non-exhaustive match failure in eval_const_expr when shift arguments differ in signedness

[msullivan]

eval_const_expr always requires the arguments of a binary op to have the same type, which needn't be true for shift operators. Forcing eval_const_expr to be called on such a shift triggers a compiler failure.

enum bs { thing = 5 >> 1u }
fn main() {
    log(error, thing as int);
}

[eholk]

If anything, should the right hand side of the shift operator be unsigned?

[msullivan]

rust allows any integral type as the rhs of shifts.