Constant panic/crashing while typing on a string inside a macro

[ThomasMiz]

Hello! I'm getting panic messages each time I type a character inside a string formatting macro. I have been able to reproduce this on an empty project with nothing but a main method like so:

fn main() {
    let some_number = 0;
    format!("hola {some_number}");
}

To trigger the bug, copy and paste this into the main.rs of a new, empty project, and then put the cursor somewhere between the { and the }, and type anything. Each character typed causes a panic message being printed to stderr. I have tested this behavior with println!, panic!, and format! and the panics happen on all three.

NOTE: The bug only happens if there is an opening AND closing bracket! The bug does NOT happen when typing like so:

println!("hola {s
println!("hola {some_num
println!("hola {some_number}");

The bug does happen when typing like so:

print
println!()
println!("")
println!("hola {}")
println!("hola {some_}") // <== Panics start here
println!("hola {some_number}")

Here is a text file with my stderr output.

rust-analyzer version: 0.3.1860-standalone (5346002 2024-02-25)
rustc 1.78.0-nightly (878c8a2a6 2024-02-29)

[flodiebold]

It seems you already reported this as #16712, or is this a different panic? If you are still using the RA version you mentioned, you'll need to update it to get the fix.

[ThomasMiz]

The crashing I reported on my previous issue stopped when I installed the nightly toolchain, so I'm guessing this is different. That said, I thought I had updated rust-analyzer, but I just discovered rustup didn't install it with the nightly toolchain, so apparently the only thing that changed is the rustc version.

Even after manually adding rust-analyzer, VS Code is refusing to switch to it, I'll figure out what's wrong and report back once I have tested this on nightly.

[ThomasMiz]

For anyone wondering, what was happening with VS Code was that it seems that on Windows it downloads its own rust-analyzer binary rather than using the one in %PATH%. I couldn't change it to do so, nor find any documentation for this on Windows.

Either way, I got VS Code to use rust-analyzer version: 0.4.1865-standalone (79e0fee6a 2024-03-01). The panics have been replaced with simple errors:

2024-03-02T14:05:46.868528Z ERROR hir::diagnostics: synthetic syntax
2024-03-02T14:05:46.905885Z ERROR hir::diagnostics: synthetic syntax
2024-03-02T14:05:47.122497Z ERROR hir::diagnostics: synthetic syntax
2024-03-02T14:05:47.202246Z ERROR hir::diagnostics: synthetic syntax
2024-03-02T14:05:47.234640Z ERROR hir::diagnostics: synthetic syntax
2024-03-02T14:05:47.479064Z ERROR hir::diagnostics: synthetic syntax

Is this intended as a fix?

[lnicola]

on Windows it downloads its own rust-analyzer binary

Doesn't download, but bundle it. The VSIX has a matching binary, you can find the path here (%USERPROFILE%\.vscode\extensions).

I couldn't change it to do so, nor find any documentation for this on Windows.

Setting "rust-analyzer.server.path": "rust-analyzer" should work, but you can set an absolute path to make sure. Anyway, this shouldn't be needed.

[ThomasMiz]

Ah, I see! Thanks!