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#![warn(clippy::declare_interior_mutable_const)]
use std::cell::Cell;
use std::sync::atomic::AtomicUsize;
enum OptionalCell {
Unfrozen(Cell<bool>),
Frozen,
}
// a constant with enums should be linted only when the used variant is unfrozen (#3962).
const UNFROZEN_VARIANT: OptionalCell = OptionalCell::Unfrozen(Cell::new(true)); //~ ERROR interior mutable
const FROZEN_VARIANT: OptionalCell = OptionalCell::Frozen;
const fn unfrozen_variant() -> OptionalCell {
OptionalCell::Unfrozen(Cell::new(false))
}
const fn frozen_variant() -> OptionalCell {
OptionalCell::Frozen
}
const UNFROZEN_VARIANT_FROM_FN: OptionalCell = unfrozen_variant(); //~ ERROR interior mutable
const FROZEN_VARIANT_FROM_FN: OptionalCell = frozen_variant();
enum NestedInnermost {
Unfrozen(AtomicUsize),
Frozen,
}
struct NestedInner {
inner: NestedInnermost,
}
enum NestedOuter {
NestedInner(NestedInner),
NotNested(usize),
}
struct NestedOutermost {
outer: NestedOuter,
}
// a constant with enums should be linted according to its value, no matter how structs involve.
const NESTED_UNFROZEN_VARIANT: NestedOutermost = NestedOutermost {
outer: NestedOuter::NestedInner(NestedInner {
inner: NestedInnermost::Unfrozen(AtomicUsize::new(2)),
}),
}; //~ ERROR interior mutable
const NESTED_FROZEN_VARIANT: NestedOutermost = NestedOutermost {
outer: NestedOuter::NestedInner(NestedInner {
inner: NestedInnermost::Frozen,
}),
};
trait AssocConsts {
// When there's no default value, lint it only according to its type.
// Further details are on the corresponding code (`NonCopyConst::check_trait_item`).
const TO_BE_UNFROZEN_VARIANT: OptionalCell; //~ ERROR interior mutable
const TO_BE_FROZEN_VARIANT: OptionalCell; //~ ERROR interior mutable
// Lint default values accordingly.
const DEFAULTED_ON_UNFROZEN_VARIANT: OptionalCell = OptionalCell::Unfrozen(Cell::new(false)); //~ ERROR interior mutable
const DEFAULTED_ON_FROZEN_VARIANT: OptionalCell = OptionalCell::Frozen;
}
// The lint doesn't trigger for an assoc constant in a trait impl with an unfrozen type even if it
// has enums. Further details are on the corresponding code in 'NonCopyConst::check_impl_item'.
impl AssocConsts for u64 {
const TO_BE_UNFROZEN_VARIANT: OptionalCell = OptionalCell::Unfrozen(Cell::new(false));
const TO_BE_FROZEN_VARIANT: OptionalCell = OptionalCell::Frozen;
// even if this sets an unfrozen variant, the lint ignores it.
const DEFAULTED_ON_FROZEN_VARIANT: OptionalCell = OptionalCell::Unfrozen(Cell::new(false));
}
// At first, I thought I'd need to check every patterns in `trait.rs`; but, what matters
// here are values; and I think substituted generics at definitions won't appear in MIR.
trait AssocTypes {
type ToBeUnfrozen;
const TO_BE_UNFROZEN_VARIANT: Option<Self::ToBeUnfrozen>;
const TO_BE_FROZEN_VARIANT: Option<Self::ToBeUnfrozen>;
}
impl AssocTypes for u64 {
type ToBeUnfrozen = AtomicUsize;
const TO_BE_UNFROZEN_VARIANT: Option<Self::ToBeUnfrozen> = Some(Self::ToBeUnfrozen::new(4)); //~ ERROR interior mutable
const TO_BE_FROZEN_VARIANT: Option<Self::ToBeUnfrozen> = None;
}
// Use raw pointers since direct generics have a false negative at the type level.
enum BothOfCellAndGeneric<T> {
Unfrozen(Cell<*const T>),
Generic(*const T),
Frozen(usize),
}
impl<T> BothOfCellAndGeneric<T> {
const UNFROZEN_VARIANT: BothOfCellAndGeneric<T> = BothOfCellAndGeneric::Unfrozen(Cell::new(std::ptr::null())); //~ ERROR interior mutable
// This is a false positive. The argument about this is on `is_value_unfrozen_raw`
const GENERIC_VARIANT: BothOfCellAndGeneric<T> = BothOfCellAndGeneric::Generic(std::ptr::null()); //~ ERROR interior mutable
const FROZEN_VARIANT: BothOfCellAndGeneric<T> = BothOfCellAndGeneric::Frozen(5);
// This is what is likely to be a false negative when one tries to fix
// the `GENERIC_VARIANT` false positive.
const NO_ENUM: Cell<*const T> = Cell::new(std::ptr::null()); //~ ERROR interior mutable
}
// associated types here is basically the same as the one above.
trait BothOfCellAndGenericWithAssocType {
type AssocType;
const UNFROZEN_VARIANT: BothOfCellAndGeneric<Self::AssocType> =
BothOfCellAndGeneric::Unfrozen(Cell::new(std::ptr::null())); //~ ERROR interior mutable
const GENERIC_VARIANT: BothOfCellAndGeneric<Self::AssocType> = BothOfCellAndGeneric::Generic(std::ptr::null()); //~ ERROR interior mutable
const FROZEN_VARIANT: BothOfCellAndGeneric<Self::AssocType> = BothOfCellAndGeneric::Frozen(5);
}
fn main() {}
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