plan to slowly phase out the old TextMate-compatible engine, in favour of the new tree-sitter engine, and at this point the team involved may extend the ability to add tree-sitter grammars via Linguist or some other means, but we're no where near that point right now as it turns out tree-sitter grammars aren't all created equal and some have severe performance issues.

So adding a tree-sitter grammar to Linguist will have no effect and the script/add-grammar script should have reported various problems and prevented the addition.

How can we get the tree-sitter-cpp grammar into the GitHub syntax highlighter then like the other languages that use it (i.e. C, C#, etc.)?

How can we get the tree-sitter-cpp grammar into the GitHub syntax highlighter then like the other languages that use it (i.e. C, C#, etc.)?

It's up to the team that maintains the engine. You would need to raise a support ticket with GitHub support to get this onto the team's radar.

I have gone ahead and went back to using my fork, removing the file with the obscenely long regular expression (which I don't think had any useful purpose).

Hi, may I ask what needs to be changed before the pull request can be merged?

It's stated right at the top of the failure output:

  1) Failure:
TestGrammars#test_readme_file_is_in_sync [test/test_grammars.rb:42]:
Grammar list is out-of-date. Run `script/list-grammars`.

This should have been run when you ran script/add-grammar:

The second failure is because the submodules aren't sorted. This too should have been done with the script/add-grammar script:

Thanks, I'll fix these

I have made the necessary changes, can the tests be run now?

Since the tests pass, is it ready to be merged yet?
I'm being told

1 review requesting changes by reviewers with write access.

But I can't seem to find the requested changes anywhere, I assume it's because the edits they were made to were thrown out.