ICE: impl-with-unconstrained-param.rs -Zsave-analysis --emit=mir : Err value: UnresolvedTy(_#0t)

[matthiaskrgr]

Code

code from src/test/ui/type-alias-impl-trait/impl-with-unconstrained-param.rs (may no longer exist)

#![feature(type_alias_impl_trait)]

trait X {
    type I;
    fn f() -> Self::I;
}

impl<T> X for () {
    type I = impl Sized;
    //~^ ERROR could not find defining uses
    fn f() -> Self::I {}
    //~^ ERROR type annotations needed
}

fn main() {}

Meta

rustc --version --verbose:

rustc 1.55.0-nightly (014026d1a 2021-07-19)
binary: rustc
commit-hash: 014026d1a7ca991f82f12efa95ef4dffb29dc8af
commit-date: 2021-07-19
host: x86_64-unknown-linux-gnu
release: 1.55.0-nightly
LLVM version: 12.0.1

Error output

error[E0658]: `impl Trait` in type aliases is unstable
  --> ./src/test/ui/type-alias-impl-trait/impl-with-unconstrained-param.rs:12:14
   |
12 |     type I = impl Sized;
   |              ^^^^^^^^^^
   |
   = note: see issue #63063 <https://github.com/rust-lang/rust/issues/63063> for more information
   = help: add `#![feature(min_type_alias_impl_trait)]` to the crate attributes to enable

warning: the feature `type_alias_impl_trait` is incomplete and may not be safe to use and/or cause compiler crashes
 --> ./src/test/ui/type-alias-impl-trait/impl-with-unconstrained-param.rs:4:12
  |
4 | #![feature(type_alias_impl_trait)]
  |            ^^^^^^^^^^^^^^^^^^^^^
  |
  = note: `#[warn(incomplete_features)]` on by default
  = note: see issue #63063 <https://github.com/rust-lang/rust/issues/63063> for more information

error[E0207]: the type parameter `T` is not constrained by the impl trait, self type, or predicates
  --> ./src/test/ui/type-alias-impl-trait/impl-with-unconstrained-param.rs:11:6
   |
11 | impl<T> X for () {
   |      ^ unconstrained type parameter

error[E0282]: type annotations needed
  --> ./src/test/ui/type-alias-impl-trait/impl-with-unconstrained-param.rs:14:23
   |
14 |     fn f() -> Self::I {}
   |                       ^^ cannot infer type for type parameter `T`

thread 'rustc' panicked at 'called `Result::unwrap()` on an `Err` value: UnresolvedTy(_#0t)', compiler/rustc_typeck/src/check/writeback.rs:499:75
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

error: internal compiler error: unexpected panic

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.55.0-nightly (014026d1a 2021-07-19) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z save-analysis

query stack during panic:
#0 [typeck] type-checking `<impl at ./src/test/ui/type-alias-impl-trait/impl-with-unconstrained-param.rs:11:1: 16:2>::f`
end of query stack
error: aborting due to 3 previous errors; 1 warning emitted

Backtrace

error[E0658]: `impl Trait` in type aliases is unstable
  --> ./src/test/ui/type-alias-impl-trait/impl-with-unconstrained-param.rs:12:14
   |
12 |     type I = impl Sized;
   |              ^^^^^^^^^^
   |
   = note: see issue #63063 <https://github.com/rust-lang/rust/issues/63063> for more information
   = help: add `#![feature(min_type_alias_impl_trait)]` to the crate attributes to enable

warning: the feature `type_alias_impl_trait` is incomplete and may not be safe to use and/or cause compiler crashes
 --> ./src/test/ui/type-alias-impl-trait/impl-with-unconstrained-param.rs:4:12
  |
4 | #![feature(type_alias_impl_trait)]
  |            ^^^^^^^^^^^^^^^^^^^^^
  |
  = note: `#[warn(incomplete_features)]` on by default
  = note: see issue #63063 <https://github.com/rust-lang/rust/issues/63063> for more information

error[E0207]: the type parameter `T` is not constrained by the impl trait, self type, or predicates
  --> ./src/test/ui/type-alias-impl-trait/impl-with-unconstrained-param.rs:11:6
   |
11 | impl<T> X for () {
   |      ^ unconstrained type parameter

error[E0282]: type annotations needed
  --> ./src/test/ui/type-alias-impl-trait/impl-with-unconstrained-param.rs:14:23
   |
14 |     fn f() -> Self::I {}
   |                       ^^ cannot infer type for type parameter `T`

thread 'rustc' panicked at 'called `Result::unwrap()` on an `Err` value: UnresolvedTy(_#0t)', compiler/rustc_typeck/src/check/writeback.rs:499:75
stack backtrace:
   0:     0x7f0497f07b90 - std::backtrace_rs::backtrace::libunwind::trace::h0f5cd2ee8b0d7274
                               at /rustc/014026d1a7ca991f82f12efa95ef4dffb29dc8af/library/std/src/../../backtrace/src/backtrace/libunwind.rs:90:5
   1:     0x7f0497f07b90 - std::backtrace_rs::backtrace::trace_unsynchronized::h06905b5aeda069a1
                               at /rustc/014026d1a7ca991f82f12efa95ef4dffb29dc8af/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f0497f07b90 - std::sys_common::backtrace::_print_fmt::h4fe4c7c875072f30
                               at /rustc/014026d1a7ca991f82f12efa95ef4dffb29dc8af/library/std/src/sys_common/backtrace.rs:67:5
   3:     0x7f0497f07b90 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hcc0746f004a9b7ef
                               at /rustc/014026d1a7ca991f82f12efa95ef4dffb29dc8af/library/std/src/sys_common/backtrace.rs:46:22
   4:     0x7f0497f756cc - core::fmt::write::h9a6d9c74526a6c1b
                               at /rustc/014026d1a7ca991f82f12efa95ef4dffb29dc8af/library/core/src/fmt/mod.rs:1115:17
   5:     0x7f0497ef9315 - std::io::Write::write_fmt::h23dab4cc9ce72ee2
                               at /rustc/014026d1a7ca991f82f12efa95ef4dffb29dc8af/library/std/src/io/mod.rs:1665:15
   6:     0x7f0497f0b8ab - std::sys_common::backtrace::_print::h173dc702502d65d2
                               at /rustc/014026d1a7ca991f82f12efa95ef4dffb29dc8af/library/std/src/sys_common/backtrace.rs:49:5
   7:     0x7f0497f0b8ab - std::sys_common::backtrace::print::h61bd27c4742ba817
                               at /rustc/014026d1a7ca991f82f12efa95ef4dffb29dc8af/library/std/src/sys_common/backtrace.rs:36:9
   8:     0x7f0497f0b8ab - std::panicking::default_hook::{{closure}}::hcaae87f0495ae613
                               at /rustc/014026d1a7ca991f82f12efa95ef4dffb29dc8af/library/std/src/panicking.rs:208:50
   9:     0x7f0497f0b381 - std::panicking::default_hook::h0538e728ee080db0
                               at /rustc/014026d1a7ca991f82f12efa95ef4dffb29dc8af/library/std/src/panicking.rs:225:9
  10:     0x7f04986e4e91 - rustc_driver::DEFAULT_HOOK::{{closure}}::{{closure}}::h9137b7ac1a66352b
  11:     0x7f0497f0c0d9 - std::panicking::rust_panic_with_hook::h3039e236b6ca482c
                               at /rustc/014026d1a7ca991f82f12efa95ef4dffb29dc8af/library/std/src/panicking.rs:626:17
  12:     0x7f0497f0bb97 - std::panicking::begin_panic_handler::{{closure}}::h884fbab544ffd91c
                               at /rustc/014026d1a7ca991f82f12efa95ef4dffb29dc8af/library/std/src/panicking.rs:519:13
  13:     0x7f0497f0808c - std::sys_common::backtrace::__rust_end_short_backtrace::hdaf2e18ba3d91210
                               at /rustc/014026d1a7ca991f82f12efa95ef4dffb29dc8af/library/std/src/sys_common/backtrace.rs:141:18
  14:     0x7f0497f0baf9 - rust_begin_unwind
                               at /rustc/014026d1a7ca991f82f12efa95ef4dffb29dc8af/library/std/src/panicking.rs:515:5
  15:     0x7f0497ed6b71 - core::panicking::panic_fmt::hcf5f6d96e1dd7099
                               at /rustc/014026d1a7ca991f82f12efa95ef4dffb29dc8af/library/core/src/panicking.rs:92:14
  16:     0x7f0497ed6c63 - core::result::unwrap_failed::he898b02f57993c42
                               at /rustc/014026d1a7ca991f82f12efa95ef4dffb29dc8af/library/core/src/result.rs:1599:5
  17:     0x7f0499988b79 - rustc_typeck::check::writeback::WritebackCx::visit_opaque_types::h232a08fae1c90ee2
  18:     0x7f04998e6fcf - rustc_typeck::check::writeback::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::resolve_type_vars_in_body::h8b54c18e0f3a4b79
  19:     0x7f0499963887 - rustc_infer::infer::InferCtxtBuilder::enter::h5b0049019ece2d91
  20:     0x7f04999c25f0 - rustc_typeck::check::typeck::h45b639d5069c89f7
  21:     0x7f0499d73a8c - rustc_query_system::query::plumbing::get_query_impl::h475bb642f2deb506
  22:     0x7f0499de5c3b - <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::typeck::h34bb83bc2eb7a080
  23:     0x7f0498735d79 - rustc_save_analysis::dump_visitor::DumpVisitor::process_method::hc8aa5dbea4311631
  24:     0x7f0498738766 - rustc_save_analysis::dump_visitor::DumpVisitor::process_impl_item::h59b684c892943cde
  25:     0x7f0498734253 - rustc_save_analysis::dump_visitor::DumpVisitor::nest_typeck_results::h253be14039dac37b
  26:     0x7f049873b40c - <rustc_save_analysis::dump_visitor::DumpVisitor as rustc_hir::intravisit::Visitor>::visit_item::h9b52cebc0df4f7b9
  27:     0x7f0498733216 - rustc_hir::intravisit::Visitor::visit_nested_item::h9e975cc0f2a00c21
  28:     0x7f0498720bb1 - rustc_hir::intravisit::walk_crate::he7f189f23867b6fd
  29:     0x7f0498738b70 - rustc_save_analysis::dump_visitor::DumpVisitor::process_crate::h8b9b619ce8c21fa3
  30:     0x7f0498713f5b - rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps::h411459e0c11e6a97
  31:     0x7f0498716487 - std::thread::local::LocalKey<T>::with::h12d2413a7a54a096
  32:     0x7f04986e6d87 - rustc_save_analysis::process_crate::hbe9c7d8fa9d24483
  33:     0x7f04986f14b7 - rustc_session::utils::<impl rustc_session::session::Session>::time::ha6483c63bbc8b307
  34:     0x7f049a1e56d8 - rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter::hc31f40c1543d1436
  35:     0x7f049a1d3dcc - rustc_span::with_source_map::h0260ea075482ae79
  36:     0x7f049a1e61ba - rustc_interface::interface::create_compiler_and_run::he7ef8517199cf024
  37:     0x7f049a1d9099 - scoped_tls::ScopedKey<T>::set::h603cbfb5f6e2dd76
  38:     0x7f049a1d5eda - std::sys_common::backtrace::__rust_begin_short_backtrace::h23393d8936f34bfc
  39:     0x7f049a1d4765 - core::ops::function::FnOnce::call_once{{vtable.shim}}::h513135f67ecd4e6b
  40:     0x7f0497f18667 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hd5b860c6542b008a
                               at /rustc/014026d1a7ca991f82f12efa95ef4dffb29dc8af/library/alloc/src/boxed.rs:1572:9
  41:     0x7f0497f18667 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hc87b98c8a3a585ed
                               at /rustc/014026d1a7ca991f82f12efa95ef4dffb29dc8af/library/alloc/src/boxed.rs:1572:9
  42:     0x7f0497f18667 - std::sys::unix::thread::Thread::new::thread_start::ha990175c8f3779cc
                               at /rustc/014026d1a7ca991f82f12efa95ef4dffb29dc8af/library/std/src/sys/unix/thread.rs:74:17
  43:     0x7f0497e24259 - start_thread
  44:     0x7f0497d395e3 - __GI___clone
  45:                0x0 - <unknown>

error: internal compiler error: unexpected panic

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.55.0-nightly (014026d1a 2021-07-19) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z save-analysis

query stack during panic:
#0 [typeck] type-checking `<impl at ./src/test/ui/type-alias-impl-trait/impl-with-unconstrained-param.rs:11:1: 16:2>::f`
end of query stack
error: aborting due to 3 previous errors; 1 warning emitted

Some errors have detailed explanations: E0207, E0282, E0658.
For more information about an error, try `rustc --explain E0207`.

[chengniansun]

Code

type PartiallyDefined<T> = impl 'static;
fn partially_defined() -> PartiallyDefined<_> {}

Meta

rustc --version --verbose:

rustc 1.56.0-nightly (9c25eb7aa 2021-07-25)
binary: rustc
commit-hash: 9c25eb7aa3a71fb951564b0ddf131be59c2c951d
commit-date: 2021-07-25
host: x86_64-unknown-linux-gnu
release: 1.56.0-nightly
LLVM version: 12.0.1

Error output

error: at least one trait must be specified
 --> mutant.rs:1:28
  |
1 | type PartiallyDefined<T> = impl 'static;
  |                            ^^^^^^^^^^^^

error[E0658]: `impl Trait` in type aliases is unstable
 --> mutant.rs:1:28
  |
1 | type PartiallyDefined<T> = impl 'static;
  |                            ^^^^^^^^^^^^
  |
  = note: see issue #63063 <https://github.com/rust-lang/rust/issues/63063> for more information
  = help: add `#![feature(min_type_alias_impl_trait)]` to the crate attributes to enable

thread 'rustc' panicked at 'called `Result::unwrap()` on an `Err` value: UnresolvedTy(_#0t)', compiler/rustc_typeck/src/check/writeback.rs:499:75
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

error: internal compiler error: unexpected panic

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.56.0-nightly (9c25eb7aa 2021-07-25) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type staticlib

query stack during panic:
#0 [typeck] type-checking `partially_defined`
#1 [fn_sig] computing function signature of `partially_defined`
end of query stack
error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0658`.

Backtrace

error: at least one trait must be specified
 --> mutant.rs:1:28
  |
1 | type PartiallyDefined<T> = impl 'static;
  |                            ^^^^^^^^^^^^

error[E0658]: `impl Trait` in type aliases is unstable
 --> mutant.rs:1:28
  |
1 | type PartiallyDefined<T> = impl 'static;
  |                            ^^^^^^^^^^^^
  |
  = note: see issue #63063 <https://github.com/rust-lang/rust/issues/63063> for more information
  = help: add `#![feature(min_type_alias_impl_trait)]` to the crate attributes to enable

thread 'rustc' panicked at 'called `Result::unwrap()` on an `Err` value: UnresolvedTy(_#0t)', compiler/rustc_typeck/src/check/writeback.rs:499:75
stack backtrace:
   0: rust_begin_unwind
             at /rustc/9c25eb7aa3a71fb951564b0ddf131be59c2c951d/library/std/src/panicking.rs:515:5
   1: core::panicking::panic_fmt
             at /rustc/9c25eb7aa3a71fb951564b0ddf131be59c2c951d/library/core/src/panicking.rs:92:14
   2: core::result::unwrap_failed
             at /rustc/9c25eb7aa3a71fb951564b0ddf131be59c2c951d/library/core/src/result.rs:1599:5
   3: rustc_typeck::check::writeback::WritebackCx::visit_opaque_types
   4: rustc_typeck::check::writeback::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::resolve_type_vars_in_body
   5: rustc_infer::infer::InferCtxtBuilder::enter
   6: rustc_typeck::check::typeck
   7: rustc_query_system::query::plumbing::get_query_impl
   8: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::typeck
   9: rustc_typeck::collect::fn_sig
  10: rustc_query_system::query::plumbing::get_query_impl
  11: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::fn_sig
  12: rustc_typeck::collect::convert_item
  13: <rustc_typeck::collect::CollectItemTypesVisitor as rustc_hir::intravisit::Visitor>::visit_item
  14: rustc_middle::hir::map::Map::visit_item_likes_in_module
  15: rustc_typeck::collect::collect_mod_item_types
  16: rustc_query_system::query::plumbing::get_query_impl
  17: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::collect_mod_item_types
  18: rustc_session::session::Session::track_errors
  19: rustc_typeck::check_crate
  20: rustc_interface::passes::analysis
  21: rustc_query_system::query::plumbing::get_query_impl
  22: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::analysis
  23: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
  24: rustc_span::with_source_map
  25: rustc_interface::interface::create_compiler_and_run
  26: scoped_tls::ScopedKey<T>::set
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

error: internal compiler error: unexpected panic

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.56.0-nightly (9c25eb7aa 2021-07-25) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type staticlib

query stack during panic:
#0 [typeck] type-checking `partially_defined`
#1 [fn_sig] computing function signature of `partially_defined`
#2 [collect_mod_item_types] collecting item types in top-level module
#3 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0658`.