Add doc comments to librustc/infer/region_inference/mod.rs
This commit is contained in:
bjorn3
GitHub
parent
6f8426ade5
commit
a555d49757
1 changed files with 66 additions and 65 deletions
|
|
@ -35,31 +35,31 @@ use std::u32;
|
|||
|
||||
mod graphviz;
|
||||
|
||||
// A constraint that influences the inference process.
|
||||
/// A constraint that influences the inference process.
|
||||
#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
|
||||
pub enum Constraint<'tcx> {
|
||||
// One region variable is subregion of another
|
||||
/// One region variable is subregion of another
|
||||
ConstrainVarSubVar(RegionVid, RegionVid),
|
||||
|
||||
// Concrete region is subregion of region variable
|
||||
/// Concrete region is subregion of region variable
|
||||
ConstrainRegSubVar(Region<'tcx>, RegionVid),
|
||||
|
||||
// Region variable is subregion of concrete region. This does not
|
||||
// directly affect inference, but instead is checked after
|
||||
// inference is complete.
|
||||
/// Region variable is subregion of concrete region. This does not
|
||||
/// directly affect inference, but instead is checked after
|
||||
/// inference is complete.
|
||||
ConstrainVarSubReg(RegionVid, Region<'tcx>),
|
||||
|
||||
// A constraint where neither side is a variable. This does not
|
||||
// directly affect inference, but instead is checked after
|
||||
// inference is complete.
|
||||
/// A constraint where neither side is a variable. This does not
|
||||
/// directly affect inference, but instead is checked after
|
||||
/// inference is complete.
|
||||
ConstrainRegSubReg(Region<'tcx>, Region<'tcx>),
|
||||
}
|
||||
|
||||
// VerifyGenericBound(T, _, R, RS): The parameter type `T` (or
|
||||
// associated type) must outlive the region `R`. `T` is known to
|
||||
// outlive `RS`. Therefore verify that `R <= RS[i]` for some
|
||||
// `i`. Inference variables may be involved (but this verification
|
||||
// step doesn't influence inference).
|
||||
/// VerifyGenericBound(T, _, R, RS): The parameter type `T` (or
|
||||
/// associated type) must outlive the region `R`. `T` is known to
|
||||
/// outlive `RS`. Therefore verify that `R <= RS[i]` for some
|
||||
/// `i`. Inference variables may be involved (but this verification
|
||||
/// step doesn't influence inference).
|
||||
#[derive(Debug)]
|
||||
pub struct Verify<'tcx> {
|
||||
kind: GenericKind<'tcx>,
|
||||
|
|
@ -74,29 +74,29 @@ pub enum GenericKind<'tcx> {
|
|||
Projection(ty::ProjectionTy<'tcx>),
|
||||
}
|
||||
|
||||
// When we introduce a verification step, we wish to test that a
|
||||
// particular region (let's call it `'min`) meets some bound.
|
||||
// The bound is described the by the following grammar:
|
||||
/// When we introduce a verification step, we wish to test that a
|
||||
/// particular region (let's call it `'min`) meets some bound.
|
||||
/// The bound is described the by the following grammar:
|
||||
#[derive(Debug)]
|
||||
pub enum VerifyBound<'tcx> {
|
||||
// B = exists {R} --> some 'r in {R} must outlive 'min
|
||||
//
|
||||
// Put another way, the subject value is known to outlive all
|
||||
// regions in {R}, so if any of those outlives 'min, then the
|
||||
// bound is met.
|
||||
/// B = exists {R} --> some 'r in {R} must outlive 'min
|
||||
///
|
||||
/// Put another way, the subject value is known to outlive all
|
||||
/// regions in {R}, so if any of those outlives 'min, then the
|
||||
/// bound is met.
|
||||
AnyRegion(Vec<Region<'tcx>>),
|
||||
|
||||
// B = forall {R} --> all 'r in {R} must outlive 'min
|
||||
//
|
||||
// Put another way, the subject value is known to outlive some
|
||||
// region in {R}, so if all of those outlives 'min, then the bound
|
||||
// is met.
|
||||
/// B = forall {R} --> all 'r in {R} must outlive 'min
|
||||
///
|
||||
/// Put another way, the subject value is known to outlive some
|
||||
/// region in {R}, so if all of those outlives 'min, then the bound
|
||||
/// is met.
|
||||
AllRegions(Vec<Region<'tcx>>),
|
||||
|
||||
// B = exists {B} --> 'min must meet some bound b in {B}
|
||||
/// B = exists {B} --> 'min must meet some bound b in {B}
|
||||
AnyBound(Vec<VerifyBound<'tcx>>),
|
||||
|
||||
// B = forall {B} --> 'min must meet all bounds b in {B}
|
||||
/// B = forall {B} --> 'min must meet all bounds b in {B}
|
||||
AllBounds(Vec<VerifyBound<'tcx>>),
|
||||
}
|
||||
|
||||
|
|
@ -183,35 +183,35 @@ pub struct RegionVarBindings<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
|
|||
tcx: TyCtxt<'a, 'gcx, 'tcx>,
|
||||
var_origins: RefCell<Vec<RegionVariableOrigin>>,
|
||||
|
||||
// Constraints of the form `A <= B` introduced by the region
|
||||
// checker. Here at least one of `A` and `B` must be a region
|
||||
// variable.
|
||||
/// Constraints of the form `A <= B` introduced by the region
|
||||
/// checker. Here at least one of `A` and `B` must be a region
|
||||
/// variable.
|
||||
constraints: RefCell<FxHashMap<Constraint<'tcx>, SubregionOrigin<'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.
|
||||
/// 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.
|
||||
verifys: RefCell<Vec<Verify<'tcx>>>,
|
||||
|
||||
// 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.
|
||||
/// 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.
|
||||
givens: RefCell<FxHashSet<(Region<'tcx>, ty::RegionVid)>>,
|
||||
|
||||
lubs: RefCell<CombineMap<'tcx>>,
|
||||
|
|
@ -219,20 +219,21 @@ pub struct RegionVarBindings<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
|
|||
skolemization_count: Cell<u32>,
|
||||
bound_count: Cell<u32>,
|
||||
|
||||
// The undo log records actions that might later be undone.
|
||||
//
|
||||
// Note: when the undo_log is empty, we are not actively
|
||||
// snapshotting. When the `start_snapshot()` method is called, we
|
||||
// push an OpenSnapshot entry onto the list to indicate that we
|
||||
// are now actively snapshotting. The reason for this is that
|
||||
// otherwise we end up adding entries for things like the lower
|
||||
// bound on a variable and so forth, which can never be rolled
|
||||
// back.
|
||||
/// The undo log records actions that might later be undone.
|
||||
///
|
||||
/// Note: when the undo_log is empty, we are not actively
|
||||
/// snapshotting. When the `start_snapshot()` method is called, we
|
||||
/// push an OpenSnapshot entry onto the list to indicate that we
|
||||
/// are now actively snapshotting. The reason for this is that
|
||||
/// otherwise we end up adding entries for things like the lower
|
||||
/// bound on a variable and so forth, which can never be rolled
|
||||
/// back.
|
||||
undo_log: RefCell<Vec<UndoLogEntry<'tcx>>>,
|
||||
|
||||
unification_table: RefCell<UnificationTable<ty::RegionVid>>,
|
||||
|
||||
// This contains the results of inference. It begins as an empty
|
||||
// option and only acquires a value after inference is complete.
|
||||
/// This contains the results of inference. It begins as an empty
|
||||
/// option and only acquires a value after inference is complete.
|
||||
values: RefCell<Option<Vec<VarValue<'tcx>>>>,
|
||||
}
|
||||
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue