Creating a recursive type with infinite size leads to ICE

[ackxolotl]

Creating a recursive type with infinite size by removing a Box leads to an internal compiler error. Might be the same issue as #57373.

To reproduce this bug, run cargo build on this code:

enum A {
    B(C),
}

struct C {
    a: Box<A>,
}

fn main() {

}

Replace Box<A> by A and run cargo build again:

enum A {
    B(C),
}

struct C {
    a: A,
}

fn main() {

}

I expected to see this happen:

error[E0072]: recursive type `A` has infinite size
 --> src/main.rs:1:1
  |
1 | enum A {
  | ^^^^^^ recursive type has infinite size
2 |     B(C),
  |       - recursive without indirection
  |
  = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `A` representable

error[E0072]: recursive type `C` has infinite size
 --> src/main.rs:5:1
  |
5 | struct C {
  | ^^^^^^^^ recursive type has infinite size
6 |     a: A,
  |     ---- recursive without indirection
  |
  = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `C` representable

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0072`.
error: Could not compile `hello_world`.

Instead, this happened:

error: internal compiler error: src/librustc/dep_graph/graph.rs:722: try_mark_previous_green() - Forcing the DepNode should have set its color

thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:635:9
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
             at src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:39
   1: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:71
   2: std::panicking::default_hook::{{closure}}
             at src/libstd/sys_common/backtrace.rs:59
             at src/libstd/panicking.rs:197
   3: std::panicking::default_hook
             at src/libstd/panicking.rs:211
   4: rustc::util::common::panic_hook
   5: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:478
   6: std::panicking::begin_panic
   7: rustc_errors::Handler::bug
   8: rustc::util::bug::opt_span_bug_fmt::{{closure}}
   9: rustc::ty::context::tls::with_opt::{{closure}}
  10: rustc::ty::context::tls::with_context_opt
  11: rustc::ty::context::tls::with_opt
  12: rustc::util::bug::opt_span_bug_fmt
  13: rustc::util::bug::bug_fmt
  14: rustc::dep_graph::graph::DepGraph::try_mark_previous_green
  15: rustc::dep_graph::graph::DepGraph::try_mark_green
  16: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  17: rustc::ty::AdtDef::sized_constraint_for_ty
  18: <core::iter::adapters::flatten::FlatMap<I,U,F> as core::iter::traits::iterator::Iterator>::next
  19: <smallvec::SmallVec<A> as core::iter::traits::collect::FromIterator<<A as smallvec::Array>::Item>>::from_iter
  20: <T as rustc::ty::context::InternIteratorElement<T,R>>::intern_with
  21: rustc::ty::adt_sized_constraint
  22: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::adt_sized_constraint>::compute
  23: rustc::dep_graph::graph::DepGraph::with_task_impl
  24: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::force_query
  25: rustc::ty::query::plumbing::force_from_dep_node
  26: rustc::dep_graph::graph::DepGraph::try_mark_previous_green
  27: rustc::dep_graph::graph::DepGraph::try_mark_previous_green
  28: rustc::dep_graph::graph::DepGraph::try_mark_previous_green
  29: rustc::dep_graph::graph::DepGraph::try_mark_previous_green
  30: rustc::dep_graph::graph::DepGraph::try_mark_green
  31: rustc::dep_graph::graph::DepGraph::try_mark_green_and_read
  32: <rustc_typeck::check::wfcheck::CheckTypeWellFormedVisitor as rustc::hir::itemlikevisit::ParItemLikeVisitor>::visit_item
  33: __rust_maybe_catch_panic
             at src/libpanic_unwind/lib.rs:87
  34: rustc_data_structures::sync::par_for_each_in
  35: __rust_maybe_catch_panic
             at src/libpanic_unwind/lib.rs:87
  36: rustc::hir::Crate::par_visit_all_item_likes
  37: rustc::util::common::time
  38: rustc_typeck::check_crate
  39: rustc_interface::passes::analysis
  40: rustc::ty::query::__query_compute::analysis
  41: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors for rustc::ty::query::queries::analysis>::compute
  42: rustc::dep_graph::graph::DepGraph::with_task_impl
  43: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt>::get_query
  44: rustc_interface::passes::BoxedGlobalCtxt::access::{{closure}}
  45: rustc_interface::passes::create_global_ctxt::{{closure}}
  46: rustc_interface::interface::run_compiler_in_existing_thread_pool
  47: std::thread::local::LocalKey<T>::with
  48: scoped_tls::ScopedKey<T>::set
  49: syntax::with_globals
query stack during panic:
#0 [adt_sized_constraint] processing `A`
#1 [adt_sized_constraint] processing `C`
#2 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to previous error


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: rustc 1.35.0 (3c235d560 2019-05-20) running on x86_64-unknown-linux-gnu

note: compiler flags: -C debuginfo=2 -C incremental --crate-type bin

note: some of the compiler flags provided by cargo are hidden

error: Could not compile `hello_world`.

Meta

rustc --version --verbose:

rustc 1.35.0 (3c235d560 2019-05-20)
binary: rustc
commit-hash: 3c235d5600393dfe6c36eeed34042efad8d4f26e
commit-date: 2019-05-20
host: x86_64-unknown-linux-gnu
release: 1.35.0
LLVM version: 8.0

[pnkfelix]

triage: P-high. Removing nomination.

[pnkfelix]

assigning to @nikomatsakis with expectation that they will delegate.

[pnkfelix]

nominating to try to find someone to investigate this.