stale diagnostic after panic

[rbtcollins]

Very weird - basic code reporting a Syntax error, but it runs fine via Cargo run :)

rust-analyzer version: rust-analyzer version: 0.3.2220-standalone (27e824f 2024-12-15) [c:\Users\robertc.vscode\extensions\rust-lang.rust-analyzer-0.3.2220-win32-x64\server\rust-analyzer.exe]

rustc version: rustc 1.83.0 (90b35a623 2024-11-26)

editor or extension: VSCode Version 0.3.2220

relevant settings: (eg. client settings, or environment variables like CARGO, RUSTC, RUSTUP_HOME or CARGO_HOME)

rustup show
$ rustup show
Default host: x86_64-pc-windows-msvc
rustup home:  C:\Users\robertc\.rustup

...

installed targets for active toolchain
--------------------------------------

x86_64-pc-windows-msvc
x86_64-unknown-linux-gnu

active toolchain
----------------

stable-x86_64-pc-windows-msvc (default)
rustc 1.83.0 (90b35a623 2024-11-26)

code snippet to reproduce:

use std::collections::HashMap;

use crate::eval::Value;

pub struct Environment {
    values: HashMap<String, Value>,
}

impl Environment {
    pub fn new() -> Self {
        Self {
            values: HashMap::new(),
        }
    }

    pub fn define(&mut self, name: String, value: Value) {
        self.values.insert(name, value);
    }

    pub fn get(&self, name: &str) -> Result<Value, Box<dyn std::error::Error>> {
        self.values
            .get(name)
            .cloned()
            .ok_or_else(|| format!("Undefined variable {name}").into())
    }
}

Reports these problems:

[{
	"resource": "/c:/Users/robertc/Documents/src/codecrafters-interpreter-rust/src/environment.rs",
	"owner": "_generated_diagnostic_collection_name_#1",
	"code": {
		"value": "syntax-error",
		"target": {
			"$mid": 1,
			"path": "/stable/reference/",
			"scheme": "https",
			"authority": "doc.rust-lang.org"
		}
	},
	"severity": 8,
	"message": "Syntax Error: expected a block",
	"source": "rust-analyzer",
	"startLineNumber": 17,
	"startColumn": 16,
	"endLineNumber": 17,
	"endColumn": 16
}]

and

[{
	"resource": "/c:/Users/robertc/Documents/src/codecrafters-interpreter-rust/src/environment.rs",
	"owner": "_generated_diagnostic_collection_name_#1",
	"code": {
		"value": "E0308",
		"target": {
			"$mid": 1,
			"path": "/stable/error_codes/E0308.html",
			"scheme": "https",
			"authority": "doc.rust-lang.org"
		}
	},
	"severity": 8,
	"message": "expected String, found &str",
	"source": "rust-analyzer",
	"startLineNumber": 18,
	"startColumn": 28,
	"endLineNumber": 18,
	"endColumn": 32
}]

[ChayimFriedman2]

When some obviously-not-syntax-error reports a SyntaxError, that usually happens in my experience after the diagnostics request has panicked. So, did you saw a popup about the server panicking before?

[rbtcollins]

I don't recall one, but the subtle corner popups in vscode rarely attract my eyeballs.

I can see this in the RA LSP output:

Panic context:
> 
version: 0.3.2220-standalone (27e824fad4 2024-12-15)
request: textDocument/diagnostic DocumentDiagnosticParams {
    text_document: TextDocumentIdentifier {
        uri: Url {
            scheme: "file",
            cannot_be_a_base: false,
            username: "",
            password: None,
            host: None,
            port: None,
            path: "/c%3A/Users/robertc/Documents/src/codecrafters-interpreter-rust/src/environment.rs",
            query: None,
            fragment: None,
        },
    },
    identifier: None,
    previous_result_id: None,
    work_done_progress_params: WorkDoneProgressParams {
        work_done_token: None,
    },
    partial_result_params: PartialResultParams {
        partial_result_token: None,
    },
}

thread 'Worker' panicked at crates\syntax\src\ast\make.rs:117:5:
Failed to make ast node `syntax::ast::generated::nodes::Name` from text mod self;
stack backtrace:
   0: std::panicking::begin_panic_handler
             at /rustc/90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf\library/std\src\panicking.rs:665
   1: core::panicking::panic_fmt
             at /rustc/90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf\library/core\src\panicking.rs:74
   2: syntax::ast::make::name
   3: ide_diagnostics::handlers::unresolved_field::unresolved_field
   4: ide_diagnostics::semantic_diagnostics
   5: ide_diagnostics::full_diagnostics
   6: ra_salsa::Cancelled::catch
   7: ide::Analysis::full_diagnostics
   8: rust_analyzer::handlers::request::handle_document_diagnostics
   9: core::ops::function::FnOnce::call_once{{vtable.shim}}
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
[Error - 3:40:10 PM] Request textDocument/diagnostic failed.
  Message: request handler panicked: Failed to make ast node `syntax::ast::generated::nodes::Name` from text mod self;
  Code: -32603 
[Error - 3:40:10 PM] Document pull failed for text document file:///c%3A/Users/robertc/Documents/src/codecrafters-interpreter-rust/src/environment.rs
  Message: request handler panicked: Failed to make ast node `syntax::ast::generated::nodes::Name` from text mod self;
  Code: -32603 

But I don't know if its connected.

I have restarted the LSP but the problem remained.

[ChayimFriedman2]

Yes this means there was a panic in diagnostics. Restarting rust-analyzer should work unless it panics again.

[Veykril]

Its definitely a bug that a panic there can cause us to leak (never clear) diagnostics

[ChayimFriedman2]

I think this is because the diagnostics request is not wrapped in catch_unwind().

[Veykril]

Ah right, I was looking at the push model style diagnostic handling, not the pull one that is actually being used.
It is implicitly wrapped by the thread pool handling so the issue lies with us returning an error it seems.
That seems a bit odd then, I'd expect vscode to ask for diagnostics again when the doc changes, causing it clear them afterwards when we give it a proper result back.

So this smells like a VSCode issue to me (though that is not confirmed). We do set an id for our pull diagnostics now though, so maybe that makes a difference (next release)