encountered a fresh type during canonicalization

[dwrensha]

rustc crashes on the following input, found by fuzz_rustc:

fn w() where F:Fn(&'a u){ b:std::ops::FromResidual & m }

error[E0261]: use of undeclared lifetime name `'a`
 --> bug.rs:1:20
  |
1 | fn w() where F:Fn(&'a u){ b:std::ops::FromResidual & m }
  |                    ^^ undeclared lifetime
  |
  = note: for more information on higher-ranked polymorphism, visit https://doc.rust-lang.org/nomicon/hrtb.html
help: consider making the bound lifetime-generic with a new `'a` lifetime
  |
1 | fn w() where F:for<'a> Fn(&'a u){ b:std::ops::FromResidual & m }
  |                +++++++
help: consider making the bound lifetime-generic with a new `'a` lifetime
  |
1 | fn w() where for<'a> F:Fn(&'a u){ b:std::ops::FromResidual & m }
  |              +++++++
help: consider introducing lifetime `'a` here
  |
1 | fn w<'a>() where F:Fn(&'a u){ b:std::ops::FromResidual & m }
  |     ++++

error[E0412]: cannot find type `F` in this scope
 --> bug.rs:1:14
  |
1 | fn w() where F:Fn(&'a u){ b:std::ops::FromResidual & m }
  |              ^
  |
help: a trait with a similar name exists
  |
1 | fn w() where Fn:Fn(&'a u){ b:std::ops::FromResidual & m }
  |              ~~
help: you might be missing a type parameter
  |
1 | fn w<F>() where F:Fn(&'a u){ b:std::ops::FromResidual & m }
  |     +++

error[E0412]: cannot find type `u` in this scope
 --> bug.rs:1:23
  |
1 | fn w() where F:Fn(&'a u){ b:std::ops::FromResidual & m }
  |                       ^ help: a builtin type with a similar name exists: `u8`

error[E0425]: cannot find value `b` in this scope
 --> bug.rs:1:27
  |
1 | fn w() where F:Fn(&'a u){ b:std::ops::FromResidual & m }
  |                           ^- help: maybe you meant to write a path separator here: `::`
  |                           |
  |                           not found in this scope

error[E0425]: cannot find value `m` in this scope
 --> bug.rs:1:54
  |
1 | fn w() where F:Fn(&'a u){ b:std::ops::FromResidual & m }
  |                                                      ^ not found in this scope

error[E0601]: `main` function not found in crate `bug`
 --> bug.rs:1:57
  |
1 | fn w() where F:Fn(&'a u){ b:std::ops::FromResidual & m }
  |                                                         ^ consider adding a `main` function to `bug.rs`

error[E0658]: use of unstable library feature 'try_trait_v2'
 --> bug.rs:1:29
  |
1 | fn w() where F:Fn(&'a u){ b:std::ops::FromResidual & m }
  |                             ^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #84277 <https://github.com/rust-lang/rust/issues/84277> for more information
  = help: add `#![feature(try_trait_v2)]` to the crate attributes to enable

warning: trait objects without an explicit `dyn` are deprecated
 --> bug.rs:1:29
  |
1 | fn w() where F:Fn(&'a u){ b:std::ops::FromResidual & m }
  |                             ^^^^^^^^^^^^^^^^^^^^^^
  |
  = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
  = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
  = note: `#[warn(bare_trait_objects)]` on by default
help: use `dyn`
  |
1 | fn w() where F:Fn(&'a u){ b:dyn std::ops::FromResidual & m }
  |                             +++

error: internal compiler error: compiler/rustc_infer/src/infer/canonical/canonicalizer.rs:420:17: encountered a fresh type during canonicalization

thread 'rustc' panicked at 'Box<dyn Any>', /rustc/bed4ad65bf7a1cef39e3d66b3670189581b3b073/compiler/rustc_errors/src/lib.rs:1519:9
stack backtrace:
   0:     0x7f0740dd95c0 - std::backtrace_rs::backtrace::libunwind::trace::hc24175774fcccc98
                               at /rustc/bed4ad65bf7a1cef39e3d66b3670189581b3b073/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   1:     0x7f0740dd95c0 - std::backtrace_rs::backtrace::trace_unsynchronized::hddff1d85f511dc1b
                               at /rustc/bed4ad65bf7a1cef39e3d66b3670189581b3b073/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f0740dd95c0 - std::sys_common::backtrace::_print_fmt::he96e84d8aca849f4
                               at /rustc/bed4ad65bf7a1cef39e3d66b3670189581b3b073/library/std/src/sys_common/backtrace.rs:65:5
   3:     0x7f0740dd95c0 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h8c690aa67f9b9f0b
                               at /rustc/bed4ad65bf7a1cef39e3d66b3670189581b3b073/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f07412587ae - core::fmt::write::h9205d5073fda8a0b
                               at /rustc/bed4ad65bf7a1cef39e3d66b3670189581b3b073/library/core/src/fmt/mod.rs:1209:17
   5:     0x7f0740dcd375 - std::io::Write::write_fmt::h72ccddbdf2befca8
                               at /rustc/bed4ad65bf7a1cef39e3d66b3670189581b3b073/library/std/src/io/mod.rs:1682:15
   6:     0x7f0740dd9385 - std::sys_common::backtrace::_print::h2243d2fa1c5bb008
                               at /rustc/bed4ad65bf7a1cef39e3d66b3670189581b3b073/library/std/src/sys_common/backtrace.rs:47:5
   7:     0x7f0740dd9385 - std::sys_common::backtrace::print::hf6a50c16875f42b0
                               at /rustc/bed4ad65bf7a1cef39e3d66b3670189581b3b073/library/std/src/sys_common/backtrace.rs:34:9
   8:     0x7f0740ddb6df - std::panicking::default_hook::{{closure}}::h57a3846e717bd3fa
                               at /rustc/bed4ad65bf7a1cef39e3d66b3670189581b3b073/library/std/src/panicking.rs:267:22
   9:     0x7f0740ddb41a - std::panicking::default_hook::h1631ff080b8ff770
                               at /rustc/bed4ad65bf7a1cef39e3d66b3670189581b3b073/library/std/src/panicking.rs:286:9
  10:     0x7f074009f634 - rustc_driver[62b0704af81f9759]::DEFAULT_HOOK::{closure#0}::{closure#0}
  11:     0x7f0740ddbec9 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h353f36a44a5eebf1
                               at /rustc/bed4ad65bf7a1cef39e3d66b3670189581b3b073/library/alloc/src/boxed.rs:2001:9
  12:     0x7f0740ddbec9 - std::panicking::rust_panic_with_hook::h483dc93595b087d7
                               at /rustc/bed4ad65bf7a1cef39e3d66b3670189581b3b073/library/std/src/panicking.rs:692:13
  13:     0x7f0740532bc1 - std[e5fb0ad32021ee83]::panicking::begin_panic::<rustc_errors[f55630e1eea6f6be]::ExplicitBug>::{closure#0}
  14:     0x7f074052f696 - std[e5fb0ad32021ee83]::sys_common::backtrace::__rust_end_short_backtrace::<std[e5fb0ad32021ee83]::panicking::begin_panic<rustc_errors[f55630e1eea6f6be]::ExplicitBug>::{closure#0}, !>
  15:     0x7f074052f636 - std[e5fb0ad32021ee83]::panicking::begin_panic::<rustc_errors[f55630e1eea6f6be]::ExplicitBug>
  16:     0x7f07404c6016 - std[e5fb0ad32021ee83]::panic::panic_any::<rustc_errors[f55630e1eea6f6be]::ExplicitBug>
  17:     0x7f07404c4eed - <rustc_errors[f55630e1eea6f6be]::HandlerInner>::bug::<&alloc[d7ff0ae8c2a4ed81]::string::String>
  18:     0x7f07404c4960 - <rustc_errors[f55630e1eea6f6be]::Handler>::bug::<&alloc[d7ff0ae8c2a4ed81]::string::String>
  19:     0x7f074057750d - rustc_middle[c0b7815efd07efec]::ty::context::tls::with_context_opt::<rustc_middle[c0b7815efd07efec]::ty::context::tls::with_opt<rustc_middle[c0b7815efd07efec]::util::bug::opt_span_bug_fmt<rustc_span[7a2d20772580c7f8]::span_encoding::Span>::{closure#0}, ()>::{closure#0}, ()>
  20:     0x7f0740577866 - rustc_middle[c0b7815efd07efec]::util::bug::opt_span_bug_fmt::<rustc_span[7a2d20772580c7f8]::span_encoding::Span>
  21:     0x7f073e37d003 - rustc_middle[c0b7815efd07efec]::util::bug::bug_fmt
  22:     0x7f073e17697b - <rustc_infer[8e0743cc678018cd]::infer::canonical::canonicalizer::Canonicalizer as rustc_middle[c0b7815efd07efec]::ty::fold::TypeFolder>::fold_ty
  23:     0x7f073e767b08 - <rustc_infer[8e0743cc678018cd]::infer::canonical::canonicalizer::Canonicalizer as rustc_middle[c0b7815efd07efec]::ty::fold::FallibleTypeFolder>::try_fold_predicate
  24:     0x7f073e767098 - <rustc_infer[8e0743cc678018cd]::infer::canonical::canonicalizer::Canonicalizer>::canonicalize::<rustc_middle[c0b7815efd07efec]::ty::ParamEnvAnd<rustc_middle[c0b7815efd07efec]::ty::Predicate>>
  25:     0x7f073e766a55 - <rustc_infer[8e0743cc678018cd]::infer::InferCtxt as rustc_trait_selection[7a29399ba840f18c]::traits::query::evaluate_obligation::InferCtxtExt>::evaluate_obligation_no_overflow
  26:     0x7f0740c09bc5 - <rustc_infer[8e0743cc678018cd]::infer::InferCtxt>::probe::<bool, <rustc_infer[8e0743cc678018cd]::infer::error_reporting::TypeErrCtxt as rustc_trait_selection[7a29399ba840f18c]::traits::error_reporting::InferCtxtPrivExt>::predicate_can_apply::{closure#0}>
  27:     0x7f0740c4f4dd - <rustc_infer[8e0743cc678018cd]::infer::error_reporting::TypeErrCtxt as rustc_trait_selection[7a29399ba840f18c]::traits::error_reporting::TypeErrCtxtExt>::report_selection_error
  28:     0x7f0740c56c4c - <rustc_infer[8e0743cc678018cd]::infer::error_reporting::TypeErrCtxt as rustc_trait_selection[7a29399ba840f18c]::traits::error_reporting::InferCtxtPrivExt>::report_fulfillment_error
  29:     0x7f0740c4b07d - <rustc_infer[8e0743cc678018cd]::infer::error_reporting::TypeErrCtxt as rustc_trait_selection[7a29399ba840f18c]::traits::error_reporting::TypeErrCtxtExt>::report_fulfillment_errors
  30:     0x7f073e4e665e - <rustc_hir_typeck[92d554a17c266936]::fn_ctxt::FnCtxt>::demand_coerce
  31:     0x7f073e4e0de5 - <rustc_hir_typeck[92d554a17c266936]::fn_ctxt::FnCtxt>::check_overloaded_binop
  32:     0x7f073e463ede - <rustc_hir_typeck[92d554a17c266936]::fn_ctxt::FnCtxt>::check_binop
  33:     0x7f073e45867b - <rustc_hir_typeck[92d554a17c266936]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  34:     0x7f073e49af27 - <rustc_hir_typeck[92d554a17c266936]::fn_ctxt::FnCtxt>::check_block_with_expected
  35:     0x7f073e45669b - <rustc_hir_typeck[92d554a17c266936]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  36:     0x7f073f0d5f86 - <rustc_hir_typeck[92d554a17c266936]::fn_ctxt::FnCtxt>::check_return_expr
  37:     0x7f073f0d386a - rustc_hir_typeck[92d554a17c266936]::check::check_fn
  38:     0x7f073f0c036c - rustc_hir_typeck[92d554a17c266936]::typeck
  39:     0x7f073e6e482d - rustc_query_system[e96faf9c245748b3]::query::plumbing::try_execute_query::<rustc_query_impl[e8c6edc993fa4034]::plumbing::QueryCtxt, rustc_query_system[e96faf9c245748b3]::query::caches::DefaultCache<rustc_span[7a2d20772580c7f8]::def_id::LocalDefId, &rustc_middle[c0b7815efd07efec]::ty::context::TypeckResults>>
  40:     0x7f073f8a3478 - rustc_data_structures[5434cf185ef65262]::sync::par_for_each_in::<&[rustc_span[7a2d20772580c7f8]::def_id::LocalDefId], <rustc_middle[c0b7815efd07efec]::hir::map::Map>::par_body_owners<rustc_hir_typeck[92d554a17c266936]::typeck_item_bodies::{closure#0}>::{closure#0}>
  41:     0x7f073f8a3153 - rustc_hir_typeck[92d554a17c266936]::typeck_item_bodies
  42:     0x7f073f79394a - rustc_query_system[e96faf9c245748b3]::query::plumbing::try_execute_query::<rustc_query_impl[e8c6edc993fa4034]::plumbing::QueryCtxt, rustc_query_system[e96faf9c245748b3]::query::caches::DefaultCache<(), ()>>
  43:     0x7f073f793647 - rustc_query_system[e96faf9c245748b3]::query::plumbing::get_query::<rustc_query_impl[e8c6edc993fa4034]::queries::typeck_item_bodies, rustc_query_impl[e8c6edc993fa4034]::plumbing::QueryCtxt>
  44:     0x7f073e6103aa - <rustc_session[f004b37ccc5cd57]::session::Session>::time::<(), rustc_hir_analysis[2e9e393b1de5c568]::check_crate::{closure#7}>
  45:     0x7f073e60f56b - rustc_hir_analysis[2e9e393b1de5c568]::check_crate
  46:     0x7f073e60f19b - rustc_interface[fd3d32691052b72b]::passes::analysis
  47:     0x7f073f8f66e4 - rustc_query_system[e96faf9c245748b3]::query::plumbing::try_execute_query::<rustc_query_impl[e8c6edc993fa4034]::plumbing::QueryCtxt, rustc_query_system[e96faf9c245748b3]::query::caches::DefaultCache<(), core[69220df7bf4c31ea]::result::Result<(), rustc_errors[f55630e1eea6f6be]::ErrorGuaranteed>>>
  48:     0x7f073f8f63e7 - rustc_query_system[e96faf9c245748b3]::query::plumbing::get_query::<rustc_query_impl[e8c6edc993fa4034]::queries::analysis, rustc_query_impl[e8c6edc993fa4034]::plumbing::QueryCtxt>
  49:     0x7f073f423f7d - <rustc_interface[fd3d32691052b72b]::passes::QueryContext>::enter::<rustc_driver[62b0704af81f9759]::run_compiler::{closure#1}::{closure#2}::{closure#3}, core[69220df7bf4c31ea]::result::Result<(), rustc_errors[f55630e1eea6f6be]::ErrorGuaranteed>>
  50:     0x7f073f4204df - <rustc_interface[fd3d32691052b72b]::interface::Compiler>::enter::<rustc_driver[62b0704af81f9759]::run_compiler::{closure#1}::{closure#2}, core[69220df7bf4c31ea]::result::Result<core[69220df7bf4c31ea]::option::Option<rustc_interface[fd3d32691052b72b]::queries::Linker>, rustc_errors[f55630e1eea6f6be]::ErrorGuaranteed>>
  51:     0x7f073f4176d2 - rustc_span[7a2d20772580c7f8]::with_source_map::<core[69220df7bf4c31ea]::result::Result<(), rustc_errors[f55630e1eea6f6be]::ErrorGuaranteed>, rustc_interface[fd3d32691052b72b]::interface::run_compiler<core[69220df7bf4c31ea]::result::Result<(), rustc_errors[f55630e1eea6f6be]::ErrorGuaranteed>, rustc_driver[62b0704af81f9759]::run_compiler::{closure#1}>::{closure#0}::{closure#1}>
  52:     0x7f073f4171c9 - <scoped_tls[c5a5fd0946957a01]::ScopedKey<rustc_span[7a2d20772580c7f8]::SessionGlobals>>::set::<rustc_interface[fd3d32691052b72b]::interface::run_compiler<core[69220df7bf4c31ea]::result::Result<(), rustc_errors[f55630e1eea6f6be]::ErrorGuaranteed>, rustc_driver[62b0704af81f9759]::run_compiler::{closure#1}>::{closure#0}, core[69220df7bf4c31ea]::result::Result<(), rustc_errors[f55630e1eea6f6be]::ErrorGuaranteed>>
  53:     0x7f073f4167d8 - std[e5fb0ad32021ee83]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[fd3d32691052b72b]::util::run_in_thread_pool_with_globals<rustc_interface[fd3d32691052b72b]::interface::run_compiler<core[69220df7bf4c31ea]::result::Result<(), rustc_errors[f55630e1eea6f6be]::ErrorGuaranteed>, rustc_driver[62b0704af81f9759]::run_compiler::{closure#1}>::{closure#0}, core[69220df7bf4c31ea]::result::Result<(), rustc_errors[f55630e1eea6f6be]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[69220df7bf4c31ea]::result::Result<(), rustc_errors[f55630e1eea6f6be]::ErrorGuaranteed>>
  54:     0x7f073f4164fc - <<std[e5fb0ad32021ee83]::thread::Builder>::spawn_unchecked_<rustc_interface[fd3d32691052b72b]::util::run_in_thread_pool_with_globals<rustc_interface[fd3d32691052b72b]::interface::run_compiler<core[69220df7bf4c31ea]::result::Result<(), rustc_errors[f55630e1eea6f6be]::ErrorGuaranteed>, rustc_driver[62b0704af81f9759]::run_compiler::{closure#1}>::{closure#0}, core[69220df7bf4c31ea]::result::Result<(), rustc_errors[f55630e1eea6f6be]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[69220df7bf4c31ea]::result::Result<(), rustc_errors[f55630e1eea6f6be]::ErrorGuaranteed>>::{closure#1} as core[69220df7bf4c31ea]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  55:     0x7f0740de2e33 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hab9c0585205bcace
                               at /rustc/bed4ad65bf7a1cef39e3d66b3670189581b3b073/library/alloc/src/boxed.rs:1987:9
  56:     0x7f0740de2e33 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hc1b376671ff7f5ba
                               at /rustc/bed4ad65bf7a1cef39e3d66b3670189581b3b073/library/alloc/src/boxed.rs:1987:9
  57:     0x7f0740de2e33 - std::sys::unix::thread::Thread::new::thread_start::h1e626d066d8b584f
                               at /rustc/bed4ad65bf7a1cef39e3d66b3670189581b3b073/library/std/src/sys/unix/thread.rs:108:17
  58:     0x7f073cc94b43 - start_thread
                               at ./nptl/./nptl/pthread_create.c:442:8
  59:     0x7f073cd26a00 - clone3
                               at ./misc/../sysdeps/unix/sysv/linux/x86_64/clone3.S:81
  60:                0x0 - <unknown>

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 1.66.0-nightly (bed4ad65b 2022-10-25) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [typeck] type-checking `w`
#1 [typeck_item_bodies] type-checking all item bodies
#2 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 8 previous errors; 1 warning emitted

Some errors have detailed explanations: E0261, E0412, E0425, E0601, E0658.
For more information about an error, try `rustc --explain E0261`.

[dwrensha]

searched nightlies: from nightly-2022-02-10 to nightly-2022-10-26
regressed nightly: nightly-2022-08-13
searched commit range: 20ffea6...f22819b
regressed commit: f22819b

bisected with cargo-bisect-rustc v0.6.4

Host triple: x86_64-unknown-linux-gnu
Reproduce with:

cargo bisect-rustc --end=2022-10-26 --regress ice 

[dwrensha]

This regressed in #100247, specifically in e1e25a8.
cc @cjgillot

[compiler-errors]

Minimized:

pub trait FromResidual<R = <Self as Try>::Residual> {
    fn from_residual(residual: R) -> Self;
}

trait Try {
    type Residual;
}

fn w<'a, F>()
where
    F: Fn(&'a U),
{
    let b: &dyn FromResidual = &();
}

[compiler-errors]

This no longer ICEs, afaict.

[dwrensha]

According to cargo bisect-rustc --start=2022-09-13 --end=2023-09-22 --regress non-ice, this got fixed in one of these commits:

found 7 bors merge commits in the specified range
commit[0] 2023-01-08: Auto merge of #106449 - GuillaumeGomez:rustdoc-gui-retry-mechanism, r=Mark-Simulacrum
commit[1] 2023-01-08: Auto merge of #90291 - geeklint:loosen_weak_debug_bound, r=dtolnay
commit[2] 2023-01-09: Auto merge of #106616 - compiler-errors:rollup-emcj0o3, r=compiler-errors
commit[3] 2023-01-09: Auto merge of #106582 - compiler-errors:better-spans-on-bad-tys, r=lcnr
commit[4] 2023-01-09: Auto merge of #106340 - saethlin:propagate-operands, r=oli-obk
commit[5] 2023-01-09: Auto merge of #101947 - aliemjay:astconv-normalize, r=lcnr
commit[6] 2023-01-09: Auto merge of #106637 - fee1-dead-contrib:rollup-ticvmsd, r=fee1-dead
ERROR: no CI builds available between cc47b06 and 3020239 within last 167 days