ICE: cat_expr Errd from array of unconstrained type -- { []; }

[rprichard]

Test case:

fn main() { []; }

Output:

$ RUST_BACKTRACE=1 rustc test.rs 
test.rs:1:13: 1:15 error: internal compiler error: cat_expr Errd
test.rs:1 fn main() { []; }
                      ^~
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: run with `RUST_BACKTRACE=1` for a backtrace
thread 'rustc' panicked at 'Box<Any>', /home/rustbuild/src/rust-buildbot/slave/nightly-dist-rustc-linux/build/src/libsyntax/diagnostic.rs:129

stack backtrace:
   1:         0xcc029720 - sys::backtrace::write::h66f3f2784d0f6c5ddgA
   2:         0xcc051b80 - panicking::on_panic::h6fdde9e4e9166fe6jaJ
   3:         0xcbf91c30 - rt::unwind::begin_unwind_inner::hba10c536ef2aae75MQI
   4:         0xc92a10c0 - rt::unwind::begin_unwind::h11287547919384241778
   5:         0xc92a1050 - diagnostic::SpanHandler::span_bug::h551f703868554ecfUBD
   6:         0xc9e32fe0 - session::Session::span_bug::h10f6b5fdbea6485fbjp
   7:         0xcb6c5920 - check::regionck::visit_expr::hc78138689559ecf8Yrd
   8:         0xcb6c35c0 - check::regionck::Rcx<'a, 'tcx>::visit_fn_body::h75e2fac33dc50b43a4c
   9:         0xcb75ee50 - check::check_bare_fn::hf42e5aabaa5cb880Oan
  10:         0xcb756f40 - check::check_item::hdbe569c101f96905stn
  11:         0xcb822f10 - check_crate::closure.36015
  12:         0xcb81d9c0 - check_crate::h9d44bf3fde687089EXB
  13:         0xcc6a38c0 - driver::phase_3_run_analysis_passes::h36c633d41f11ca74wFa
  14:         0xcc689ec0 - driver::compile_input::h0de317319ab5c701Hba
  15:         0xcc754e20 - run_compiler::hffa0c0711e361de8E5b
  16:         0xcc753720 - thunk::F.Invoke<A, R>::invoke::h12673221910893163557
  17:         0xcc752610 - rt::unwind::try::try_fn::h15130568597725528481
  18:         0xcc0bd740 - rust_try_inner
  19:         0xcc0bd730 - rust_try
  20:         0xcc752910 - thunk::F.Invoke<A, R>::invoke::h3924406537784056782
  21:         0xcc03d990 - sys::thread::thread_start::h3734be2229bd3edegEE
  22:         0xc5f650c0 - start_thread
  23:         0xcbc0a449 - __clone
  24:                0x0 - <unknown>

Compiler version:

rustc 1.0.0-nightly (b47aebe3f 2015-02-26) (built 2015-02-27)
binary: rustc
commit-hash: b47aebe3fc2da06c760fd8ea19f84cbc41d34831
commit-date: 2015-02-26
build-date: 2015-02-27
host: x86_64-unknown-linux-gnu
release: 1.0.0-nightly

I modified the test case in #22894 by moving the &*"" into fn main(), and I saw the same ICE. I then changed the "" to the similar &[], and I saw an ICE with a different error message and a different stack trace (e.g. phase 3 instead of phase 4). The & and * are unnecessary.

I also see the cat_expr Errd message in #22037, but there are differences -- this issue happens in phase 3 rather than 4, and there is no "fictitious type" message.

[gkoz]

This seems to trigger the same bug:

fn main() { 0 as *mut _; }

[seppo0010]

I think I ran into the same problem running similar code

pub fn hello(mystr: &str) -> &[str] {
    &[];
}

pub fn main() {
}

Compiler output

$ RUST_BACKTRACE=1 rustc ./test.rs
./test.rs:2:5: 2:8 error: internal compiler error: cat_expr Errd
./test.rs:2     &[];
                ^~~
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: run with `RUST_BACKTRACE=1` for a backtrace

thread 'rustc' panicked at 'Box<Any>', /Users/rustbuild/src/rust-buildbot/slave/beta-dist-rustc-mac/build/src/libsyntax/diagnostic.rs:130

stack backtrace:
   1:        0x1106d3f77 - sys::backtrace::write::h799ab135045ca9ca1LC
   2:        0x110701e4d - panicking::on_panic::h9502e488a92fc8bcHAI
   3:        0x1106262de - rt::unwind::begin_unwind_inner::hf0537788ee16eadbiiI
   4:        0x10fdf85ae - rt::unwind::begin_unwind::h447731439410619827
   5:        0x10fdf855b - diagnostic::SpanHandler::span_bug::h3f51c1d819f22bcfjnB
   6:        0x10d5631ac - session::Session::span_bug::h460cdb4f2d9be26b5Xq
   7:        0x10cc93991 - check::regionck::visit_expr::h5f402212d9d0fff7PJd
   8:        0x10cc8e2e3 - check::regionck::Rcx<'a, 'tcx>::visit_fn_body::h9e50b5f998fa9b18amd
   9:        0x10cd2c76c - check::check_bare_fn::h05c77be534ada2cfUQn
  10:        0x10cd25ee2 - check::check_item::h9d89bedf29e4fe82F9n
  11:        0x10ce02676 - check_crate::closure.36302
  12:        0x10cdfcae7 - check_crate::h09aa7856a322fd44bwC
  13:        0x10cb1b355 - driver::phase_3_run_analysis_passes::h1af60e7c926ca39dgGa
  14:        0x10caffa85 - driver::compile_input::h27cf4320fd56e5cbQba
  15:        0x10cbbda15 - run_compiler::h93c68a2a3c26052bV4b
  16:        0x10cbbb1e2 - boxed::F.FnBox<A>::call_box::h4498816167135712709
  17:        0x10cbba6d7 - rt::unwind::try::try_fn::h2387014819904265058
  18:        0x11078bea8 - rust_try_inner
  19:        0x11078be95 - rust_try
  20:        0x10cbba9ca - boxed::F.FnBox<A>::call_box::h4850138824497903476
  21:        0x1106eb37d - sys::thread::create::thread_start::h42d6d904fce5365aihH
  22:     0x7fff97b50267 - _pthread_body
  23:     0x7fff97b501e4 - _pthread_start

version

$ rustc --version --verbose
rustc 1.0.0-beta (9854143cb 2015-04-02) (built 2015-04-02)
binary: rustc
commit-hash: 9854143cba679834bc4ef932858cd5303f015a0e
commit-date: 2015-04-02
build-date: 2015-04-02
host: x86_64-apple-darwin
release: 1.0.0-beta