# Struct rustc_trait_selection::traits::ObligationCause

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    pub struct ObligationCause<'tcx> {
        pub span: Span,
        pub body_id: LocalDefId,
        code: InternedObligationCauseCode<'tcx>,
    }

Expand description

The reason why we incurred this obligation; used for error reporting.

Non-misc `ObligationCauseCode`s are stored on the heap. This gives the best trade-off between keeping the type small (which makes copies cheaper) while not doing too many heap allocations.

We do not want to intern this as there are a lot of obligation causes which only live for a short period of time.

## Fields§

§`span: Span`§`body_id: LocalDefId`

The ID of the fn body that triggered this obligation. This is used for region obligations to determine the precise environment in which the region obligation should be evaluated (in particular, closures can add new assumptions). See the field `region_obligations` of the `FulfillmentContext` for more information.

§`code: InternedObligationCauseCode<'tcx>`

## Auto Trait Implementations§

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### impl<'tcx> !RefUnwindSafe for ObligationCause<'tcx>

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### impl<'tcx> Send for ObligationCause<'tcx>

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### impl<'tcx> Sync for ObligationCause<'tcx>

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### impl<'tcx> Unpin for ObligationCause<'tcx>

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### impl<'tcx> !UnwindSafe for ObligationCause<'tcx>

## Blanket Implementations§

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### impl<T> Any for T
where 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 T
where T: ?Sized,

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#### fn borrow(&self) -> &T

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

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#### 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

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#### fn from(t: T) -> T

Returns the argument unchanged.

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

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#### 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 T
where 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 T
where U: Into<T>,

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#### type Error = Infallible

The type returned in the event of a conversion error.
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#### 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 T
where U: TryFrom<T>,

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

The type returned in the event of a conversion error.
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#### 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: 24 bytes