use crate::rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt; use rustc_hir as hir; use rustc_infer::infer::{InferOk, TyCtxtInferExt}; use rustc_infer::traits; use rustc_middle::ty::ToPredicate; use rustc_span::DUMMY_SP; use super::*; pub(crate) struct BlanketImplFinder<'a, 'tcx> { pub(crate) cx: &'a mut core::DocContext<'tcx>, } impl<'a, 'tcx> BlanketImplFinder<'a, 'tcx> { pub(crate) fn get_blanket_impls(&mut self, item_def_id: DefId) -> Vec { let cx = &mut self.cx; let param_env = cx.tcx.param_env(item_def_id); let ty = cx.tcx.bound_type_of(item_def_id); trace!("get_blanket_impls({:?})", ty); let mut impls = Vec::new(); for trait_def_id in cx.tcx.all_traits() { if !cx.cache.effective_visibilities.is_directly_public(cx.tcx, trait_def_id) || cx.generated_synthetics.get(&(ty.0, trait_def_id)).is_some() { continue; } // NOTE: doesn't use `for_each_relevant_impl` to avoid looking at anything besides blanket impls let trait_impls = cx.tcx.trait_impls_of(trait_def_id); 'blanket_impls: for &impl_def_id in trait_impls.blanket_impls() { trace!( "get_blanket_impls: Considering impl for trait '{:?}' {:?}", trait_def_id, impl_def_id ); let trait_ref = cx.tcx.bound_impl_trait_ref(impl_def_id).unwrap(); if !matches!(trait_ref.0.self_ty().kind(), ty::Param(_)) { continue; } let infcx = cx.tcx.infer_ctxt().build(); let substs = infcx.fresh_substs_for_item(DUMMY_SP, item_def_id); let impl_ty = ty.subst(infcx.tcx, substs); let param_env = EarlyBinder(param_env).subst(infcx.tcx, substs); let impl_substs = infcx.fresh_substs_for_item(DUMMY_SP, impl_def_id); let impl_trait_ref = trait_ref.subst(infcx.tcx, impl_substs); // Require the type the impl is implemented on to match // our type, and ignore the impl if there was a mismatch. let cause = traits::ObligationCause::dummy(); let Ok(eq_result) = infcx.at(&cause, param_env).eq(impl_trait_ref.self_ty(), impl_ty) else { continue }; let InferOk { value: (), obligations } = eq_result; // FIXME(eddyb) ignoring `obligations` might cause false positives. drop(obligations); trace!( "invoking predicate_may_hold: param_env={:?}, impl_trait_ref={:?}, impl_ty={:?}", param_env, impl_trait_ref, impl_ty ); let predicates = cx .tcx .predicates_of(impl_def_id) .instantiate(cx.tcx, impl_substs) .predicates .into_iter() .chain(Some(ty::Binder::dummy(impl_trait_ref).to_predicate(infcx.tcx))); for predicate in predicates { debug!("testing predicate {:?}", predicate); let obligation = traits::Obligation::new( infcx.tcx, traits::ObligationCause::dummy(), param_env, predicate, ); match infcx.evaluate_obligation(&obligation) { Ok(eval_result) if eval_result.may_apply() => {} Err(traits::OverflowError::Canonical) => {} Err(traits::OverflowError::ErrorReporting) => {} _ => continue 'blanket_impls, } } debug!( "get_blanket_impls: found applicable impl for trait_ref={:?}, ty={:?}", trait_ref, ty ); cx.generated_synthetics.insert((ty.0, trait_def_id)); impls.push(Item { name: None, attrs: Default::default(), item_id: ItemId::Blanket { impl_id: impl_def_id, for_: item_def_id }, kind: Box::new(ImplItem(Box::new(Impl { unsafety: hir::Unsafety::Normal, generics: clean_ty_generics( cx, cx.tcx.generics_of(impl_def_id), cx.tcx.explicit_predicates_of(impl_def_id), ), // FIXME(eddyb) compute both `trait_` and `for_` from // the post-inference `trait_ref`, as it's more accurate. trait_: Some(clean_trait_ref_with_bindings( cx, trait_ref.0, ThinVec::new(), )), for_: clean_middle_ty(ty.0, cx, None), items: cx .tcx .associated_items(impl_def_id) .in_definition_order() .map(|x| clean_middle_assoc_item(x, cx)) .collect::>(), polarity: ty::ImplPolarity::Positive, kind: ImplKind::Blanket(Box::new(clean_middle_ty( trait_ref.0.self_ty(), cx, None, ))), }))), cfg: None, inline_stmt_id: None, }); } } impls } }