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Minimize parameter of coerce_borrowed_pointer() #71524

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Apr 28, 2020
Merged

Minimize parameter of coerce_borrowed_pointer() #71524

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21 changes: 9 additions & 12 deletions src/librustc_typeck/check/coercion.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -211,12 +211,9 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
ty::RawPtr(mt_b) => {
return self.coerce_unsafe_ptr(a, b, mt_b.mutbl);
}

ty::Ref(r_b, ty, mutbl) => {
let mt_b = ty::TypeAndMut { ty, mutbl };
return self.coerce_borrowed_pointer(a, b, r_b, mt_b);
ty::Ref(r_b, _, mutbl_b) => {
return self.coerce_borrowed_pointer(a, b, r_b, mutbl_b);
}

_ => {}
}

Expand Down Expand Up @@ -255,7 +252,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
a: Ty<'tcx>,
b: Ty<'tcx>,
r_b: ty::Region<'tcx>,
mt_b: TypeAndMut<'tcx>,
mutbl_b: hir::Mutability,
) -> CoerceResult<'tcx> {
debug!("coerce_borrowed_pointer(a={:?}, b={:?})", a, b);

Expand All @@ -268,7 +265,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
let (r_a, mt_a) = match a.kind {
ty::Ref(r_a, ty, mutbl) => {
let mt_a = ty::TypeAndMut { ty, mutbl };
coerce_mutbls(mt_a.mutbl, mt_b.mutbl)?;
coerce_mutbls(mt_a.mutbl, mutbl_b)?;
(r_a, mt_a)
}
_ => return self.unify_and(a, b, identity),
Expand Down Expand Up @@ -364,7 +361,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
r_a // [3] above
} else {
if r_borrow_var.is_none() {
// create var lazilly, at most once
// create var lazily, at most once
let coercion = Coercion(span);
let r = self.next_region_var(coercion);
r_borrow_var = Some(r); // [4] above
Expand All @@ -375,7 +372,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
r,
TypeAndMut {
ty: referent_ty,
mutbl: mt_b.mutbl, // [1] above
mutbl: mutbl_b, // [1] above
},
);
match self.unify(derefd_ty_a, b) {
Expand Down Expand Up @@ -417,11 +414,11 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
// `self.x` both have `&mut `type would be a move of
// `self.x`, but we auto-coerce it to `foo(&mut *self.x)`,
// which is a borrow.
assert_eq!(mt_b.mutbl, hir::Mutability::Not); // can only coerce &T -> &U
assert_eq!(mutbl_b, hir::Mutability::Not); // can only coerce &T -> &U
return success(vec![], ty, obligations);
}

let needs = Needs::maybe_mut_place(mt_b.mutbl);
let needs = Needs::maybe_mut_place(mutbl_b);
let InferOk { value: mut adjustments, obligations: o } =
autoderef.adjust_steps_as_infer_ok(self, needs);
obligations.extend(o);
Expand All @@ -433,7 +430,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
ty::Ref(r_borrow, _, _) => r_borrow,
_ => span_bug!(span, "expected a ref type, got {:?}", ty),
};
let mutbl = match mt_b.mutbl {
let mutbl = match mutbl_b {
hir::Mutability::Not => AutoBorrowMutability::Not,
hir::Mutability::Mut => {
AutoBorrowMutability::Mut { allow_two_phase_borrow: self.allow_two_phase }
Expand Down