user0/rust
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

avoid downcasting for enum variants without further fields

Browse source
This commit is contained in:
Ralf Jung 2017-06-19 23:49:57 -07:00 • committed by Oliver Schneider
parent a91ee4bb03
commit fda5cc9b4c
No known key found for this signature in database
GPG key ID: A69F8D225B3AD7D9
1 changed files with 11 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

17
src/librustc_mir/interpret/lvalue.rs
View file

@ -561,13 +561,18 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
let variant_idx = adt.discriminants(self.tcx)
.position(|variant_discr| variant_discr.to_u128_unchecked() == discr)
.ok_or(EvalError::InvalidDiscriminant)?;
// Downcast to this variant
let lvalue = self.eval_lvalue_projection(lvalue, ty, &mir::ProjectionElem::Downcast(adt, variant_idx))?;
// Recursively validate the fields
let variant = &adt.variants[variant_idx];
self.validate_variant(lvalue, ty, variant, subst, outer_mutbl)
if variant.fields.len() > 0 {
// Downcast to this variant
let lvalue = self.eval_lvalue_projection(lvalue, ty, &mir::ProjectionElem::Downcast(adt, variant_idx))?;
// Recursively validate the fields
self.validate_variant(lvalue, ty, variant, subst, outer_mutbl)
} else {
// No fields, nothing left to check. Downcasting may fail, e.g. in case of a CEnum.
Ok(())
}
}
AdtKind::Struct => {
self.validate_variant(lvalue, ty, adt.struct_variant(), subst, outer_mutbl)