Cross-crate regions in statics ICE

[alexcrichton]

This code:

// test.rs
extern mod other;
static a: other::Foo<'static> = other::A;

fn main() {}

// other.rs
pub enum Foo<'self> {
    A,
    B(&'self str),
}

Causes the ICE

test.rs:2:32: 2:40 error: internal compiler error: Cannot relate bound region as superregion: br_self
test.rs:2 static a: other::Foo<'static> = other::A;
                                          ^~~~~~~~

cc @nikomatsakis

[alexcrichton]

Also a similar, but different error:

// test.rs
extern mod other;
static a: other::Bar<'static> = other::C(&other::A);

fn main() {}

// other.rs
pub enum Foo<'self> {
    A,
    B(&'self str),
}
pub enum Bar<'self> {
    C(&'self Foo<'self>),
}

test.rs:2:32: 2:52 error: cannot infer an appropriate lifetime due to conflicting requirements
test.rs:2 static a: other::Bar<'static> = other::C(&other::A);
                                          ^~~~~~~~~~~~~~~~~~~~
note: first, the lifetime cannot outlive lifetime re_bound(br_self)...
test.rs:2:41: 2:50 note: ...due to the following expression
test.rs:2 static a: other::Bar<'static> = other::C(&other::A);
                                                   ^~~~~~~~~
note: but, the lifetime must be valid for the static lifetime...
test.rs:2:32: 2:52 note: ...due to the following expression
test.rs:2 static a: other::Bar<'static> = other::C(&other::A);
                                          ^~~~~~~~~~~~~~~~~~~~
error: aborting due to previous error

[alexcrichton]

I've also confirmed that if everything is defined in the same crate, it all compiles just fine.

[alexcrichton]

This may be related to #7634, although it's a different error message so I'm not sure of it.

[alexcrichton]

This is not related to #7634

[erickt]

I just ran into this myself. One interesting thing I found is that the error happens due to the empty variant. This compiles fine for me:

// test.rs
extern mod other;
static a: other::Foo<'static> = other::A(());

fn main() {}

// other.rs
pub enum Foo<'self> {
    A(()),
    B(&'self str),
}

[alexcrichton]

Appears to be fixed now, flagging as needstest.