Deriving structs with backtrace fails since fn backtrace has been removed from Error

[Systemcluster]

As of rust-lang/rust#99431 fn backtrace is not part of Error anymore. This causes derives with backtrace to fail; And the following example results in a compilation error.

method `backtrace` is not a member of trait `std::error::Error`
not a member of trait `std::error::Error`

#[derive(Error, Debug)]
#[error("Platform Error {code}")]
pub struct PlatformError {
    backtrace: Backtrace,
    code:      i32,
}

[dtolnay]

This is blocked on rust-lang/rust#100399.

[dtolnay]

Perhaps not — it looks like anyhow uses BacktraceStatus but thiserror does not.

[Xuanwo]

Do we need to remove the backtrace method?

thiserror/impl/src/expand.rs

Lines 62 to 104 in 1442e27

	let backtrace_method = input.backtrace_field().map(|backtrace_field| {
	let backtrace = &backtrace_field.member;
	let body = if let Some(source_field) = input.source_field() {
	let source = &source_field.member;
	let source_backtrace = if type_is_option(source_field.ty) {
	quote_spanned! {source.span()=>
	self.#source.as_ref().and_then(|source| source.as_dyn_error().backtrace())
	}
	} else {
	quote_spanned! {source.span()=>
	self.#source.as_dyn_error().backtrace()
	}
	};
	let combinator = if source == backtrace {
	source_backtrace
	} else if type_is_option(backtrace_field.ty) {
	quote! {
	#source_backtrace.or(self.#backtrace.as_ref())
	}
	} else {
	quote! {
	std::option::Option::Some(#source_backtrace.unwrap_or(&self.#backtrace))
	}
	};
	quote! {
	use thiserror::private::AsDynError;
	#combinator
	}
	} else if type_is_option(backtrace_field.ty) {
	quote! {
	self.#backtrace.as_ref()
	}
	} else {
	quote! {
	std::option::Option::Some(&self.#backtrace)
	}
	};
	quote! {
	fn backtrace(&self) -> std::option::Option<&std::backtrace::Backtrace> {
	#body
	}
	}
	});