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ICE when using "Generic Associated Types" feature with references for impl block #80433
Description
Code
#![allow(incomplete_features)]
#![feature(generic_associated_types)]
#[derive(Default)]
struct E<T> {
data: T,
}
trait TestMut {
type Output<'a>;
fn test_mut<'a>(&'a mut self) -> Self::Output<'a>;
}
impl<T> TestMut for E<T>
where
T: 'static,
{
type Output<'a> = &'a mut T;
fn test_mut<'a>(&'a mut self) -> Self::Output<'a> {
&mut self.data
}
}
fn test_simpler<'a>(dst: &'a mut impl TestMut<Output = &'a mut f32>)
{
for n in 0i16..100 {
*dst.test_mut() = n.into();
}
}
fn main() {
let mut t1: E<f32> = Default::default();
test_simpler(&mut t1);
}Meta
rustc --version --verbose:
rustc 1.50.0-nightly (bb178237c 2020-12-25)
binary: rustc
commit-hash: bb178237c5539c75e1b85ab78a8ab902b1f333d5
commit-date: 2020-12-25
host: x86_64-apple-darwin
release: 1.50.0-nightly
Error output
error: internal compiler error: impl item and trait item have different parameter counts
--> src/main.rs:33:5
|
33 | test_simpler(&mut t1);
| ^^^^^^^^^^^^
|
= note: delayed at compiler/rustc_trait_selection/src/traits/project.rs:1418:23
error: internal compiler error: TyKind::Error constructed but no error reported
|
= note: delayed at /rustc/bb178237c5539c75e1b85ab78a8ab902b1f333d5/compiler/rustc_middle/src/ty/relate.rs:347:59
error: internal compiler error: impl item and trait item have different parameter counts
|
= note: delayed at compiler/rustc_trait_selection/src/traits/project.rs:1418:23
thread 'rustc' panicked at 'no errors encountered even though `delay_span_bug` issued', compiler/rustc_errors/src/lib.rs:974:13
Backtrace
0: 0x1107200dc - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::ha6f5ddd5259d3e16
1: 0x110784c8d - core::fmt::write::hefe95a44532fe6ed
2: 0x110711e86 - std::io::Write::write_fmt::hf513c99961415bff
3: 0x110723d89 - std::panicking::default_hook::{{closure}}::h70a3a940826edea5
4: 0x110723910 - std::panicking::default_hook::h9520f36dd50be056
5: 0x108cb1458 - rustc_driver::report_ice::h64178aa7cd01307c
6: 0x11072456e - std::panicking::rust_panic_with_hook::h102f8bee4e0ef4c7
7: 0x110724075 - std::panicking::begin_panic_handler::{{closure}}::hb72eee9aad2e147c
8: 0x110720598 - std::sys_common::backtrace::__rust_end_short_backtrace::h372ff87ecb2667f3
9: 0x110723fda - _rust_begin_unwind
10: 0x1107ab27b - std::panicking::begin_panic_fmt::hf0e714fa3e981e6e
11: 0x10d3472a6 - rustc_errors::HandlerInner::flush_delayed::he9da53448a9bd660
12: 0x10d3434eb - <rustc_errors::HandlerInner as core::ops::drop::Drop>::drop::h44af1dc5df0a1fa4
13: 0x108ccba5a - core::ptr::drop_in_place::hd03156b954b70984
14: 0x108ccefb8 - <alloc::rc::Rc<T> as core::ops::drop::Drop>::drop::hd4c9eabf652375d9
15: 0x108cc8112 - core::ptr::drop_in_place::h83698f86dd7e4a49
16: 0x108cb3ab1 - rustc_span::with_source_map::hb3cfcc431ed11000
17: 0x108ce7694 - rustc_interface::interface::create_compiler_and_run::he8e7b2281c1964ad
18: 0x108cbff94 - std::sys_common::backtrace::__rust_begin_short_backtrace::h9bf0a320b59d4a76
19: 0x108c56799 - core::ops::function::FnOnce::call_once{{vtable.shim}}::hb43737fa064e4b63
20: 0x11073150d - std::sys::unix::thread::Thread::new::thread_start::h93dd3097fa4fa219
21: 0x7fff20358950 - __pthread_start
Activity
[-]ICE when using "Generic Assotiated Types" feature with mutable borrows[/-][+]ICE when using "Generic Assotiated Types" feature with mutable references[/+][-]ICE when using "Generic Assotiated Types" feature with mutable references[/-][+]ICE when using "Generic Associated Types" feature with mutable references[/+][-]ICE when using "Generic Associated Types" feature with mutable references[/-][+]ICE when using "Generic Associated Types" feature with references for impl block[/+]fanninpm commentedon Dec 29, 2020
Playground link to example
Add 80433
jyn514 commentedon Dec 29, 2020
Slightly smaller:
Playground
b-naber commentedon Jan 10, 2021
This should work once #79554 lands using
fn test_simpler<'a>(dst: &'a mut impl TestMut<Output<'a> = &'a mut f32>)b-naber commentedon Feb 3, 2021
There's another error in @rxcompile 's code, you mutably borrow in the loop, you might be able to fix this if you re-borrow.
Rollup merge of rust-lang#79554 - b-naber:generic-associated-types-in…
Rollup merge of rust-lang#79554 - b-naber:generic-associated-types-in…