Illustration of difference between debug and release builds

THIS CODE IS FOR A BUG REPORT. DO NOT USE IT IN PRODUCTION CODE!

This simplified project illustrates the difference in behavior between debug and release builds. When this code is executed using cargo run, it will execute as expected, without any crashes. When run with cargo run --release, it will panic with the following message:

thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', src/libcore/option.rs:345:21
note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.

Here is the backtrace:

$ RUST_BACKTRACE=full cargo run --release
    Finished release [optimized] target(s) in 0.02s
     Running `target/release/noisy_float_issue`
thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', src/libcore/option.rs:345:21
stack backtrace:
   0:     0x55817fea0963 - std::sys::unix::backtrace::tracing::imp::unwind_backtrace::hd71462e61ec5c76e
                               at src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:39
   1:     0x55817fe9ca6b - std::sys_common::backtrace::_print::hae2106692f421f30
                               at src/libstd/sys_common/backtrace.rs:70
   2:     0x55817fe9f946 - std::panicking::default_hook::{{closure}}::h4e372307f318ae92
                               at src/libstd/sys_common/backtrace.rs:58
                               at src/libstd/panicking.rs:200
   3:     0x55817fe9f6c4 - std::panicking::default_hook::hb6f777c87029e950
                               at src/libstd/panicking.rs:215
   4:     0x55817fe9ff9f - std::panicking::rust_panic_with_hook::h49d43efebcb63d45
                               at src/libstd/panicking.rs:478
   5:     0x55817fe9fb21 - std::panicking::continue_panic_fmt::h87cb4de2c26b0fa7
                               at src/libstd/panicking.rs:385
   6:     0x55817fe9fa05 - rust_begin_unwind
                               at src/libstd/panicking.rs:312
   7:     0x55817feafccc - core::panicking::panic_fmt::h472d766e4dff71a2
                               at src/libcore/panicking.rs:85
   8:     0x55817feafc0b - core::panicking::panic::h3c512c7c2bb6da25
                               at src/libcore/panicking.rs:49
   9:     0x55817fe97a5d - noisy_float_issue::main::h02b74e2a4af883fd
  10:     0x55817fe97a22 - std::rt::lang_start::{{closure}}::h1bc09f850a1cd95c
  11:     0x55817fe9f9f2 - std::panicking::try::do_call::hf75bca0b71ecc6e0
                               at src/libstd/rt.rs:49
                               at src/libstd/panicking.rs:297
  12:     0x55817fea18d9 - __rust_maybe_catch_panic
                               at src/libpanic_unwind/lib.rs:87
  13:     0x55817fea04ac - std::rt::lang_start_internal::h5a74da15a365d5aa
                               at src/libstd/panicking.rs:276
                               at src/libstd/panic.rs:388
                               at src/libstd/rt.rs:48
  14:     0x55817fe97a81 - main
  15:     0x7fd672c62b96 - __libc_start_main
  16:     0x55817fe97939 - _start
  17:                0x0 - <unknown>

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$ uname -a
Linux EMANE 4.15.0-47-generic #50-Ubuntu SMP Wed Mar 13 10:44:52 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 18.04.2 LTS
Release:    18.04
Codename:   bionic

$ cargo -vV
cargo 1.34.0 (6789d8a0a 2019-04-01)
release: 1.34.0
commit-hash: 6789d8a0a54a96d95365c4e1fb01d47a5eed9937
commit-date: 2019-04-01

$ rustc -vV
rustc 1.34.0 (91856ed52 2019-04-10)
binary: rustc
commit-hash: 91856ed52c58aa5ba66a015354d1cc69e9779bdf
commit-date: 2019-04-10
host: x86_64-unknown-linux-gnu
release: 1.34.0
LLVM version: 8.0