Projectable in rustc_const_eval::interpret::projection - Rust
Description: A thing that we can project into, and that has a layout.

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## Projectable

# Trait Projectable

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    pub trait Projectable<'tcx, Prov: Provenance>: Sized + Debug {
        // Required methods
        fn layout(&self) -> TyAndLayout<'tcx>;
        fn meta(&self) -> MemPlaceMeta<Prov>;
        fn offset_with_meta<M: Machine<'tcx, Provenance = Prov>>(
            &self,
            offset: Size,
            mode: OffsetMode,
            meta: MemPlaceMeta<Prov>,
            layout: TyAndLayout<'tcx>,
            ecx: &InterpCx<'tcx, M>,
        ) -> InterpResult<'tcx, Self>;
        fn to_op<M: Machine<'tcx, Provenance = Prov>>(
            &self,
            ecx: &InterpCx<'tcx, M>,
        ) -> InterpResult<'tcx, OpTy<'tcx, M::Provenance>>;

        // Provided methods
        fn len<M: Machine<'tcx, Provenance = Prov>>(
            &self,
            ecx: &InterpCx<'tcx, M>,
        ) -> InterpResult<'tcx, u64> { ... }
        fn offset<M: Machine<'tcx, Provenance = Prov>>(
            &self,
            offset: Size,
            layout: TyAndLayout<'tcx>,
            ecx: &InterpCx<'tcx, M>,
        ) -> InterpResult<'tcx, Self> { ... }
        fn transmute<M: Machine<'tcx, Provenance = Prov>>(
            &self,
            layout: TyAndLayout<'tcx>,
            ecx: &InterpCx<'tcx, M>,
        ) -> InterpResult<'tcx, Self> { ... }
    }

Expand description

A thing that we can project into, and that has a layout.

## Required Methods§

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#### fn layout(&self) -> TyAndLayout<'tcx>

Get the layout.

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#### fn meta(&self) -> MemPlaceMeta<Prov>

Get the metadata of a wide value.

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#### fn offset_with_meta<M: Machine<'tcx, Provenance = Prov>>( &self, offset: Size, mode: OffsetMode, meta: MemPlaceMeta<Prov>, layout: TyAndLayout<'tcx>, ecx: &InterpCx<'tcx, M>, ) -> InterpResult<'tcx, Self>

Offset the value by the given amount, replacing the layout and metadata.

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#### fn to_op<M: Machine<'tcx, Provenance = Prov>>( &self, ecx: &InterpCx<'tcx, M>, ) -> InterpResult<'tcx, OpTy<'tcx, M::Provenance>>

Convert this to an `OpTy`. This might be an irreversible transformation, but is useful for reading from this thing. This will never actually do a read from memory!

## Provided Methods§

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#### fn len<M: Machine<'tcx, Provenance = Prov>>( &self, ecx: &InterpCx<'tcx, M>, ) -> InterpResult<'tcx, u64>

Get the length of a slice/string/array stored here.

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#### fn offset<M: Machine<'tcx, Provenance = Prov>>( &self, offset: Size, layout: TyAndLayout<'tcx>, ecx: &InterpCx<'tcx, M>, ) -> InterpResult<'tcx, Self>

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#### fn transmute<M: Machine<'tcx, Provenance = Prov>>( &self, layout: TyAndLayout<'tcx>, ecx: &InterpCx<'tcx, M>, ) -> InterpResult<'tcx, Self>

This does an offset-by-zero, which is effectively a transmute. Note however that not all transmutes are supported by all projectables – specifically, if this is an `OpTy` or `ImmTy`, the new layout must have almost the same ABI as the old one (only changing the `valid_range` is allowed and turning integers into pointers).

## Dyn Compatibility§

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

## Implementors§

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### impl<'tcx, Prov: Provenance> Projectable<'tcx, Prov> for ImmTy<'tcx, Prov>

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### impl<'tcx, Prov: Provenance> Projectable<'tcx, Prov> for MPlaceTy<'tcx, Prov>

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### impl<'tcx, Prov: Provenance> Projectable<'tcx, Prov> for OpTy<'tcx, Prov>

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### impl<'tcx, Prov: Provenance> Projectable<'tcx, Prov> for PlaceTy<'tcx, Prov>