bjoernager/rust
bjoernager/rust
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incorporate some review feedback

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This commit is contained in:
Ralf Jung 2022-07-19 19:50:04 -04:00
parent 8affef2ccb
commit 5e840c5c8c
6 changed files with 18 additions and 38 deletions
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27
compiler/rustc_const_eval/src/interpret/cast.rs
View file

@ -297,32 +297,11 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
Immediate::new_slice(ptr, length.eval_usize(*self.tcx, self.param_env), self);
self.write_immediate(val, dest)
}
(&ty::Dynamic(ref data_a, ..), &ty::Dynamic(ref data_b, ..)) => {
let val = self.read_immediate(src)?;
let (old_data, old_vptr) = val.to_scalar_pair()?;
(&ty::Dynamic(ref _data_a, ..), &ty::Dynamic(ref data_b, ..)) => {
let (old_data, old_vptr) = self.read_immediate(src)?.to_scalar_pair()?;
let old_vptr = self.scalar_to_ptr(old_vptr)?;
if data_a.principal_def_id() == data_b.principal_def_id() {
return self.write_immediate(*val, dest);
}
// trait upcasting coercion
let Some(vptr_entry_idx) = self.tcx.vtable_trait_upcasting_coercion_new_vptr_slot((
src_pointee_ty,
dest_pointee_ty,
)) else {
return self.write_immediate(*val, dest);
};
let (ty, _) = self.get_ptr_vtable(old_vptr)?;
let Some(ty::VtblEntry::TraitVPtr(new_trait)) = self.get_vtable_entries(old_vptr)?.get(vptr_entry_idx) else {
throw_ub_format!(
"upcasting to index {vptr_entry_idx} of vtable {old_vptr} but \
that vtable is too small or does not have an upcast-vtable at that index"
)
};
let new_trait = new_trait.map_bound(|trait_ref| {
ty::ExistentialTraitRef::erase_self_ty(*self.tcx, trait_ref)
});
let new_vptr = self.get_vtable_ptr(ty, Some(new_trait))?;
let new_vptr = self.get_vtable_ptr(ty, data_b.principal())?;
self.write_immediate(Immediate::new_dyn_trait(old_data, new_vptr, self), dest)
}
(_, &ty::Dynamic(ref data, _)) => {

2
compiler/rustc_const_eval/src/interpret/memory.rs
View file

@ -875,7 +875,7 @@ impl<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> std::fmt::Debug for DumpAllocs<'a,
write!(fmt, " (vtable: impl {trait_ref} for {ty})")?;
}
Some(GlobalAlloc::Vtable(ty, None)) => {
write!(fmt, " (vtable: impl ? for {ty})")?;
write!(fmt, " (vtable: impl <auto trait> for {ty})")?;
}
Some(GlobalAlloc::Static(did)) => {
write!(fmt, " (static: {})", self.ecx.tcx.def_path_str(did))?;

7
compiler/rustc_const_eval/src/interpret/traits.rs
View file

@ -10,9 +10,10 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
/// Creates a dynamic vtable for the given type and vtable origin. This is used only for
/// objects.
///
/// The `trait_ref` encodes the erased self type. Hence, if we are
/// making an object `Foo<Trait>` from a value of type `Foo<T>`, then
/// `trait_ref` would map `T: Trait`.
/// The `trait_ref` encodes the erased self type. Hence, if we are making an object `Foo<Trait>`
/// from a value of type `Foo<T>`, then `trait_ref` would map `T: Trait`. `None` here means that
/// this is an auto trait without any methods, so we only need the basic vtable (drop, size,
/// align).
pub fn get_vtable_ptr(
&self,
ty: Ty<'tcx>,