move `ClosureRegionRequirements` to `rustc_borrowck`

1 files changed, 2 insertions, 140 deletions

diff --git a/compiler/rustc_middle/src/mir/query.rs b/compiler/rustc_middle/src/mir/query.rs
index 5b44fedeaed..3fc05f2caf2 100644
--- a/compiler/rustc_middle/src/mir/query.rs
+++ b/compiler/rustc_middle/src/mir/query.rs
@@ -6,13 +6,13 @@ use rustc_abi::{FieldIdx, VariantIdx};
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir::def_id::LocalDefId;
+use rustc_index::IndexVec;
 use rustc_index::bit_set::BitMatrix;
-use rustc_index::{Idx, IndexVec};
 use rustc_macros::{HashStable, TyDecodable, TyEncodable, TypeFoldable, TypeVisitable};
 use rustc_span::{Span, Symbol};
 
 use super::{ConstValue, SourceInfo};
-use crate::ty::{self, CoroutineArgsExt, OpaqueHiddenType, Ty, TyCtxt, fold_regions};
+use crate::ty::{self, CoroutineArgsExt, OpaqueHiddenType, Ty};
 
 rustc_index::newtype_index! {
     #[derive(HashStable)]
@@ -102,84 +102,6 @@ pub struct ConstQualifs {
     pub needs_non_const_drop: bool,
     pub tainted_by_errors: Option<ErrorGuaranteed>,
 }
-
-/// After we borrow check a closure, we are left with various
-/// requirements that we have inferred between the free regions that
-/// appear in the closure's signature or on its field types. These
-/// requirements are then verified and proved by the closure's
-/// creating function. This struct encodes those requirements.
-///
-/// The requirements are listed as being between various `RegionVid`. The 0th
-/// region refers to `'static`; subsequent region vids refer to the free
-/// regions that appear in the closure (or coroutine's) type, in order of
-/// appearance. (This numbering is actually defined by the `UniversalRegions`
-/// struct in the NLL region checker. See for example
-/// `UniversalRegions::closure_mapping`.) Note the free regions in the
-/// closure's signature and captures are erased.
-///
-/// Example: If type check produces a closure with the closure args:
-///
-/// ```text
-/// ClosureArgs = [
-///     'a,                                         // From the parent.
-///     'b,
-///     i8,                                         // the "closure kind"
-///     for<'x> fn(&'<erased> &'x u32) -> &'x u32,  // the "closure signature"
-///     &'<erased> String,                          // some upvar
-/// ]
-/// ```
-///
-/// We would "renumber" each free region to a unique vid, as follows:
-///
-/// ```text
-/// ClosureArgs = [
-///     '1,                                         // From the parent.
-///     '2,
-///     i8,                                         // the "closure kind"
-///     for<'x> fn(&'3 &'x u32) -> &'x u32,         // the "closure signature"
-///     &'4 String,                                 // some upvar
-/// ]
-/// ```
-///
-/// Now the code might impose a requirement like `'1: '2`. When an
-/// instance of the closure is created, the corresponding free regions
-/// can be extracted from its type and constrained to have the given
-/// outlives relationship.
-#[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)]
-pub struct ClosureRegionRequirements<'tcx> {
-    /// The number of external regions defined on the closure. In our
-    /// example above, it would be 3 -- one for `'static`, then `'1`
-    /// and `'2`. This is just used for a sanity check later on, to
-    /// make sure that the number of regions we see at the callsite
-    /// matches.
-    pub num_external_vids: usize,
-
-    /// Requirements between the various free regions defined in
-    /// indices.
-    pub outlives_requirements: Vec<ClosureOutlivesRequirement<'tcx>>,
-}
-
-/// Indicates an outlives-constraint between a type or between two
-/// free regions declared on the closure.
-#[derive(Copy, Clone, Debug, TyEncodable, TyDecodable, HashStable)]
-pub struct ClosureOutlivesRequirement<'tcx> {
-    // This region or type ...
-    pub subject: ClosureOutlivesSubject<'tcx>,
-
-    // ... must outlive this one.
-    pub outlived_free_region: ty::RegionVid,
-
-    // If not, report an error here ...
-    pub blame_span: Span,
-
-    // ... due to this reason.
-    pub category: ConstraintCategory<'tcx>,
-}
-
-// Make sure this enum doesn't unintentionally grow
-#[cfg(target_pointer_width = "64")]
-rustc_data_structures::static_assert_size!(ConstraintCategory<'_>, 16);
-
 /// Outlives-constraints can be categorized to determine whether and why they
 /// are interesting (for error reporting). Order of variants indicates sort
 /// order of the category, thereby influencing diagnostic output.
@@ -247,66 +169,6 @@ pub enum AnnotationSource {
     GenericArg,
 }
 
-/// The subject of a `ClosureOutlivesRequirement` -- that is, the thing
-/// that must outlive some region.
-#[derive(Copy, Clone, Debug, TyEncodable, TyDecodable, HashStable)]
-pub enum ClosureOutlivesSubject<'tcx> {
-    /// Subject is a type, typically a type parameter, but could also
-    /// be a projection. Indicates a requirement like `T: 'a` being
-    /// passed to the caller, where the type here is `T`.
-    Ty(ClosureOutlivesSubjectTy<'tcx>),
-
-    /// Subject is a free region from the closure. Indicates a requirement
-    /// like `'a: 'b` being passed to the caller; the region here is `'a`.
-    Region(ty::RegionVid),
-}
-
-/// Represents a `ty::Ty` for use in [`ClosureOutlivesSubject`].
-///
-/// This abstraction is necessary because the type may include `ReVar` regions,
-/// which is what we use internally within NLL code, and they can't be used in
-/// a query response.
-///
-/// DO NOT implement `TypeVisitable` or `TypeFoldable` traits, because this
-/// type is not recognized as a binder for late-bound region.
-#[derive(Copy, Clone, Debug, TyEncodable, TyDecodable, HashStable)]
-pub struct ClosureOutlivesSubjectTy<'tcx> {
-    inner: Ty<'tcx>,
-}
-
-impl<'tcx> ClosureOutlivesSubjectTy<'tcx> {
-    /// All regions of `ty` must be of kind `ReVar` and must represent
-    /// universal regions *external* to the closure.
-    pub fn bind(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Self {
-        let inner = fold_regions(tcx, ty, |r, depth| match r.kind() {
-            ty::ReVar(vid) => {
-                let br = ty::BoundRegion {
-                    var: ty::BoundVar::new(vid.index()),
-                    kind: ty::BoundRegionKind::Anon,
-                };
-                ty::Region::new_bound(tcx, depth, br)
-            }
-            _ => bug!("unexpected region in ClosureOutlivesSubjectTy: {r:?}"),
-        });
-
-        Self { inner }
-    }
-
-    pub fn instantiate(
-        self,
-        tcx: TyCtxt<'tcx>,
-        mut map: impl FnMut(ty::RegionVid) -> ty::Region<'tcx>,
-    ) -> Ty<'tcx> {
-        fold_regions(tcx, self.inner, |r, depth| match r.kind() {
-            ty::ReBound(debruijn, br) => {
-                debug_assert_eq!(debruijn, depth);
-                map(ty::RegionVid::new(br.var.index()))
-            }
-            _ => bug!("unexpected region {r:?}"),
-        })
-    }
-}
-
 /// The constituent parts of a mir constant of kind ADT or array.
 #[derive(Copy, Clone, Debug, HashStable)]
 pub struct DestructuredConstant<'tcx> {