`broken MIR` `NoSolution` sized array initialiser with addition in generic tuple destructure

[thepowersgang]

According to my CI this started 2020-04-16 (https://travis-ci.org/github/thepowersgang/rust_os/builds/675740673) - nightly-x86_64-unknown-linux-gnu installed - rustc 1.44.0-nightly (d2230290f 2020-04-15)

Code

fn main() {}
// NOTE: Lifetime param needed.
struct DirEnts<'a>
{
    _cluster: ::std::marker::PhantomData<&'a ()>,
}
impl<'a> DirEnts<'a>
{
    #[allow(dead_code)]
    fn next(&mut self) -> [u8; 12] {
        // NOTE: Tuple destructure needed
        // NOTE: Arithmatic needed
        let (outname,) = ([0u8; 12+0],);
        outname
    }
}

Meta

rustc --version --verbose:

rustc 1.44.0-nightly (52fa23add 2020-04-18)
binary: rustc
commit-hash: 52fa23add6fb0776b32cc591ac928618391bdf41
commit-date: 2020-04-18
host: x86_64-unknown-linux-gnu
release: 1.44.0-nightly
LLVM version: 9.0

Error output

[No write since last change]
error: internal compiler error: broken MIR in DefId(0:9 ~ 1[317d]::{{impl}}[0]::next[0]) ((_3.0: [u8; 12])): bad field access ([u8; _]: [u8; 12]): NoSolution
  --> /home/tpg/1.rs:15:8
   |
15 |         let (outname,) = ([0u8; 12+0],);
   |              ^^^^^^^

thread 'rustc' panicked at 'no errors encountered even though `delay_span_bug` issued', src/librustc_errors/lib.rs:366:17
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/libunwind.rs:86
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/mod.rs:66
   2: std::sys_common::backtrace::_print_fmt
             at src/libstd/sys_common/backtrace.rs:78
   3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
             at src/libstd/sys_common/backtrace.rs:59
   4: core::fmt::write
             at src/libcore/fmt/mod.rs:1069
   5: std::io::Write::write_fmt
             at src/libstd/io/mod.rs:1504
   6: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:62
   7: std::sys_common::backtrace::print
             at src/libstd/sys_common/backtrace.rs:49
   8: std::panicking::default_hook::{{closure}}
             at src/libstd/panicking.rs:198
   9: std::panicking::default_hook
             at src/libstd/panicking.rs:218
  10: rustc_driver::report_ice
  11: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:515
  12: std::panicking::begin_panic
  13: <rustc_errors::HandlerInner as core::ops::drop::Drop>::drop
  14: core::ptr::drop_in_place
  15: <alloc::rc::Rc<T> as core::ops::drop::Drop>::drop
  16: core::ptr::drop_in_place
  17: rustc_interface::interface::run_compiler_in_existing_thread_pool
  18: scoped_tls::ScopedKey<T>::set
  19: rustc_ast::attr::with_globals
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

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/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.44.0-nightly (52fa23add 2020-04-18) running on x86_64-unknown-linux-gnu

query stack during panic:
end of query stack

shell returned 101

[LeSeulArtichaut]

cargo-bisect-rustc reports a regression in d12f030 (PR #70452), cc @eddyb

searched nightlies: from nightly-2020-04-15 to nightly-2020-04-16
regressed nightly: nightly-2020-04-16
searched commits: from https://github.com/rust-lang/rust/commit/edc02580e4e80476ac1ded2cc1008eaf8b8400e6 to https://github.com/rust-lang/rust/commit/d2230290f7220e740ec08f4d844bf5951e1b74b8
regressed commit: https://github.com/rust-lang/rust/commit/d12f0304839e599d498b3faaa652336b273bdcc8

[spastorino]

Assigning P-high as discussed as part of the Prioritization Working Group process and removing I-prioritize.

[pnkfelix]

@rustbot assign @eddyb