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ICE: "cannot convert ReErased to a region vid" after adding unused variable #104247
Description
Code
I didn't yet come up with a minimal example. So far for reproduction elfo crate is needed (which is quite big bruh). Here's the repo with the code: https://github.com/l4l/ice-bwck-unused-todo
Meta
Tried on stable 1.64.0, 1.65.0 and nightly 1.66.0 (470e518 2022-09-27).
Error output
compiler/rustc_borrowck/src/universal_regions.rs:810:36: cannot convert `ReErased` to a region vid
Shortened backtrace
20: 0x7f01cd89aea3 - rustc_middle[b6cf56a787d1e2a1]::util::bug::bug_fmt
21: 0x7f01cdc58c49 - <rustc_borrowck[9bf94ea6123d60bb]::type_check::constraint_conversion::ConstraintConversion>::convert_all
22: 0x7f01cdc29a8a - <rustc_borrowck[9bf94ea6123d60bb]::type_check::TypeChecker>::normalize_and_prove_instantiated_predicates
23: 0x7f01cdc26156 - <rustc_borrowck[9bf94ea6123d60bb]::type_check::TypeVerifier as rustc_middle[b6cf56a787d1e2a1]::mir::visit::Visitor>::visit_constant
24: 0x7f01cdc10769 - <rustc_borrowck[9bf94ea6123d60bb]::type_check::TypeVerifier as rustc_middle[b6cf56a787d1e2a1]::mir::visit::Visitor>::visit_body
25: 0x7f01cdbb5c32 - rustc_borrowck[9bf94ea6123d60bb]::type_check::type_check
26: 0x7f01cdb922ce - rustc_borrowck[9bf94ea6123d60bb]::nll::compute_regions
27: 0x7f01cdb7cdaf - rustc_borrowck[9bf94ea6123d60bb]::do_mir_borrowck
28: 0x7f01ce82794d - rustc_borrowck[9bf94ea6123d60bb]::mir_borrowck
29: 0x7f01ce826e60 - <rustc_borrowck[9bf94ea6123d60bb]::provide::{closure#0} as core[6fcc70bcc91a5bf5]::ops::function::FnOnce<(rustc_middle[b6cf56a787d1e2a1]::ty::context::TyCtxt, rustc_span[721a57c036170ce]::def_id::LocalDefId)>>::call_once
30: 0x7f01ce13a39f - <rustc_query_system[8caf4755e287670e]::dep_graph::graph::DepGraph<rustc_middle[b6cf56a787d1e2a1]::dep_graph::dep_node::DepKind>>::with_task::<rustc_middle[b6cf56a787d1e2a1]::ty::context::TyCtxt, rustc_span[721a57c036170ce]::def_id::LocalDefId, &rustc_middle[b6cf56a787d1e2a1]::mir::query::BorrowCheckResult>
31: 0x7f01ce13967d - rustc_query_system[8caf4755e287670e]::query::plumbing::try_execute_query::<rustc_query_impl[232efbc2900411f9]::plumbing::QueryCtxt, rustc_query_system[8caf4755e287670e]::query::caches::DefaultCache<rustc_span[721a57c036170ce]::def_id::LocalDefId, &rustc_middle[b6cf56a787d1e2a1]::mir::query::BorrowCheckResult>>
32: 0x7f01ced4356a - <rustc_query_impl[232efbc2900411f9]::Queries as rustc_middle[b6cf56a787d1e2a1]::ty::query::QueryEngine>::mir_borrowck
33: 0x7f01ce8304d3 - rustc_data_structures[49e7163a34b889d1]::sync::par_for_each_in::<&[rustc_span[721a57c036170ce]::def_id::LocalDefId], <rustc_middle[b6cf56a787d1e2a1]::hir::map::Map>::par_body_owners<rustc_interface[f934826ba4c12dd9]::passes::analysis::{closure#2}::{closure#0}>::{closure#0}>
34: 0x7f01ce82fc8b - <rustc_middle[b6cf56a787d1e2a1]::hir::map::Map>::par_body_owners::<rustc_interface[f934826ba4c12dd9]::passes::analysis::{closure#2}::{closure#0}>
35: 0x7f01ce82fb63 - <rustc_session[98f7faf1d37bb5fb]::session::Session>::time::<(), rustc_interface[f934826ba4c12dd9]::passes::analysis::{closure#2}>
36: 0x7f01ce82f955 - rustc_interface[f934826ba4c12dd9]::passes::analysis
37: 0x7f01cebea2bc - <rustc_query_system[8caf4755e287670e]::dep_graph::graph::DepGraph<rustc_middle[b6cf56a787d1e2a1]::dep_graph::dep_node::DepKind>>::with_task::<rustc_middle[b6cf56a787d1e2a1]::ty::context::TyCtxt, (), core[6fcc70bcc91a5bf5]::result::Result<(), rustc_errors[5fcb1a1f56a762e6]::ErrorGuaranteed>>
38: 0x7f01cebe9aab - rustc_query_system[8caf4755e287670e]::query::plumbing::try_execute_query::<rustc_query_impl[232efbc2900411f9]::plumbing::QueryCtxt, rustc_query_system[8caf4755e287670e]::query::caches::DefaultCache<(), core[6fcc70bcc91a5bf5]::result::Result<(), rustc_errors[5fcb1a1f56a762e6]::ErrorGuaranteed>>>
39: 0x7f01cebe95fe - rustc_query_system[8caf4755e287670e]::query::plumbing::get_query::<rustc_query_impl[232efbc2900411f9]::queries::analysis, rustc_query_impl[232efbc2900411f9]::plumbing::QueryCtxt>
40: 0x7f01ce5c3d87 - <rustc_interface[f934826ba4c12dd9]::passes::QueryContext>::enter::<rustc_driver[4568cc0a685fd94d]::run_compiler::{closure#1}::{closure#2}::{closure#3}, core[6fcc70bcc91a5bf5]::result::Result<(), rustc_errors[5fcb1a1f56a762e6]::ErrorGuaranteed>>
41: 0x7f01ce5bc97f - <rustc_interface[f934826ba4c12dd9]::interface::Compiler>::enter::<rustc_driver[4568cc0a685fd94d]::run_compiler::{closure#1}::{closure#2}, core[6fcc70bcc91a5bf5]::result::Result<core[6fcc70bcc91a5bf5]::option::Option<rustc_interface[f934826ba4c12dd9]::queries::Linker>, rustc_errors[5fcb1a1f56a762e6]::ErrorGuaranteed>>
42: 0x7f01ce5b186a - rustc_span[721a57c036170ce]::with_source_map::<core[6fcc70bcc91a5bf5]::result::Result<(), rustc_errors[5fcb1a1f56a762e6]::ErrorGuaranteed>, rustc_interface[f934826ba4c12dd9]::interface::create_compiler_and_run<core[6fcc70bcc91a5bf5]::result::Result<(), rustc_errors[5fcb1a1f56a762e6]::ErrorGuaranteed>, rustc_driver[4568cc0a685fd94d]::run_compiler::{closure#1}>::{closure#1}>
43: 0x7f01ce5b11a2 - <scoped_tls[80743de900a7f844]::ScopedKey<rustc_span[721a57c036170ce]::SessionGlobals>>::set::<rustc_interface[f934826ba4c12dd9]::interface::run_compiler<core[6fcc70bcc91a5bf5]::result::Result<(), rustc_errors[5fcb1a1f56a762e6]::ErrorGuaranteed>, rustc_driver[4568cc0a685fd94d]::run_compiler::{closure#1}>::{closure#0}, core[6fcc70bcc91a5bf5]::result::Result<(), rustc_errors[5fcb1a1f56a762e6]::ErrorGuaranteed>>
44: 0x7f01ce5af5cf - std[306a94a967d8f5ee]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[f934826ba4c12dd9]::util::run_in_thread_pool_with_globals<rustc_interface[f934826ba4c12dd9]::interface::run_compiler<core[6fcc70bcc91a5bf5]::result::Result<(), rustc_errors[5fcb1a1f56a762e6]::ErrorGuaranteed>, rustc_driver[4568cc0a685fd94d]::run_compiler::{closure#1}>::{closure#0}, core[6fcc70bcc91a5bf5]::result::Result<(), rustc_errors[5fcb1a1f56a762e6]::ErrorGuaranteed>>::{closure#0}, core[6fcc70bcc91a5bf5]::result::Result<(), rustc_errors[5fcb1a1f56a762e6]::ErrorGuaranteed>>
Triggered this after adding let x: <ty> = todo(), if literal is set instead there's no ICE.
Looks similar to #96304 or #78174 but this one doesn't require nightly features.
Activity
albertlarsan68 commentedon Nov 10, 2022
I can't reproduce with
rustc 1.66.0-beta.1onx86_64-pc-windows-msvc.compiler-errors commentedon Nov 10, 2022
@l4l, this is a pretty old nightly version -- can you update your compiler and see if it still reproduces the issue?
albertlarsan68 commentedon Nov 10, 2022
However, it reproduces with
rustc 1.65.0l4l commentedon Nov 10, 2022
Hmm, wonder when it was resolved. I've found no recent relevant issues.
No longer reproduces with 1.67.0-nightly (9286a1beb 2022-11-04), sorry for misreporting.
albertlarsan68 commentedon Nov 11, 2022
The fix was deployed in
nightly-2022-10-29, currently continuing the bisection for the exact mergealbertlarsan68 commentedon Nov 11, 2022
It seems like #103629 is the merge that fixed it.