Creating a struct that includes a self-referential type causes an internal compiler error

[martica]

Creating a struct that includes a self-referential type causes an internal compiler error. It clearly needs to be boxed, but hopefully there could be an error message instead. This appears to be similar to #742, the closed ticket for a similar issues with enums (nee tags).

Starting with a naïve implementation such as:

struct RecursiveType {
    self_reference: RecursiveType
}

You get:

crash.rs:3:0: 5:1 error: this type cannot be instantiated without an instance of itself; consider using `option<RecursiveType>`
crash.rs:3 struct RecursiveType {
crash.rs:4     self_reference: RecursiveType
crash.rs:5 }

Switching to option doesn't work, as it should be Option:

crash.rs:4:20: 4:41 error: found type name used as a variable
crash.rs:4     self_reference: option<RecursiveType>
                               ^~~~~~~~~~~~~~~~~~~~~

Switching to Option triggers the error:

struct RecursiveType {
    self_reference: Option<RecursiveType>
}
$ RUST_LOG=rustc=1,::rt::backtrace rustc crash.rs
rust: task 7fa823d01170 ran out of stack
error: internal compiler error: unexpected failure
note: the compiler hit an unexpected failure path. this is a bug
note: try running with RUST_LOG=rustc=1,::rt::backtrace to get further details and report the results to github.com/mozilla/rust/issues
rust: task failed at 'explicit failure', /private/tmp/rust-3z40/rust-0.5/src/librustc/rustc.rc:425
rust: domain main @0x7fa824800010 root task failed
rust: task failed at 'killed', /private/tmp/rust-3z40/rust-0.5/src/libcore/task/mod.rs:570

I've tested this in the released 0.5 and the current master branch version of 0.6.

[jdm]

Presumably the same issue as #4218.

[martica]

That it is. Curses. I found all the old issues about enums and missed the current one about structs. Sigh.