Enum rustc_trait_selection::traits::wf::Elaborate

source · [−]

enum Elaborate {
    All,
    None,
}

Expand description

Controls whether we “elaborate” supertraits and so forth on the WF predicates. This is a kind of hack to address #43784. The underlying problem in that issue was a trait structure like:

trait Foo: Copy { }
trait Bar: Foo { }
impl<T: Bar> Foo for T { }
impl<T> Bar for T { }

Here, in the Foo impl, we will check that T: Copy holds – but we decide that this is true because T: Bar is in the where-clauses (and we can elaborate that to include T: Copy). This wouldn’t be a problem, except that when we check the Bar impl, we decide that T: Foo must hold because of the Foo impl. And so nowhere did we check that T: Copy holds!

To resolve this, we elaborate the WF requirements that must be proven when checking impls. This means that (e.g.) the impl Bar for T will be forced to prove not only that T: Foo but also T: Copy (which it won’t be able to do, because there is no Copy impl for T).

Enum rustc_trait_selection::traits::wf::Elaborate

Variants

All

None

Trait Implementations

impl Clone for Elaborate

fn clone(&self) -> Elaborate

fn clone_from(&mut self, source: &Self)

impl Debug for Elaborate

fn fmt(&self, f: &mut Formatter<'_>) -> Result

impl PartialEq<Elaborate> for Elaborate

fn eq(&self, other: &Elaborate) -> bool

fn ne(&self, other: &Rhs) -> bool

impl Copy for Elaborate

impl Eq for Elaborate

impl StructuralEq for Elaborate

impl StructuralPartialEq for Elaborate

Auto Trait Implementations

impl RefUnwindSafe for Elaborate

impl Send for Elaborate

impl Sync for Elaborate

impl Unpin for Elaborate

impl UnwindSafe for Elaborate

Blanket Implementations

impl<T> Any for T where T: 'static + ?Sized,

pub fn type_id(&self) -> TypeId

impl<'tcx, T> ArenaAllocatable<'tcx, IsCopy> for T where T: Copy,

pub fn allocate_on(self, arena: &'a Arena<'tcx>) -> &'a mut T

pub fn allocate_from_iter( arena: &'a Arena<'tcx>, iter: impl IntoIterator<Item = T>) -> &'a mut [T]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]

impl<T> Borrow<T> for T where T: ?Sized,

pub fn borrow(&self) -> &T

impl<T> BorrowMut<T> for T where T: ?Sized,

pub fn borrow_mut(&mut self) -> &mut T

impl<T> From<T> for T

pub fn from(t: T) -> T

impl<T, U> Into<U> for T where U: From<T>,

pub fn into(self) -> U

impl<T> ToOwned for T where T: Clone,

type Owned = T

pub fn to_owned(&self) -> T

pub fn clone_into(&self, target: &mut T)

impl<T, U> TryFrom<U> for T where U: Into<T>,

type Error = Infallible

pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

impl<T, U> TryInto<U> for T where U: TryFrom<T>,

type Error = <U as TryFrom<T>>::Error

pub fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Layout

`All`

`None`

impl<T> Any for T where
T: 'static + ?Sized,

impl<'tcx, T> ArenaAllocatable<'tcx, IsCopy> for T where
T: Copy,

pub fn allocate_from_iter(
arena: &'a Arena<'tcx>,
iter: impl IntoIterator<Item = T>
) -> &'a mut [T]ⓘNotable traits for &'_ [u8 ]`impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]`

impl<T> Borrow<T> for T where
T: ?Sized,

impl<T> BorrowMut<T> for T where
T: ?Sized,

impl<T, U> Into<U> for T where
U: From<T>,

impl<T> ToOwned for T where
T: Clone,

impl<T, U> TryFrom<U> for T where
U: Into<T>,

impl<T, U> TryInto<U> for T where
U: TryFrom<T>,