crash when running on modified community PCRE regexp library

[matthargett]

When running selene on this code:
https://devforum.roblox.com/t/100a2-pcre2-based-regex-implemention-for-luau-a-better-string-pattern-library/872807/7

I was fixing a selene warning:

warning[empty_if]: empty if block
     ┌─ src/RegEx/init.lua:1894:1
1894 │ ╭ if not cacheSize then
1895 │ │ elseif cacheSize < 0 or cacheSize ~= cacheSize then

and started getting this crash:

RUST_BACKTRACE=full selene src/
thread '<unnamed>' panicked at 'called `Result::unwrap()` on an `Err` value: ParseIntError { kind: InvalidDigit }', selene-lib/src/rules/bad_string_escape.rs:129:80
stack backtrace:
   0:        0x109292d44 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h6a8908fa3ed6f9e8
   1:        0x1092b10ac - core::fmt::write::h4be00f71c5582919
   2:        0x10928cdca - std::io::Write::write_fmt::h49e76926070788f1
   3:        0x109294baf - std::panicking::default_hook::{{closure}}::h1577f0656e419c0e
   4:        0x1092946ad - std::panicking::default_hook::h1aef594179c4fd25
   5:        0x1092952b0 - std::panicking::rust_panic_with_hook::h10bc487d002f6c42
   6:        0x109294d55 - std::panicking::begin_panic_handler::{{closure}}::hf4cfa78c105ce648
   7:        0x1092931b8 - std::sys_common::backtrace::__rust_end_short_backtrace::h1df96a166e4351c4
   8:        0x109294cba - _rust_begin_unwind
   9:        0x1092d3bef - core::panicking::panic_fmt::hea8fe6c9e0720810
  10:        0x1092d3cd5 - core::result::unwrap_failed::h58357c1be19e8a7d
  11:        0x108ffc255 - <selene_lib::rules::bad_string_escape::BadStringEscapeVisitor as full_moon::visitors::Visitor>::visit_value::h7705d6a9d59e51ae
  12:        0x108f57a7c - <full_moon::ast::Value as full_moon::visitors::Visit>::visit::hfbfa5a712309c6c8
  13:        0x108f68f55 - full_moon::ast::visitors::<impl full_moon::visitors::Visit for full_moon::ast::Expression>::visit::h59ec5d6caa34aa57
  14:        0x108fca2b7 - <full_moon::ast::punctuated::Pair<T> as full_moon::visitors::Visit>::visit::h0ff0a91119ff1706
  15:        0x108f57bff - <full_moon::ast::Value as full_moon::visitors::Visit>::visit::hfbfa5a712309c6c8
  16:        0x108f68f55 - full_moon::ast::visitors::<impl full_moon::visitors::Visit for full_moon::ast::Expression>::visit::h59ec5d6caa34aa57
  17:        0x108fca2b7 - <full_moon::ast::punctuated::Pair<T> as full_moon::visitors::Visit>::visit::h0ff0a91119ff1706
  18:        0x108f57bff - <full_moon::ast::Value as full_moon::visitors::Visit>::visit::hfbfa5a712309c6c8
  19:        0x108f68f55 - full_moon::ast::visitors::<impl full_moon::visitors::Visit for full_moon::ast::Expression>::visit::h59ec5d6caa34aa57
  20:        0x108fca2b7 - <full_moon::ast::punctuated::Pair<T> as full_moon::visitors::Visit>::visit::h0ff0a91119ff1706
  21:        0x108f57bff - <full_moon::ast::Value as full_moon::visitors::Visit>::visit::hfbfa5a712309c6c8
  22:        0x108f68f55 - full_moon::ast::visitors::<impl full_moon::visitors::Visit for full_moon::ast::Expression>::visit::h59ec5d6caa34aa57
  23:        0x108fca2b7 - <full_moon::ast::punctuated::Pair<T> as full_moon::visitors::Visit>::visit::h0ff0a91119ff1706
  24:        0x108f57bff - <full_moon::ast::Value as full_moon::visitors::Visit>::visit::hfbfa5a712309c6c8
  25:        0x108f68f55 - full_moon::ast::visitors::<impl full_moon::visitors::Visit for full_moon::ast::Expression>::visit::h59ec5d6caa34aa57
  26:        0x108f2b6af - <(A,B) as full_moon::visitors::Visit>::visit::h4ad88bb7f24a3e83
  27:        0x108ffb863 - <selene_lib::rules::bad_string_escape::BadStringEscapeLint as selene_lib::rules::Rule>::pass::hdac45c0b4cca7844
  28:        0x108cfd665 - selene_lib::Checker<V>::test_on::h5d35db0b4f8daf43
  29:        0x108d52ff0 - selene::read_file::h7d486277c45b338c
  30:        0x108d4c998 - <F as threadpool::FnBox>::call_box::h58f78c904762d642
  31:        0x108ed3dcb - std::sys_common::backtrace::__rust_begin_short_backtrace::h866782205e6bdaea
  32:        0x108ed45d9 - core::ops::function::FnOnce::call_once{{vtable.shim}}::h4d237c38049ec789
  33:        0x10929869b - std::sys::unix::thread::Thread::new::thread_start::h63f8b299c7b9d50c
  34:     0x7fff203208fc - __pthread_start

which I narrowed to this construct:

return {
	{
		source = [==[^[\000-\037]]==],
		tests = {
			{
				input = "\01B",
				matches = {{ index = 0, match = "\001" }},
			},
		},
	},
}

if you remove the \01B part of the string, analysis is fine.

[matthargett]

A similar thing in the same file:

return {
	{
		source = [==[abc[\1]de]==],
		tests = {
			{
				input = "abc\1de",
				matches = {{ index = 0, match = "abc\001de" }},
			},
		},
	},
}