Rustc panic when wrong namespace in destructuring patern

[michalsrb]

Rustc panics when trying to compile this (incorrect) code:

struct SomeStruct {
    a: i32
}

fn main() {
    let s = SomeStruct { a: 1 };

    let SomeStruct::SomeStruct{ a } = s;
//      ^^^^^^^^^^^^ - this part is nonsense, but instead of an error rustc crashes
}

This is the smallest example I could get. The same error happens when that pattern is used inside if let or a match.

Backtrace:

> RUST_BACKTRACE=1 rustc main.rs 
error: internal compiler error: ../src/librustc/hir/def.rs:77: path not fully resolved: PathResolution { base_def: Struct(DefId { krate: 0, node: DefIndex(4) => SomeStruct }), depth: 1 }
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:     0x7fb77ad4d7df - std::sys::backtrace::tracing::imp::write::h6528da8103c51ab9
   2:     0x7fb77ad5b78b - std::panicking::default_hook::_$u7b$$u7b$closure$u7d$$u7d$::hbe741a5cc3c49508
   3:     0x7fb77ad5b328 - std::panicking::default_hook::he0146e6a74621cb4
   4:     0x7fb77ad2131e - std::panicking::rust_panic_with_hook::h983af77c1a2e581b
   5:     0x7fb776137b07 - std::panicking::begin_panic::hf9f206df23a555af
   6:     0x7fb77613746e - syntax::errors::Handler::bug::hd25802f012f6858b
   7:     0x7fb777325f14 - rustc::session::opt_span_bug_fmt::_$u7b$$u7b$closure$u7d$$u7d$::h083e19915ee66466
   8:     0x7fb777325d1d - rustc::session::opt_span_bug_fmt::h157ddeb5b4622d22
   9:     0x7fb777340696 - rustc::session::bug_fmt::h166f9667daf4dd54
  10:     0x7fb777325b8f - rustc::ty::_<impl rustc..ty..context..TyCtxt<'a, 'gcx, 'tcx>>::expect_def::h1bba3da31e27b082
  11:     0x7fb779acb834 - rustc_typeck::check::_match::_<impl rustc_typeck..check..FnCtxt<'a, 'gcx, 'tcx>>::check_pat_struct::hb2aac908ea2f3898
  12:     0x7fb779a6a9e2 - rustc_typeck::check::_match::_<impl rustc_typeck..check..FnCtxt<'a, 'gcx, 'tcx>>::check_pat::hb68aedceeb2eae7b
  13:     0x7fb779ac3eab - rustc_typeck::check::FnCtxt::check_decl_local::ha8db63787b369f3c
  14:     0x7fb779ac4041 - rustc_typeck::check::FnCtxt::check_stmt::h7bb4ce1dbc8a215f
  15:     0x7fb779a6c933 - rustc_typeck::check::FnCtxt::check_block_with_expected::h66a8dcc154a53b83
  16:     0x7fb779a63c93 - rustc_typeck::check::check_fn::h74a0e95f02904d77
  17:     0x7fb779a60d8e - rustc_typeck::check::check_bare_fn::h7683dfd1c7fc31d1
  18:     0x7fb779a5c4e2 - rustc_typeck::check::check_item_body::h33cafe2320cee00a
  19:     0x7fb779a53fde - rustc_typeck::check::check_item_bodies::h0649c58896094a63
  20:     0x7fb779a49dd6 - rustc_typeck::check_crate::h9ad81a238efa1992
  21:     0x7fb77b280ccc - rustc_driver::driver::phase_3_run_analysis_passes::_$u7b$$u7b$closure$u7d$$u7d$::hd565ad56c5876a16
  22:     0x7fb77b27edb9 - rustc::ty::context::TyCtxt::create_and_enter::habef58c7230d34f9
  23:     0x7fb77b249f5f - rustc_driver::driver::compile_input::hfd60b020f6d0208d
  24:     0x7fb77b235e84 - rustc_driver::run_compiler::h884d01d12eb76bbb
  25:     0x7fb77b232f5e - std::panicking::try::call::hd72cf79141f67e60
  26:     0x7fb77ad69c4b - __rust_try
  27:     0x7fb77ad69bee - __rust_maybe_catch_panic
  28:     0x7fb77b233a44 - _<F as alloc..boxed..FnBox<A>>::call_box::h589d2091babf223a
  29:     0x7fb77ad598b4 - std::sys::thread::Thread::new::thread_start::h9c883b6d445ece46
  30:     0x7fb7728cb0a3 - start_thread
  31:     0x7fb77a99efec - __clone
  32:                0x0 - <unknown>

It happens with nightly (installed using rustup):

> rustc --version --verbose
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

It does not happen with stable (rustc 1.10.0-beta.2 (39f3c16cc 2016-05-26)) or beta (rustc 1.9.0 (e4e8b6668 2016-05-18)) versions. With them I get error message as expected:

main.rs:8:9: 8:31 error: failed to resolve. Use of undeclared type or module `SomeStruct` [E0433]
main.rs:8     let SomeStruct::SomeStruct{a} = s;
                  ^~~~~~~~~~~~~~~~~~~~~~
main.rs:8:9: 8:31 help: run `rustc --explain E0433` to see a detailed explanation
main.rs:8:9: 8:34 error: `SomeStruct::SomeStruct` does not name a struct or a struct variant [E0163]
main.rs:8     let SomeStruct::SomeStruct{a} = s;
                  ^~~~~~~~~~~~~~~~~~~~~~~~~
main.rs:8:9: 8:34 help: run `rustc --explain E0163` to see a detailed explanation
error: aborting due to previous error

[petrochenkov]

Duplicate of #34209, fixed in #34365

[alexcrichton]

Yay!