-use crate::infer::{InferCtxt, TyCtxtInferExt};
-use crate::traits::ObligationCause;
-use crate::traits::{TraitEngine, TraitEngineExt};
-
use rustc_data_structures::fx::FxHashSet;
use rustc_hir as hir;
-use rustc_hir::lang_items::LangItem;
-use rustc_middle::ty::query::Providers;
use rustc_middle::ty::{self, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitor};
use rustc_span::Span;
use std::ops::ControlFlow;
.break_value()
}
-/// This method returns true if and only if `adt_ty` itself has been marked as
-/// eligible for structural-match: namely, if it implements both
-/// `StructuralPartialEq` and `StructuralEq` (which are respectively injected by
-/// `#[derive(PartialEq)]` and `#[derive(Eq)]`).
-///
-/// Note that this does *not* recursively check if the substructure of `adt_ty`
-/// implements the traits.
-fn type_marked_structural<'tcx>(
- infcx: &InferCtxt<'_, 'tcx>,
- adt_ty: Ty<'tcx>,
- cause: ObligationCause<'tcx>,
-) -> bool {
- let mut fulfillment_cx = <dyn TraitEngine<'tcx>>::new(infcx.tcx);
- // require `#[derive(PartialEq)]`
- let structural_peq_def_id =
- infcx.tcx.require_lang_item(LangItem::StructuralPeq, Some(cause.span));
- fulfillment_cx.register_bound(
- infcx,
- ty::ParamEnv::empty(),
- adt_ty,
- structural_peq_def_id,
- cause.clone(),
- );
- // for now, require `#[derive(Eq)]`. (Doing so is a hack to work around
- // the type `for<'a> fn(&'a ())` failing to implement `Eq` itself.)
- let structural_teq_def_id =
- infcx.tcx.require_lang_item(LangItem::StructuralTeq, Some(cause.span));
- fulfillment_cx.register_bound(
- infcx,
- ty::ParamEnv::empty(),
- adt_ty,
- structural_teq_def_id,
- cause,
- );
-
- // We deliberately skip *reporting* fulfillment errors (via
- // `report_fulfillment_errors`), for two reasons:
- //
- // 1. The error messages would mention `std::marker::StructuralPartialEq`
- // (a trait which is solely meant as an implementation detail
- // for now), and
- //
- // 2. We are sometimes doing future-incompatibility lints for
- // now, so we do not want unconditional errors here.
- fulfillment_cx.select_all_or_error(infcx).is_empty()
-}
-
/// 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`).
ty::Foreign(_) => {
return ControlFlow::Break(ty);
}
- ty::Opaque(..) => {
- return ControlFlow::Break(ty);
- }
- ty::Projection(..) => {
+ ty::Alias(..) => {
return ControlFlow::Break(ty);
}
ty::Closure(..) => {
})
}
}
-
-pub fn provide(providers: &mut Providers) {
- providers.has_structural_eq_impls = |tcx, ty| {
- tcx.infer_ctxt().enter(|infcx| {
- let cause = ObligationCause::dummy();
- type_marked_structural(&infcx, ty, cause)
- })
- };
-}