Unstable fingerprints at 'predicates_of(...)' error

[Azgrom]

Hi there! I was practicing this CodeWars kata and stumbled with the following compiler error:

Code

As I was in the middle of the solution, this code's logic does not what it is intended to.

fn counting_duplicates(text: &str) -> u32 {
    let mut occurrence = String::new();
    let mut count: u32 = 0;

    for letter in text.chars() {
        if text.contains(letter) || occurrence.contains(letter) {
            occurrence.push(letter);
        } else {
            count += 1;
        }
    }
    count
}

fn main() {
    // let mut test = String::from("Hello, world!");
    // println!("{}", &test.rev().next());
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_abcde() {
        assert_eq!(counting_duplicates("abcde"), 0);
    }

    #[test]
    fn test_abcdea() {
        assert_eq!(counting_duplicates("abcdea"), 1);
    }

    #[test]
    fn test_indivisibility() {
        assert_eq!(counting_duplicates("indivisibility"), 1);
    }
}

Meta

rustc --version --verbose:

rustc 1.53.0-nightly (07e0e2ec2 2021-03-24)
binary: rustc
commit-hash: 07e0e2ec268c140e607e1ac7f49f145612d0f597
commit-date: 2021-03-24
host: x86_64-unknown-linux-gnu
release: 1.53.0-nightly
LLVM version: 12.0.0

Don't know if it is relevant, but I have updated rustup. But the problem is the same. Here is the update log:

$ rustup self update
info: checking for self-updates
info: downloading self-update
  rustup updated - 1.24.1 (from 1.23.1)

Error output

$ cargo test
   Compiling counting_duplicates v0.1.0 (/home/rafael/Documents/Repos/CodeArchive/CodeWars/counting_duplicates)
thread 'rustc' panicked at 'found unstable fingerprints for predicates_of(core[3998]::iter::traits::collect::IntoIterator): GenericPredicates { parent: None, predicates: [(Binder(TraitPredicate(<Self as std::iter::IntoIterator>)), /home/rafael/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/iter/traits/collect.rs:202:1: 202:23 (#0))] }', /rustc/07e0e2ec268c140e607e1ac7f49f145612d0f597/compiler/rustc_query_system/src/query/plumbing.rs:593:5
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 1.53.0-nightly (07e0e2ec2 2021-03-24) running on x86_64-unknown-linux-gnu

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental

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

query stack during panic:
#0 [predicates_of] computing predicates of `std::iter::IntoIterator`
#1 [typeck] type-checking `counting_duplicates`
end of query stack
error: could not compile `counting_duplicates`

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

Backtrace

$ RUST_BACKTRACE=1 cargo test
   Compiling counting_duplicates v0.1.0 (/home/rafael/Documents/Repos/CodeArchive/CodeWars/counting_duplicates)
thread 'rustc' panicked at 'found unstable fingerprints for predicates_of(core[3998]::iter::traits::collect::IntoIterator): GenericPredicates { parent: None, predicates: [(Binder(TraitPredicate(<Self as std::iter::IntoIterator>)), /home/rafael/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/iter/traits/collect.rs:202:1: 202:23 (#0))] }', /rustc/07e0e2ec268c140e607e1ac7f49f145612d0f597/compiler/rustc_query_system/src/query/plumbing.rs:593:5
stack backtrace:
   0: rust_begin_unwind
             at /rustc/07e0e2ec268c140e607e1ac7f49f145612d0f597/library/std/src/panicking.rs:493:5
   1: std::panicking::begin_panic_fmt
             at /rustc/07e0e2ec268c140e607e1ac7f49f145612d0f597/library/std/src/panicking.rs:435:5
   2: rustc_query_system::query::plumbing::incremental_verify_ich
   3: rustc_query_system::query::plumbing::load_from_disk_and_cache_in_memory
   4: rustc_query_system::query::plumbing::get_query_impl
   5: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::predicates_of
   6: rustc_middle::ty::generics::GenericPredicates::instantiate_into
   7: rustc_middle::ty::generics::GenericPredicates::instantiate
   8: rustc_typeck::check::fn_ctxt::_impl::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::instantiate_bounds
   9: rustc_typeck::check::fn_ctxt::_impl::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::add_required_obligations
  10: rustc_typeck::check::fn_ctxt::_impl::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::resolve_lang_item_path
  11: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_kind
  12: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_with_expectation
  13: rustc_typeck::check::callee::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_call
  14: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_kind
  15: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_with_expectation
  16: rustc_typeck::check::_match::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::demand_scrutinee_type
  17: rustc_typeck::check::_match::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_match
  18: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_kind
  19: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_with_expectation
  20: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_with_expectation
  21: rustc_typeck::check::fn_ctxt::checks::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_stmt
  22: rustc_typeck::check::fn_ctxt::checks::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_block_with_expected
  23: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_expr_with_expectation
  24: rustc_typeck::check::expr::<impl rustc_typeck::check::fn_ctxt::FnCtxt>::check_return_expr
  25: rustc_typeck::check::check::check_fn
  26: rustc_infer::infer::InferCtxtBuilder::enter
  27: rustc_typeck::check::typeck
  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::force_query_with_job
  31: rustc_query_system::query::plumbing::get_query_impl
  32: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::typeck
  33: rustc_middle::ty::<impl rustc_middle::ty::context::TyCtxt>::par_body_owners
  34: rustc_typeck::check::typeck_item_bodies
  35: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
  36: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  37: rustc_data_structures::stack::ensure_sufficient_stack
  38: rustc_query_system::query::plumbing::force_query_with_job
  39: rustc_query_system::query::plumbing::get_query_impl
  40: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::typeck_item_bodies
  41: rustc_session::utils::<impl rustc_session::session::Session>::time
  42: rustc_typeck::check_crate
  43: rustc_interface::passes::analysis
  44: rustc_middle::dep_graph::<impl rustc_query_system::dep_graph::DepKind for rustc_middle::dep_graph::dep_node::DepKind>::with_deps
  45: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  46: rustc_data_structures::stack::ensure_sufficient_stack
  47: rustc_query_system::query::plumbing::force_query_with_job
  48: rustc_query_system::query::plumbing::get_query_impl
  49: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::analysis
  50: rustc_interface::passes::QueryContext::enter
  51: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
  52: rustc_span::with_source_map
  53: rustc_interface::interface::create_compiler_and_run
  54: 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 1.53.0-nightly (07e0e2ec2 2021-03-24) running on x86_64-unknown-linux-gnu

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental

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

query stack during panic:
#0 [predicates_of] computing predicates of `std::iter::IntoIterator`
#1 [typeck] type-checking `counting_duplicates`
#2 [typeck_item_bodies] type-checking all item bodies
#3 [analysis] running analysis passes on this crate
end of query stack
error: could not compile `counting_duplicates`

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

[lopopolo]

I got a similar error in Clippy on the new 1.52.0 stable: rust-lang/rust-clippy#7186.

[wesleywiser]

Thanks for filing the bug report! We are currently triaging issues related to #84970 to ensure each underlying problem gets resolved. Since this appears to be a duplicate of #83259, I'm going to close in favor of that issue.