Proc macro server crashed after add sqlx as depedency

[neo-clon]

Hello guys

I have a problem in my projects with the last 3 versions of rust analyzer

Every time I add them as a sqlx dependency, it marks an error in the structures that use the derive Serialize or Deserialize macros

My dev enviroment is:
arch linux x64
NVIM: 0.4.4
rustc 1.48.0
coc.nvim version: 0.0.80-cf0e8400a4
coc-rust-analyzer 0.25.0
rust-analyzer 1d53075 (stable channel)
CocConfig:
rust-analyzer.procMacro.enable: true
rust-analyzer.cargo.loadOutDirsFromCheck: true

[ssankko]

Hi!
Though #7116 might have fixed this bug, but i still experience this error on latest stable RA release.
I am using VSCode (1.52) with RA extension (0.2.441) on Win10.

It's not required to add sqlx dependency in order to trigger this kind of error. Serde by itself is enough.

main.rs

use serde::{Deserialize, Serialize};

#[derive(Deserialize, Serialize)]
struct Example {}

fn main() {}

Cargo.toml

...
[dependencies]
serde = {version = "1.0.118", features = ["derive"]}

RA error in logs:

thread 'main' panicked at 'internal error: entered unreachable code', crates\proc_macro_srv\src\proc_macro\bridge\mod.rs:259:5
...

Note that this error is identical to errors in earlier versions of RA, so i presume fix didn't work.

[bjorn3]

Which rustc version are you using?

[ssankko]

@bjorn3 rustc 1.45.2 (d3fb005a3 2020-07-31)
Should i try use newer versions?
I am stuck at 1.45 because of nasty rustc bug that drastically slows compilation time if nested async functions are used.

[ssankko]

Update to rustc 1.49.0 (e1884a8e3 2020-12-29) seems to fix this behavior.

[bjorn3]

Rust-analyzer only supports proc macros compiled with the latest stable version of rustc or sometimes versions a bit newer or older. Rust-analyzer depends on the specific abi between the proc-macro and rustc. This is an implementation detail and occasionally changes.

[human-bean-555]

Hello, I came across this issue while tinkering with one of my own macros. It seems the use of a println!() in a derive macro causes it to happen:

#[proc_macro_derive(Hello)]
pub fn hello(_: proc_macro::TokenStream) -> proc_macro::TokenStream {
    println!("fail"); // This will cause the error
    proc_macro::TokenStream::new()
}

I'm using rustc 1.5.0 & RA v0.2.513