ICE: assertion failed: elem.index() < self.domain_size

[jruderman]

Code

struct Apple((Apple, Option(Banana ? Citron)));

fn main(){}

Error output

thread 'rustc' panicked at 'assertion failed: elem.index() < self.domain_size', /rustc/0da281b6068a7d889ae89a9bd8991284cc9b7535/compiler/rustc_index/src/bit_set.rs:161:9

Full output including backtrace

error: invalid `?` in type
 --> u.rs:1:36
  |
1 | struct Apple((Apple, Option(Banana ? Citron)));
  |                                    ^ `?` is only allowed on expressions, not types
  |
help: if you meant to express that the type might not contain a value, use the `Option` wrapper type
  |
1 | struct Apple((Apple, Option(Option<Banana > Citron)));
  |                             +++++++       ~

error: expected one of `)` or `,`, found `Citron`
 --> u.rs:1:38
  |
1 | struct Apple((Apple, Option(Banana ? Citron)));
  |                                     -^^^^^^ expected one of `)` or `,`
  |                                     |
  |                                     help: missing `,`

error[E0412]: cannot find type `Citron` in this scope
 --> u.rs:1:38
  |
1 | struct Apple((Apple, Option(Banana ? Citron)));
  |                                      ^^^^^^ not found in this scope

error[E0214]: parenthesized type parameters may only be used with a `Fn` trait
 --> u.rs:1:22
  |
1 | struct Apple((Apple, Option(Banana ? Citron)));
  |                      ^^^^^^^^^^^^^^^^^^^^^^^ only `Fn` traits may use parentheses
  |
help: use angle brackets instead
  |
1 | struct Apple((Apple, Option<Banana ? Citron>));
  |                            ~               ~

thread 'rustc' panicked at 'assertion failed: elem.index() < self.domain_size', /rustc/0da281b6068a7d889ae89a9bd8991284cc9b7535/compiler/rustc_index/src/bit_set.rs:161:9
stack backtrace:
   0:        0x106f8a8a2 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h98e7719cdb057d8f
   1:        0x106fe274a - core::fmt::write::he324e6f3a7ef7ed0
   2:        0x106f7c97c - std::io::Write::write_fmt::h295c914c323e508a
   3:        0x106f8a66a - std::sys_common::backtrace::print::hb2f2bd76d0a1d9b2
   4:        0x106f8da76 - std::panicking::default_hook::{{closure}}::h7f2a23a911934152
   5:        0x106f8d7c7 - std::panicking::default_hook::h576cf5867894044c
   6:        0x112f8262d - rustc_driver[ba5c792b9438c2b]::DEFAULT_HOOK::{closure#0}::{closure#0}
   7:        0x106f8e271 - std::panicking::rust_panic_with_hook::hf0781b554a936fbf
   8:        0x106f8dfc2 - std::panicking::begin_panic_handler::{{closure}}::h8d2525e276d552d8
   9:        0x106f8ad38 - std::sys_common::backtrace::__rust_end_short_backtrace::hf3badbbd5492e2d6
  10:        0x106f8dccd - _rust_begin_unwind
  11:        0x10700f1b3 - core::panicking::panic_fmt::h15d4409e62dc090a
  12:        0x10700f287 - core::panicking::panic::h503de31a4470d5f7
  13:        0x117747a5b - rustc_middle[298407787cc28eff]::values::find_item_ty_spans
  14:        0x1177477e5 - rustc_middle[298407787cc28eff]::values::find_item_ty_spans
  15:        0x11774601c - rustc_middle[298407787cc28eff]::values::recursive_type_error
  16:        0x1177eb5a9 - <rustc_middle[298407787cc28eff]::ty::adt::Representability as rustc_query_system[fd3d689380a50de4]::values::Value<rustc_middle[298407787cc28eff]::ty::context::TyCtxt>>::from_cycle_error
  17:        0x117c5c66d - rustc_query_system[fd3d689380a50de4]::query::plumbing::mk_cycle::<rustc_query_impl[f77634870212a75e]::plumbing::QueryCtxt, rustc_middle[298407787cc28eff]::ty::adt::Representability, rustc_middle[298407787cc28eff]::ty::adt::Representability>
  18:        0x116767a32 - rustc_query_system[fd3d689380a50de4]::query::plumbing::try_execute_query::<rustc_query_impl[f77634870212a75e]::plumbing::QueryCtxt, rustc_query_system[fd3d689380a50de4]::query::caches::DefaultCache<rustc_span[73e074df7cba0abf]::def_id::LocalDefId, rustc_middle[298407787cc28eff]::ty::adt::Representability>>
  19:        0x11685f309 - rustc_query_system[fd3d689380a50de4]::query::plumbing::get_query::<rustc_query_impl[f77634870212a75e]::queries::representability, rustc_query_impl[f77634870212a75e]::plumbing::QueryCtxt>
  20:        0x115748f97 - rustc_ty_utils[c85f993db90c93e8]::representability::representability_adt_ty
  21:        0x11675ab4c - rustc_query_system[fd3d689380a50de4]::query::plumbing::try_execute_query::<rustc_query_impl[f77634870212a75e]::plumbing::QueryCtxt, rustc_query_system[fd3d689380a50de4]::query::caches::DefaultCache<rustc_middle[298407787cc28eff]::ty::Ty, rustc_middle[298407787cc28eff]::ty::adt::Representability>>
  22:        0x116867cd8 - rustc_query_system[fd3d689380a50de4]::query::plumbing::get_query::<rustc_query_impl[f77634870212a75e]::queries::representability_adt_ty, rustc_query_impl[f77634870212a75e]::plumbing::QueryCtxt>
  23:        0x115748bc9 - rustc_ty_utils[c85f993db90c93e8]::representability::representability_ty
  24:        0x115748a65 - rustc_ty_utils[c85f993db90c93e8]::representability::representability_ty
  25:        0x1157486f0 - rustc_ty_utils[c85f993db90c93e8]::representability::representability
  26:        0x116767502 - rustc_query_system[fd3d689380a50de4]::query::plumbing::try_execute_query::<rustc_query_impl[f77634870212a75e]::plumbing::QueryCtxt, rustc_query_system[fd3d689380a50de4]::query::caches::DefaultCache<rustc_span[73e074df7cba0abf]::def_id::LocalDefId, rustc_middle[298407787cc28eff]::ty::adt::Representability>>
  27:        0x11685f309 - rustc_query_system[fd3d689380a50de4]::query::plumbing::get_query::<rustc_query_impl[f77634870212a75e]::queries::representability, rustc_query_impl[f77634870212a75e]::plumbing::QueryCtxt>
  28:        0x1157484b8 - rustc_ty_utils[c85f993db90c93e8]::representability::representability
  29:        0x116767502 - rustc_query_system[fd3d689380a50de4]::query::plumbing::try_execute_query::<rustc_query_impl[f77634870212a75e]::plumbing::QueryCtxt, rustc_query_system[fd3d689380a50de4]::query::caches::DefaultCache<rustc_span[73e074df7cba0abf]::def_id::LocalDefId, rustc_middle[298407787cc28eff]::ty::adt::Representability>>
  30:        0x11685f309 - rustc_query_system[fd3d689380a50de4]::query::plumbing::get_query::<rustc_query_impl[f77634870212a75e]::queries::representability, rustc_query_impl[f77634870212a75e]::plumbing::QueryCtxt>
  31:        0x115a83b18 - rustc_hir_analysis[3f5a3f8b91adb05]::check::wfcheck::check_item
  32:        0x115a7511f - rustc_hir_analysis[3f5a3f8b91adb05]::check::wfcheck::check_well_formed
  33:        0x1167ca855 - rustc_query_system[fd3d689380a50de4]::query::plumbing::try_execute_query::<rustc_query_impl[f77634870212a75e]::plumbing::QueryCtxt, rustc_query_system[fd3d689380a50de4]::query::caches::DefaultCache<rustc_hir[7dceeafd8b0a3ae3]::hir_id::OwnerId, ()>>
  34:        0x11685fba5 - rustc_query_system[fd3d689380a50de4]::query::plumbing::get_query::<rustc_query_impl[f77634870212a75e]::queries::check_well_formed, rustc_query_impl[f77634870212a75e]::plumbing::QueryCtxt>
  35:        0x11597bf8b - rustc_data_structures[445d045225b5bae3]::sync::par_for_each_in::<&[rustc_hir[7dceeafd8b0a3ae3]::hir::ItemId], <rustc_middle[298407787cc28eff]::hir::ModuleItems>::par_items<rustc_hir_analysis[3f5a3f8b91adb05]::check::wfcheck::check_mod_type_wf::{closure#0}>::{closure#0}>
  36:        0x115a7e411 - rustc_hir_analysis[3f5a3f8b91adb05]::check::wfcheck::check_mod_type_wf
  37:        0x116770855 - rustc_query_system[fd3d689380a50de4]::query::plumbing::try_execute_query::<rustc_query_impl[f77634870212a75e]::plumbing::QueryCtxt, rustc_query_system[fd3d689380a50de4]::query::caches::DefaultCache<rustc_span[73e074df7cba0abf]::def_id::LocalDefId, ()>>
  38:        0x11685fa85 - rustc_query_system[fd3d689380a50de4]::query::plumbing::get_query::<rustc_query_impl[f77634870212a75e]::queries::check_mod_type_wf, rustc_query_impl[f77634870212a75e]::plumbing::QueryCtxt>
  39:        0x11597c08b - rustc_data_structures[445d045225b5bae3]::sync::par_for_each_in::<&[rustc_hir[7dceeafd8b0a3ae3]::hir_id::OwnerId], <rustc_middle[298407787cc28eff]::hir::map::Map>::par_for_each_module<rustc_hir_analysis[3f5a3f8b91adb05]::check_crate::{closure#5}::{closure#0}::{closure#0}>::{closure#0}>
  40:        0x1159e6f20 - <rustc_session[43d2d941ace548e5]::session::Session>::track_errors::<rustc_hir_analysis[3f5a3f8b91adb05]::check_crate::{closure#5}, ()>
  41:        0x115995352 - rustc_hir_analysis[3f5a3f8b91adb05]::check_crate
  42:        0x11305afda - rustc_interface[a666f6d755ed9279]::passes::analysis
  43:        0x1167f326c - rustc_query_system[fd3d689380a50de4]::query::plumbing::try_execute_query::<rustc_query_impl[f77634870212a75e]::plumbing::QueryCtxt, rustc_query_system[fd3d689380a50de4]::query::caches::DefaultCache<(), core[13371b8ce97f01bb]::result::Result<(), rustc_errors[b0e16a209d58ca7d]::ErrorGuaranteed>>>
  44:        0x11686d3f9 - rustc_query_system[fd3d689380a50de4]::query::plumbing::get_query::<rustc_query_impl[f77634870212a75e]::queries::analysis, rustc_query_impl[f77634870212a75e]::plumbing::QueryCtxt>
  45:        0x112f11296 - <rustc_interface[a666f6d755ed9279]::passes::QueryContext>::enter::<rustc_driver[ba5c792b9438c2b]::run_compiler::{closure#1}::{closure#2}::{closure#3}, core[13371b8ce97f01bb]::result::Result<(), rustc_errors[b0e16a209d58ca7d]::ErrorGuaranteed>>
  46:        0x112f55a4d - rustc_span[73e074df7cba0abf]::with_source_map::<core[13371b8ce97f01bb]::result::Result<(), rustc_errors[b0e16a209d58ca7d]::ErrorGuaranteed>, rustc_interface[a666f6d755ed9279]::interface::run_compiler<core[13371b8ce97f01bb]::result::Result<(), rustc_errors[b0e16a209d58ca7d]::ErrorGuaranteed>, rustc_driver[ba5c792b9438c2b]::run_compiler::{closure#1}>::{closure#0}::{closure#1}>
  47:        0x112f4534c - <scoped_tls[c17fceff1b2b43d8]::ScopedKey<rustc_span[73e074df7cba0abf]::SessionGlobals>>::set::<rustc_interface[a666f6d755ed9279]::interface::run_compiler<core[13371b8ce97f01bb]::result::Result<(), rustc_errors[b0e16a209d58ca7d]::ErrorGuaranteed>, rustc_driver[ba5c792b9438c2b]::run_compiler::{closure#1}>::{closure#0}, core[13371b8ce97f01bb]::result::Result<(), rustc_errors[b0e16a209d58ca7d]::ErrorGuaranteed>>
  48:        0x112f14e5a - std[8878bd7dd366d71b]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[a666f6d755ed9279]::util::run_in_thread_pool_with_globals<rustc_interface[a666f6d755ed9279]::interface::run_compiler<core[13371b8ce97f01bb]::result::Result<(), rustc_errors[b0e16a209d58ca7d]::ErrorGuaranteed>, rustc_driver[ba5c792b9438c2b]::run_compiler::{closure#1}>::{closure#0}, core[13371b8ce97f01bb]::result::Result<(), rustc_errors[b0e16a209d58ca7d]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[13371b8ce97f01bb]::result::Result<(), rustc_errors[b0e16a209d58ca7d]::ErrorGuaranteed>>
  49:        0x112efaf7b - <<std[8878bd7dd366d71b]::thread::Builder>::spawn_unchecked_<rustc_interface[a666f6d755ed9279]::util::run_in_thread_pool_with_globals<rustc_interface[a666f6d755ed9279]::interface::run_compiler<core[13371b8ce97f01bb]::result::Result<(), rustc_errors[b0e16a209d58ca7d]::ErrorGuaranteed>, rustc_driver[ba5c792b9438c2b]::run_compiler::{closure#1}>::{closure#0}, core[13371b8ce97f01bb]::result::Result<(), rustc_errors[b0e16a209d58ca7d]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[13371b8ce97f01bb]::result::Result<(), rustc_errors[b0e16a209d58ca7d]::ErrorGuaranteed>>::{closure#1} as core[13371b8ce97f01bb]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  50:        0x106f97387 - std::sys::unix::thread::Thread::new::thread_start::hfd54df40dd14130e
  51:     0x7ff814d514e1 - __pthread_start

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 1.66.0-nightly (0da281b60 2022-10-27) running on x86_64-apple-darwin

query stack during panic:
#0 [representability_adt_ty] checking if `Apple` is representable
#1 [representability] checking if `Apple::0` is representable
#2 [representability] checking if `Apple` is representable
#3 [check_well_formed] checking that `Apple` is well-formed
#4 [check_mod_type_wf] checking that types are well-formed in top-level module
#5 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 4 previous errors

Version

rustc 1.66.0-nightly (0da281b60 2022-10-27)
binary: rustc
commit-hash: 0da281b6068a7d889ae89a9bd8991284cc9b7535
commit-date: 2022-10-27
host: x86_64-apple-darwin
release: 1.66.0-nightly
LLVM version: 15.0.2

Regression

Regression from bba9785 (#100720)

Bisection details

bisected with cargo-bisect-rustc v0.6.4

searched nightlies: from nightly-2022-10-06 to nightly-2022-10-28
regressed nightly: nightly-2022-10-09
searched commit range: 8b0c05d...8796e7a
regressed commit: bba9785

Host triple: x86_64-apple-darwin

[chenyukang]

@camsteffen

rust/compiler/rustc_middle/src/values.rs

Line 189 in 4596f4f

if let hir::GenericArg::Type(ty) = arg && params_in_repr.contains(i as u32) {

params_in_repr.contains(i as u32) this function call crash for the assertion fail,
from the log, params_in_repr is with count = 1, and i is also 1 when crashing.
Do you have any clue?

params_in_repr is implemented at here, I'm still not quite familar with the query part:

rust/compiler/rustc_middle/src/query/mod.rs

Line 326 in 4596f4f

query params_in_repr(key: DefId) -> rustc_index::bit_set::BitSet<u32> {

[camsteffen]

It looks like the parens are parsed as generic parameters for a type that doesn't have generic parameters? The simple fix is just check i < params_in_repr.domain_size().

[chenyukang]

I think a reasonable fix is modifying the API for BitSet,

   /// Returns `true` if `self` contains `elem`.
    #[inline]
    pub fn contains(&self, elem: T) -> bool {
-        assert!(elem.index() < self.domain_size);
+        if elem.index() >= self.domain_size { return false; }        
        let (word_index, mask) = word_index_and_mask(elem);
        (self.words[word_index] & mask) != 0
    }

It reasonable to add assertion assert!(elem.index() < self.domain_size) for insert, but it's better to return false for idx outside of expected range?

[chenyukang]

Have a test on C++'s bitset, which also has this assertion:

terminate called after throwing an instance of 'std::out_of_range'
  what():  bitset::test: __position (which is 20) >= _Nb (which is 10)

emm, it's better to keep it for POLA.

[chenyukang]

@rustbot claim

[camsteffen]

I'd be curious to know if we can maintain an invariant in the HIR that it does not contain generics that do not align with generics_of. That was what I assumed when writing that code, but that may be too optimistic.

[camsteffen]

I considered removing the assert too, but I think it's better to have it since it exposes invalid assumptions as in this case.

[compiler-errors]

We should delay a bug (replacing the assertion) -- that's probably fine as long as it's understood why the generics_of does not line up here, and it's understood why we can't fix it somewhere upstream (e.g. in parsing or lowering instead)

[chenyukang]

@compiler-errors
I have a general question for rustc, why we just exit when we find a fatal error in parsing (which can not recover by simply autofix).

I have a real Dev experience when working on rustc, I was editing an file with 3k+ lines of code, and I forgetted remove an extra '{', then the compiler give about 20+ errors, the first two are from parsing:

error: this file contains an unclosed delimiter
    --> compiler/rustc_hir_typeck/src/method/suggest.rs:2649:3
     |
38   | impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     |                                 - unclosed delimiter
...
110  |                                  sugg_span: Span| {
     |                                                   - this delimiter might not be properly closed...
...
240  |         };
     |         - ...as it matches this but it has different indentation
...
2649 | }
     |   ^

error: expected one of `.`, `;`, `?`, `else`, or an operator, found `{`
    --> compiler/rustc_hir_typeck/src/method/suggest.rs:1448:49
     |
1448 |             let self_ty = self.check_expr(expr) {
     |                                                 ^ expected one of `.`, `;`, `?`, `else`, or an operator

error: enum is not supported in `trait`s or `impl`s
    --> compiler/rustc_hir_typeck/src/method/suggest.rs:2557:1
     |
2557 | pub enum SelfSource<'a> {
     | ^^^^^^^^^^^^^^^^^^^^^^^

But there are many many other errors from later phases...
I need to scroll up several pages to the beginning of error to find the rootcause.

[chenyukang]

If we can not get valid AST in parsing, later phases such as analysising will report out extra (mostly unhelpful) errors?

[camsteffen]

We should delay a bug (replacing the assertion)

The assertion is inside of the BitSet data structure. I generally expect data structures to simply assert on pre-conditions. We could put a delay-bug before the contains call, but that also seems like overkill since that is already on the error-reporting path.

I have a general question for rustc, why we just exit when we find a fatal error in parsing

I agree there are cases where rustc should quit sooner. But in general I think we have to err on the side of recover-and-continue if there is some possibility that more helpful errors may be emitted.