'rustc' panicked at 'visit_mac disabled by default'

[spelufo]

#[derive(Debug)]
struct NoneSense<T> {
    shouldBeVecT: vec![T]
}

fn main() { }

I accidentally used vec![T] as a type instead of Vec<T>, and got an error: internal compiler error: unexpected panic. Without the #[derive(Debug)], rustc gives this error:

 ▸ RUST_BACKTRACE=1 rustc -Z unstable-options --pretty expanded nonsense.rs 
nonsense.rs:3:16: 3:23 error: type macros are experimental (see issue #27336)
nonsense.rs:3   shouldBeVecT: vec![T]
                              ^~~~~~~
nonsense.rs:3:16: 3:23 help: add #![feature(type_macros)] to the crate attributes to enable
error: aborting due to previous error

but with it it panics.

Meta

 ▸ rustc --version --verbose
rustc 1.9.0-dev (98f0a9128 2016-03-23)
binary: rustc
commit-hash: 98f0a9128f0fc6545de14a5de8f0e91675045e56
commit-date: 2016-03-23
host: x86_64-unknown-linux-gnu
release: 1.9.0-dev

 ▸ RUST_BACKTRACE=1 rustc -Z unstable-options --pretty expanded nonsense.rs 
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
thread 'rustc' panicked at 'visit_mac disabled by default', src/libsyntax/visit.rs:106
stack backtrace:
   1:     0x7fcfa63e9340 - sys::backtrace::tracing::imp::write::h6559e17e2156431eGxu
   2:     0x7fcfa63f69cb - panicking::default_hook::_$u7b$$u7b$closure$u7d$$u7d$::closure.45009
   3:     0x7fcfa63f657c - panicking::default_hook::h6dd74158f7e250f0xJz
   4:     0x7fcfa63baf0f - sys_common::unwind::begin_unwind_inner::h7c5a5cd9fc65b5412ot
   5:     0x7fcfa494e49f - sys_common::unwind::begin_unwind::h6359867539345201166
   6:     0x7fcfa49a13b8 - visit::Visitor::visit_mac::h16549959366189755243
   7:     0x7fcfa499f8d6 - deriving::generic::find_type_parameters::Visitor<'a>.visit..Visitor<'a>::visit_ty::h116e561ccbab3742wDd
   8:     0x7fcfa49a33e1 - deriving::generic::TraitDef<'a>::create_derived_impl::h39b900a1397ae1a5YHd
   9:     0x7fcfa498a197 - deriving::generic::TraitDef<'a>::expand::hc13cde2c74a8c5b9JFd
  10:     0x7fcfa49877ec - deriving::debug::expand_deriving_debug::hf61e50c721bf05d7bgc
  11:     0x7fcfa4980273 - deriving::register_all::DeriveExtension.MultiItemDecorator::expand::hf9210c167ff074e5pPe
  12:     0x7fcfa23f61aa - ext::expand::expand_annotatable::h796edb48e8c92246FS4
  13:     0x7fcfa23f4648 - ext::expand::expand_item::h20c21c0b97772740Sl4
  14:     0x7fcfa240254e - ext::expand::MacroExpander<'a, 'b>.Folder::fold_item::h8d372ee48f4fc33djb5
  15:     0x7fcfa2402193 - fold::noop_fold_mod::h16414683612833474929
  16:     0x7fcfa23fba9a - ext::expand::expand_item_kind::hdad4b81657b878c0tm4
  17:     0x7fcfa2437059 - fold::noop_fold_item_simple::h717855624644524380
  18:     0x7fcfa2436bc0 - fold::noop_fold_item::h6171340203445854305
  19:     0x7fcfa23f8bd0 - ext::expand::expand_annotatable::h796edb48e8c92246FS4
  20:     0x7fcfa23f4648 - ext::expand::expand_item::h20c21c0b97772740Sl4
  21:     0x7fcfa240283e - ext::expand::MacroExpander<'a, 'b>.Folder::fold_item::h8d372ee48f4fc33djb5
  22:     0x7fcfa244317b - ext::expand::MacroExpander<'a, 'b>.Folder::fold_crate::h61090e51fa056378la5
  23:     0x7fcfa244463a - ext::expand::expand_crate::h6480936e5df691539j5
  24:     0x7fcfa6970691 - driver::phase_2_configure_and_expand::_$u7b$$u7b$closure$u7d$$u7d$::closure.35957
  25:     0x7fcfa691cd3c - driver::phase_2_configure_and_expand::h6f797358d9ef36f2uAa
  26:     0x7fcfa68fbf78 - pretty::pretty_print_input::hb5b8102303287e84t4b
  27:     0x7fcfa68f0035 - run_compiler::hb1c75f3272b9a9c6VDc
  28:     0x7fcfa68ed801 - sys_common::unwind::try::try_fn::h16475092432511726611
  29:     0x7fcfa63e699b - __rust_try
  30:     0x7fcfa63e692d - sys_common::unwind::inner_try::hcf46b1587e9940b44lt
  31:     0x7fcfa68ee04a - boxed::F.FnBox<A>::call_box::h2552470165920174793
  32:     0x7fcfa63f4ab4 - sys::thread::Thread::new::thread_start::hb7a9acf17d27d8536Gy
  33:     0x7fcf9f818423 - start_thread
  34:     0x7fcfa606ccbc - clone
  35:                0x0 - <unknown>

 ▸ echo $?
101

[durka]

Moreover, even with #![feature(type_macros)] enabled, you can't use type macros with deriving: http://is.gd/RcacUK

cc #27245