Using map_err on a SelectorErrorKind error results in a panic #212
Description
Hey there, absolutely love your work on this library!
Unfortunately, the way that the SelectorErrorKind error behaves is a bit unusual.
use anyhow::anyhow;
use scraper::Selector;
fn main() {
let selector_result = Selector::parse("div138293@!#@!!@#").map_err(|e| anyhow!("oh no: {e}"));
println!("====> {:?}", selector_result);
}The following code panics instead of gracefully printing the result via println!.
thread 'main' panicked at C:\Users\Fots\.cargo\registry\src\index.crates.io-6f17d22bba15001f\scraper-0.20.0\src\error\utils.rs:56:18:
Token Delim('@') is not supposed to match as a single-character token!
stack backtrace:
0: std::panicking::begin_panic_handler
at /rustc/f6e511eec7342f59a25f7c0534f1dbea00d01b14\library/std\src\panicking.rs:662
1: core::panicking::panic_fmt
at /rustc/f6e511eec7342f59a25f7c0534f1dbea00d01b14\library/core\src\panicking.rs:74
2: scraper::error::utils::render_single_char_token
at C:\Users\Fots\.cargo\registry\src\index.crates.io-6f17d22bba15001f\scraper-0.20.0\src\error\utils.rs:56
3: scraper::error::utils::render_token
at C:\Users\Fots\.cargo\registry\src\index.crates.io-6f17d22bba15001f\scraper-0.20.0\src\error\utils.rs:34
4: scraper::error::impl$3::fmt
at C:\Users\Fots\.cargo\registry\src\index.crates.io-6f17d22bba15001f\scraper-0.20.0\src\error.rs:83
5: core::fmt::rt::Argument::fmt
at /rustc/f6e511eec7342f59a25f7c0534f1dbea00d01b14\library/core\src\fmt\rt.rs:177
6: core::fmt::write
at /rustc/f6e511eec7342f59a25f7c0534f1dbea00d01b14\library/core\src\fmt\mod.rs:1178
7: core::fmt::Write::write_fmt::impl$1::spec_write_fmt
at /rustc/f6e511eec7342f59a25f7c0534f1dbea00d01b14\library/core\src\fmt\mod.rs:226
8: core::fmt::Write::write_fmt
at /rustc/f6e511eec7342f59a25f7c0534f1dbea00d01b14\library/core\src\fmt\mod.rs:231
9: alloc::fmt::format::format_inner
at /rustc/f6e511eec7342f59a25f7c0534f1dbea00d01b14\library/alloc\src\fmt.rs:637
10: alloc::fmt::format::closure$0
at /rustc/f6e511eec7342f59a25f7c0534f1dbea00d01b14\library\alloc\src\fmt.rs:642
11: enum2$<core::option::Option<ref$<str$> > >::map_or_else<ref$<str$>,alloc::string::String,alloc::fmt::format::closure_env$0,alloc::string::String (*)(ref$<str$>)>
at /rustc/f6e511eec7342f59a25f7c0534f1dbea00d01b14\library\core\src\option.rs:1211
12: alloc::fmt::format
at /rustc/f6e511eec7342f59a25f7c0534f1dbea00d01b14\library\alloc\src\fmt.rs:642
13: anyhow::__private::format_err
at C:\Users\Fots\.cargo\registry\src\index.crates.io-6f17d22bba15001f\anyhow-1.0.89\src\lib.rs:693
14: ableton_downloads::main::closure$0
at .\src\main.rs:5
15: enum2$<core::result::Result<scraper::selector::Selector,enum2$<scraper::error::SelectorErrorKind> > >::map_err<scraper::selector::Selector,enum2$<scraper::error::SelectorErrorKind>,anyhow::Error,ableton_downloads::main::closure_env$0>
at /rustc/f6e511eec7342f59a25f7c0534f1dbea00d01b14\library\core\src\result.rs:854
16: ableton_downloads::main
at .\src\main.rs:5
17: core::ops::function::FnOnce::call_once<void (*)(),tuple$<> >
at /rustc/f6e511eec7342f59a25f7c0534f1dbea00d01b14\library\core\src\ops\function.rs:250
18: core::hint::black_box
at /rustc/f6e511eec7342f59a25f7c0534f1dbea00d01b14\library\core\src\hint.rs:388
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
The panic is found at https://github.com/rust-scraper/scraper/blob/master/scraper/src/error/utils.rs#L56.
Just as a bonus, it also is impossible to use the .context or .with_context anyhow methods to add context to this error enum due to the following trait bounds not being met.
e.g.
let selector_result = Selector::parse("div138293@!#@!!@#").context("unable to parse selector");Results in the following:
error[E0599]: the method `context` exists for enum `Result<Selector, SelectorErrorKind<'_>>`, but its trait bounds were not satisfied
--> src/main.rs:5:64
|
5 | let selector_result = Selector::parse("div138293@!#@!!@#").context("unable to parse selector");
| ^^^^^^^ method cannot be called on `Result<Selector, SelectorErrorKind<'_>>` due to unsatisfied trait bounds
|
::: C:\Users\Fots\.rustup\toolchains\stable-x86_64-pc-windows-msvc\lib/rustlib/src/rust\library\core\src\result.rs:527:1
|
527 | pub enum Result<T, E> {
| --------------------- doesn't satisfy `_: Context<Selector, SelectorErrorKind<'_>>`
|
::: C:\Users\Fots\.cargo\registry\src\index.crates.io-6f17d22bba15001f\scraper-0.20.0\src\error.rs:13:1
|
13 | pub enum SelectorErrorKind<'a> {
| ------------------------------ doesn't satisfy `SelectorErrorKind<'_>: Send`, `SelectorErrorKind<'_>: Sync` or `_: StdError`
|
= note: the following trait bounds were not satisfied:
`SelectorErrorKind<'_>: anyhow::context::ext::StdError`
which is required by `Result<Selector, SelectorErrorKind<'_>>: anyhow::Context<Selector, SelectorErrorKind<'_>>`
`SelectorErrorKind<'_>: Send`
which is required by `Result<Selector, SelectorErrorKind<'_>>: anyhow::Context<Selector, SelectorErrorKind<'_>>`
`SelectorErrorKind<'_>: Sync`
which is required by `Result<Selector, SelectorErrorKind<'_>>: anyhow::Context<Selector, SelectorErrorKind<'_>>`
As per the output, I'm testing on Windows using the MSVC Rust toolchain.
Thanks heaps in advance! 😄
Fotis