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be even more precise about "cast" vs "coercion"
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Lukas Markeffsky committed Sep 15, 2024
1 parent 85f4395 commit 759ff3c
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Showing 90 changed files with 289 additions and 231 deletions.
8 changes: 5 additions & 3 deletions compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -333,8 +333,10 @@ impl<'tcx> BorrowExplanation<'tcx> {
}
}

if let ConstraintCategory::Cast { is_coercion: true, unsize_to: Some(unsize_ty) } =
category
if let ConstraintCategory::Cast {
is_implicit_coercion: true,
unsize_to: Some(unsize_ty),
} = category
{
self.add_object_lifetime_default_note(tcx, err, unsize_ty);
}
Expand Down Expand Up @@ -742,7 +744,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, 'tcx> {
// If we see an unsized cast, then if it is our data we should check
// whether it is being cast to a trait object.
Rvalue::Cast(
CastKind::PointerCoercion(PointerCoercion::Unsize),
CastKind::PointerCoercion(PointerCoercion::Unsize, _),
operand,
ty,
) => {
Expand Down
4 changes: 2 additions & 2 deletions compiler/rustc_borrowck/src/diagnostics/region_errors.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -47,8 +47,8 @@ impl<'tcx> ConstraintDescription for ConstraintCategory<'tcx> {
ConstraintCategory::Yield => "yielding this value ",
ConstraintCategory::UseAsConst => "using this value as a constant ",
ConstraintCategory::UseAsStatic => "using this value as a static ",
ConstraintCategory::Cast { is_coercion: false, .. } => "cast ",
ConstraintCategory::Cast { is_coercion: true, .. } => "coercion ",
ConstraintCategory::Cast { is_implicit_coercion: false, .. } => "cast ",
ConstraintCategory::Cast { is_implicit_coercion: true, .. } => "coercion ",
ConstraintCategory::CallArgument(_) => "argument ",
ConstraintCategory::TypeAnnotation => "type annotation ",
ConstraintCategory::ClosureBounds => "closure body ",
Expand Down
69 changes: 41 additions & 28 deletions compiler/rustc_borrowck/src/type_check/mod.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1977,8 +1977,9 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
Rvalue::Cast(cast_kind, op, ty) => {
self.check_operand(op, location);

match cast_kind {
CastKind::PointerCoercion(PointerCoercion::ReifyFnPointer) => {
match *cast_kind {
CastKind::PointerCoercion(PointerCoercion::ReifyFnPointer, coercion_source) => {
let is_implicit_coercion = coercion_source == CoercionSource::Implicit;
let src_sig = op.ty(body, tcx).fn_sig(tcx);

// HACK: This shouldn't be necessary... We can remove this when we actually
Expand Down Expand Up @@ -2009,15 +2010,15 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
self.prove_predicate(
ty::ClauseKind::WellFormed(src_ty.into()),
location.to_locations(),
ConstraintCategory::Cast { is_coercion: true, unsize_to: None },
ConstraintCategory::Cast { is_implicit_coercion, unsize_to: None },
);

let src_ty = self.normalize(src_ty, location);
if let Err(terr) = self.sub_types(
src_ty,
*ty,
location.to_locations(),
ConstraintCategory::Cast { is_coercion: true, unsize_to: None },
ConstraintCategory::Cast { is_implicit_coercion, unsize_to: None },
) {
span_mirbug!(
self,
Expand All @@ -2038,7 +2039,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
self.prove_predicate(
ty::ClauseKind::WellFormed(src_ty.into()),
location.to_locations(),
ConstraintCategory::Cast { is_coercion: true, unsize_to: None },
ConstraintCategory::Cast { is_implicit_coercion, unsize_to: None },
);

// The type that we see in the fcx is like
Expand All @@ -2051,7 +2052,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
src_ty,
*ty,
location.to_locations(),
ConstraintCategory::Cast { is_coercion: true, unsize_to: None },
ConstraintCategory::Cast { is_implicit_coercion, unsize_to: None },
) {
span_mirbug!(
self,
Expand All @@ -2064,19 +2065,23 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
}
}

CastKind::PointerCoercion(PointerCoercion::ClosureFnPointer(safety)) => {
CastKind::PointerCoercion(
PointerCoercion::ClosureFnPointer(safety),
coercion_source,
) => {
let sig = match op.ty(body, tcx).kind() {
ty::Closure(_, args) => args.as_closure().sig(),
_ => bug!(),
};
let ty_fn_ptr_from =
Ty::new_fn_ptr(tcx, tcx.signature_unclosure(sig, *safety));
Ty::new_fn_ptr(tcx, tcx.signature_unclosure(sig, safety));

let is_implicit_coercion = coercion_source == CoercionSource::Implicit;
if let Err(terr) = self.sub_types(
ty_fn_ptr_from,
*ty,
location.to_locations(),
ConstraintCategory::Cast { is_coercion: true, unsize_to: None },
ConstraintCategory::Cast { is_implicit_coercion, unsize_to: None },
) {
span_mirbug!(
self,
Expand All @@ -2089,7 +2094,10 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
}
}

CastKind::PointerCoercion(PointerCoercion::UnsafeFnPointer) => {
CastKind::PointerCoercion(
PointerCoercion::UnsafeFnPointer,
coercion_source,
) => {
let fn_sig = op.ty(body, tcx).fn_sig(tcx);

// The type that we see in the fcx is like
Expand All @@ -2101,11 +2109,12 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {

let ty_fn_ptr_from = tcx.safe_to_unsafe_fn_ty(fn_sig);

let is_implicit_coercion = coercion_source == CoercionSource::Implicit;
if let Err(terr) = self.sub_types(
ty_fn_ptr_from,
*ty,
location.to_locations(),
ConstraintCategory::Cast { is_coercion: true, unsize_to: None },
ConstraintCategory::Cast { is_implicit_coercion, unsize_to: None },
) {
span_mirbug!(
self,
Expand All @@ -2118,31 +2127,29 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
}
}

CastKind::PointerCoercion(PointerCoercion::Unsize) => {
CastKind::PointerCoercion(PointerCoercion::Unsize, coercion_source) => {
let &ty = ty;
let trait_ref = ty::TraitRef::new(
tcx,
tcx.require_lang_item(LangItem::CoerceUnsized, Some(span)),
[op.ty(body, tcx), ty],
);

let is_implicit_coercion = coercion_source == CoercionSource::Implicit;
let unsize_to = tcx.fold_regions(ty, |r, _| {
if let ty::ReVar(_) = r.kind() { tcx.lifetimes.re_erased } else { r }
});
self.prove_trait_ref(
trait_ref,
location.to_locations(),
ConstraintCategory::Cast {
is_coercion: true,
unsize_to: Some(tcx.fold_regions(ty, |r, _| {
if let ty::ReVar(_) = r.kind() {
tcx.lifetimes.re_erased
} else {
r
}
})),
is_implicit_coercion,
unsize_to: Some(unsize_to),
},
);
}

CastKind::PointerCoercion(PointerCoercion::DynStar) => {
CastKind::PointerCoercion(PointerCoercion::DynStar, coercion_source) => {
// get the constraints from the target type (`dyn* Clone`)
//
// apply them to prove that the source type `Foo` implements `Clone` etc
Expand All @@ -2153,12 +2160,13 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {

let self_ty = op.ty(body, tcx);

let is_implicit_coercion = coercion_source == CoercionSource::Implicit;
self.prove_predicates(
existential_predicates
.iter()
.map(|predicate| predicate.with_self_ty(tcx, self_ty)),
location.to_locations(),
ConstraintCategory::Cast { is_coercion: true, unsize_to: None },
ConstraintCategory::Cast { is_implicit_coercion, unsize_to: None },
);

let outlives_predicate = tcx.mk_predicate(Binder::dummy(
Expand All @@ -2169,11 +2177,14 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
self.prove_predicate(
outlives_predicate,
location.to_locations(),
ConstraintCategory::Cast { is_coercion: true, unsize_to: None },
ConstraintCategory::Cast { is_implicit_coercion, unsize_to: None },
);
}

CastKind::PointerCoercion(PointerCoercion::MutToConstPointer) => {
CastKind::PointerCoercion(
PointerCoercion::MutToConstPointer,
coercion_source,
) => {
let ty::RawPtr(ty_from, hir::Mutability::Mut) = op.ty(body, tcx).kind()
else {
span_mirbug!(self, rvalue, "unexpected base type for cast {:?}", ty,);
Expand All @@ -2183,11 +2194,12 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
span_mirbug!(self, rvalue, "unexpected target type for cast {:?}", ty,);
return;
};
let is_implicit_coercion = coercion_source == CoercionSource::Implicit;
if let Err(terr) = self.sub_types(
*ty_from,
*ty_to,
location.to_locations(),
ConstraintCategory::Cast { is_coercion: true, unsize_to: None },
ConstraintCategory::Cast { is_implicit_coercion, unsize_to: None },
) {
span_mirbug!(
self,
Expand All @@ -2200,7 +2212,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
}
}

CastKind::PointerCoercion(PointerCoercion::ArrayToPointer) => {
CastKind::PointerCoercion(PointerCoercion::ArrayToPointer, coercion_source) => {
let ty_from = op.ty(body, tcx);

let opt_ty_elem_mut = match ty_from.kind() {
Expand Down Expand Up @@ -2245,11 +2257,12 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
return;
}

let is_implicit_coercion = coercion_source == CoercionSource::Implicit;
if let Err(terr) = self.sub_types(
*ty_elem,
*ty_to,
location.to_locations(),
ConstraintCategory::Cast { is_coercion: true, unsize_to: None },
ConstraintCategory::Cast { is_implicit_coercion, unsize_to: None },
) {
span_mirbug!(
self,
Expand Down Expand Up @@ -2431,7 +2444,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
dst_obj,
location.to_locations(),
ConstraintCategory::Cast {
is_coercion: false,
is_implicit_coercion: false,
unsize_to: None,
},
)
Expand Down
11 changes: 6 additions & 5 deletions compiler/rustc_codegen_cranelift/src/base.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -652,7 +652,7 @@ fn codegen_stmt<'tcx>(
lval.write_cvalue(fx, res);
}
Rvalue::Cast(
CastKind::PointerCoercion(PointerCoercion::ReifyFnPointer),
CastKind::PointerCoercion(PointerCoercion::ReifyFnPointer, _),
ref operand,
to_ty,
) => {
Expand All @@ -677,7 +677,7 @@ fn codegen_stmt<'tcx>(
}
}
Rvalue::Cast(
CastKind::PointerCoercion(PointerCoercion::UnsafeFnPointer),
CastKind::PointerCoercion(PointerCoercion::UnsafeFnPointer, _),
ref operand,
to_ty,
) => {
Expand All @@ -688,6 +688,7 @@ fn codegen_stmt<'tcx>(
Rvalue::Cast(
CastKind::PointerCoercion(
PointerCoercion::MutToConstPointer | PointerCoercion::ArrayToPointer,
_,
),
..,
) => {
Expand Down Expand Up @@ -741,7 +742,7 @@ fn codegen_stmt<'tcx>(
}
}
Rvalue::Cast(
CastKind::PointerCoercion(PointerCoercion::ClosureFnPointer(_)),
CastKind::PointerCoercion(PointerCoercion::ClosureFnPointer(_), _),
ref operand,
_to_ty,
) => {
Expand All @@ -763,15 +764,15 @@ fn codegen_stmt<'tcx>(
}
}
Rvalue::Cast(
CastKind::PointerCoercion(PointerCoercion::Unsize),
CastKind::PointerCoercion(PointerCoercion::Unsize, _),
ref operand,
_to_ty,
) => {
let operand = codegen_operand(fx, operand);
crate::unsize::coerce_unsized_into(fx, operand, lval);
}
Rvalue::Cast(
CastKind::PointerCoercion(PointerCoercion::DynStar),
CastKind::PointerCoercion(PointerCoercion::DynStar, _),
ref operand,
_,
) => {
Expand Down
14 changes: 7 additions & 7 deletions compiler/rustc_codegen_ssa/src/mir/rvalue.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -34,7 +34,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
}

mir::Rvalue::Cast(
mir::CastKind::PointerCoercion(PointerCoercion::Unsize),
mir::CastKind::PointerCoercion(PointerCoercion::Unsize, _),
ref source,
_,
) => {
Expand Down Expand Up @@ -464,7 +464,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
let lladdr = bx.ptrtoint(llptr, llcast_ty);
OperandValue::Immediate(lladdr)
}
mir::CastKind::PointerCoercion(PointerCoercion::ReifyFnPointer) => {
mir::CastKind::PointerCoercion(PointerCoercion::ReifyFnPointer, _) => {
match *operand.layout.ty.kind() {
ty::FnDef(def_id, args) => {
let instance = ty::Instance::resolve_for_fn_ptr(
Expand All @@ -480,7 +480,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
_ => bug!("{} cannot be reified to a fn ptr", operand.layout.ty),
}
}
mir::CastKind::PointerCoercion(PointerCoercion::ClosureFnPointer(_)) => {
mir::CastKind::PointerCoercion(PointerCoercion::ClosureFnPointer(_), _) => {
match *operand.layout.ty.kind() {
ty::Closure(def_id, args) => {
let instance = Instance::resolve_closure(
Expand All @@ -495,19 +495,19 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
_ => bug!("{} cannot be cast to a fn ptr", operand.layout.ty),
}
}
mir::CastKind::PointerCoercion(PointerCoercion::UnsafeFnPointer) => {
mir::CastKind::PointerCoercion(PointerCoercion::UnsafeFnPointer, _) => {
// This is a no-op at the LLVM level.
operand.val
}
mir::CastKind::PointerCoercion(PointerCoercion::Unsize) => {
mir::CastKind::PointerCoercion(PointerCoercion::Unsize, _) => {
assert!(bx.cx().is_backend_scalar_pair(cast));
let (lldata, llextra) = operand.val.pointer_parts();
let (lldata, llextra) =
base::unsize_ptr(bx, lldata, operand.layout.ty, cast.ty, llextra);
OperandValue::Pair(lldata, llextra)
}
mir::CastKind::PointerCoercion(
PointerCoercion::MutToConstPointer | PointerCoercion::ArrayToPointer,
PointerCoercion::MutToConstPointer | PointerCoercion::ArrayToPointer, _
) => {
bug!("{kind:?} is for borrowck, and should never appear in codegen");
}
Expand All @@ -525,7 +525,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
bug!("unexpected non-pair operand");
}
}
mir::CastKind::PointerCoercion(PointerCoercion::DynStar) => {
mir::CastKind::PointerCoercion(PointerCoercion::DynStar, _) => {
let (lldata, llextra) = operand.val.pointer_parts();
let (lldata, llextra) =
base::cast_to_dyn_star(bx, lldata, operand.layout, cast.ty, llextra);
Expand Down
3 changes: 2 additions & 1 deletion compiler/rustc_const_eval/src/check_consts/check.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -440,6 +440,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
| PointerCoercion::UnsafeFnPointer
| PointerCoercion::ClosureFnPointer(_)
| PointerCoercion::ReifyFnPointer,
_,
),
_,
_,
Expand All @@ -448,7 +449,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
}

Rvalue::Cast(
CastKind::PointerCoercion(PointerCoercion::Unsize | PointerCoercion::DynStar),
CastKind::PointerCoercion(PointerCoercion::Unsize | PointerCoercion::DynStar, _),
_,
_,
) => {
Expand Down
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