Certain uses of polymorphic lifetimes seems to trigger an internal compiler error.

[andersrein]

Code

trait Foo<'t> {
    type Inner;
}


fn foo<T>(_f: for<'f> fn(<T as Foo<'f>>::Inner))
    where T: for<'t> Foo<'t>
{ }

impl<'t> Foo<'t> for i32 {
    type Inner = &'t i32;
}

fn main() { foo::<i32>(|_inner| { }); }

Meta

rustc --version --verbose:

rustc 1.44.1 (c7087fe00 2020-06-17)
binary: rustc
commit-hash: c7087fe00d2ba919df1d813c040a5d47e43b0fe7
commit-date: 2020-06-17
host: x86_64-unknown-linux-gnu
release: 1.44.1
LLVM version: 9.0

Error output

   Compiling minimal_compiler_crash v0.1.0 (/home/are/source/rust_playground/minimal_compiler_crash)
error: internal compiler error: src/librustc_trait_selection/traits/codegen/mod.rs:61: Encountered error `OutputTypeParameterMismatch(Binder(<[closure@src/main.rs:14:24: 14:36] as std::ops::FnMut<(<i32 as Foo<'_>>::Inner,)>>), Binder(<[closure@src/main.rs:14:24: 14:36] as std::ops::FnMut<(&i32,)>>), Sorts(ExpectedFound { expected: &i32, found: <i32 as Foo<'_>>::Inner }))` selecting `Binder(<[closure@src/main.rs:14:24: 14:36] as std::ops::FnMut<(&i32,)>>)` during codegen

thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:904:9
note: run with `RUST_BACKTRACE=1` environment variable to display a 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 1.44.1 (c7087fe00 2020-06-17) running on x86_64-unknown-linux-gnu

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

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

error: aborting due to previous error

error: could not compile `minimal_compiler_crash`.

Backtrace

thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:904:9
stack backtrace:
thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:904:9
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/libunwind.rs:86
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/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:1504
   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_middle::util::bug::opt_span_bug_fmt::{{closure}}
  16: rustc_middle::ty::context::tls::with_opt::{{closure}}
  17: rustc_middle::ty::context::tls::with_opt
  18: rustc_middle::util::bug::opt_span_bug_fmt
  19: rustc_middle::util::bug::bug_fmt
  20: rustc_middle::ty::context::tls::with_context::{{closure}}
  21: rustc_trait_selection::traits::codegen::codegen_fulfill_obligation
  22: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::codegen_fulfill_obligation>::compute
  23: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
  24: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  25: rustc_query_system::query::plumbing::get_query
  26: rustc_ty::instance::resolve_instance
  27: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::resolve_instance>::compute
  28: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
  29: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  30: rustc_query_system::query::plumbing::get_query
  31: rustc_middle::ty::instance::Instance::resolve
  32: <rustc_mir::monomorphize::collector::MirNeighborCollector as rustc_middle::mir::visit::Visitor>::visit_terminator_kind
  33: rustc_mir::monomorphize::collector::collect_items_rec
  34: rustc_mir::monomorphize::collector::collect_items_rec
  35: rustc_mir::monomorphize::collector::collect_crate_mono_items
  36: rustc_mir::monomorphize::partitioning::collect_and_partition_mono_items
  37: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::collect_and_partition_mono_items>::compute
  38: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
  39: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  40: rustc_query_system::query::plumbing::get_query
  41: rustc_codegen_ssa::base::codegen_crate
  42: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_ssa::traits::backend::CodegenBackend>::codegen_crate
  43: rustc_session::utils::<impl rustc_session::session::Session>::time
  44: rustc_interface::passes::start_codegen
  45: rustc_middle::ty::context::tls::enter_global
  46: rustc_interface::queries::Queries::ongoing_codegen
  47: rustc_interface::interface::run_compiler_in_existing_thread_pool
  48: scoped_tls::ScopedKey<T>::set
  49: rustc_ast::attr::with_globals

[jackh726]

Closing as duplicate of #62529