Struct rustc_mir::borrow_check::universal_regions::UniversalRegions

pub struct UniversalRegions<'tcx> {
    indices: UniversalRegionIndices<'tcx>,
    pub fr_static: RegionVid,
    pub fr_fn_body: RegionVid,
    first_extern_index: usize,
    first_local_index: usize,
    num_universals: usize,
    pub root_empty: RegionVid,
    pub defining_ty: DefiningTy<'tcx>,
    pub unnormalized_output_ty: Ty<'tcx>,
    pub unnormalized_input_tys: &'tcx [Ty<'tcx>],
    pub yield_ty: Option<Ty<'tcx>>,
}

Fields

indices: UniversalRegionIndices<'tcx>

fr_static: RegionVid

The vid assigned to 'static

fr_fn_body: RegionVid

A special region vid created to represent the current MIR fn body. It will outlive the entire CFG but it will not outlive any other universal regions.

first_extern_index: usize

We create region variables such that they are ordered by their RegionClassification. The first block are globals, then externals, then locals. So, things from:

• FIRST_GLOBAL_INDEX..first_extern_index are global,
• first_extern_index..first_local_index are external,
• first_local_index..num_universals are local.

first_local_index: usize

See first_extern_index.

num_universals: usize

The total number of universal region variables instantiated.

root_empty: RegionVid

A special region variable created for the 'empty(U0) region. Note that this is not a “universal” region, as it doesn’t represent a universally bound placeholder or any such thing. But we do create it here in this type because it’s a useful region to have around in a few limited cases.

defining_ty: DefiningTy<'tcx>

The “defining” type for this function, with all universal regions instantiated. For a closure or generator, this is the closure type, but for a top-level function it’s the FnDef.

unnormalized_output_ty: Ty<'tcx>

The return type of this function, with all regions replaced by their universal RegionVid equivalents.

N.B., associated types in this type have not been normalized, as the name suggests. =)

unnormalized_input_tys: &'tcx [Ty<'tcx>]

The fully liberated input types of this function, with all regions replaced by their universal RegionVid equivalents.

N.B., associated types in these types have not been normalized, as the name suggests. =)

yield_ty: Option<Ty<'tcx>>

Implementations

impl<'tcx> UniversalRegions<'tcx>

pub fn new(
    infcx: &InferCtxt<'_, 'tcx>,
    mir_def: WithOptConstParam<LocalDefId>,
    param_env: ParamEnv<'tcx>
) -> Self

Creates a new and fully initialized UniversalRegions that contains indices for all the free regions found in the given MIR – that is, all the regions that appear in the function’s signature. This will also compute the relationships that are known between those regions.

pub fn closure_mapping(
    tcx: TyCtxt<'tcx>,
    closure_substs: SubstsRef<'tcx>,
    expected_num_vars: usize,
    closure_base_def_id: DefId
) -> IndexVec<RegionVid, Region<'tcx>>

Given a reference to a closure type, extracts all the values from its free regions and returns a vector with them. This is used when the closure’s creator checks that the ClosureRegionRequirements are met. The requirements from ClosureRegionRequirements are expressed in terms of RegionVid entries that map into the returned vector V: so if the ClosureRegionRequirements contains something like '1: '2, then the caller would impose the constraint that V[1]: V[2].

pub fn is_universal_region(&self, r: RegionVid) -> bool

Returns true if r is a member of this set of universal regions.

pub fn region_classification(
    &self,
    r: RegionVid
) -> Option<RegionClassification>

Classifies r as a universal region, returning None if this is not a member of this set of universal regions.

pub fn universal_regions(&self) -> impl Iterator<Item = RegionVid>

Returns an iterator over all the RegionVids corresponding to universally quantified free regions.

pub fn is_local_free_region(&self, r: RegionVid) -> bool

Returns true if r is classified as an local region.

pub fn len(&self) -> usize

Returns the number of universal regions created in any category.

pub fn num_global_and_external_regions(&self) -> usize

Returns the number of global plus external universal regions. For closures, these are the regions that appear free in the closure type (versus those bound in the closure signature). They are therefore the regions between which the closure may impose constraints that its creator must verify.

pub fn named_universal_regions<'s>(
    &'s self
) -> impl Iterator<Item = (Region<'tcx>, RegionVid)> + 's

Gets an iterator over all the early-bound regions that have names.

pub fn to_region_vid(&self, r: Region<'tcx>) -> RegionVid

See UniversalRegionIndices::to_region_vid.

pub(crate) fn annotate(
    &self,
    tcx: TyCtxt<'tcx>,
    err: &mut DiagnosticBuilder<'_>
)

As part of the NLL unit tests, you can annotate a function with #[rustc_regions], and we will emit information about the region inference context and – in particular – the external constraints that this region imposes on others. The methods in this file handle the part about dumping the inference context internal state.

Trait Implementations

impl<'tcx> Debug for UniversalRegions<'tcx>

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

Formats the value using the given formatter.