[experiment] Introduce a reliable way to refer to the standard library and use it for calling panic
#62002
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(rust_highfive has picked a reviewer for you, use r? to override) |
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cc @rust-lang/lang |
Centril
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What prevents us from writing this as |
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The job Click to expand the log.I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact |
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@joshtriplett If |
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We discussed this in the @rust-lang/lang meeting and were all fairly apprehensive about this approach. There are a number of strange interactions e.g. around As a potential alternative, we discussed that Example: mod some_private_mod {
#[no_mangle]
pub extern "C" fn __panic_internal() {
println!("the one from core");
}
}
extern "C" {
fn __panic_internal();
}
pub fn function_in_core() {
unsafe { __panic_internal() }
}in crate // whether or not this function is included will change what is printed
// this is analogous to including `std` or not
#[no_mangle]
pub extern "C" fn __panic_internal() {
println!("the one from std");
}
fn main() {
// prints "the one from std" or "the one from core" based on whether or not the
// above function is commented out
corelike::function_in_core();
} |
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@nikomatsakis also mentioned @alexcrichton might have opinions about my linkage hack idea, so cc'ing them here. |
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Sorry I haven't followed this a ton so I wouldn't say I'm at all up to speed on all the relevant ins and outs here. That being said there's an important difference between the std/core macros which I think justifies their current state. For invocations like That functionality difference may be resolvable with linkage still, but I'd have to dig into it myself to get a better idea. I'm not really entirely certain though what the motivation is to make these hygienic. I feel like it'd be nice to do so but it doesn't really seem like we need to bend over backwards. I could be missing something though! |
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I'll close this PR since this should preferably be solved through lang items and/or linkage rather than name resolution, and I won't work on that in the near future.
I'm not sure what is the practical impact, but the situation with the |
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The second part of #61629.
__rustc_standard_libraryis introduced (it can be further uglified as much as necessary, but it must be a valid identifier).__rustc_standard_libraryrefers to the standard library crate when used in a path.#![no_std]settings, regardless of shadowing or renaming.This PR is minimal, but
__rustc_standard_librarycould also be used for std paths likestd::option::Optionin built-in derives, which currently use a special compiler hack ($cratein built-in macros specifically is re-routed to the standard library).Unlike
$cratere-routing, this PR's approach feels like a "proper" solution to the problem to me, the only downside is an introduction of a niche keyword.TODO: Feature gating.