static mut: allow reference to arbitrary types, not just slices and a… · rust-lang/rust@9a819ab (original) (raw)
`@@ -476,35 +476,27 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
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`}
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`}
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Rvalue::Ref(_, BorrowKind::Mut { .. }, place) => {
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let ty = place.ty(self.body, self.tcx).ty;
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let is_allowed = match ty.kind() {
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// Inside a static mut, &mut [...] is allowed.
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ty::Array(..) | ty::Slice(_)
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if self.const_kind() == hir::ConstContext::Static(hir::Mutability::Mut) =>
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{
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true
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``
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}
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``
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// FIXME(ecstaticmorse): We could allow &mut [] inside a const context given
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// that this is merely a ZST and it is already eligible for promotion.
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// This may require an RFC?
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/*
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ty::Array(_, len) if len.try_eval_target_usize(cx.tcx, cx.param_env) == Some(0)
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=> true,
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*/
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_ => false,
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};
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Rvalue::Ref(_, BorrowKind::Mut { .. }, place)
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| Rvalue::AddressOf(Mutability::Mut, place) => {
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// Inside mutable statics, we allow arbitrary mutable references.
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// We've allowed static mut FOO = &mut [elements]; for a long time (the exact
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// reasons why are lost to history), and there is no reason to restrict that to
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// arrays and slices.
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let is_allowed =
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self.const_kind() == hir::ConstContext::Static(hir::Mutability::Mut);
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`if !is_allowed {
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self.check_mut_borrow(place.local, hir::BorrowKind::Ref)
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self.check_mut_borrow(
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place.local,
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if matches!(rvalue, Rvalue::Ref(..)) {
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hir::BorrowKind::Ref
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} else {
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hir::BorrowKind::Raw
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},
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);
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`}
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`}
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``
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Rvalue::AddressOf(Mutability::Mut, place) => {
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self.check_mut_borrow(place.local, hir::BorrowKind::Raw)
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}
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`Rvalue::Ref(_, BorrowKind::Shared | BorrowKind::Fake, place)
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` | Rvalue::AddressOf(Mutability::Not, place) => {
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`let borrowed_place_has_mut_interior = qualifs::in_place::<HasMutInterior, _>(
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