rust-lang / rust-lang/rust

[ICE]: guard_patterns: local still has storage when returning from function

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C-bug F-guard_patterns I-ICE S-bug-has-test S-has-mcve T-compiler
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Rust
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Description

snippet:

//@compile-flags: -Zlint-mir
#![feature(guard_patterns)]

fn guard<T>(x: T) -> bool {
    unimplemented!()
}

fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}

fn main() {}

Version information

rustc 1.96.0-nightly (fff9e4432 2026-04-06)
binary: rustc
commit-hash: fff9e4432233df859e4fadb30ab7f0eda22580a6
commit-date: 2026-04-06
host: x86_64-unknown-linux-gnu
release: 1.96.0-nightly
LLVM version: 22.1.2

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc -Zlint-mir

Program output

warning: the feature `guard_patterns` is incomplete and may not be safe to use and/or cause compiler crashes
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:1:12
  |
1 | #![feature(guard_patterns)]
  |            ^^^^^^^^^^^^^^
  |
  = note: see issue #129967 <https://github.com/rust-lang/rust/issues/129967> for more information
  = note: `#[warn(incomplete_features)]` on by default

warning: unused variable: `x`
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:3:13
  |
3 | fn guard<T>(x: T) -> bool {
  |             ^ help: if this is intentional, prefix it with an underscore: `_x`
  |
  = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default

warning: unreachable pattern
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:29
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |       -------------------   ^^^^^^ no value can reach this
  |       |
  |       matches any value
  |
  = note: `#[warn(unreachable_patterns)]` (part of `#[warn(unused)]`) on by default

warning: unused variable: `x`
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:33
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                 ^ help: if this is intentional, prefix it with an underscore: `_x`

warning: function `guard` is never used
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:3:4
  |
3 | fn guard<T>(x: T) -> bool {
  |    ^^^^^
  |
  = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default

warning: function `a` is never used
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:4
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |    ^

warning: 6 warnings emitted

note: no errors encountered even though delayed bugs were created

note: those delayed bugs will now be shown as internal compiler errors

error: internal compiler error: broken MIR in Item(DefId(0:5 ~ mvce[9c68]::a)) (after pass CheckForceInline) at bb4[1]:
                                local _2 still has storage when returning from function
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^
  |
note: delayed at /rustc-dev/fff9e4432233df859e4fadb30ab7f0eda22580a6/compiler/rustc_mir_transform/src/lint.rs:137:34
         0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
         1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
         2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
         3: <rustc_errors::DiagCtxtHandle>::span_delayed_bug::<rustc_span::span_encoding::Span, alloc::string::String>
         4: <rustc_mir_transform::lint::Lint>::fail::<alloc::string::String>
         5: <rustc_mir_transform::lint::Lint as rustc_middle::mir::visit::Visitor>::visit_terminator
         6: rustc_mir_transform::lint::lint_body
         7: rustc_mir_transform::mir_built
         8: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 8]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
         9: rustc_query_impl::query_impl::mir_built::execute_query_non_incr::__rust_end_short_backtrace
        10: rustc_mir_build::check_unsafety::check_unsafety
        11: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 0]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
        12: rustc_query_impl::query_impl::check_unsafety::execute_query_non_incr::__rust_end_short_backtrace
        13: <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners::<rustc_interface::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}
        14: rustc_interface::passes::analysis
        15: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::SingleCache<rustc_middle::query::erase::ErasedData<[u8; 0]>>, false>
        16: rustc_query_impl::query_impl::analysis::execute_query_non_incr::__rust_end_short_backtrace
        17: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
        18: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
        19: <std::thread::lifecycle::spawn_unchecked<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
        20: <std::sys::thread::unix::Thread>::new::thread_start
        21: <unknown>
        22: <unknown>
      
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^

error: internal compiler error: broken MIR in Item(DefId(0:5 ~ mvce[9c68]::a)) (after pass CheckCallRecursion) at bb4[1]:
                                local _2 still has storage when returning from function
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^
  |
note: delayed at /rustc-dev/fff9e4432233df859e4fadb30ab7f0eda22580a6/compiler/rustc_mir_transform/src/lint.rs:137:34
         0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
         1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
         2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
         3: <rustc_errors::DiagCtxtHandle>::span_delayed_bug::<rustc_span::span_encoding::Span, alloc::string::String>
         4: <rustc_mir_transform::lint::Lint>::fail::<alloc::string::String>
         5: <rustc_mir_transform::lint::Lint as rustc_middle::mir::visit::Visitor>::visit_terminator
         6: rustc_mir_transform::lint::lint_body
         7: rustc_mir_transform::mir_built
         8: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 8]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
         9: rustc_query_impl::query_impl::mir_built::execute_query_non_incr::__rust_end_short_backtrace
        10: rustc_mir_build::check_unsafety::check_unsafety
        11: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 0]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
        12: rustc_query_impl::query_impl::check_unsafety::execute_query_non_incr::__rust_end_short_backtrace
        13: <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners::<rustc_interface::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}
        14: rustc_interface::passes::analysis
        15: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::SingleCache<rustc_middle::query::erase::ErasedData<[u8; 0]>>, false>
        16: rustc_query_impl::query_impl::analysis::execute_query_non_incr::__rust_end_short_backtrace
        17: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
        18: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
        19: <std::thread::lifecycle::spawn_unchecked<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
        20: <std::sys::thread::unix::Thread>::new::thread_start
        21: <unknown>
        22: <unknown>
      
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^

error: internal compiler error: broken MIR in Item(DefId(0:5 ~ mvce[9c68]::a)) (after pass CheckInlineAlwaysTargetFeature) at bb4[1]:
                                local _2 still has storage when returning from function
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^
  |
note: delayed at /rustc-dev/fff9e4432233df859e4fadb30ab7f0eda22580a6/compiler/rustc_mir_transform/src/lint.rs:137:34
         0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
         1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
         2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
         3: <rustc_errors::DiagCtxtHandle>::span_delayed_bug::<rustc_span::span_encoding::Span, alloc::string::String>
         4: <rustc_mir_transform::lint::Lint>::fail::<alloc::string::String>
         5: <rustc_mir_transform::lint::Lint as rustc_middle::mir::visit::Visitor>::visit_terminator
         6: rustc_mir_transform::lint::lint_body
         7: rustc_mir_transform::mir_built
         8: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 8]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
         9: rustc_query_impl::query_impl::mir_built::execute_query_non_incr::__rust_end_short_backtrace
        10: rustc_mir_build::check_unsafety::check_unsafety
        11: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 0]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
        12: rustc_query_impl::query_impl::check_unsafety::execute_query_non_incr::__rust_end_short_backtrace
        13: <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners::<rustc_interface::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}
        14: rustc_interface::passes::analysis
        15: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::SingleCache<rustc_middle::query::erase::ErasedData<[u8; 0]>>, false>
        16: rustc_query_impl::query_impl::analysis::execute_query_non_incr::__rust_end_short_backtrace
        17: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
        18: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
        19: <std::thread::lifecycle::spawn_unchecked<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
        20: <std::sys::thread::unix::Thread>::new::thread_start
        21: <unknown>
        22: <unknown>
      
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^

error: internal compiler error: broken MIR in Item(DefId(0:5 ~ mvce[9c68]::a)) (after pass CheckPackedRef) at bb4[1]:
                                local _2 still has storage when returning from function
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^
  |
note: delayed at /rustc-dev/fff9e4432233df859e4fadb30ab7f0eda22580a6/compiler/rustc_mir_transform/src/lint.rs:137:34
         0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
         1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
         2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
         3: <rustc_errors::DiagCtxtHandle>::span_delayed_bug::<rustc_span::span_encoding::Span, alloc::string::String>
         4: <rustc_mir_transform::lint::Lint>::fail::<alloc::string::String>
         5: <rustc_mir_transform::lint::Lint as rustc_middle::mir::visit::Visitor>::visit_terminator
         6: rustc_mir_transform::lint::lint_body
         7: rustc_mir_transform::mir_built
         8: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 8]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
         9: rustc_query_impl::query_impl::mir_built::execute_query_non_incr::__rust_end_short_backtrace
        10: rustc_mir_build::check_unsafety::check_unsafety
        11: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 0]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
        12: rustc_query_impl::query_impl::check_unsafety::execute_query_non_incr::__rust_end_short_backtrace
        13: <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners::<rustc_interface::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}
        14: rustc_interface::passes::analysis
        15: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::SingleCache<rustc_middle::query::erase::ErasedData<[u8; 0]>>, false>
        16: rustc_query_impl::query_impl::analysis::execute_query_non_incr::__rust_end_short_backtrace
        17: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
        18: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
        19: <std::thread::lifecycle::spawn_unchecked<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
        20: <std::sys::thread::unix::Thread>::new::thread_start
        21: <unknown>
        22: <unknown>
      
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^

error: internal compiler error: broken MIR in Item(DefId(0:5 ~ mvce[9c68]::a)) (after pass CheckConstItemMutation) at bb4[1]:
                                local _2 still has storage when returning from function
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^
  |
note: delayed at /rustc-dev/fff9e4432233df859e4fadb30ab7f0eda22580a6/compiler/rustc_mir_transform/src/lint.rs:137:34
         0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
         1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
         2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
         3: <rustc_errors::DiagCtxtHandle>::span_delayed_bug::<rustc_span::span_encoding::Span, alloc::string::String>
         4: <rustc_mir_transform::lint::Lint>::fail::<alloc::string::String>
         5: <rustc_mir_transform::lint::Lint as rustc_middle::mir::visit::Visitor>::visit_terminator
         6: rustc_mir_transform::lint::lint_body
         7: rustc_mir_transform::mir_built
         8: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 8]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
         9: rustc_query_impl::query_impl::mir_built::execute_query_non_incr::__rust_end_short_backtrace
        10: rustc_mir_build::check_unsafety::check_unsafety
        11: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 0]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
        12: rustc_query_impl::query_impl::check_unsafety::execute_query_non_incr::__rust_end_short_backtrace
        13: <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners::<rustc_interface::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}
        14: rustc_interface::passes::analysis
        15: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::SingleCache<rustc_middle::query::erase::ErasedData<[u8; 0]>>, false>
        16: rustc_query_impl::query_impl::analysis::execute_query_non_incr::__rust_end_short_backtrace
        17: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
        18: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
        19: <std::thread::lifecycle::spawn_unchecked<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
        20: <std::sys::thread::unix::Thread>::new::thread_start
        21: <unknown>
        22: <unknown>
      
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^

error: internal compiler error: broken MIR in Item(DefId(0:5 ~ mvce[9c68]::a)) (after pass FunctionItemReferences) at bb4[1]:
                                local _2 still has storage when returning from function
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^
  |
note: delayed at /rustc-dev/fff9e4432233df859e4fadb30ab7f0eda22580a6/compiler/rustc_mir_transform/src/lint.rs:137:34
         0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
         1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
         2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
         3: <rustc_errors::DiagCtxtHandle>::span_delayed_bug::<rustc_span::span_encoding::Span, alloc::string::String>
         4: <rustc_mir_transform::lint::Lint>::fail::<alloc::string::String>
         5: <rustc_mir_transform::lint::Lint as rustc_middle::mir::visit::Visitor>::visit_terminator
         6: rustc_mir_transform::lint::lint_body
         7: rustc_mir_transform::mir_built
         8: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 8]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
         9: rustc_query_impl::query_impl::mir_built::execute_query_non_incr::__rust_end_short_backtrace
        10: rustc_mir_build::check_unsafety::check_unsafety
        11: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 0]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
        12: rustc_query_impl::query_impl::check_unsafety::execute_query_non_incr::__rust_end_short_backtrace
        13: <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners::<rustc_interface::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}
        14: rustc_interface::passes::analysis
        15: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::SingleCache<rustc_middle::query::erase::ErasedData<[u8; 0]>>, false>
        16: rustc_query_impl::query_impl::analysis::execute_query_non_incr::__rust_end_short_backtrace
        17: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
        18: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
        19: <std::thread::lifecycle::spawn_unchecked<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
        20: <std::sys::thread::unix::Thread>::new::thread_start
        21: <unknown>
        22: <unknown>
      
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^

error: internal compiler error: broken MIR in Item(DefId(0:5 ~ mvce[9c68]::a)) (after pass SimplifyCfg-initial) at bb2[1]:
                                local _2 still has storage when returning from function
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^
  |
note: delayed at /rustc-dev/fff9e4432233df859e4fadb30ab7f0eda22580a6/compiler/rustc_mir_transform/src/lint.rs:137:34
         0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
         1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
         2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
         3: <rustc_errors::DiagCtxtHandle>::span_delayed_bug::<rustc_span::span_encoding::Span, alloc::string::String>
         4: <rustc_mir_transform::lint::Lint>::fail::<alloc::string::String>
         5: <rustc_mir_transform::lint::Lint as rustc_middle::mir::visit::Visitor>::visit_terminator
         6: rustc_mir_transform::lint::lint_body
         7: rustc_mir_transform::mir_built
         8: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 8]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
         9: rustc_query_impl::query_impl::mir_built::execute_query_non_incr::__rust_end_short_backtrace
        10: rustc_mir_build::check_unsafety::check_unsafety
        11: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 0]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
        12: rustc_query_impl::query_impl::check_unsafety::execute_query_non_incr::__rust_end_short_backtrace
        13: <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners::<rustc_interface::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}
        14: rustc_interface::passes::analysis
        15: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::SingleCache<rustc_middle::query::erase::ErasedData<[u8; 0]>>, false>
        16: rustc_query_impl::query_impl::analysis::execute_query_non_incr::__rust_end_short_backtrace
        17: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
        18: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
        19: <std::thread::lifecycle::spawn_unchecked<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
        20: <std::sys::thread::unix::Thread>::new::thread_start
        21: <unknown>
        22: <unknown>
      
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^

error: internal compiler error: broken MIR in Item(DefId(0:5 ~ mvce[9c68]::a)) (after pass SanityCheck) at bb2[1]:
                                local _2 still has storage when returning from function
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^
  |
note: delayed at /rustc-dev/fff9e4432233df859e4fadb30ab7f0eda22580a6/compiler/rustc_mir_transform/src/lint.rs:137:34
         0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
         1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
         2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
         3: <rustc_errors::DiagCtxtHandle>::span_delayed_bug::<rustc_span::span_encoding::Span, alloc::string::String>
         4: <rustc_mir_transform::lint::Lint>::fail::<alloc::string::String>
         5: <rustc_mir_transform::lint::Lint as rustc_middle::mir::visit::Visitor>::visit_terminator
         6: rustc_mir_transform::lint::lint_body
         7: rustc_mir_transform::mir_built
         8: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 8]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
         9: rustc_query_impl::query_impl::mir_built::execute_query_non_incr::__rust_end_short_backtrace
        10: rustc_mir_build::check_unsafety::check_unsafety
        11: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 0]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
        12: rustc_query_impl::query_impl::check_unsafety::execute_query_non_incr::__rust_end_short_backtrace
        13: <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners::<rustc_interface::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}
        14: rustc_interface::passes::analysis
        15: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::SingleCache<rustc_middle::query::erase::ErasedData<[u8; 0]>>, false>
        16: rustc_query_impl::query_impl::analysis::execute_query_non_incr::__rust_end_short_backtrace
        17: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
        18: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
        19: <std::thread::lifecycle::spawn_unchecked<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
        20: <std::sys::thread::unix::Thread>::new::thread_start
        21: <unknown>
        22: <unknown>
      
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^

error: internal compiler error: broken MIR in Item(DefId(0:5 ~ mvce[9c68]::a)) (after pass PromoteTemps) at bb2[1]:
                                local _2 still has storage when returning from function
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^
  |
note: delayed at /rustc-dev/fff9e4432233df859e4fadb30ab7f0eda22580a6/compiler/rustc_mir_transform/src/lint.rs:137:34
         0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
         1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
         2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
         3: <rustc_errors::DiagCtxtHandle>::span_delayed_bug::<rustc_span::span_encoding::Span, alloc::string::String>
         4: <rustc_mir_transform::lint::Lint>::fail::<alloc::string::String>
         5: <rustc_mir_transform::lint::Lint as rustc_middle::mir::visit::Visitor>::visit_terminator
         6: rustc_mir_transform::lint::lint_body
         7: rustc_mir_transform::mir_promoted
         8: rustc_query_impl::query_impl::mir_promoted::invoke_provider_fn::__rust_begin_short_backtrace
         9: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 16]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
        10: rustc_query_impl::query_impl::mir_promoted::execute_query_non_incr::__rust_end_short_backtrace
        11: rustc_borrowck::mir_borrowck
        12: rustc_query_impl::query_impl::mir_borrowck::invoke_provider_fn::__rust_begin_short_backtrace
        13: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 8]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
        14: rustc_query_impl::query_impl::mir_borrowck::execute_query_non_incr::__rust_end_short_backtrace
        15: <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners::<rustc_interface::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}
        16: rustc_interface::passes::analysis
        17: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::SingleCache<rustc_middle::query::erase::ErasedData<[u8; 0]>>, false>
        18: rustc_query_impl::query_impl::analysis::execute_query_non_incr::__rust_end_short_backtrace
        19: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
        20: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
        21: <std::thread::lifecycle::spawn_unchecked<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
        22: <std::sys::thread::unix::Thread>::new::thread_start
        23: <unknown>
        24: <unknown>
      
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^

error: internal compiler error: broken MIR in Item(DefId(0:5 ~ mvce[9c68]::a)) (after pass SimplifyCfg-promote-consts) at bb2[1]:
                                local _2 still has storage when returning from function
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^
  |
note: delayed at /rustc-dev/fff9e4432233df859e4fadb30ab7f0eda22580a6/compiler/rustc_mir_transform/src/lint.rs:137:34
         0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
         1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
         2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
         3: <rustc_errors::DiagCtxtHandle>::span_delayed_bug::<rustc_span::span_encoding::Span, alloc::string::String>
         4: <rustc_mir_transform::lint::Lint>::fail::<alloc::string::String>
         5: <rustc_mir_transform::lint::Lint as rustc_middle::mir::visit::Visitor>::visit_terminator
         6: rustc_mir_transform::lint::lint_body
         7: rustc_mir_transform::mir_promoted
         8: rustc_query_impl::query_impl::mir_promoted::invoke_provider_fn::__rust_begin_short_backtrace
         9: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 16]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
        10: rustc_query_impl::query_impl::mir_promoted::execute_query_non_incr::__rust_end_short_backtrace
        11: rustc_borrowck::mir_borrowck
        12: rustc_query_impl::query_impl::mir_borrowck::invoke_provider_fn::__rust_begin_short_backtrace
        13: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 8]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
        14: rustc_query_impl::query_impl::mir_borrowck::execute_query_non_incr::__rust_end_short_backtrace
        15: <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners::<rustc_interface::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}
        16: rustc_interface::passes::analysis
        17: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::SingleCache<rustc_middle::query::erase::ErasedData<[u8; 0]>>, false>
        18: rustc_query_impl::query_impl::analysis::execute_query_non_incr::__rust_end_short_backtrace
        19: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
        20: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
        21: <std::thread::lifecycle::spawn_unchecked<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
        22: <std::sys::thread::unix::Thread>::new::thread_start
        23: <unknown>
        24: <unknown>
      
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^

error: internal compiler error: broken MIR in Item(DefId(0:5 ~ mvce[9c68]::a)) (after phase change to analysis) at bb2[1]:
                                local _2 still has storage when returning from function
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^
  |
note: delayed at /rustc-dev/fff9e4432233df859e4fadb30ab7f0eda22580a6/compiler/rustc_mir_transform/src/lint.rs:137:34
         0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
         1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
         2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
         3: <rustc_errors::DiagCtxtHandle>::span_delayed_bug::<rustc_span::span_encoding::Span, alloc::string::String>
         4: <rustc_mir_transform::lint::Lint>::fail::<alloc::string::String>
         5: <rustc_mir_transform::lint::Lint as rustc_middle::mir::visit::Visitor>::visit_terminator
         6: rustc_mir_transform::lint::lint_body
         7: rustc_mir_transform::mir_promoted
         8: rustc_query_impl::query_impl::mir_promoted::invoke_provider_fn::__rust_begin_short_backtrace
         9: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 16]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
        10: rustc_query_impl::query_impl::mir_promoted::execute_query_non_incr::__rust_end_short_backtrace
        11: rustc_borrowck::mir_borrowck
        12: rustc_query_impl::query_impl::mir_borrowck::invoke_provider_fn::__rust_begin_short_backtrace
        13: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 8]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
        14: rustc_query_impl::query_impl::mir_borrowck::execute_query_non_incr::__rust_end_short_backtrace
        15: <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners::<rustc_interface::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}
        16: rustc_interface::passes::analysis
        17: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::SingleCache<rustc_middle::query::erase::ErasedData<[u8; 0]>>, false>
        18: rustc_query_impl::query_impl::analysis::execute_query_non_incr::__rust_end_short_backtrace
        19: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
        20: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
        21: <std::thread::lifecycle::spawn_unchecked<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
        22: <std::sys::thread::unix::Thread>::new::thread_start
        23: <unknown>
        24: <unknown>
      
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^

error: internal compiler error: broken MIR in Item(DefId(0:5 ~ mvce[9c68]::a)) (after pass ImpossiblePredicates) at bb2[1]:
                                local _2 still has storage when returning from function
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^
  |
note: delayed at /rustc-dev/fff9e4432233df859e4fadb30ab7f0eda22580a6/compiler/rustc_mir_transform/src/lint.rs:137:34
         0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
         1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
         2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
         3: <rustc_errors::DiagCtxtHandle>::span_delayed_bug::<rustc_span::span_encoding::Span, alloc::string::String>
         4: <rustc_mir_transform::lint::Lint>::fail::<alloc::string::String>
         5: <rustc_mir_transform::lint::Lint as rustc_middle::mir::visit::Visitor>::visit_terminator
         6: rustc_mir_transform::lint::lint_body
         7: rustc_mir_transform::run_analysis_to_runtime_passes
         8: rustc_mir_transform::mir_drops_elaborated_and_const_checked
         9: rustc_query_impl::query_impl::mir_drops_elaborated_and_const_checked::invoke_provider_fn::__rust_begin_short_backtrace
        10: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 8]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
        11: rustc_query_impl::query_impl::mir_drops_elaborated_and_const_checked::execute_query_non_incr::__rust_end_short_backtrace
        12: <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners::<rustc_interface::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}
        13: rustc_interface::passes::analysis
        14: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::SingleCache<rustc_middle::query::erase::ErasedData<[u8; 0]>>, false>
        15: rustc_query_impl::query_impl::analysis::execute_query_non_incr::__rust_end_short_backtrace
        16: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
        17: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
        18: <std::thread::lifecycle::spawn_unchecked<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
        19: <std::sys::thread::unix::Thread>::new::thread_start
        20: <unknown>
        21: <unknown>
      
 --> /tmp/icemaker_global_tempdir.gmqFyrERGYRw/rustc_testrunner_tmpdir_reporting.m0fw6nHOTPMw/mvce.rs:7:52
  |
7 | fn a(((x if guard (x), _) | (_, x)): (i32, i32)) {}
  |                                                    ^

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 1.96.0-nightly (fff9e4432 2026-04-06) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z lint-mir -Z dump-mir-dir=dir

query stack during panic:
end of query stack

@rustbot label +F-guard_patterns

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the supplied guard_patterns example with rustc -Zlint-mir and inspect the broken MIR diagnostic, especially the lint path at compiler/rustc_mir_transform/src/lint.rs:137. Trace how the pattern is lowered and verify the example no longer reports that local storage remains at function return, adding a regression test if the surrounding test location is identified.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
45/100

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