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An optimization for pest-2.1.3 #98654

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merged 2 commits into from
Jul 8, 2022
Merged

An optimization for pest-2.1.3 #98654

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9e76fcc
Change `Search::infcx` to `tcx`.
nnethercote Jun 29, 2022
687e391
Avoid constructing an unnecessary `InferCtxt`.
nnethercote Jun 29, 2022
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27 changes: 10 additions & 17 deletions compiler/rustc_trait_selection/src/traits/structural_match.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -58,10 +58,7 @@ pub fn search_for_structural_match_violation<'tcx>(
tcx: TyCtxt<'tcx>,
ty: Ty<'tcx>,
) -> Option<NonStructuralMatchTy<'tcx>> {
// FIXME: we should instead pass in an `infcx` from the outside.
tcx.infer_ctxt().enter(|infcx| {
ty.visit_with(&mut Search { infcx, span, seen: FxHashSet::default() }).break_value()
})
ty.visit_with(&mut Search { tcx, span, seen: FxHashSet::default() }).break_value()
}

/// This method returns true if and only if `adt_ty` itself has been marked as
Expand Down Expand Up @@ -114,27 +111,23 @@ fn type_marked_structural<'tcx>(
/// This implements the traversal over the structure of a given type to try to
/// find instances of ADTs (specifically structs or enums) that do not implement
/// the structural-match traits (`StructuralPartialEq` and `StructuralEq`).
struct Search<'a, 'tcx> {
struct Search<'tcx> {
span: Span,

infcx: InferCtxt<'a, 'tcx>,
tcx: TyCtxt<'tcx>,

/// Tracks ADTs previously encountered during search, so that
/// we will not recur on them again.
seen: FxHashSet<hir::def_id::DefId>,
}

impl<'a, 'tcx> Search<'a, 'tcx> {
fn tcx(&self) -> TyCtxt<'tcx> {
self.infcx.tcx
}

impl<'tcx> Search<'tcx> {
fn type_marked_structural(&self, adt_ty: Ty<'tcx>) -> bool {
adt_ty.is_structural_eq_shallow(self.tcx())
adt_ty.is_structural_eq_shallow(self.tcx)
}
}

impl<'a, 'tcx> TypeVisitor<'tcx> for Search<'a, 'tcx> {
impl<'tcx> TypeVisitor<'tcx> for Search<'tcx> {
type BreakTy = NonStructuralMatchTy<'tcx>;

fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
Expand Down Expand Up @@ -193,7 +186,7 @@ impl<'a, 'tcx> TypeVisitor<'tcx> for Search<'a, 'tcx> {
return ControlFlow::CONTINUE;
}
ty::Array(_, n)
if { n.try_eval_usize(self.tcx(), ty::ParamEnv::reveal_all()) == Some(0) } =>
if { n.try_eval_usize(self.tcx, ty::ParamEnv::reveal_all()) == Some(0) } =>
{
// rust-lang/rust#62336: ignore type of contents
// for empty array.
Expand All @@ -214,7 +207,7 @@ impl<'a, 'tcx> TypeVisitor<'tcx> for Search<'a, 'tcx> {
bug!("unexpected type during structural-match checking: {:?}", ty);
}
ty::Error(_) => {
self.tcx().sess.delay_span_bug(self.span, "ty::Error in structural-match check");
self.tcx.sess.delay_span_bug(self.span, "ty::Error in structural-match check");
// We still want to check other types after encountering an error,
// as this may still emit relevant errors.
return ControlFlow::CONTINUE;
Expand Down Expand Up @@ -244,9 +237,9 @@ impl<'a, 'tcx> TypeVisitor<'tcx> for Search<'a, 'tcx> {

// even though we skip super_visit_with, we must recur on
// fields of ADT.
let tcx = self.tcx();
let tcx = self.tcx;
adt_def.all_fields().map(|field| field.ty(tcx, substs)).try_for_each(|field_ty| {
let ty = self.tcx().normalize_erasing_regions(ty::ParamEnv::empty(), field_ty);
let ty = self.tcx.normalize_erasing_regions(ty::ParamEnv::empty(), field_ty);
debug!("structural-match ADT: field_ty={:?}, ty={:?}", field_ty, ty);
ty.visit_with(self)
})
Expand Down