There is no way to create objects of intrinsically unsized types at compile time.

[mahkoh]

For example:

struct CStr([u8]);

[oli-obk]

it could be possible to allow const-casting arrays to their unsized equivalents. We already have str as an unsized const value. Should be easy enough to add another one for slices.

You already reported an ICE trying to do this: rust-lang/rust#30355 So basically we'd just need to fix that bug.