ICE: `no type for local variable`

[matthiaskrgr]

auto-reduced (treereduce-rust):

fn main() {
    

    // #1
    

    // #2
    

    // #3
    

    // #4
    if Some(let x == Some(_)) = x {}
}

original:

fn main() {
    let x = Some(123);

    // #1
    if let Some(_) == x {}

    // #2
    if let x = Some(_) {}

    // #3
    if let x == Some(_) {}

    // #4
    if Some(let x == Some(_)) = x {}
}

Version information

rustc 1.89.0-nightly (337c11e59 2025-06-01)
binary: rustc
commit-hash: 337c11e5932275e7d450c1f2e26f289f0ddfa717
commit-date: 2025-06-01
host: x86_64-unknown-linux-gnu
release: 1.89.0-nightly
LLVM version: 20.1.5

Possibly related line of code:

rust/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs

Lines 135 to 147 in 337c11e

	fn tag(&self) -> String {
	format!("{self:p}")
	}
	pub(crate) fn local_ty(&self, span: Span, nid: HirId) -> Ty<'tcx> {
	self.locals.borrow().get(&nid).cloned().unwrap_or_else(|| {
	span_bug!(span, "no type for local variable {}", self.tcx.hir_id_to_string(nid))
	})
	}
	#[inline]
	pub(crate) fn write_ty(&self, id: HirId, ty: Ty<'tcx>) {
	debug!("write_ty({:?}, {:?}) in fcx {}", id, self.resolve_vars_if_possible(ty), self.tag());

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc

Program output

error: expected expression, found `let` statement
  --> /tmp/icemaker_global_tempdir.qNli0TH4IAHO/rustc_testrunner_tmpdir_reporting.0GrbsUdTQx1S/mvce.rs:14:13
   |
14 |     if Some(let x == Some(_)) = x {}
   |             ^^^
   |
   = note: only supported directly in conditions of `if` and `while` expressions

error: expected `=`, found `==`
  --> /tmp/icemaker_global_tempdir.qNli0TH4IAHO/rustc_testrunner_tmpdir_reporting.0GrbsUdTQx1S/mvce.rs:14:19
   |
14 |     if Some(let x == Some(_)) = x {}
   |                   ^^
   |
help: consider using `=` here
   |
14 -     if Some(let x == Some(_)) = x {}
14 +     if Some(let x = Some(_)) = x {}
   |

error: in expressions, `_` can only be used on the left-hand side of an assignment
  --> /tmp/icemaker_global_tempdir.qNli0TH4IAHO/rustc_testrunner_tmpdir_reporting.0GrbsUdTQx1S/mvce.rs:14:27
   |
14 |     if Some(let x == Some(_)) = x {}
   |                           ^ `_` not allowed here

error: internal compiler error: compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs:141:13: no type for local variable HirId(DefId(0:3 ~ mvce[7859]::main).8) (pat `x`)
  --> /tmp/icemaker_global_tempdir.qNli0TH4IAHO/rustc_testrunner_tmpdir_reporting.0GrbsUdTQx1S/mvce.rs:14:33
   |
14 |     if Some(let x == Some(_)) = x {}
   |                                 ^


thread 'rustc' panicked at compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs:141:13:
Box<dyn Any>
stack backtrace:
   0:     0x706656cde993 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::hf8ee8b6b352ca661
   1:     0x706657403237 - core::fmt::write::hcd9fe40a26b64d70
   2:     0x706656cd4723 - std::io::Write::write_fmt::h5f94532440194dbd
   3:     0x706656cde7f2 - std::sys::backtrace::BacktraceLock::print::hc29614df06844315
   4:     0x706656ce23ea - std::panicking::default_hook::{{closure}}::h47671d985641cc52
   5:     0x706656ce1f6f - std::panicking::default_hook::h0bb111aee907609c
   6:     0x706655dfa3f3 - std[a1f017d000edeeff]::panicking::update_hook::<alloc[776b61ca0bea01d8]::boxed::Box<rustc_driver_impl[a8c06d39e8948878]::install_ice_hook::{closure#1}>>::{closure#0}
   7:     0x706656ce2c63 - std::panicking::rust_panic_with_hook::h5930974b9fd29227
   8:     0x706655e37121 - std[a1f017d000edeeff]::panicking::begin_panic::<rustc_errors[693c8abe97730fa9]::ExplicitBug>::{closure#0}
   9:     0x706655e2ba16 - std[a1f017d000edeeff]::sys::backtrace::__rust_end_short_backtrace::<std[a1f017d000edeeff]::panicking::begin_panic<rustc_errors[693c8abe97730fa9]::ExplicitBug>::{closure#0}, !>
  10:     0x706655e2826b - std[a1f017d000edeeff]::panicking::begin_panic::<rustc_errors[693c8abe97730fa9]::ExplicitBug>
  11:     0x706655e40c11 - <rustc_errors[693c8abe97730fa9]::diagnostic::BugAbort as rustc_errors[693c8abe97730fa9]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  12:     0x706656350c9c - <rustc_errors[693c8abe97730fa9]::DiagCtxtHandle>::span_bug::<rustc_span[14520476a1722fe1]::span_encoding::Span, alloc[776b61ca0bea01d8]::string::String>
  13:     0x7066563e2257 - rustc_middle[fd2e613c2dd7156e]::util::bug::opt_span_bug_fmt::<rustc_span[14520476a1722fe1]::span_encoding::Span>::{closure#0}
  14:     0x7066563c1cda - rustc_middle[fd2e613c2dd7156e]::ty::context::tls::with_opt::<rustc_middle[fd2e613c2dd7156e]::util::bug::opt_span_bug_fmt<rustc_span[14520476a1722fe1]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  15:     0x7066563c1b4b - rustc_middle[fd2e613c2dd7156e]::ty::context::tls::with_context_opt::<rustc_middle[fd2e613c2dd7156e]::ty::context::tls::with_opt<rustc_middle[fd2e613c2dd7156e]::util::bug::opt_span_bug_fmt<rustc_span[14520476a1722fe1]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  16:     0x706653f74107 - rustc_middle[fd2e613c2dd7156e]::util::bug::span_bug_fmt::<rustc_span[14520476a1722fe1]::span_encoding::Span>
  17:     0x706657daf2ab - <rustc_hir_typeck[aaf7cd0e8485b9d]::fn_ctxt::FnCtxt>::instantiate_value_path
  18:     0x706657da5da6 - <rustc_hir_typeck[aaf7cd0e8485b9d]::fn_ctxt::FnCtxt>::check_expr_path
  19:     0x706658056720 - <rustc_hir_typeck[aaf7cd0e8485b9d]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  20:     0x70665803ed25 - <rustc_hir_typeck[aaf7cd0e8485b9d]::fn_ctxt::FnCtxt>::check_decl
  21:     0x70665802d729 - <rustc_hir_typeck[aaf7cd0e8485b9d]::fn_ctxt::FnCtxt>::check_expr_block
  22:     0x7066580577b0 - <rustc_hir_typeck[aaf7cd0e8485b9d]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  23:     0x70665805a5e0 - <rustc_hir_typeck[aaf7cd0e8485b9d]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  24:     0x70665804b8e0 - <rustc_hir_typeck[aaf7cd0e8485b9d]::fn_ctxt::FnCtxt>::check_expr_if
  25:     0x70665805a58e - <rustc_hir_typeck[aaf7cd0e8485b9d]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  26:     0x70665802c99c - <rustc_hir_typeck[aaf7cd0e8485b9d]::fn_ctxt::FnCtxt>::check_expr_block
  27:     0x7066580577b0 - <rustc_hir_typeck[aaf7cd0e8485b9d]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  28:     0x7066580383e4 - rustc_hir_typeck[aaf7cd0e8485b9d]::check::check_fn
  29:     0x706657fe9e65 - rustc_hir_typeck[aaf7cd0e8485b9d]::typeck_with_inspect::{closure#0}
  30:     0x706657fe89be - rustc_query_impl[9415a893a92592b2]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[9415a893a92592b2]::query_impl::typeck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[fd2e613c2dd7156e]::query::erase::Erased<[u8; 8usize]>>
  31:     0x7066575cb726 - rustc_query_system[b2478213cc4322cf]::query::plumbing::try_execute_query::<rustc_query_impl[9415a893a92592b2]::DynamicConfig<rustc_data_structures[b91cd40af62c43e6]::vec_cache::VecCache<rustc_span[14520476a1722fe1]::def_id::LocalDefId, rustc_middle[fd2e613c2dd7156e]::query::erase::Erased<[u8; 8usize]>, rustc_query_system[b2478213cc4322cf]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[9415a893a92592b2]::plumbing::QueryCtxt, false>
  32:     0x7066575cb189 - rustc_query_impl[9415a893a92592b2]::query_impl::typeck::get_query_non_incr::__rust_end_short_backtrace
  33:     0x7066575ca0a4 - rustc_hir_analysis[fae52809c300b748]::check_crate
  34:     0x7066575c59b7 - rustc_interface[2840816492762d3c]::passes::run_required_analyses
  35:     0x70665817f3de - rustc_interface[2840816492762d3c]::passes::analysis
  36:     0x70665817f3b3 - rustc_query_impl[9415a893a92592b2]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[9415a893a92592b2]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[fd2e613c2dd7156e]::query::erase::Erased<[u8; 0usize]>>
  37:     0x70665818228e - rustc_query_system[b2478213cc4322cf]::query::plumbing::try_execute_query::<rustc_query_impl[9415a893a92592b2]::DynamicConfig<rustc_query_system[b2478213cc4322cf]::query::caches::SingleCache<rustc_middle[fd2e613c2dd7156e]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[9415a893a92592b2]::plumbing::QueryCtxt, false>
  38:     0x706658181e76 - rustc_query_impl[9415a893a92592b2]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  39:     0x7066588fb8ff - rustc_interface[2840816492762d3c]::passes::create_and_enter_global_ctxt::<core[c4bb63f569d6be2b]::option::Option<rustc_interface[2840816492762d3c]::queries::Linker>, rustc_driver_impl[a8c06d39e8948878]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
  40:     0x7066586528cc - rustc_interface[2840816492762d3c]::interface::run_compiler::<(), rustc_driver_impl[a8c06d39e8948878]::run_compiler::{closure#0}>::{closure#1}
  41:     0x7066587a1a3e - std[a1f017d000edeeff]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[2840816492762d3c]::util::run_in_thread_with_globals<rustc_interface[2840816492762d3c]::util::run_in_thread_pool_with_globals<rustc_interface[2840816492762d3c]::interface::run_compiler<(), rustc_driver_impl[a8c06d39e8948878]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  42:     0x7066587a1716 - <<std[a1f017d000edeeff]::thread::Builder>::spawn_unchecked_<rustc_interface[2840816492762d3c]::util::run_in_thread_with_globals<rustc_interface[2840816492762d3c]::util::run_in_thread_pool_with_globals<rustc_interface[2840816492762d3c]::interface::run_compiler<(), rustc_driver_impl[a8c06d39e8948878]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[c4bb63f569d6be2b]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  43:     0x7066584fa03d - std::sys::pal::unix::thread::Thread::new::thread_start::h20008e16f7cd9b41
  44:     0x7066520a57eb - <unknown>
  45:     0x70665212918c - <unknown>
  46:                0x0 - <unknown>

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: please make sure that you have updated to the latest nightly

note: rustc 1.89.0-nightly (337c11e59 2025-06-01) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [typeck] type-checking `main`
#1 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 4 previous errors

[matthiaskrgr]

fn main {
  if Some (let x == Some0)
    = x {}
}

, since #140561