Code causes Compile Error without any Cause

[EvilsSouls]

Code

use std::collections::HashMap;

#[derive(PartialEq, Eq)]
pub enum Associativity {
    LeftAssociative,
    RightAssociative
}

fn get_higher_precedence_operators(operators: &HashMap<char, (u8, Associativity)>, operator_stack: &mut Vec<char>, new_operator_precedence: u8) -> Vec<String> {
    let mut higher_precedence_operators = Vec::new();

    loop {
        if operator_stack.len() <= 0 {return higher_precedence_operators;}

        let top_operator = operator_stack[operator_stack.len() - 1];
        let top_operator_properties = operators.get(&top_operator);
        let top_operator_precedence: u8;
        let top_operator_associativity: Associativity;

        if top_operator_properties.is_some() {
            (top_operator_precedence, top_operator_associativity) = *top_operator_properties.expect("There is no way in hell, that this is None");
        } else {
            return higher_precedence_operators;
        }

        if top_operator_precedence > new_operator_precedence || (top_operator_precedence == new_operator_precedence && top_operator_associativity == Associativity::LeftAssociative) {
            higher_precedence_operators.push(operator_stack.pop().expect("Once again... there is no way that this Option Enum has the value of None").to_string());
        } else {
            return higher_precedence_operators;
        }
    }
}

pub fn to_postfix(raw_infix_expression: &str, operators: &HashMap<char, (u8, Associativity)>) -> Vec<String> {
    let infix_expression = raw_infix_expression.replace('"', "");
    let mut postfix_expression: Vec<String> = Vec::new();
    let mut operator_stack: Vec<char> = Vec::new();
    let mut number_buffer = String::new();

    for current_char in infix_expression.chars() {
        if operators.contains_key(&current_char) {
            if number_buffer.len() > 0 {
                postfix_expression.push(number_buffer.clone());
                number_buffer.clear();
            } else if current_char == '-' {
                number_buffer.push(current_char);
                continue;
            } else {
                panic!("Syntax Error! Expected number before operator in math expression");
            }

            let (operator_precedence, _) = *(operators.get(&current_char)).expect("You won't see this error message");
            postfix_expression.append(&mut get_higher_precedence_operators(&operators, &mut operator_stack, operator_precedence));
            operator_stack.push(current_char);
        }

        else if current_char == '(' {
            if number_buffer.len() > 0 {
                postfix_expression.push(number_buffer.clone());
                number_buffer.clear();
            }

            operator_stack.push('(');
        }

        else if current_char == ')' {
            if number_buffer.len() > 0 {
                postfix_expression.push(number_buffer.clone());
                number_buffer.clear();
            }

            postfix_expression.append(&mut get_higher_precedence_operators(&operators, &mut operator_stack, 0));

            if operator_stack.len() > 0 && operator_stack[operator_stack.len() - 1] == '(' {
                operator_stack.pop();
            } else {panic!("Unmatched Paranthesis in Math Expression!");}
        }

        else {
            number_buffer.push(current_char);
        }
    }

    postfix_expression.append(&mut get_higher_precedence_operators(&operators, &mut operator_stack, 0));

    postfix_expression
}

Meta

rustc --version --verbose:

rustc 1.89.0 (29483883e 2025-08-04)
binary: rustc
commit-hash: 29483883eed69d5fb4db01964cdf2af4d86e9cb2
commit-date: 2025-08-04
host: x86_64-unknown-linux-gnu
release: 1.89.0
LLVM version: 20.1.7

Error output

thread 'rustc' panicked at compiler/rustc_borrowck/src/diagnostics/move_errors.rs:828:76:
called `Option::unwrap()` on a `None` value
stack backtrace:
   0:     0x7ff8108d8203 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::hf435e8e9347709a8
   1:     0x7ff811002bff - core::fmt::write::h0a51fad3804c5e7c
   2:     0x7ff8124d1591 - std::io::Write::write_fmt::h9759e4151bf4a45e
   3:     0x7ff8108d8062 - std::sys::backtrace::BacktraceLock::print::h1ec5ce5bb8ee285e
   4:     0x7ff8108dbb5a - std::panicking::default_hook::{{closure}}::h5ffefe997a3c75e4
   5:     0x7ff8108db6df - std::panicking::default_hook::h820c77ba0601d6bb
   6:     0x7ff80f9c9103 - std[da76efc55aba569b]::panicking::update_hook::<alloc[679dddab44c6194d]::boxed::Box<rustc_driver_impl[aa7064ecaea87566]::install_ice_hook::{closure#1}>>::{closure#0}
   7:     0x7ff8108dc3ab - std::panicking::rust_panic_with_hook::h8b29cbe181d50030
   8:     0x7ff8108dc076 - std::panicking::begin_panic_handler::{{closure}}::h9f5b6f6dc6fde83e
   9:     0x7ff8108d86d9 - std::sys::backtrace::__rust_end_short_backtrace::hd7b0c344383b0b61
  10:     0x7ff8108dbd8d - __rustc[5224e6b81cd82a8f]::rust_begin_unwind
  11:     0x7ff80d091480 - core::panicking::panic_fmt::hc49fc28484033487
  12:     0x7ff80d09943c - core::panicking::panic::h239804395728b21f
  13:     0x7ff80d092f89 - core::option::unwrap_failed::hec54eb4737b382ca
  14:     0x7ff80f766c28 - <rustc_borrowck[655779ff03f826b6]::MirBorrowckCtxt>::add_move_error_details
  15:     0x7ff80f763b01 - <rustc_borrowck[655779ff03f826b6]::MirBorrowckCtxt>::report
  16:     0x7ff812595d44 - rustc_borrowck[655779ff03f826b6]::do_mir_borrowck
  17:     0x7ff8112688a8 - rustc_borrowck[655779ff03f826b6]::mir_borrowck
  18:     0x7ff8112685d9 - rustc_query_impl[36e6800b9757404d]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[36e6800b9757404d]::query_impl::mir_borrowck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[e0a019250b2560b5]::query::erase::Erased<[u8; 8usize]>>
  19:     0x7ff81126403e - rustc_query_system[4eadbad177027a71]::query::plumbing::try_execute_query::<rustc_query_impl[36e6800b9757404d]::DynamicConfig<rustc_data_structures[f798075dc9c9ee18]::vec_cache::VecCache<rustc_span[93f6ac7b0b889bbe]::def_id::LocalDefId, rustc_middle[e0a019250b2560b5]::query::erase::Erased<[u8; 8usize]>, rustc_query_system[4eadbad177027a71]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[36e6800b9757404d]::plumbing::QueryCtxt, true>
  20:     0x7ff8111efbd4 - rustc_query_impl[36e6800b9757404d]::query_impl::mir_borrowck::get_query_incr::__rust_end_short_backtrace
  21:     0x7ff811971955 - <rustc_middle[e0a019250b2560b5]::ty::context::TyCtxt>::par_hir_body_owners::<rustc_interface[5344109f4998426e]::passes::run_required_analyses::{closure#1}::{closure#0}>::{closure#0}
  22:     0x7ff81196f3a8 - rustc_interface[5344109f4998426e]::passes::analysis
  23:     0x7ff81196e875 - rustc_query_impl[36e6800b9757404d]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[36e6800b9757404d]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[e0a019250b2560b5]::query::erase::Erased<[u8; 0usize]>>
  24:     0x7ff8121cca02 - rustc_query_system[4eadbad177027a71]::query::plumbing::try_execute_query::<rustc_query_impl[36e6800b9757404d]::DynamicConfig<rustc_query_system[4eadbad177027a71]::query::caches::SingleCache<rustc_middle[e0a019250b2560b5]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[36e6800b9757404d]::plumbing::QueryCtxt, true>
  25:     0x7ff8121cc323 - rustc_query_impl[36e6800b9757404d]::query_impl::analysis::get_query_incr::__rust_end_short_backtrace
  26:     0x7ff812447f16 - rustc_interface[5344109f4998426e]::passes::create_and_enter_global_ctxt::<core[4727a1a5e2f8bf41]::option::Option<rustc_interface[5344109f4998426e]::queries::Linker>, rustc_driver_impl[aa7064ecaea87566]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
  27:     0x7ff8122ea125 - rustc_interface[5344109f4998426e]::interface::run_compiler::<(), rustc_driver_impl[aa7064ecaea87566]::run_compiler::{closure#0}>::{closure#1}
  28:     0x7ff8122366b8 - std[da76efc55aba569b]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[5344109f4998426e]::util::run_in_thread_with_globals<rustc_interface[5344109f4998426e]::util::run_in_thread_pool_with_globals<rustc_interface[5344109f4998426e]::interface::run_compiler<(), rustc_driver_impl[aa7064ecaea87566]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  29:     0x7ff812236396 - <<std[da76efc55aba569b]::thread::Builder>::spawn_unchecked_<rustc_interface[5344109f4998426e]::util::run_in_thread_with_globals<rustc_interface[5344109f4998426e]::util::run_in_thread_pool_with_globals<rustc_interface[5344109f4998426e]::interface::run_compiler<(), rustc_driver_impl[aa7064ecaea87566]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[4727a1a5e2f8bf41]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  30:     0x7ff81223c385 - std::sys::pal::unix::thread::Thread::new::thread_start::h1ff51d6e85162efd
  31:     0x7ff80ba969cb - <unknown>
  32:     0x7ff80bb1aa0c - <unknown>
  33:                0x0 - <unknown>

error: 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 1.89.0 (29483883e 2025-08-04) running on x86_64-unknown-linux-gnu

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

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

query stack during panic:
#0 [mir_borrowck] borrow-checking `topostfix::get_higher_precedence_operators`
#1 [analysis] running analysis passes on this crate
end of query stack
error: could not compile `slmcompiler` (bin "slmcompiler")

Caused by:
  process didn't exit successfully: `/home/evilssouls/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/rustc --crate-name slmcompiler --edition=2024 src/main.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --diagnostic-width=232 --crate-type bin --emit=dep-info,link -C embed-bitcode=no -C debuginfo=2 --check-cfg 'cfg(docsrs,test)' --check-cfg 'cfg(feature, values())' -C metadata=a455d1093776e0ce -C extra-filename=-71e51354082a1ebf --out-dir /home/evilssouls/repos/local/Rust/slmcompiler/target/debug/deps -C incremental=/home/evilssouls/repos/local/Rust/slmcompiler/target/debug/incremental -L dependency=/home/evilssouls/repos/local/Rust/slmcompiler/target/debug/deps` (exit status: 101)

Backtrace

thread 'rustc' panicked at compiler/rustc_borrowck/src/diagnostics/move_errors.rs:828:76:
called `Option::unwrap()` on a `None` value
stack backtrace:
   0: __rustc::rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::panicking::panic
   3: core::option::unwrap_failed
   4: <rustc_borrowck::MirBorrowckCtxt>::add_move_error_details
   5: <rustc_borrowck::MirBorrowckCtxt>::report
   6: rustc_borrowck::do_mir_borrowck
   7: rustc_borrowck::mir_borrowck
      [... omitted 1 frame ...]
   8: <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners::<rustc_interface::passes::run_required_analyses::{closure#1}::{closure#0}>::{closure#0}
   9: rustc_interface::passes::analysis
      [... omitted 1 frame ...]
  10: rustc_interface::passes::create_and_enter_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
  11: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

[ais523]

Manually reduced:

#![allow(unused_variables)]
#![allow(unused_assignments)]

pub struct NonCopy;
fn cause_ice() {
    let tuple = &(NonCopy,);
    let b: NonCopy;
    (b,) = *tuple;
}

Both the code in the original report, and this reduced version, reproduce on stable 1.89, but not nightly or beta. As such, it's probable that this bug has already been fixed.

@rustbot label +S-has-mcve

[EvilsSouls]

Manually reduced:

#![allow(unused_variables)]
#![allow(unused_assignments)]

pub struct NonCopy;
fn cause_ice() {
let tuple = &(NonCopy,);
let b: NonCopy;
(b,) = *tuple;
}

Both the code in the original report, and this reduced version, reproduce on stable 1.89, but not nightly or beta. As such, it's probable that this bug has already been fixed.

@rustbot label +S-has-mcve

Aha, thank you very much!

[lukaslueg]

This was fixed in a7baff8