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Resolve a FIXME around type equality checks in Relate for constants

This commit is contained in:
Oli Scherer 2021-03-02 11:22:37 +00:00
parent 09f7f91532
commit 019dba0ceb
1 changed files with 9 additions and 6 deletions
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15
compiler/rustc_middle/src/ty/relate.rs
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@ -498,12 +498,15 @@ pub fn super_relate_consts<R: TypeRelation<'tcx>>(
debug!("{}.super_relate_consts(a = {:?}, b = {:?})", relation.tag(), a, b);
let tcx = relation.tcx();
let eagerly_eval = |x: &'tcx ty::Const<'tcx>| x.eval(tcx, relation.param_env()).val;
// FIXME(oli-obk): once const generics can have generic types, this assertion
// will likely get triggered. Move to `normalize_erasing_regions` at that point.
assert_eq!(
tcx.erase_regions(a.ty),
tcx.erase_regions(b.ty),
"cannot relate constants of different types"
);
// FIXME(eddyb) doesn't look like everything below checks that `a.ty == b.ty`.
// We could probably always assert it early, as const generic parameters
// are not allowed to depend on other generic parameters, i.e. are concrete.
// (although there could be normalization differences)
let eagerly_eval = |x: &'tcx ty::Const<'tcx>| x.eval(tcx, relation.param_env()).val;
// Currently, the values that can be unified are primitive types,
// and those that derive both `PartialEq` and `Eq`, corresponding
@ -524,7 +527,7 @@ pub fn super_relate_consts<R: TypeRelation<'tcx>>(
}
(ty::ConstKind::Value(a_val), ty::ConstKind::Value(b_val)) => {
let new_val = match (a_val, b_val) {
(ConstValue::Scalar(a_val), ConstValue::Scalar(b_val)) if a.ty == b.ty => {
(ConstValue::Scalar(a_val), ConstValue::Scalar(b_val)) => {
if a_val == b_val {
Ok(ConstValue::Scalar(a_val))
} else if let ty::FnPtr(_) = a.ty.kind() {