[Feature] Semantic highlighting for `asm!` and `global_asm!` strings?

[repnop]

Hi, I was wondering if it would be possible to have inline syntax highlighting for raw literals that are used with the asm! and global_asm! macros via semantic highlighting, kind of like what happens with format string literals. Certainly wouldn't mind giving it a go myself if this is desired/possible :)

Thanks!

[lnicola]

I can't give mentoring instructions, but it would probably be possible to implement this (and also awesome!). We have a couple of sub-languages supported: Rust code in docstrings and test fixtures and highlighting for format!-like macros. See crates/ide/src/syntax_highlighting.rs and crates/ide/src/syntax_highlighting/injection.rs.

[matklad]

I can't give mentoring instructions,

Well, you just did :-)

[bjorn3]

It would be nice if it also supported comments, labels and assembly directives highlighting. Those are almost the same across architectures with the exception of all comments other than //.

[matklad]

Hm, the syntax of asm is some specific llvm-assmebly syntax? I wonder if this yak shave should start with building and llvm_asm_syntax crate, a-la ra's rowan-based syntax? I think think it has a potential of being re-usable in various settings, not only in ra.

[lnicola]

I think asm! is standardized (portable) and llvm_asm! is the old asm!.

[bjorn3]

The actual asm in an asm! call is GNU assembly. Or at least LLVM is trying it's best to reproduce it for GCC compatibility.

[lnicola]

I think the new syntax is closer to Intel? Talking about https://blog.rust-lang.org/inside-rust/2020/06/08/new-inline-asm.html and https://github.com/Amanieu/rfcs/blob/inline-asm/text/0000-inline-asm.md.

Reusing asm! was a bit confusing, I guess 😅.

[bjorn3]

The new syntax is equivalent to wrapping the asm in .intel_syntax noprefix and .att_syntax. This is literally what I did when implementing asm for cg_clif using an external assembler

[repnop]

I thought about this a few times since I've made the issue but always got stuck on how to detect which flavor of assembly is being used inside of the macro, because the project I'm currently using asm! in is a RISC-V kernel but I imagine x86_64 dwarfs most other architectures except for perhaps ARM in terms of usage. Would it make sense for that to be something that you configure in the settings and select which assembly you're using since it's usually per-project? Otherwise, especially for small snippets, I feel like it can be difficult to differentiate exactly which one is being used (if that's even a problem) 🤔

[Diggsey]

It's still an unresolved question whether the asm macro will be namespaced under the corresponding arch module or not.

If it is, then detecting the correct flavor should be fairly straightforward. If not, then rust-analyzer could attempt to infer that based on what cfg options are "live" at that point in the code.

[repnop]

Oh, I wasn't aware that was even being considered! I'll have to keep a closer eye on the tracking issue :) but that does sound pretty reasonable to discern if that does end up being the case 👍