False positive unnecessary 'unsafe' block warning?

[Vurv78]

I'm not sure if this is a part of GenericDetour::call being generated by a macro, I thought this was fixed with expanding macros though. Removing the unsafe block just causes a missing-unsafe error

use detour::GenericDetour;

type Add5 = extern "Rust" fn(i32) -> i32;
extern "Rust" fn add_5(n: i32) -> i32 { n + 5 }
extern "Rust" fn hookfn(n: i32) -> i32 { n + 50 }

fn main() -> Result<(), detour::Error> {
	let hook = unsafe { GenericDetour::<Add5>::new(add_5, hookfn)? };
	
	// This unsafe is needed (afaik) yet causes a ``unnecessary `unsafe` block`` diagnostic?
	let _res = unsafe { hook.call(50) }; 

	Ok(())
}

[flodiebold]

missing-unsafe is our diagnostic, "unnecessary unsafe block" comes from rustc. When in doubt, rustc is right ;) Apparently the call method is generated by a macro; depending on the macro (I didn't spend much time looking for the call), it might be necessary to enable rust-analyzer.experimental.procAttrMacros, or it might be another problem.

[bjorn3]

It is a decl macro: https://docs.rs/detour/0.8.0/src/detour/macros.rs.html#36-165

[flodiebold]

Oof. There are a lot of unsafe and safe versions of the method there, so RA might be getting the method selection wrong.

[Vurv78]

Oops, I didn't see the missing-unsafe error is from ra, but the warning is from rustc... So it should be safe but it is seen as unsafe by rust-analyzer

[rossmacarthur]

Encountered this when using wasm-bindgen

#[wasm_bindgen(module = "/index.js")]
extern "C" {
    #[wasm_bindgen]
    pub fn my_function() -> JsValue
}

my_function is safe here but ra thinks it is unsafe.

[lnicola]

@rossmacarthur try enabling rust-analyzer.experimental.procAttrMacros.

[nbars]

I believe I've got the same issue when using the log crates logging functions:

However, cargo build and cargo check work just fine. I'm using rust-analyzer 996300f4a 2021-08-23 stable and also tried the previous release.

Is there any way for me to get more details about why the rust-analyzer suspects the logging functions to be unsafe?

Keep up the good work :)

[nbars]

It appears that using the nightly channel via "rust-analyzer.updates.channel": "nightly" solves the problem.

[lnicola]

@nbars see #10022

[yatesco]

It appears that using the nightly channel via "rust-analyzer.updates.channel": "nightly" solves the problem.

I'm still getting this error, even with the nightly rust-analyzer (with stable rust and 2021 profile)
nevermind this might be an error with my vim config. VScode seems to work fine.

[ModProg]

nevermind this might be an error with my vim config. VScode
seems to work fine.

@yatesco if you still have the problem with vim, idk if you use lspconfig, but this is working for me with rust-tools (a wrapper around lspconfig)

My Config

            require('rust-tools').setup {
                tools = {
                    autoSetHints = true,
                    hover_with_actions = true,
                    runnables = {use_telescope = true},
                    inlay_hints = {
                        show_parameter_hints = false,
                        parameter_hints_prefix = "",
                        other_hints_prefix = ""
                    }
                },
                -- see https://github.com/neovim/nvim-lspconfig/blob/master/CONFIG.md#rust_analyzer
                server = {
                    settings = {
                        -- https://github.com/rust-analyzer/rust-analyzer/blob/master/docs/user/generated_config.adoc
                        ["rust-analyzer"] = {
                            checkOnSave = {command = "clippy"},
                            experimental = {procAttrMacros = true},
                            updates = {channel = "nightly"}
                        }
                    }
                }
            }

[yatesco]

Thanks @ModProg - it's working on the latest nightly now.

[Veykril]

triage: this still happens

[zicklag]

For anybody else still running into this, disabling the missing-unsafe diagnostic might help:

  "rust-analyzer.diagnostics.disabled": [
    "missing-unsafe"
  ],

I was having issues with wasm_bindgen even on the latest stable rust and latest RA, util I disabled that.

[Veykril]

This doesn't happen for me anymore