Rustc panics if enum has unsized attribute.

Consider this code:

#![allow(dead_code)]

fn main() {
    println!("Hello world");
}

struct StructTest {
    x: EnumTest,
}

enum EnumTest {
    A([usize]),
}

impl StructTest {
    fn test(&mut self) {
    }
}

What I get:

rustc 1.11.0 (9b21dcd 2016-08-15)
error: internal compiler error: ../src/librustc_trans/type_of.rs:178: Unexpected tail in unsized_info_ty: EnumTest for ty=StructTest
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', ../src/librustc_errors/lib.rs:619
stack backtrace:
1: 0x7fa0c066fe2f - std::sys::backtrace::tracing::imp::write::h46e546df6e4e4fe6
2: 0x7fa0c067e13b - std::panicking::default_hook::$u7b$$u7b$closure$u7d$$u7d$::h077deeda8b799591
3: 0x7fa0c067dcd8 - std::panicking::default_hook::heb8b6fd640571a4f
4: 0x7fa0c0643ade - std::panicking::rust_panic_with_hook::hd7b83626099d3416
5: 0x7fa0b91f4187 - std::panicking::begin_panic::h3e029d5f110b4661
6: 0x7fa0b91f3ad1 - rustc_errors::Handler::bug::he60f76b829c68950
7: 0x7fa0bcc0ceb4 - rustc::session::opt_span_bug_fmt::$u7b$$u7b$closure$u7d$$u7d$::h11fa08f71c1e9d84
8: 0x7fa0bcc0ccbd - rustc::session::opt_span_bug_fmt::hdc2517bf24a762d0
9: 0x7fa0bcc27886 - rustc::session::bug_fmt::h4bff3cf11871f37a
10: 0x7fa0bf68c3e3 - rustc_trans::type_of::unsized_info_ty::h367c20592955858c
11: 0x7fa0bf5403d2 - rustc_trans::type_of::in_memory_type_of::h063fab02861e60cf
12: 0x7fa0bf53413a - rustc_trans::abi::FnType::unadjusted::$u7b$$u7b$closure$u7d$$u7d$::hc2595e37370d1c41
13: 0x7fa0bf531702 - rustc_trans::abi::FnType::unadjusted::hbb725f7f80132831
14: 0x7fa0bf53fe42 - rustc_trans::type_of::in_memory_type_of::h063fab02861e60cf
15: 0x7fa0bf5a6e6a - rustc_trans::callee::get_fn::h95e52f4d5bcb804b
16: 0x7fa0bf54a5e0 - rustc_trans::callee::Callee::def::h91a0eebd5a5325c7
17: 0x7fa0bf575b9c - rustc_trans::base::trans_item::hcfc6f2f68b9918b0
18: 0x7fa0bf58d893 - <rustc_trans..base..TransItemsWithinModVisitor<'a, 'tcx> as rustc..hir..intravisit..Visitor<'v>>::visit_item::hfffd713d2b3de363
19: 0x7fa0bf57e337 - rustc_trans::base::trans_crate::h75826f6271b49faf
20: 0x7fa0c0bc407f - rustc_driver::driver::phase_4_translate_to_llvm::hbc7e9672529bb439
21: 0x7fa0c0bc106c - rustc_driver::driver::compile_input::$u7b$$u7b$closure$u7d$$u7d$::h7168080c5b7e33b9
22: 0x7fa0c0bbd77d - rustc_driver::driver::phase_3_run_analysis_passes::$u7b$$u7b$closure$u7d$$u7d$::hded790081e457a76
23: 0x7fa0c0bb6f49 - rustc::ty::context::TyCtxt::create_and_enter::h7622c0f52ea2e7fe
24: 0x7fa0c0b7480f - rustc_driver::driver::compile_input::hdfe4405d66704c31
25: 0x7fa0c0b60f44 - rustc_driver::run_compiler::h581448fb74257353
26: 0x7fa0c0b5e04e - std::panicking::try::call::hf081e8ea5e252d1a
27: 0x7fa0c068c63b - __rust_try
28: 0x7fa0c068c5de - __rust_maybe_catch_panic
29: 0x7fa0c0b5eb34 - _<F as alloc..boxed..FnBox>::call_box::h2d5dcb354b3ff8db
30: 0x7fa0c067c264 - std::sys::thread::Thread::new::thread_start::hf2eed4b6f7149599
31: 0x7fa0b88e16f9 - start_thread
32: 0x7fa0c02beb5c - clone
33: 0x0 -

I expected the compiler to tell me, that
enum EnumTest { A([usize]), }

is not possible, as the size of A is not known at compile-time. Instead it panics. Test it https://play.rust-lang.org/?gist=2f36e717877a374b267eb072a0279614&version=stable&backtrace=1 in the Playground.

[apasel422]

Duplicate of #16812.