Called Option::unwrap() on a None value, warning in simple hello world Rocket app

[joemooney]

This compiles and runs fine but there is a rust-analyzer warning present in 2.776 and 2.768 but not in 2.760 and earlier versions of rust-analyzer.

 ::::::::::::::
Cargo.toml
::::::::::::::
[package]
name = "foobar"
version = "0.0.1"
edition = "2018"

[dependencies]
rocket = "0.4"
::::::::::::::
src/main.rs
::::::::::::::
#![feature(decl_macro, proc_macro_hygiene)]
#[macro_use]
extern crate rocket;

#[get("/hello")]
fn status() -> String {
    format!("rust-analyzer No warnings in this function")
}

// Compiles fine but rust-analyzer highlights function with:
// called `Option::unwrap()` on a `None` value

#[get("/foobar/<_a>")]
fn foobar(_a: bool) -> String {
    format!("rust-analyzer Warnings in this function")
}

fn main() {
    rocket::ignite()
        .mount("/", routes![status, foobar])
        .launch();
}

[bjorn3]

Which rustc version do you use?

[lnicola]

Can reproduce in rustc 1.57.0-nightly (a8f2463c6 2021-10-09).

[lnicola]

This doesn't look like our panic. We might be missing some part of the Span API, causing a crash inside the proc macro.

[ripxorip]

This is happening to me as well using rust-analyzer 2021-11-08 on arch

[lnicola]

Possibly a dupe of #10710.

[MiroFurtado]

This is still occurring on latest nightly release.

[Tamschi]

Here's a smaller reproduction that builds on stable Rust 1.57.0:

[package]
name = "macro-test"
version = "0.0.0"
edition = "2021"
publish = false

[lib]
# Needed because `unquote`'s syn dependency isn't set up correctly. It's hopefully not relevant.
proc_macro = true

[dependencies]
quote = "1.0.10"
syn = "1.0.83"
unquote = "0.0.6"

use quote::quote;
use syn::parse::ParseStream;
use unquote::unquote;

#[allow(dead_code)]
fn parse(input: ParseStream) -> syn::Result<()> {
    unquote!(input, a); // <--
    Ok(())
}

Settings (not minimal):

{
    "rust-analyzer.cargo-watch.command": "clippy",
    "rust-analyzer.rainbowHighlightingOn": true,
    "rust-analyzer.procMacro.enabled": true,
    "rust-analyzer.procMacro.enable": true,
    "rust-analyzer.cargo.loadOutDirsFromCheck": true,
    "rust-analyzer.checkOnSave.command": "clippy",
    "rust-analyzer.experimental.procAttrMacros": true,
    "rust-analyzer.cargo.allFeatures": true,
    "rust-analyzer.checkOnSave.extraArgs": [
        "--locked"
    ],
    "rust-analyzer.updates.channel": "nightly"
}

---

cargo expand:

Probably not relevant, but it's a fairly simple macro:

#![feature(prelude_import)]
#[prelude_import]
use std::prelude::rust_2021::*;
#[macro_use]
extern crate std;
use quote::quote;
use syn::parse::ParseStream;
use unquote::unquote;
#[allow(dead_code)]
fn parse(input: ParseStream) -> syn::Result<()> {
    let input = input;
    let mut prev_span = input.cursor().span();
    if input.call(<syn::Ident as syn::ext::IdentExt>::parse_any)?
        != syn::parse::Parser::parse2(<syn::Ident as syn::ext::IdentExt>::parse_any, {
            let mut _s = ::quote::__private::TokenStream::new();
            ::quote::__private::push_ident(&mut _s, "a");
            _s
        })
        .unwrap()
    {
        return Err(syn::Error::new(input.cursor().span(), "Expected `a`"));
    };
    Ok(())
}
const _: () = {
    extern crate proc_macro;
    #[rustc_proc_macro_decls]
    #[allow(deprecated)]
    static _DECLS: &[proc_macro::bridge::client::ProcMacro] = &[];
};

---

Error:

[{
	"resource": "[project directory]/src/lib.rs",
	"owner": "rustc",
	"code": {
		"value": "macro-error",
		"target": {
			"$mid": 1,
			"external": "https://rust-analyzer.github.io/manual.html#macro-error",
			"path": "/manual.html",
			"scheme": "https",
			"authority": "rust-analyzer.github.io",
			"fragment": "macro-error"
		}
	},
	"severity": 8,
	"message": "called `Option::unwrap()` on a `None` value",
	"source": "rust-analyzer",
	"startLineNumber": 7,
	"startColumn": 5,
	"endLineNumber": 7,
	"endColumn": 23
}]

---

Rust Analyzer Client output (abbreviated):

INFO [25.12.2021, 18:38:34]: Extension version: 0.3.875
INFO [25.12.2021, 18:38:34]: Using configuration {
  […]
}
INFO [25.12.2021, 18:38:34]: PersistentState: { serverVersion: '0.3.875' }
INFO [25.12.2021, 18:38:34]: Using server binary at [~]\.vscode\extensions\matklad.rust-analyzer-0.3.875\server\rust-analyzer.exe

Rust Analyzer Language Server Trace appears to be empty.

[oren0e]

Hi, I am having this same issue with rocket. I use rustc 1.56.0-nightly (0035d9dce 2021-08-16) with coc-rust-analyzer 0.57.0. Any updates on a fix?

[lnicola]

@MiroFurtado, @Tamschi, @oren0e see #10710 (comment).

Updating to a newer version of Rocket might fix it.

[Tamschi]

@MiroFurtado, @Tamschi, @oren0e see #10710 (comment).

Updating to a newer version of Rocket might fix it.

I'm not using Rocket and I'm on stable, so that's not the issue/fix for me, unfortunately.

[Tamschi]

(A separate comment since @lnicola already saw the previous reply.)

Should I open a separate issue?
It looks like my problem is likely unrelated then, if this error message can be caused by not implemented endpoints generally.

[oren0e]

@MiroFurtado, @Tamschi, @oren0e see #10710 (comment).

Updating to a newer version of Rocket might fix it.

Unfortunately I can't use the rc version of rocket for various stability and dependency reasons, so that fix is not for me either (I use rocket 0.4.10). Any chance to work it out in rust-analyzer itself?

[zojize]

this also occurred to me with realworld-rust-rocket. Any updates?

[nbittich]

Same Here.
nightly-x86_64-unknown-linux-gnu (default)
rustc 1.60.0-nightly (09cb29c64 2022-02-15)

[jonas-schievink]

I hope #11797 has properly fixed this. If not, please leave a comment.

[oren0e]

Not for me. I still have

macro-error: called Option::unwrap() on a None value

error in my vim (I use coc.nvim with rust-analyzer) on each one of my endpoints with rocket

[jonas-schievink]

Presumably because of the same issue as #10772 (comment)

[jonas-schievink]

@oren0e If you're still using the same nightly version as in #10570 (comment), it is quite outdated. We can't reasonably support outdated nightly versions.