Highligh issue with another textmate grammar

[woprandi]

Describe the bug
I'm working on this extension : https://marketplace.visualstudio.com/items?itemName=GraphQL.vscode-graphql to add support to syntax hightlight inside Dart source code.
The port is straightforward (Draft PR here : graphql/graphiql#3612).
Without extension it works but with the Dart extension the hightlight stops to work after few seconds. I guess there are a kind of conflict between grammars (https://github.com/Dart-Code/Dart-Code/blob/master/syntaxes/dart.json and https://github.com/graphql/graphiql/pull/3612/files#diff-1a844416b43dcd649c939cc179b8a5157efd1860392a397657656fdbd6e9168d) but I don't know which and I'm not an expert
I found set settings "editor.semanticHighlighting.enabled": false "fixes" the issue but I guess I'll get some behavior changes elsewhere (and I don't know if it's legitimate)

To Reproduce
Steps to reproduce the behavior:

1. Clone my fork https://github.com/woprandi/graphiql/tree/main
2. cd vscode-graphql-syntax
3. yarn && yarn vsce:package
4. Install vscode-graphql-syntax-1.3.6.vsix
5. Open tests/__fixtures__/test.dart, graphql block highlight should works
6. Install Dart extension
7. Highlighting will disappears like the video

Expected behavior
Hightlighting works

Screenshots

test.webm

Without Dart extension

With Dart extension

Please complete the following information:

You can run the Dart: Collect Diagnostic Information command from the VS Code command palette (F1) to easily capture this information or provide it manually.

• Operating System and version: Fedora 40
• VS Code version: 1.89.1
• Dart extension version: 3.88.1
• Dart/Flutter SDK version: 3.4.1
• Target device (if the issue relates to Flutter debugging):

[DanTup]

I found set settings "editor.semanticHighlighting.enabled": false "fixes" the issue

The reason for this is that there are two ways VS Code uses to provide syntax highlighting. When you first open the file, it is coloured using the textmate grammar. Textmate grammars do not have semantic information (for example they can't tell the difference between a reference to a property or a method because it may be defined in another file) so VS Code also supports "semantic tokens" which are provided by the language server (and therefore have more information) and override the textmate grammar.

More info on semantic tokens in VS Code can be found at https://code.visualstudio.com/api/language-extensions/semantic-highlight-guide

So the problem here is that the semantic tokens are being provided by the Dart language server and overriding everything in the textmate grammar.

Unfortunately VS Code does not support embedded languages when semantic tokens are enabled - I've filed an issue about that in the past at microsoft/vscode#163292 because this has come up before (actually also for GraphQL).

I'll close this as a dupe of #4212 (you can add your 👍 there and also on the VS Code issue at microsoft/vscode#163292), although right now I don't have a great solution besides waiting for VS Code to add support.