Unsized tuples shouldn't compile

[alecmocatta]

rustc 1.11.0-nightly (5522e678b 2016-06-20)
binary: rustc
commit-hash: 5522e678bcefe14cc2ab3d0ab329b7059ce52b36
commit-date: 2016-06-20
host: x86_64-unknown-linux-gnu
release: 1.11.0-nightly

   Compiling shared v0.1.0 (file:///rust)
     Running `rustc /rust/src/lib.rs --crate-name shared --crate-type lib -g --cfg feature=\"job_network\" --cfg feature=\"network\" -C metadata=4a7ff01c4e736677 -C extra-filename=-4a7ff01c4e736677 --out-dir /platform/src/target/debug/deps --emit=dep-info,link -L dependency=/platform/src/target/debug/deps -L dependency=/platform/src/target/debug/deps --extern libc=/platform/src/target/debug/deps/liblibc-6b483f9a7097e9a4.rlib --extern num_cpus=/platform/src/target/debug/deps/libnum_cpus-b50c8a4bade044aa.rlib --extern network=/platform/src/target/debug/deps/libnetwork-185a522f56e53476.rlib --extern time=/platform/src/target/debug/deps/libtime-750bfdd52feafcb7.rlib --extern tenacious=/platform/src/target/debug/deps/libtenacious-02abd60f9f387669.so -L native=/platform/src/target/debug/build/network-7ccf86279f1eaf03/out`
error: internal compiler error: ../src/librustc_trans/type_of.rs:143: size differs (rustc: 8, llvm: 24) for type `(usize, [&[u8]])` / Univariant {
    variant: Struct {
        align: Align {
            raw: 51
        },
        packed: false,
        sized: false,
        offset_after_field: [
            Size {
                raw: 8
            },
            Size {
                raw: 8
            }
        ]
    },
    non_zero: false
}
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>', ../src/libsyntax/errors/mod.rs:584
stack backtrace:
   1:     0x7f1e5587c62f - std::sys::backtrace::tracing::imp::write::h6528da8103c51ab9
   2:     0x7f1e5588a2ab - std::panicking::default_hook::_$u7b$$u7b$closure$u7d$$u7d$::hbe741a5cc3c49508
   3:     0x7f1e55889e48 - std::panicking::default_hook::he0146e6a74621cb4
   4:     0x7f1e5585016e - std::panicking::rust_panic_with_hook::h983af77c1a2e581b
   5:     0x7f1e50bffa67 - std::panicking::begin_panic::hf9f206df23a555af
   6:     0x7f1e50bff3ce - syntax::errors::Handler::bug::hd25802f012f6858b
   7:     0x7f1e51e42b84 - rustc::session::opt_span_bug_fmt::_$u7b$$u7b$closure$u7d$$u7d$::h083e19915ee66466
   8:     0x7f1e51e4298d - rustc::session::opt_span_bug_fmt::h157ddeb5b4622d22
   9:     0x7f1e51e5d366 - rustc::session::bug_fmt::h166f9667daf4dd54
  10:     0x7f1e5328f6bf - rustc_trans::type_of::sizing_type_of::hf1ac5f8b6f66decc
  11:     0x7f1e5328bbb9 - rustc_trans::abi::FnType::unadjusted::hdf4ab7ff60d3c827
  12:     0x7f1e5329a292 - rustc_trans::type_of::in_memory_type_of::h8a5b5f0d28dddacd
  13:     0x7f1e5330068c - rustc_trans::callee::get_fn::hc9dd3345932f2570
  14:     0x7f1e532a69cb - rustc_trans::callee::Callee::def::hc7f23805201545e4
  15:     0x7f1e532d19fc - rustc_trans::base::trans_item::hca2904a0eb6b2a6f
  16:     0x7f1e532e9643 - _<rustc_trans..base..TransItemsWithinModVisitor<'a, 'tcx> as rustc..hir..intravisit..Visitor<'v>>::visit_item::hc86f557d139a067e
  17:     0x7f1e532e7bcf - rustc::hir::intravisit::walk_item::he9a143fadf3af5d7
  18:     0x7f1e532da3f4 - rustc_trans::base::trans_crate::h999c47a06d45abea
  19:     0x7f1e55db9eff - rustc_driver::driver::phase_4_translate_to_llvm::had910d0e745bc40f
  20:     0x7f1e55db7d8d - rustc_driver::driver::compile_input::_$u7b$$u7b$closure$u7d$$u7d$::hf187cb470aad2bf2
  21:     0x7f1e55db44ed - rustc_driver::driver::phase_3_run_analysis_passes::_$u7b$$u7b$closure$u7d$$u7d$::hd565ad56c5876a16
  22:     0x7f1e55dadcb9 - rustc::ty::context::TyCtxt::create_and_enter::habef58c7230d34f9
  23:     0x7f1e55d770af - rustc_driver::driver::compile_input::hfd60b020f6d0208d
  24:     0x7f1e55d630a4 - rustc_driver::run_compiler::h884d01d12eb76bbb
  25:     0x7f1e55d6017e - std::panicking::try::call::hd72cf79141f67e60
  26:     0x7f1e5589876b - __rust_try
  27:     0x7f1e5589870e - __rust_maybe_catch_panic
  28:     0x7f1e55d60c64 - _<F as alloc..boxed..FnBox<A>>::call_box::h589d2091babf223a
  29:     0x7f1e558883d4 - std::sys::thread::Thread::new::thread_start::h9c883b6d445ece46
  30:     0x7f1e4d3916f9 - start_thread
  31:     0x7f1e554ceb5c - clone
  32:                0x0 - <unknown>

error: Could not compile `shared`.

Caused by:
  Process didn't exit successfully: `rustc /rust/src/lib.rs --crate-name shared --crate-type lib -g --cfg feature="job_network" --cfg feature="network" -C metadata=4a7ff01c4e736677 -C extra-filename=-4a7ff01c4e736677 --out-dir /platform/src/target/debug/deps --emit=dep-info,link -L dependency=/platform/src/target/debug/deps -L dependency=/platform/src/target/debug/deps --extern libc=/platform/src/target/debug/deps/liblibc-6b483f9a7097e9a4.rlib --extern num_cpus=/platform/src/target/debug/deps/libnum_cpus-b50c8a4bade044aa.rlib --extern network=/platform/src/target/debug/deps/libnetwork-185a522f56e53476.rlib --extern time=/platform/src/target/debug/deps/libtime-750bfdd52feafcb7.rlib --extern tenacious=/platform/src/target/debug/deps/libtenacious-02abd60f9f387669.so -L native=/platform/src/target/debug/build/network-7ccf86279f1eaf03/out` (exit code: 101)

Small testcase here.

[jonas-schievink]

cc @eddyb

[eddyb]

Unsized tuples are not implemented yet, did we choose to allow them prematurely? cc @arielb1

[Mark-Simulacrum]

Small testcase compiles without errors. E-needstest.

trait A {
	fn b(&self);
}
impl<'c> A for (usize,[&'c [u8]]) {
	fn b(&self) {
	    0;
	}
}

fn main() {}

[eddyb]

No, it shouldn't compile, I just don't think we ever bothered banning it.
An ICE not triggering on this example is accidental.

[Mark-Simulacrum]

Removing E-needstest. @eddyb That seems.. bad. Is that just because in this case the type isn't really used anywhere?

[eddyb]

The ICE here is a mismatch between LLVM's view of the type and ours but the LLVM type is computed in such a way that I don't think that mismatch is ever possible. Some operations might still ICE.

[steveklabnik]

Triage: still compiles without error.

[eddyb]

I think unsized tuples are implemented now. cc @nikomatsakis

[alecmocatta]

This has compiled for a while now. Unsized tuples are being exercised, incl by tests related to #42877. Closing.