compiler errors sometimes made nugatory (closures, struct derive?) #60
Description
Hi. Thanks again for this excellent package.
To reproduce:
#[allow(unused_imports)]
use fehler::throws;
fn parse_args(_f: &dyn Fn(&mut ())) { }
#[throws(std::io::Error)]
fn main()
{
#[derive(Default,Debug)]
struct Args { }
let args = parse_args(&|ma|{ });
let spec = 42;
}
And run cargo build, with fehler="1" in your dependencies.
Actual output:
warning: unused variable: `ma`
|
= note: `#[warn(unused_variables)]` on by default
warning: unused variable: `args`
warning: unused variable: `spec`
warning: 3 warnings emitted
Finished dev [unoptimized + debuginfo] target(s) in 0.01s
Note the very unhelpful error messages, with no location information and no suggestions.
Expected output:
warning: unused variable: `ma`
--> src/bin/report.rs:11:29
|
11 | let args = parse_args(&|ma|{ });
| ^^ help: if this is intentional, prefix it with an underscore: `_ma`
|
= note: `#[warn(unused_variables)]` on by default
warning: unused variable: `args`
--> src/bin/report.rs:11:9
|
11 | let args = parse_args(&|ma|{ });
| ^^^^ help: if this is intentional, prefix it with an underscore: `_args`
warning: unused variable: `spec`
--> src/bin/report.rs:12:9
|
12 | let spec = 42;
| ^^^^ help: if this is intentional, prefix it with an underscore: `_spec`
warning: 3 warnings emitted
Finished dev [unoptimized + debuginfo] target(s) in 0.17s
This rather odd test case was minimised from a more complicated program. Empirically, the issue goes away if I remove any of (a) #[throws] (b) the #[derive] on the struct (c) the closure. The problem can occur with errors as well as warnings. In one particular version of my actual program I got the very unhelpful output type annotations needed without any indication of where!
Thanks for your attention.