ICE: `-Znext-solver=coherence`: `unexpected infer in QueryInput { .. }`

[matthiaskrgr]

auto-reduced (treereduce-rust):

pub struct VSet<T, const S: &'static str> {
    ,
}


impl<T> VSet<T, {  }> {
    pub fn new() -> Self {}
}


impl<T> VSet<T, {  }> {
    pub fn new() -> Self {
        
    }
}

original code

original:

#![allow(incomplete_features)]
#![feature(adt_const_params)]
#![crate_name = "foo"]

use std::marker::ConstParamTy;

#[derive(PartialEq, Eq, ConstParamTy)]
pub enum Order {
    Sorted,
    Unsorted,
}

// @has foo/struct.VSet.html '//pre[@class="rust item-decl"]' 'pub struct VSet<T, const ORDER: Order>'
// @has foo/struct.VSet.html '//*[@id="impl-Send-for-VSet%3CT,+ORDER%3E"]/h3[@class="code-header"]' 'impl<T, const ORDER: Order> Send for VSet<T, ORDER>'
// @has foo/struct.VSet.html '//*[@id="impl-Sync-for-VSet%3CT,+ORDER%3E"]/h3[@class="code-header"]' 'impl<T, const ORDER: Order> Sync for VSet<T, ORDER>'
pub struct VSet<T, const S: &'static str> {
    inner: Vec<T>,
}

// @has foo/struct.VSet.html '//*[@id="impl-VSet%3CT,+%7B+Order::Sorted+%7D%3E"]/h3[@class="code-header"]' 'impl<T> VSet<T, { Order::Sorted }>'
impl<T> VSet<T, { Order::Sorted }> {
    pub fn new() -> Self {}
}

// @has foo/struct.VSet.html '//*[@id="impl-VSet%3CT,+%7B+Order::Unsorted+%7D%3E"]/h3[@class="code-header"]' 'impl<T> VSet<T, { Order::Unsorted }>'
impl<T> VSet<T, { Order::Unsorted }> {
    pub fn new() -> Self {
        Self { inner: Vec::new() }
    }
}

pub struct Escape<const S: &'static str>;

// @has foo/struct.Escape.html '//*[@id="impl-Escape%3C%22%3Cscript%3Ealert(%5C%22Escape%5C%22);%3C/script%3E%22%3E"]/h3[@class="code-header"]' 'impl Escape<r#"<script>alert("Escape");</script>"#>'
impl Escape<r#"<script>alert("Escape");</script>"#> {
    pub fn f() {}
}

Version information

rustc 1.76.0-nightly (ae612bedc 2023-12-08)
binary: rustc
commit-hash: ae612bedcbfc7098d1711eb35bc7ca994eb17a4c
commit-date: 2023-12-08
host: x86_64-unknown-linux-gnu
release: 1.76.0-nightly
LLVM version: 17.0.5

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc -Ztrait-solver=next-coherence

Program output

error: expected identifier, found `,`
  --> /tmp/icemaker_global_tempdir.k7uu7Q3HV2DR/rustc_testrunner_tmpdir_reporting.WpKyDCisrmgv/mvce.rs:14:5
   |
13 | pub struct VSet<T, const S: &'static str> {
   |            ---- while parsing this struct
14 |     ,
   |     ^ expected identifier

error[E0601]: `main` function not found in crate `mvce`
  --> /tmp/icemaker_global_tempdir.k7uu7Q3HV2DR/rustc_testrunner_tmpdir_reporting.WpKyDCisrmgv/mvce.rs:27:2
   |
27 | }
   |  ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.k7uu7Q3HV2DR/rustc_testrunner_tmpdir_reporting.WpKyDCisrmgv/mvce.rs`

thread 'rustc' panicked at compiler/rustc_trait_selection/src/solve/canonicalize.rs:72:9:
unexpected infer in QueryInput { goal: Goal { predicate: Binder { value: NormalizesTo(AliasTy { args: [], def_id: DefId(0:8 ~ mvce[e03b]::{impl#0}::{constant#0}) }, Term::Ct(^1_0: &'?0 str)), bound_vars: [] }, param_env: ParamEnv { caller_bounds: [], reveal: UserFacing } }, anchor: Bubble, predefined_opaques_in_body: PredefinedOpaques(PredefinedOpaquesData { opaque_types: [] }) }
stack backtrace:
   0:     0x7fdcb15cc45c - std::backtrace_rs::backtrace::libunwind::trace::hc023cf82594bd262
                               at /rustc/ae612bedcbfc7098d1711eb35bc7ca994eb17a4c/library/std/src/../../backtrace/src/backtrace/libunwind.rs:104:5
   1:     0x7fdcb15cc45c - std::backtrace_rs::backtrace::trace_unsynchronized::h9ed98bf495579d82
                               at /rustc/ae612bedcbfc7098d1711eb35bc7ca994eb17a4c/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7fdcb15cc45c - std::sys_common::backtrace::_print_fmt::h1211a11268324512
                               at /rustc/ae612bedcbfc7098d1711eb35bc7ca994eb17a4c/library/std/src/sys_common/backtrace.rs:68:5
   3:     0x7fdcb15cc45c - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h137b3c46227e29ac
                               at /rustc/ae612bedcbfc7098d1711eb35bc7ca994eb17a4c/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7fdcb161f4a0 - core::fmt::rt::Argument::fmt::h8ec24b23ce773c3d
                               at /rustc/ae612bedcbfc7098d1711eb35bc7ca994eb17a4c/library/core/src/fmt/rt.rs:142:9
   5:     0x7fdcb161f4a0 - core::fmt::write::h130e509b28bd9faf
                               at /rustc/ae612bedcbfc7098d1711eb35bc7ca994eb17a4c/library/core/src/fmt/mod.rs:1120:17
   6:     0x7fdcb15c02bf - std::io::Write::write_fmt::h14f1c178a01176d6
                               at /rustc/ae612bedcbfc7098d1711eb35bc7ca994eb17a4c/library/std/src/io/mod.rs:1810:15
   7:     0x7fdcb15cc244 - std::sys_common::backtrace::_print::h6c3c715eb9a83636
                               at /rustc/ae612bedcbfc7098d1711eb35bc7ca994eb17a4c/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7fdcb15cc244 - std::sys_common::backtrace::print::h348f78f0a08306e5
                               at /rustc/ae612bedcbfc7098d1711eb35bc7ca994eb17a4c/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7fdcb15ceed7 - std::panicking::default_hook::{{closure}}::hd2f2770d686014d7
  10:     0x7fdcb15cec3f - std::panicking::default_hook::h89eb7b752553c214
                               at /rustc/ae612bedcbfc7098d1711eb35bc7ca994eb17a4c/library/std/src/panicking.rs:292:9
  11:     0x7fdcae2ee850 - std[b87f00a22d58bbc]::panicking::update_hook::<alloc[77b1a1b708fdb7c4]::boxed::Box<rustc_driver_impl[853436051cc34aaf]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x7fdcb15cf618 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h84df13128e07b6a2
                               at /rustc/ae612bedcbfc7098d1711eb35bc7ca994eb17a4c/library/alloc/src/boxed.rs:2029:9
  13:     0x7fdcb15cf618 - std::panicking::rust_panic_with_hook::hb29ddd35ba3c20d3
                               at /rustc/ae612bedcbfc7098d1711eb35bc7ca994eb17a4c/library/std/src/panicking.rs:783:13
  14:     0x7fdcb15cf36e - std::panicking::begin_panic_handler::{{closure}}::h286ad4e1f9c74532
                               at /rustc/ae612bedcbfc7098d1711eb35bc7ca994eb17a4c/library/std/src/panicking.rs:657:13
  15:     0x7fdcb15cc926 - std::sys_common::backtrace::__rust_end_short_backtrace::h511f6dfe386703fe
                               at /rustc/ae612bedcbfc7098d1711eb35bc7ca994eb17a4c/library/std/src/sys_common/backtrace.rs:171:18
  16:     0x7fdcb15cf0d2 - rust_begin_unwind
                               at /rustc/ae612bedcbfc7098d1711eb35bc7ca994eb17a4c/library/std/src/panicking.rs:645:5
  17:     0x7fdcb161bb65 - core::panicking::panic_fmt::h7befc05beec83a23
                               at /rustc/ae612bedcbfc7098d1711eb35bc7ca994eb17a4c/library/core/src/panicking.rs:72:14
  18:     0x7fdcaedd7ca1 - <rustc_trait_selection[6a1c4ff094925b1c]::solve::eval_ctxt::EvalCtxt>::canonicalize_goal::<rustc_middle[b86048caae43f56]::ty::Predicate>
  19:     0x7fdcaeddcce1 - <rustc_trait_selection[6a1c4ff094925b1c]::solve::eval_ctxt::EvalCtxt>::evaluate_goal
  20:     0x7fdcaee4abdf - <rustc_trait_selection[6a1c4ff094925b1c]::solve::eval_ctxt::EvalCtxt>::try_evaluate_added_goals
  21:     0x7fdcaee46f85 - <rustc_trait_selection[6a1c4ff094925b1c]::solve::eval_ctxt::EvalCtxt>::try_normalize_term
  22:     0x7fdcaedec2fe - <rustc_trait_selection[6a1c4ff094925b1c]::solve::search_graph::SearchGraph>::with_new_goal::<<rustc_trait_selection[6a1c4ff094925b1c]::solve::eval_ctxt::EvalCtxt>::evaluate_canonical_goal::{closure#0}::{closure#0}::{closure#0}>::{closure#2}
  23:     0x7fdcaede99d3 - <rustc_trait_selection[6a1c4ff094925b1c]::solve::search_graph::SearchGraph>::with_new_goal::<<rustc_trait_selection[6a1c4ff094925b1c]::solve::eval_ctxt::EvalCtxt>::evaluate_canonical_goal::{closure#0}::{closure#0}::{closure#0}>
  24:     0x7fdcaeddcf9a - <rustc_trait_selection[6a1c4ff094925b1c]::solve::eval_ctxt::EvalCtxt>::evaluate_goal
  25:     0x7fdcaee4a282 - <rustc_infer[f37cdfef595741af]::infer::InferCtxt as rustc_trait_selection[6a1c4ff094925b1c]::solve::eval_ctxt::InferCtxtEvalExt>::evaluate_root_goal
  26:     0x7fdcaedde964 - <rustc_trait_selection[6a1c4ff094925b1c]::solve::fulfill::FulfillmentCtxt as rustc_infer[f37cdfef595741af]::traits::engine::TraitEngine>::select_where_possible
  27:     0x7fdcac79210b - <rustc_infer[f37cdfef595741af]::infer::InferCtxt as rustc_trait_selection[6a1c4ff094925b1c]::traits::query::evaluate_obligation::InferCtxtExt>::evaluate_obligation
  28:     0x7fdcb034cbee - rustc_trait_selection[6a1c4ff094925b1c]::traits::coherence::overlap
  29:     0x7fdcb0199c6f - rustc_trait_selection[6a1c4ff094925b1c]::traits::coherence::overlapping_impls
  30:     0x7fdcb0198f53 - <rustc_hir_analysis[b89fcc8215517ac9]::coherence::inherent_impls_overlap::InherentOverlapChecker>::check_for_overlapping_inherent_impls
  31:     0x7fdcb019776d - rustc_hir_analysis[b89fcc8215517ac9]::coherence::inherent_impls_overlap::crate_inherent_impls_overlap_check
  32:     0x7fdcb0197649 - rustc_query_impl[f69bc6cabb3ff86d]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[f69bc6cabb3ff86d]::query_impl::crate_inherent_impls_overlap_check::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b86048caae43f56]::query::erase::Erased<[u8; 0usize]>>
  33:     0x7fdcb019636d - rustc_query_system[642b9b293580cb87]::query::plumbing::try_execute_query::<rustc_query_impl[f69bc6cabb3ff86d]::DynamicConfig<rustc_query_system[642b9b293580cb87]::query::caches::SingleCache<rustc_middle[b86048caae43f56]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[f69bc6cabb3ff86d]::plumbing::QueryCtxt, false>
  34:     0x7fdcb01960d1 - rustc_query_impl[f69bc6cabb3ff86d]::query_impl::crate_inherent_impls_overlap_check::get_query_non_incr::__rust_end_short_backtrace
  35:     0x7fdcb005284c - rustc_hir_analysis[b89fcc8215517ac9]::check_crate
  36:     0x7fdcafec8962 - rustc_interface[404e90b0ed735256]::passes::analysis
  37:     0x7fdcafec859d - rustc_query_impl[f69bc6cabb3ff86d]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[f69bc6cabb3ff86d]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[b86048caae43f56]::query::erase::Erased<[u8; 1usize]>>
  38:     0x7fdcb0193d80 - rustc_query_system[642b9b293580cb87]::query::plumbing::try_execute_query::<rustc_query_impl[f69bc6cabb3ff86d]::DynamicConfig<rustc_query_system[642b9b293580cb87]::query::caches::SingleCache<rustc_middle[b86048caae43f56]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[f69bc6cabb3ff86d]::plumbing::QueryCtxt, false>
  39:     0x7fdcb0193b87 - rustc_query_impl[f69bc6cabb3ff86d]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  40:     0x7fdcb0625497 - rustc_interface[404e90b0ed735256]::interface::run_compiler::<core[830e0d4e2a210027]::result::Result<(), rustc_span[adf7fe9d68e4b410]::ErrorGuaranteed>, rustc_driver_impl[853436051cc34aaf]::run_compiler::{closure#0}>::{closure#0}
  41:     0x7fdcb059dc9f - std[b87f00a22d58bbc]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[404e90b0ed735256]::util::run_in_thread_with_globals<rustc_interface[404e90b0ed735256]::util::run_in_thread_pool_with_globals<rustc_interface[404e90b0ed735256]::interface::run_compiler<core[830e0d4e2a210027]::result::Result<(), rustc_span[adf7fe9d68e4b410]::ErrorGuaranteed>, rustc_driver_impl[853436051cc34aaf]::run_compiler::{closure#0}>::{closure#0}, core[830e0d4e2a210027]::result::Result<(), rustc_span[adf7fe9d68e4b410]::ErrorGuaranteed>>::{closure#0}, core[830e0d4e2a210027]::result::Result<(), rustc_span[adf7fe9d68e4b410]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[830e0d4e2a210027]::result::Result<(), rustc_span[adf7fe9d68e4b410]::ErrorGuaranteed>>
  42:     0x7fdcb059dac9 - <<std[b87f00a22d58bbc]::thread::Builder>::spawn_unchecked_<rustc_interface[404e90b0ed735256]::util::run_in_thread_with_globals<rustc_interface[404e90b0ed735256]::util::run_in_thread_pool_with_globals<rustc_interface[404e90b0ed735256]::interface::run_compiler<core[830e0d4e2a210027]::result::Result<(), rustc_span[adf7fe9d68e4b410]::ErrorGuaranteed>, rustc_driver_impl[853436051cc34aaf]::run_compiler::{closure#0}>::{closure#0}, core[830e0d4e2a210027]::result::Result<(), rustc_span[adf7fe9d68e4b410]::ErrorGuaranteed>>::{closure#0}, core[830e0d4e2a210027]::result::Result<(), rustc_span[adf7fe9d68e4b410]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[830e0d4e2a210027]::result::Result<(), rustc_span[adf7fe9d68e4b410]::ErrorGuaranteed>>::{closure#1} as core[830e0d4e2a210027]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  43:     0x7fdcb15d94a5 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h5e10d53125c64acc
                               at /rustc/ae612bedcbfc7098d1711eb35bc7ca994eb17a4c/library/alloc/src/boxed.rs:2015:9
  44:     0x7fdcb15d94a5 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h0041a451249f900a
                               at /rustc/ae612bedcbfc7098d1711eb35bc7ca994eb17a4c/library/alloc/src/boxed.rs:2015:9
  45:     0x7fdcb15d94a5 - std::sys::unix::thread::Thread::new::thread_start::h9579239664cc1d8d
                               at /rustc/ae612bedcbfc7098d1711eb35bc7ca994eb17a4c/library/std/src/sys/unix/thread.rs:108:17
  46:     0x7fdcab4aa9eb - <unknown>
  47:     0x7fdcab52e7cc - <unknown>
  48:                0x0 - <unknown>

error: 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 1.76.0-nightly (ae612bedc 2023-12-08) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z trait-solver=next-coherence -Z dump-mir-dir=dir

query stack during panic:
#0 [crate_inherent_impls_overlap_check] check for overlap between inherent impls defined in this crate
#1 [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 E0601`.

[compiler-errors]

More minimal:

pub struct VSet<const S: &'static str> {}

impl VSet<""> {
    pub fn a() {}
}

impl VSet<{}> {
    pub fn a() {}
}

Also, @matthiaskrgr: Do you know why treereduce-rust isn't minimizing away simple things like that spurious ","?

[matthiaskrgr]

It's based on treesitter https://github.com/tree-sitter/tree-sitter-rust , maybe when on parent node has multiple children, the comma does not really belong to any of the child nodes or something and thus is left over when you remove the parent?

[compiler-errors]

huh, i wonder if there's a way to sanitize out any non-syntactical tokens using treesitter.

[matthiaskrgr]

I've opened langston-barrett/treereduce#180