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Auto merge of #95576 - DrMeepster:box_erasure, r=oli-obk

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Remove dereferencing of Box from codegen

Through #94043, #94414, #94873, and #95328, I've been fixing issues caused by Box being treated like a pointer when it is not a pointer. However, these PRs just introduced special cases for Box. This PR removes those special cases and instead transforms a deref of Box into a deref of the pointer it contains.

Hopefully, this is the end of the Box<T, A> ICEs.
This commit is contained in:
bors 2022-06-21 11:00:39 +00:00
commit a25b1315ee
18 changed files with 477 additions and 162 deletions
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5
compiler/rustc_const_eval/src/interpret/place.rs
View file

@ -313,6 +313,11 @@ where
) -> InterpResult<'tcx, MPlaceTy<'tcx, M::PointerTag>> {
let val = self.read_immediate(src)?;
trace!("deref to {} on {:?}", val.layout.ty, *val);
if val.layout.ty.is_box() {
bug!("dereferencing {:?}", val.layout.ty);
}
let mplace = self.ref_to_mplace(&val)?;
self.check_mplace_access(mplace, CheckInAllocMsg::DerefTest)?;
Ok(mplace)

114
compiler/rustc_const_eval/src/transform/validate.rs
View file

@ -240,65 +240,79 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
context: PlaceContext,
location: Location,
) {
if let ProjectionElem::Index(index) = elem {
let index_ty = self.body.local_decls[index].ty;
if index_ty != self.tcx.types.usize {
self.fail(location, format!("bad index ({:?} != usize)", index_ty))
match elem {
ProjectionElem::Index(index) => {
let index_ty = self.body.local_decls[index].ty;
if index_ty != self.tcx.types.usize {
self.fail(location, format!("bad index ({:?} != usize)", index_ty))
}
}
}
if let ProjectionElem::Field(f, ty) = elem {
let parent = Place { local, projection: self.tcx.intern_place_elems(proj_base) };
let parent_ty = parent.ty(&self.body.local_decls, self.tcx);
let fail_out_of_bounds = |this: &Self, location| {
this.fail(location, format!("Out of bounds field {:?} for {:?}", f, parent_ty));
};
let check_equal = |this: &Self, location, f_ty| {
if !this.mir_assign_valid_types(ty, f_ty) {
this.fail(
ProjectionElem::Deref if self.mir_phase >= MirPhase::GeneratorsLowered => {
let base_ty = Place::ty_from(local, proj_base, &self.body.local_decls, self.tcx).ty;
if base_ty.is_box() {
self.fail(
location,
format!("{:?} dereferenced after ElaborateBoxDerefs", base_ty),
)
}
}
ProjectionElem::Field(f, ty) => {
let parent = Place { local, projection: self.tcx.intern_place_elems(proj_base) };
let parent_ty = parent.ty(&self.body.local_decls, self.tcx);
let fail_out_of_bounds = |this: &Self, location| {
this.fail(location, format!("Out of bounds field {:?} for {:?}", f, parent_ty));
};
let check_equal = |this: &Self, location, f_ty| {
if !this.mir_assign_valid_types(ty, f_ty) {
this.fail(
location,
format!(
"Field projection `{:?}.{:?}` specified type `{:?}`, but actual type is {:?}",
parent, f, ty, f_ty
)
)
}
};
match parent_ty.ty.kind() {
ty::Tuple(fields) => {
let Some(f_ty) = fields.get(f.as_usize()) else {
fail_out_of_bounds(self, location);
return;
};
check_equal(self, location, *f_ty);
}
ty::Adt(adt_def, substs) => {
let var = parent_ty.variant_index.unwrap_or(VariantIdx::from_u32(0));
let Some(field) = adt_def.variant(var).fields.get(f.as_usize()) else {
fail_out_of_bounds(self, location);
return;
};
check_equal(self, location, field.ty(self.tcx, substs));
}
ty::Closure(_, substs) => {
let substs = substs.as_closure();
let Some(f_ty) = substs.upvar_tys().nth(f.as_usize()) else {
fail_out_of_bounds(self, location);
return;
};
check_equal(self, location, f_ty);
}
ty::Generator(_, substs, _) => {
let substs = substs.as_generator();
let Some(f_ty) = substs.upvar_tys().nth(f.as_usize()) else {
fail_out_of_bounds(self, location);
return;
};
check_equal(self, location, f_ty);
}
_ => {
self.fail(location, format!("{:?} does not have fields", parent_ty.ty));
}
};
match parent_ty.ty.kind() {
ty::Tuple(fields) => {
let Some(f_ty) = fields.get(f.as_usize()) else {
fail_out_of_bounds(self, location);
return;
};
check_equal(self, location, *f_ty);
}
ty::Adt(adt_def, substs) => {
let var = parent_ty.variant_index.unwrap_or(VariantIdx::from_u32(0));
let Some(field) = adt_def.variant(var).fields.get(f.as_usize()) else {
fail_out_of_bounds(self, location);
return;
};
check_equal(self, location, field.ty(self.tcx, substs));
}
ty::Closure(_, substs) => {
let substs = substs.as_closure();
let Some(f_ty) = substs.upvar_tys().nth(f.as_usize()) else {
fail_out_of_bounds(self, location);
return;
};
check_equal(self, location, f_ty);
}
ty::Generator(_, substs, _) => {
let substs = substs.as_generator();
let Some(f_ty) = substs.upvar_tys().nth(f.as_usize()) else {
fail_out_of_bounds(self, location);
return;
};
check_equal(self, location, f_ty);
}
_ => {
self.fail(location, format!("{:?} does not have fields", parent_ty.ty));
}
}
}
_ => {}
}
self.super_projection_elem(local, proj_base, elem, context, location);
}