126 lines
3.9 KiB
Rust
126 lines
3.9 KiB
Rust
#![deny(rustc::untranslatable_diagnostic)]
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#![deny(rustc::diagnostic_outside_of_impl)]
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use crate::BorrowckInferCtxt;
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use rustc_index::IndexSlice;
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use rustc_infer::infer::NllRegionVariableOrigin;
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use rustc_middle::mir::visit::{MutVisitor, TyContext};
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use rustc_middle::mir::Constant;
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use rustc_middle::mir::{Body, Location, Promoted};
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use rustc_middle::ty::GenericArgsRef;
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use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable};
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use rustc_span::{Span, Symbol};
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/// Replaces all free regions appearing in the MIR with fresh
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/// inference variables, returning the number of variables created.
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#[instrument(skip(infcx, body, promoted), level = "debug")]
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pub fn renumber_mir<'tcx>(
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infcx: &BorrowckInferCtxt<'_, 'tcx>,
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body: &mut Body<'tcx>,
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promoted: &mut IndexSlice<Promoted, Body<'tcx>>,
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) {
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debug!(?body.arg_count);
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let mut renumberer = RegionRenumberer { infcx };
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for body in promoted.iter_mut() {
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renumberer.visit_body(body);
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}
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renumberer.visit_body(body);
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}
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#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
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pub(crate) enum BoundRegionInfo {
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Name(Symbol),
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Span(Span),
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}
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#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
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pub(crate) enum RegionCtxt {
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Location(Location),
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TyContext(TyContext),
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Free(Symbol),
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Bound(BoundRegionInfo),
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LateBound(BoundRegionInfo),
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Existential(Option<Symbol>),
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Placeholder(BoundRegionInfo),
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Unknown,
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}
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impl RegionCtxt {
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/// Used to determine the representative of a component in the strongly connected
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/// constraint graph
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pub(crate) fn preference_value(self) -> usize {
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match self {
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RegionCtxt::Unknown => 1,
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RegionCtxt::Existential(None) => 2,
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RegionCtxt::Existential(Some(_)) | RegionCtxt::Free(_) => 2,
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RegionCtxt::Location(_) => 3,
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RegionCtxt::TyContext(_) => 4,
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_ => 5,
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}
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}
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}
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struct RegionRenumberer<'a, 'tcx> {
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infcx: &'a BorrowckInferCtxt<'a, 'tcx>,
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}
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impl<'a, 'tcx> RegionRenumberer<'a, 'tcx> {
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/// Replaces all regions appearing in `value` with fresh inference
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/// variables.
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fn renumber_regions<T, F>(&mut self, value: T, region_ctxt_fn: F) -> T
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where
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T: TypeFoldable<TyCtxt<'tcx>>,
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F: Fn() -> RegionCtxt,
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{
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let origin = NllRegionVariableOrigin::Existential { from_forall: false };
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self.infcx.tcx.fold_regions(value, |_region, _depth| {
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self.infcx.next_nll_region_var(origin, || region_ctxt_fn())
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})
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}
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}
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impl<'a, 'tcx> MutVisitor<'tcx> for RegionRenumberer<'a, 'tcx> {
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fn tcx(&self) -> TyCtxt<'tcx> {
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self.infcx.tcx
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}
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#[instrument(skip(self), level = "debug")]
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fn visit_ty(&mut self, ty: &mut Ty<'tcx>, ty_context: TyContext) {
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*ty = self.renumber_regions(*ty, || RegionCtxt::TyContext(ty_context));
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debug!(?ty);
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}
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#[instrument(skip(self), level = "debug")]
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fn visit_args(&mut self, args: &mut GenericArgsRef<'tcx>, location: Location) {
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*args = self.renumber_regions(*args, || RegionCtxt::Location(location));
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debug!(?args);
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}
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#[instrument(skip(self), level = "debug")]
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fn visit_region(&mut self, region: &mut ty::Region<'tcx>, location: Location) {
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let old_region = *region;
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*region = self.renumber_regions(old_region, || RegionCtxt::Location(location));
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debug!(?region);
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}
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#[instrument(skip(self), level = "debug")]
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fn visit_ty_const(&mut self, ct: &mut ty::Const<'tcx>, location: Location) {
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let old_ct = *ct;
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*ct = self.renumber_regions(old_ct, || RegionCtxt::Location(location));
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debug!(?ct);
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}
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#[instrument(skip(self), level = "debug")]
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fn visit_constant(&mut self, constant: &mut Constant<'tcx>, location: Location) {
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let literal = constant.literal;
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constant.literal = self.renumber_regions(literal, || RegionCtxt::Location(location));
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debug!("constant: {:#?}", constant);
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}
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}
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