pub struct RegionConstraintData<'tcx> {
    pub constraints: BTreeMap<Constraint<'tcx>, SubregionOrigin<'tcx>>,
    pub member_constraints: Vec<MemberConstraint<'tcx>>,
    pub verifys: Vec<Verify<'tcx>>,
    pub givens: FxIndexSet<(Region<'tcx>, RegionVid)>,
}
Expand description

The full set of region constraints gathered up by the collector. Describes constraints between the region variables and other regions, as well as other conditions that must be verified, or assumptions that can be made.

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§constraints: BTreeMap<Constraint<'tcx>, SubregionOrigin<'tcx>>

Constraints of the form A <= B, where either A or B can be a region variable (or neither, as it happens).

§member_constraints: Vec<MemberConstraint<'tcx>>

Constraints of the form R0 member of [R1, ..., Rn], meaning that R0 must be equal to one of the regions R1..Rn. These occur with impl Trait quite frequently.

§verifys: Vec<Verify<'tcx>>

A “verify” is something that we need to verify after inference is done, but which does not directly affect inference in any way.

An example is a A <= B where neither A nor B are inference variables.

§givens: FxIndexSet<(Region<'tcx>, RegionVid)>

A “given” is a relationship that is known to hold. In particular, we often know from closure fn signatures that a particular free region must be a subregion of a region variable:

foo.iter().filter(<’a> |x: &’a &’b T| …)

In situations like this, 'b is in fact a region variable introduced by the call to iter(), and 'a is a bound region on the closure (as indicated by the <'a> prefix). If we are naive, we wind up inferring that 'b must be 'static, because we require that it be greater than 'a and we do not know what 'a is precisely.

This hashmap is used to avoid that naive scenario. Basically we record the fact that 'a <= 'b is implied by the fn signature, and then ignore the constraint when solving equations. This is a bit of a hack but seems to work.

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impl<'tcx> RegionConstraintData<'tcx>

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pub fn is_empty(&self) -> bool

Returns true if this region constraint data contains no constraints, and false otherwise.

Trait Implementations§

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impl<'tcx> Clone for RegionConstraintData<'tcx>

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fn clone(&self) -> RegionConstraintData<'tcx>

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl<'tcx> Debug for RegionConstraintData<'tcx>

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

Formats the value using the given formatter. Read more
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impl<'tcx> Default for RegionConstraintData<'tcx>

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fn default() -> RegionConstraintData<'tcx>

Returns the “default value” for a type. Read more

Auto Trait Implementations§

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impl<'tcx> !RefUnwindSafe for RegionConstraintData<'tcx>

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impl<'tcx> !Send for RegionConstraintData<'tcx>

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impl<'tcx> !Sync for RegionConstraintData<'tcx>

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impl<'tcx> Unpin for RegionConstraintData<'tcx>

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impl<'tcx> !UnwindSafe for RegionConstraintData<'tcx>

Blanket Implementations§

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

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for Twhere
T: ?Sized,

const: unstable · source§

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere
T: ?Sized,

const: unstable · source§

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

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

const: unstable · source§

fn from(t: T) -> T

Returns the argument unchanged.

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

const: unstable · source§

fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> ToOwned for Twhere
T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for Twhere
U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
const: unstable · source§

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

Performs the conversion.
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impl<T, U> TryInto<U> for Twhere
U: TryFrom<T>,

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

The type returned in the event of a conversion error.
const: unstable · source§

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

Performs the conversion.

Layout§

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference’s “Type Layout” chapter for details on type layout guarantees.

Size: 128 bytes