ICE (broken MIR) with GAT + tuple type inference

[SevenO2]

I included the (commented out) workaround I found in case it's helpful.

Bonus

uncomment fn fail2 for a different ICE (Likely a duplicate of #92954)

Code

#![feature(generic_associated_types)]

pub trait Fooey: Sized {
    type Context<'c> where Self: 'c;
    /* // workaround
    type CallMe; */

    // fn fail2(callback: impl for<'c> Fn(&mut Self::Context<'c>)) -> Box<dyn for<'c> Fn(&mut Self::Context<'c>)> {
    //     Box::new(callback)
    // }
}

/* // workaround
pub struct Handle<E: Fooey>(Option<E::CallMe>); */
pub struct Handle<E: Fooey>(Option<Box<dyn for<'c> Fn(&mut E::Context<'c>)>>);

fn tuple<T>() -> (Option<T>,) { (Option::None,) }

pub struct FooImpl {}
impl Fooey for FooImpl {
    type Context<'c> = &'c ();
    /* // workaround
    type CallMe = Box<dyn for<'c> Fn(&mut Self::Context<'c>)>; */
}

impl FooImpl {
    pub fn fail1() -> Handle<Self> {
        let (tx,) = tuple();
        Handle(tx)
    }
}

fn main() {}

Meta

rustc --version --verbose:

rustc 1.60.0-nightly (1bd4fdc94 2022-01-12)
binary: rustc
commit-hash: 1bd4fdc943513e1004f498bbf289279c9784fc6f
commit-date: 2022-01-12
host: x86_64-pc-windows-msvc
release: 1.60.0-nightly
LLVM version: 13.0.0

Error output

warning: Error finalizing incremental compilation session directory `\\?\C:\{CODEDIR}\ice\target\debug\incremental\ice-39n3zl63hdtbj\s-g6aobrx569-1gdp4fd-working`: The system cannot find the file specified. (os error 2)

error: internal compiler error: broken MIR in DefId(0:18 ~ ice[d6e3]::{impl#1}::fail1) ((_2.0: std::option::Option<std::boxed::Box<dyn for<'r, 'c> std::ops::Fn(&'r mut <FooImpl as Fooey>::Context<'c>)>>)): bad field access (std::option::Option<std::boxed::Box<dyn for<'r, 'c> std::ops::Fn(&'r mut &'c ())>>: std::option::Option<std::boxed::Box<dyn for<'r, 'c> std::ops::Fn(&'r mut <FooImpl as Fooey>::Context<'c>)>>): NoSolution
  --> src\main.rs:29:14
   |
29 |         let (tx,) = tuple();
   |              ^^
   |
   = note: delayed at compiler\rustc_borrowck\src\type_check\mod.rs:319:27

thread 'rustc' panicked at 'no errors encountered even though `delay_span_bug` issued', compiler\rustc_errors\src\lib.rs:1188:13

Backtrace

stack backtrace:
   0:     0x7ffd6e2f609f - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hee8a33be9cbca634
   1:     0x7ffd6e32510a - core::fmt::write::hb90322eafe83ee3b
   2:     0x7ffd6e2e7308 - <std::io::IoSliceMut as core::fmt::Debug>::fmt::h65fc8b4617290485
   3:     0x7ffd6e2f9acb - std::panicking::take_hook::h0b31ee4140f1c0b3
   4:     0x7ffd6e2f95c4 - std::panicking::take_hook::h0b31ee4140f1c0b3
   5:     0x7ffd6e943c99 - <rustc_middle[10899ac215e07fa4]::ty::SymbolName as core[a132f262969784d3]::fmt::Debug>::fmt
   6:     0x7ffd6e2fa1f6 - std::panicking::rust_panic_with_hook::h82a702bd362db81c
   7:     0x7ffd6e2f9ffb - <std::panicking::begin_panic_handler::StrPanicPayload as core::panic::BoxMeUp>::get::h0345b9cc73fc451e
   8:     0x7ffd6e2f69e7 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hee8a33be9cbca634
   9:     0x7ffd6e2f9cf9 - rust_begin_unwind
  10:     0x7ffd6e357a20 - core::panicking::panic_fmt::h45d28ddfb378495a
  11:     0x7ffd730e00a7 - <rustc_errors[d623bed5aaf56acd]::ErrorReported as core[a132f262969784d3]::fmt::Debug>::fmt
  12:     0x7ffd730dcd18 - <rustc_errors[d623bed5aaf56acd]::HandlerInner>::delay_as_bug
  13:     0x7ffd730d8822 - <rustc_errors[d623bed5aaf56acd]::HandlerInner as core[a132f262969784d3]::ops::drop::Drop>::drop
  14:     0x7ffd6e93d4e4 - <rustc_middle[10899ac215e07fa4]::ty::SymbolName as core[a132f262969784d3]::fmt::Debug>::fmt
  15:     0x7ffd6e9405d7 - <rustc_middle[10899ac215e07fa4]::ty::SymbolName as core[a132f262969784d3]::fmt::Debug>::fmt
  16:     0x7ffd6e8d0b3c - <rustc_target[25420bd4fd783bf8]::abi::call::Reg>::i32
  17:     0x7ffd6e8d2600 - <rustc_target[25420bd4fd783bf8]::abi::call::Reg>::i32
  18:     0x7ffd6e8f3131 - <rustc_target[25420bd4fd783bf8]::abi::call::Reg>::i32
  19:     0x7ffd6e8d5ab7 - <rustc_target[25420bd4fd783bf8]::abi::call::Reg>::i32
  20:     0x7ffd6e8d46fc - <rustc_target[25420bd4fd783bf8]::abi::call::Reg>::i32
  21:     0x7ffd6e8f90a8 - <rustc_middle[10899ac215e07fa4]::ty::SymbolName as core[a132f262969784d3]::fmt::Debug>::fmt
  22:     0x7ffd6e309bac - std::sys::windows::thread::Thread::new::heeee0f662b911fa1
  23:     0x7ffde0d57034 - BaseThreadInitThunk
  24:     0x7ffde2442651 - RtlUserThreadStart

error: internal compiler error: unexpected panic

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.60.0-nightly (1bd4fdc94 2022-01-12) running on x86_64-pc-windows-msvc

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental --crate-type bin

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
end of query stack

[pierwill]

@rustbot label +A-incr-comp

[compiler-errors]

@rustbot claim