let_chains causes a compiler panic

[irevoire]

Code

#![feature(str_split_once)]
#![feature(let_chains)]

fn main() {
    let mut bug = "lalacoollolo".to_string();
    if !bug.contains("🔢") && (let Some((start, end)) = bug.split_once("1234")) {
        bug = format!("{}🔢{}", start, end);
    }

    println!("{}", bug);
}

Meta

rustc --version --verbose:

rustc 1.52.0-nightly (8e54a2113 2021-02-13)
binary: rustc
commit-hash: 8e54a21139ae96a2aca3129100b057662e2799b9
commit-date: 2021-02-13
host: x86_64-unknown-linux-gnu
release: 1.52.0-nightly
LLVM version: 11.0.1

Error output

thread 'rustc' panicked at 'expected `NodeId` to be lowered already for res Local(
    NodeId(28),
)', compiler/rustc_ast_lowering/src/lib.rs:714:17
note: run with `RUST_BACKTRACE=1` environment variable to display a 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 1.52.0-nightly (8e54a2113 2021-02-13) running on x86_64-unknown-linux-gnu

note: compiler flags: -C opt-level=3 -C embed-bitcode=no --crate-type bin

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

query stack during panic:
end of query stack

Backtrace

thread 'rustc' panicked at 'expected `NodeId` to be lowered already for res Local(
    NodeId(28),
)', compiler/rustc_ast_lowering/src/lib.rs:714:17
stack backtrace:
   0: rust_begin_unwind
             at /rustc/8e54a21139ae96a2aca3129100b057662e2799b9/library/std/src/panicking.rs:493:5
   1: std::panicking::begin_panic_fmt
             at /rustc/8e54a21139ae96a2aca3129100b057662e2799b9/library/std/src/panicking.rs:435:5
   2: rustc_ast_lowering::LoweringContext::lower_node_id_generic
   3: rustc_ast_lowering::path::<impl rustc_ast_lowering::LoweringContext>::lower_qpath
   4: rustc_data_structures::stack::ensure_sufficient_stack
   5: rustc_data_structures::stack::ensure_sufficient_stack
   6: <smallvec::SmallVec<A> as core::iter::traits::collect::Extend<<A as smallvec::Array>::Item>>::extend
   7: rustc_ast_lowering::expr::<impl rustc_ast_lowering::LoweringContext>::lower_exprs
   8: rustc_data_structures::stack::ensure_sufficient_stack
   9: rustc_data_structures::stack::ensure_sufficient_stack
  10: rustc_data_structures::stack::ensure_sufficient_stack
  11: <smallvec::SmallVec<A> as core::iter::traits::collect::Extend<<A as smallvec::Array>::Item>>::extend
  12: rustc_ast_lowering::expr::<impl rustc_ast_lowering::LoweringContext>::lower_exprs
  13: rustc_data_structures::stack::ensure_sufficient_stack
  14: <smallvec::SmallVec<A> as core::iter::traits::collect::Extend<<A as smallvec::Array>::Item>>::extend
  15: rustc_ast_lowering::expr::<impl rustc_ast_lowering::LoweringContext>::lower_exprs
  16: rustc_data_structures::stack::ensure_sufficient_stack
  17: rustc_ast_lowering::LoweringContext::lower_stmt
  18: core::ops::function::impls::<impl core::ops::function::FnMut<A> for &mut F>::call_mut
  19: <core::iter::adapters::flatten::Flatten<I> as core::iter::traits::iterator::Iterator>::next
  20: <smallvec::SmallVec<A> as core::iter::traits::collect::Extend<<A as smallvec::Array>::Item>>::extend
  21: rustc_arena::cold_path
  22: rustc_ast_lowering::LoweringContext::lower_block
  23: rustc_data_structures::stack::ensure_sufficient_stack
  24: rustc_ast_lowering::expr::<impl rustc_ast_lowering::LoweringContext>::lower_expr_assign
  25: rustc_data_structures::stack::ensure_sufficient_stack
  26: rustc_ast_lowering::LoweringContext::lower_stmt
  27: core::ops::function::impls::<impl core::ops::function::FnMut<A> for &mut F>::call_mut
  28: <core::iter::adapters::flatten::Flatten<I> as core::iter::traits::iterator::Iterator>::next
  29: <smallvec::SmallVec<A> as core::iter::traits::collect::Extend<<A as smallvec::Array>::Item>>::extend
  30: rustc_arena::cold_path
  31: rustc_ast_lowering::expr::<impl rustc_ast_lowering::LoweringContext>::lower_expr_if
  32: rustc_data_structures::stack::ensure_sufficient_stack
  33: rustc_ast_lowering::LoweringContext::lower_stmt
  34: core::ops::function::impls::<impl core::ops::function::FnMut<A> for &mut F>::call_mut
  35: <core::iter::adapters::flatten::Flatten<I> as core::iter::traits::iterator::Iterator>::next
  36: <smallvec::SmallVec<A> as core::iter::traits::collect::Extend<<A as smallvec::Array>::Item>>::extend
  37: rustc_arena::cold_path
  38: rustc_ast_lowering::item::<impl rustc_ast_lowering::LoweringContext>::lower_fn_body_block
  39: rustc_ast_lowering::item::<impl rustc_ast_lowering::LoweringContext>::lower_maybe_async_body
  40: rustc_ast_lowering::item::<impl rustc_ast_lowering::LoweringContext>::lower_item
  41: rustc_ast_lowering::LoweringContext::with_hir_id_owner
  42: <rustc_ast_lowering::item::ItemLowerer as rustc_ast::visit::Visitor>::visit_mod
  43: rustc_ast_lowering::lower_crate
  44: rustc_interface::passes::BoxedResolver::access::{{closure}}
  45: rustc_interface::passes::configure_and_expand::{{closure}}
  46: rustc_interface::queries::Queries::lower_to_hir
  47: rustc_interface::queries::Queries::global_ctxt
  48: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
  49: rustc_span::with_source_map
  50: scoped_tls::ScopedKey<T>::set
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 1.52.0-nightly (8e54a2113 2021-02-13) running on x86_64-unknown-linux-gnu

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental --crate-type bin

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

query stack during panic:
end of query stack
error: could not compile `bug`

To learn more, run the command again with --verbose.

I made a small git repo to reproduce the bug here

[jyn514]

MCVE (playground):

#![feature(let_chains)]

fn main() {
    if true && let x = 1 {
        let _ = x;
    }
}

[osa1]

Probably a duplicate of #82250.

[estebank]

I think I found the problem, lowering not being done in source order would cause this. The block of the then expression was being lowered before the condition, leading to the node corresponding to the x pattern not being populated when expected.