bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

add relaxed_struct_unsize feature gate

Browse source
This commit is contained in:
Bastian Kauschke 2021-02-03 23:56:47 +01:00
parent 50e394a05e
commit 031cce8cfc
6 changed files with 75 additions and 17 deletions
Download patch file Download diff file Expand all files Collapse all files

63
compiler/rustc_trait_selection/src/traits/select/confirmation.rs
View file

@ -823,33 +823,62 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
},
};
// FIXME(eddyb) cache this (including computing `unsizing_params`)
// by putting it in a query; it would only need the `DefId` as it
// looks at declared field types, not anything substituted.
// The last field of the structure has to exist and contain type/const parameters.
let (tail_field, prefix_fields) =
def.non_enum_variant().fields.split_last().ok_or(Unimplemented)?;
let tail_field_ty = tcx.type_of(tail_field.did);
let mut unsizing_params = GrowableBitSet::new_empty();
for arg in tail_field_ty.walk() {
if let Some(i) = maybe_unsizing_param_idx(arg) {
unsizing_params.insert(i);
}
}
// Ensure none of the other fields mention the parameters used
// in unsizing.
// FIXME(eddyb) cache this (including computing `unsizing_params`)
// by putting it in a query; it would only need the `DefId` as it
// looks at declared field types, not anything substituted.
for field in prefix_fields {
for arg in tcx.type_of(field.did).walk() {
if tcx.features().relaxed_struct_unsize {
for arg in tail_field_ty.walk() {
if let Some(i) = maybe_unsizing_param_idx(arg) {
unsizing_params.remove(i);
unsizing_params.insert(i);
}
}
}
if unsizing_params.is_empty() {
return Err(Unimplemented);
// Ensure none of the other fields mention the parameters used
// in unsizing.
for field in prefix_fields {
for arg in tcx.type_of(field.did).walk() {
if let Some(i) = maybe_unsizing_param_idx(arg) {
unsizing_params.remove(i);
}
}
}
if unsizing_params.is_empty() {
return Err(Unimplemented);
}
} else {
let mut found = false;
for arg in tail_field_ty.walk() {
if let Some(i) = maybe_unsizing_param_idx(arg) {
unsizing_params.insert(i);
found = true;
}
}
if !found {
return Err(Unimplemented);
}
// Ensure none of the other fields mention the parameters used
// in unsizing.
// FIXME(eddyb) cache this (including computing `unsizing_params`)
// by putting it in a query; it would only need the `DefId` as it
// looks at declared field types, not anything substituted.
for field in prefix_fields {
for arg in tcx.type_of(field.did).walk() {
if let Some(i) = maybe_unsizing_param_idx(arg) {
if unsizing_params.contains(i) {
return Err(Unimplemented);
}
}
}
}
}
// Extract `TailField<T>` and `TailField<U>` from `Struct<T>` and `Struct<U>`.