rustc SIGSEGV reproducer

This crate contains two binaries:

• distinct_three_fields_arcset (crashes rustc in --release on this machine)
• distinct_three_fields_u64_set (control variant that compiles)

Environment used

• rustc 1.90.0
• LLVM 20.1.8
• x86_64-unknown-linux-gnu

Repro steps

From this directory:

cargo clean
cargo build --release --bin distinct_three_fields_arcset

Expected: rustc fails with:

• signal: 11, SIGSEGV: invalid memory reference

Control variant

cargo clean
cargo build --release --bin distinct_three_fields_u64_set

Expected: build succeeds.

Stack-size mitigation

This appears stack-sensitive. On this machine:

cargo clean
RUST_MIN_STACK=3145728 cargo build --release --bin distinct_three_fields_arcset

Expected: build succeeds.

Notes:

• ulimit -s unlimited did not avoid the crash.
• For the full project build, RUST_MIN_STACK=4194304 was sufficient in testing.