conditional preprocessor syntax highlighting in C language

[masriomarm]

How to highlight inactive regions as greyed out like the image attached? I'm using clang.

[the-mikedavis]

Syntax highlighting is done with tree-sitter which doesn't have semantic information about these blocks, so turning off highlighting depending on your machine/architecture for example isn't possible

[masriomarm]

I've read your reply few times until I realized the image content. Apologies for the confusion.
I just need to grey out sections of code that are inactive for example

#undef foo
#define bar
#ifdef foo
// this area syntax highlighting should be greyed out
#endif // foo

#ifdef bar
// this are syntax highlighting should be normal
#endif // bar

clangd is aware of the inactive sections, since it refuse to jump to deceleration of symbols that are conditionally defined. VSCode has a similar feature, I think it's a clangd client side dependent feature.

[A-Walrus]

In helix syntax highlighting is handled entirely by tree-sitter, so the LSP (in this case clang) has no effect.
In vscode the plugin takes into account information from clangd to determine highlighting