Compiler panic with unknown identifier followed by function call in if statement

[NoraCodes]

I wrote an if statement with not in it, as if I were in Python, and left in the match statement syntax, and the compiler panicked.

The code was truly a mangled mess:

if not  is_command_valid(&arg0) {

    false => return Err(String::from("Invalid command ") + &arg0);

}

I would expect this to complain about either syntax or about not not being a known identifier.

Instead, the compiler error was:

src/commands.rs:60:17: 60:33 error: expected `{`, found `is_command_valid`
src/commands.rs:60         if not  is_command_valid(&arg0) {
                                   ^~~~~~~~~~~~~~~~
src/commands.rs:60:17: 60:33 help: place this code inside a block
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/blob/master/CONTRIBUTING.md#bug-reports
note: run with `RUST_BACKTRACE=1` for a backtrace
thread 'rustc' panicked at 'called `Result::unwrap()` on an `Err` value: Utf8Error { valid_up_to: 0 }', ../src/libcore/result.rs:746

The backtrace was:

stack backtrace:
   1:     0x7fee3be27570 - std::sys::backtrace::tracing::imp::write::h4c73fcd3363076f5
   2:     0x7fee3be34c6b - std::panicking::default_hook::_$u7b$$u7b$closure$u7d$$u7d$::h0422dbb3077e6747
   3:     0x7fee3be3480c - std::panicking::default_hook::haac48fa641db8fa2
   4:     0x7fee3bdf979f - std::sys_common::unwind::begin_unwind_inner::h39d40f52add53ef7
   5:     0x7fee3bdfb888 - std::sys_common::unwind::begin_unwind_fmt::h64c0ff793199cc1b
   6:     0x7fee3be24d81 - rust_begin_unwind
   7:     0x7fee3be7e85f - core::panicking::panic_fmt::h73bf9d7e8e891a73
   8:     0x7fee333aba0b - core::result::unwrap_failed::h82c81d60621f70bd
   9:     0x7fee333ab97e - rbml::Doc::as_str_slice::hd88d17b04c3f2cca
  10:     0x7fee39c07a62 - rustc_metadata::decoder::maybe_get_crate_hash::h1c0939ce4d9ba236
  11:     0x7fee39c3b01b - rustc_metadata::loader::Context::extract_one::h56453781fb65bffa
  12:     0x7fee39c32db5 - rustc_metadata::loader::Context::find_library_crate::h30ea71d32623d713
  13:     0x7fee39c18f96 - rustc_metadata::loader::Context::load_library_crate::h7787c1fa9559d604
  14:     0x7fee39c17e1f - rustc_metadata::creader::CrateReader::resolve_crate::h98decfaedbcfe12a
  15:     0x7fee39c196eb - rustc_metadata::creader::CrateReader::resolve_crate_deps::_$u7b$$u7b$closure$u7d$$u7d$::h4bd0eba4f8aa0bca
  16:     0x7fee39c1949c - _<std..collections..HashMap<K, V, S> as std..iter..FromIterator<(K, V)>>::from_iter::h7ccc89cd3e9da036
  17:     0x7fee39c151ba - rustc_metadata::creader::CrateReader::register_crate::hdfd966766b932c68
  18:     0x7fee39c1a562 - rustc_metadata::creader::CrateReader::read_extension_crate::hb0997de4fb0918fb
  19:     0x7fee39c1c85e - rustc_metadata::creader::CrateReader::read_exported_macros::hf3b61431145aafb6
  20:     0x7fee39c400e8 - _<macro_import..MacroLoader<'a> as syntax..visit..Visitor<'v>>::visit_item::h668e7bfc1acab9b3
  21:     0x7fee39c3eeea - rustc_metadata::macro_import::read_macro_defs::h240a20dad60749cc
  22:     0x7fee3c35d9ec - rustc_driver::driver::phase_2_configure_and_expand::h505e157de342d54f
  23:     0x7fee3c34409a - rustc_driver::driver::compile_input::h6491aaddd9e61258
  24:     0x7fee3c32c4e4 - rustc_driver::run_compiler::h80b2ba5e4d787c5f
  25:     0x7fee3c329941 - std::sys_common::unwind::try::try_fn::h34e27823ddd1d5e9
  26:     0x7fee3be24d0b - __rust_try
  27:     0x7fee3be24c9d - std::sys_common::unwind::inner_try::h9eebd8dc83f388a6
  28:     0x7fee3c32a18a - _<F as std..boxed..FnBox<A>>::call_box::h3d5d78986dfac5b2
  29:     0x7fee3be32e04 - std::sys::thread::Thread::new::thread_start::h471ad90789353b5b
  30:     0x7fee347f16f9 - start_thread
  31:     0x7fee3ba88b5c - clone
  32:                0x0 - <unknown>

[jonas-schievink]

Looks like #33778

And damn that help is bad

[NoraCodes]

Oh, yeah definitely the same bug - I was using rustup run nightly cargo clippy on the source. Builds perfectly after cargo clean.