incr. comp. ICE: try_mark_green() - Forcing the DepNode should have set its color

[remexre]

Note that this code doesn't compile regardless (ast::Decl contains ast::Expr by value, which contains an ast::Decl), but the ICE looks related to incremental compilation, so it might be reproducible under other circumstances.

Code, Travis Reproduction

$ cargo check
   Compiling oftb v0.1.0 (file:///home/nathan/Projects/oftlisp/oftb)
warning: unused import: `literal::Literal`
  --> src/flatanf/convert.rs:10:5
   |
10 | use literal::Literal;
   |     ^^^^^^^^^^^^^^^^
   |
   = note: #[warn(unused_imports)] on by default

error[E0391]: unsupported cyclic reference between types/traits detected
  --> src/ast/mod.rs:62:1
   |
62 | pub enum Decl {
   | ^^^^^^^^^^^^^ cyclic reference
   |
note: the cycle begins when processing `ast::Decl`...
  --> src/ast/mod.rs:62:1
   |
62 | pub enum Decl {
   | ^^^^^^^^^^^^^
   = note: ...which then again requires processing `ast::Decl`, completing the cycle.

error: internal compiler error: /checkout/src/librustc/dep_graph/graph.rs:615: try_mark_green() - Forcing the DepNode should have set its color

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 1.24.1 (d3ae9a9e0 2018-02-27) running on x86_64-unknown-linux-gnu

thread 'rustc' panicked at 'Box<Any>', /checkout/src/librustc_errors/lib.rs:504:9
note: Run with `RUST_BACKTRACE=1` for a backtrace.

error: Could not compile `oftb`.

To learn more, run the command again with --verbose.

[michaelwoerister]

Thanks for the bug report, @remexre!

[Zoxc]

Running this on x86_64-pc-windows-msvc gives me:

warning: unused import: `literal::Literal`
  --> src\flatanf\convert.rs:10:5
   |
10 | use literal::Literal;
   |     ^^^^^^^^^^^^^^^^
   |
   = note: #[warn(unused_imports)] on by default

error[E0072]: recursive type `ast::Decl` has infinite size
  --> src\ast\mod.rs:62:1
   |
62 | pub enum Decl {
   | ^^^^^^^^^^^^^ recursive type has infinite size
63 |     Def(Symbol, Expr),
   |                 ----- recursive without indirection
64 |     Defn(Symbol, Vec<Symbol>, Vec<Expr>, Expr),
   |                                          ----- recursive without indirection
   |
   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `ast::Decl` representable

error[E0072]: recursive type `ast::Expr` has infinite size
   --> src\ast\mod.rs:112:1
    |
112 | pub enum Expr {
    | ^^^^^^^^^^^^^ recursive type has infinite size
113 |     Call(Box<Expr>, Vec<Expr>),
114 |     Decl(Decl),
    |          ----- recursive without indirection
    |
    = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `ast::Expr` representable

error: aborting due to 2 previous errors

It seems like travis keeps around the incremental cache. Does this happen for clean builds too?

[michaelwoerister]

Does this happen for clean builds too?

Clean builds should not hit this code path, because there's no previous dep-graph.

[michaelwoerister]

OK, in order to reproduce this, one has to fill the incr. comp. cache with something valid first, then introduce the error and then compile again:

git checkout 3ad54e30371a166c10bea4180c7c874f6e6c3e5c
cargo build
git checkout ice
cargo build

[nikomatsakis]

triage: P-high