thread 'rustc' panicked at 'f64 failed to parse `9E`: ParseFloatError { kind: Invalid }'

[Badel2]

I'm seeing an internal compiler error on the following input, found by fuzz-rustc:

Code

fn main() {
    [9; [[9E; h]]];
}

Error output

error: expected at least one digit in exponent
 --> src/main.rs:2:11
  |
2 |     [9; [[9E; h]]];
  |           ^^

error[E0425]: cannot find value `h` in this scope
 --> src/main.rs:2:15
  |
2 |     [9; [[9E; h]]];
  |               ^ not found in this scope

thread 'rustc' panicked at 'f64 failed to parse `9E`: ParseFloatError { kind: Invalid }', compiler/rustc_mir_build/src/thir/constant.rs:87:37

The ICE happens after correctly reporting a malformed float error, so low priority. Note that slight modifications of the input fix the panic. For example using 0 instead of h results in no panic. Also there is no panic if compling only the string [9E; h]. Affected versions: I tried nightly 2021-11-30 and stable 1.56.1 and they both show the same ICE.

Backtrace

   Compiling playground v0.0.1 (/playground)
error: expected at least one digit in exponent
 --> src/main.rs:2:11
  |
2 |     [9; [[9E; h]]];
  |           ^^

error[E0425]: cannot find value `h` in this scope
 --> src/main.rs:2:15
  |
2 |     [9; [[9E; h]]];
  |               ^ not found in this scope

thread 'rustc' panicked at 'f64 failed to parse `9E`: ParseFloatError { kind: Invalid }', compiler/rustc_mir_build/src/thir/constant.rs:87:37
stack backtrace:
   0: rust_begin_unwind
             at /rustc/207c80f105282245d93024c95ac408c622f70114/library/std/src/panicking.rs:498:5
   1: core::panicking::panic_fmt
             at /rustc/207c80f105282245d93024c95ac408c622f70114/library/core/src/panicking.rs:107:14
   2: rustc_mir_build::thir::constant::lit_to_const
   3: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<rustc_middle::mir::interpret::LitToConstInput, core::result::Result<&rustc_middle::ty::consts::Const, rustc_middle::mir::interpret::LitToConstError>>>
   4: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::lit_to_const
   5: <rustc_mir_build::thir::cx::Cx>::mirror_expr_inner
   6: <rustc_mir_build::thir::cx::Cx>::mirror_expr_inner
   7: <rustc_mir_build::thir::cx::Cx>::mirror_expr_inner
   8: rustc_mir_build::thir::cx::thir_body
   9: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<rustc_middle::ty::WithOptConstParam<rustc_span::def_id::LocalDefId>, (&rustc_data_structures::steal::Steal<rustc_middle::thir::Thir>, rustc_middle::thir::ExprId)>>
  10: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::thir_body
  11: <rustc_infer::infer::InferCtxtBuilder>::enter::<rustc_middle::mir::Body, rustc_mir_build::build::mir_build::{closure#1}>
  12: rustc_mir_build::build::mir_built
  13: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<rustc_middle::ty::WithOptConstParam<rustc_span::def_id::LocalDefId>, &rustc_data_structures::steal::Steal<rustc_middle::mir::Body>>>
  14: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::mir_built
  15: rustc_mir_transform::check_unsafety::unsafety_check_result
  16: <rustc_mir_transform::check_unsafety::provide::{closure#0} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::LocalDefId)>>::call_once
  17: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::LocalDefId, &rustc_middle::mir::query::UnsafetyCheckResult>>
  18: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::unsafety_check_result
  19: rustc_mir_transform::mir_const
  20: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<rustc_middle::ty::WithOptConstParam<rustc_span::def_id::LocalDefId>, &rustc_data_structures::steal::Steal<rustc_middle::mir::Body>>>
  21: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::mir_const
  22: <rustc_mir_transform::provide::{closure#0} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::DefId)>>::call_once
  23: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::DefId, rustc_middle::mir::query::ConstQualifs>>
  24: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::mir_const_qualif
  25: rustc_const_eval::const_eval::eval_queries::eval_to_allocation_raw_provider
  26: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::eval_to_allocation_raw, rustc_query_impl::plumbing::QueryCtxt>
  27: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::eval_to_allocation_raw
  28: rustc_const_eval::const_eval::eval_queries::eval_to_const_value_raw_provider
  29: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<rustc_middle::ty::ParamEnvAnd<rustc_middle::mir::interpret::GlobalId>, core::result::Result<rustc_middle::mir::interpret::value::ConstValue, rustc_middle::mir::interpret::error::ErrorHandled>>>
  30: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::eval_to_const_value_raw
  31: <rustc_middle::ty::context::TyCtxt>::const_eval_global_id
  32: <rustc_middle::ty::context::TyCtxt>::const_eval_resolve
  33: <rustc_infer::infer::InferCtxt>::const_eval_resolve
  34: rustc_trait_selection::traits::const_evaluatable::is_const_evaluatable
  35: <rustc_trait_selection::traits::fulfill::FulfillProcessor>::progress_changed_obligations
  36: <rustc_data_structures::obligation_forest::ObligationForest<rustc_trait_selection::traits::fulfill::PendingPredicateObligation>>::process_obligations::<rustc_trait_selection::traits::fulfill::FulfillProcessor, rustc_data_structures::obligation_forest::Outcome<rustc_trait_selection::traits::fulfill::PendingPredicateObligation, rustc_infer::traits::FulfillmentErrorCode>>
  37: <rustc_trait_selection::traits::fulfill::FulfillmentContext as rustc_infer::traits::engine::TraitEngine>::select_with_constness_where_possible
  38: <rustc_typeck::check::fn_ctxt::FnCtxt>::type_inference_fallback
  39: <rustc_infer::infer::InferCtxtBuilder>::enter::<&rustc_middle::ty::context::TypeckResults, <rustc_typeck::check::inherited::InheritedBuilder>::enter<rustc_typeck::check::typeck_with_fallback<rustc_typeck::check::typeck::{closure#0}>::{closure#1}, &rustc_middle::ty::context::TypeckResults>::{closure#0}>
  40: rustc_typeck::check::typeck
  41: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::LocalDefId, &rustc_middle::ty::context::TypeckResults>>
  42: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::typeck
  43: <rustc_middle::hir::map::Map>::par_body_owners::<rustc_typeck::check::typeck_item_bodies::{closure#0}>
  44: rustc_typeck::check::typeck_item_bodies
  45: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<(), ()>>
  46: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::typeck_item_bodies, rustc_query_impl::plumbing::QueryCtxt>
  47: <rustc_session::session::Session>::time::<(), rustc_typeck::check_crate::{closure#7}>
  48: rustc_typeck::check_crate
  49: rustc_interface::passes::analysis
  50: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<(), core::result::Result<(), rustc_errors::ErrorReported>>>
  51: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::analysis, rustc_query_impl::plumbing::QueryCtxt>
  52: <rustc_interface::passes::QueryContext>::enter::<rustc_driver::run_compiler::{closure#1}::{closure#2}::{closure#3}, core::result::Result<(), rustc_errors::ErrorReported>>
  53: <rustc_interface::interface::Compiler>::enter::<rustc_driver::run_compiler::{closure#1}::{closure#2}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_errors::ErrorReported>>
  54: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorReported>, rustc_interface::interface::create_compiler_and_run<core::result::Result<(), rustc_errors::ErrorReported>, rustc_driver::run_compiler::{closure#1}>::{closure#1}>
  55: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<rustc_interface::util::setup_callbacks_and_run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorReported>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorReported>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorReported>>
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 1.59.0-nightly (207c80f10 2021-11-30) running on x86_64-unknown-linux-gnu

note: compiler flags: -C embed-bitcode=no -C codegen-units=1 -C debuginfo=2 --crate-type bin

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

query stack during panic:
#0 [lit_to_const] converting literal to const
#1 [thir_body] building THIR for `main::{constant#0}`
#2 [mir_built] building MIR for `main::{constant#0}`
#3 [unsafety_check_result] unsafety-checking `main::{constant#0}`
#4 [mir_const] processing MIR for `main::{constant#0}`
#5 [mir_const_qualif] const checking `main::{constant#0}`
#6 [eval_to_allocation_raw] const-evaluating + checking `main::{constant#0}`
#7 [eval_to_const_value_raw] simplifying constant for the type system `main::{constant#0}`
#8 [typeck] type-checking `main`
#9 [typeck_item_bodies] type-checking all item bodies
#10 [analysis] running analysis passes on this crate
end of query stack
For more information about this error, try `rustc --explain E0425`.
error: could not compile `playground` due to 2 previous errors

[terrarier2111]

@rustbot claim

[chadbrewbaker]

Might be related? apache/arrow-rs#1043 (comment)

Formatting of "1e-15" behavior seems to have changed on nightly for f64 and f32.

[Badel2]

It may have a common cause, but you should open a separate issue because the pull request that fixes this doesn't fix your problem.