Invisible delimiters after asm `sym` operand causes parsing errors

[oxalica]

rust-analyzer version: 0.3.2711-standalone [/home/oxa/.config/VSCodium/User/globalStorage/rust-lang.rust-analyzer/rust-analyzer]

rustc version: rustc 1.93.0 (254b59607 2026-01-19)

editor or extension: VSCode

repository link (if public, optional): https://github.com/oxalica/sjlj2/blob/8c9bfbb566f7e2b72250e0d007756715056d4da2/src/lib.rs#L360

code snippet to reproduce:

The following minimized code compiles fine with rustc, but rust-analyzer emits an error.

macro_rules! m {
    ($e:expr) => {
        core::arch::asm!("/*{f}*/", f = sym $e, out("ax") _)
    };
}

fn generic<T>() {}

fn main() {
    unsafe {
        m!(generic::<i32>); 
     // ^^ invalid `_` expression, expected type `()` [rust-analyzer(typed-hole)]
    }
}

The issue occurs when the next TT after sym is a invisible-delimited group captured by macro expr specifier. I have to admit that it is technically more correct to use path specifier in this case (and then rust-analyzer will parse everything fine), but expr should work since it is also accepted by rustc.

[railgun-0402]

@oxalica
Hi! I’d like to work on this.

I’ll try to reproduce it locally and investigate how the sym operand is parsed when the next token is an invisible-delimited group produced by macro expansion. I’ll aim to add a regression test first, then propose a fix.

[railgun-0402]

Hi! I opened a PR to address this issue: #21588.

When capturing a path via $e:expr, macro expansion treats it as Fragment::Expr and wraps it in parentheses to preserve operator precedence.

Feedback welcome 🙏