pub mod misc;
mod object_safety;
mod on_unimplemented;
+pub mod outlives_bounds;
mod project;
pub mod query;
pub(crate) mod relationships;
mod util;
pub mod wf;
+use crate::errors::DumpVTableEntries;
use crate::infer::outlives::env::OutlivesEnvironment;
use crate::infer::{InferCtxt, TyCtxtInferExt};
use crate::traits::error_reporting::InferCtxtExt as _;
use rustc_hir as hir;
use rustc_hir::def_id::DefId;
use rustc_hir::lang_items::LangItem;
+use rustc_infer::traits::TraitEngineExt as _;
use rustc_middle::ty::fold::TypeFoldable;
use rustc_middle::ty::subst::{InternalSubsts, SubstsRef};
use rustc_middle::ty::visit::TypeVisitable;
-use rustc_middle::ty::{self, GenericParamDefKind, ToPredicate, Ty, TyCtxt, VtblEntry};
+use rustc_middle::ty::{
+ self, DefIdTree, GenericParamDefKind, Subst, ToPredicate, Ty, TyCtxt, TypeSuperVisitable,
+ VtblEntry,
+};
use rustc_span::{sym, Span};
use smallvec::SmallVec;
/// Creates predicate obligations from the generic bounds.
pub fn predicates_for_generics<'tcx>(
- cause: ObligationCause<'tcx>,
+ cause: impl Fn(usize, Span) -> ObligationCause<'tcx>,
param_env: ty::ParamEnv<'tcx>,
generic_bounds: ty::InstantiatedPredicates<'tcx>,
) -> impl Iterator<Item = PredicateObligation<'tcx>> {
- util::predicates_for_generics(cause, 0, param_env, generic_bounds)
+ let generic_bounds = generic_bounds;
+ debug!("predicates_for_generics(generic_bounds={:?})", generic_bounds);
+
+ std::iter::zip(generic_bounds.predicates, generic_bounds.spans).enumerate().map(
+ move |(idx, (predicate, span))| Obligation {
+ cause: cause(idx, span),
+ recursion_depth: 0,
+ param_env: param_env,
+ predicate,
+ },
+ )
}
/// Determines whether the type `ty` is known to meet `bound` and
// this function's result remains infallible, we must confirm
// that guess. While imperfect, I believe this is sound.
- // The handling of regions in this area of the code is terrible,
- // see issue #29149. We should be able to improve on this with
- // NLL.
- let mut fulfill_cx = <dyn TraitEngine<'tcx>>::new(infcx.tcx);
-
// We can use a dummy node-id here because we won't pay any mind
// to region obligations that arise (there shouldn't really be any
// anyhow).
let cause = ObligationCause::misc(span, hir::CRATE_HIR_ID);
- fulfill_cx.register_bound(infcx, param_env, ty, def_id, cause);
+ // The handling of regions in this area of the code is terrible,
+ // see issue #29149. We should be able to improve on this with
+ // NLL.
+ let errors = fully_solve_bound(infcx, cause, param_env, ty, def_id);
// Note: we only assume something is `Copy` if we can
// *definitively* show that it implements `Copy`. Otherwise,
// assume it is move; linear is always ok.
- match fulfill_cx.select_all_or_error(infcx).as_slice() {
+ match &errors[..] {
[] => {
debug!(
"type_known_to_meet_bound_modulo_regions: ty={:?} bound={} success",
// them here too, and we will remove this function when
// we move over to lazy normalization *anyway*.
tcx.infer_ctxt().ignoring_regions().enter(|infcx| {
- let fulfill_cx = FulfillmentContext::new();
- let predicates =
- match fully_normalize(&infcx, fulfill_cx, cause, elaborated_env, predicates) {
- Ok(predicates) => predicates,
- Err(errors) => {
- let reported = infcx.report_fulfillment_errors(&errors, None, false);
- return Err(reported);
- }
- };
+ let predicates = match fully_normalize(&infcx, cause, elaborated_env, predicates) {
+ Ok(predicates) => predicates,
+ Err(errors) => {
+ let reported = infcx.report_fulfillment_errors(&errors, None, false);
+ return Err(reported);
+ }
+ };
debug!("do_normalize_predictes: normalized predicates = {:?}", predicates);
)
}
+/// Normalize a type and process all resulting obligations, returning any errors
pub fn fully_normalize<'a, 'tcx, T>(
infcx: &InferCtxt<'a, 'tcx>,
- mut fulfill_cx: FulfillmentContext<'tcx>,
cause: ObligationCause<'tcx>,
param_env: ty::ParamEnv<'tcx>,
value: T,
"fully_normalize: normalized_value={:?} obligations={:?}",
normalized_value, obligations
);
+
+ let mut fulfill_cx = FulfillmentContext::new();
for obligation in obligations {
- fulfill_cx.register_predicate_obligation(selcx.infcx(), obligation);
+ fulfill_cx.register_predicate_obligation(infcx, obligation);
}
debug!("fully_normalize: select_all_or_error start");
Ok(resolved_value)
}
+/// Process an obligation (and any nested obligations that come from it) to
+/// completion, returning any errors
+pub fn fully_solve_obligation<'a, 'tcx>(
+ infcx: &InferCtxt<'a, 'tcx>,
+ obligation: PredicateObligation<'tcx>,
+) -> Vec<FulfillmentError<'tcx>> {
+ let mut engine = <dyn TraitEngine<'tcx>>::new(infcx.tcx);
+ engine.register_predicate_obligation(infcx, obligation);
+ engine.select_all_or_error(infcx)
+}
+
+/// Process a set of obligations (and any nested obligations that come from them)
+/// to completion
+pub fn fully_solve_obligations<'a, 'tcx>(
+ infcx: &InferCtxt<'a, 'tcx>,
+ obligations: impl IntoIterator<Item = PredicateObligation<'tcx>>,
+) -> Vec<FulfillmentError<'tcx>> {
+ let mut engine = <dyn TraitEngine<'tcx>>::new(infcx.tcx);
+ engine.register_predicate_obligations(infcx, obligations);
+ engine.select_all_or_error(infcx)
+}
+
+/// Process a bound (and any nested obligations that come from it) to completion.
+/// This is a convenience function for traits that have no generic arguments, such
+/// as auto traits, and builtin traits like Copy or Sized.
+pub fn fully_solve_bound<'a, 'tcx>(
+ infcx: &InferCtxt<'a, 'tcx>,
+ cause: ObligationCause<'tcx>,
+ param_env: ty::ParamEnv<'tcx>,
+ ty: Ty<'tcx>,
+ bound: DefId,
+) -> Vec<FulfillmentError<'tcx>> {
+ let mut engine = <dyn TraitEngine<'tcx>>::new(infcx.tcx);
+ engine.register_bound(infcx, param_env, ty, bound, cause);
+ engine.select_all_or_error(infcx)
+}
+
/// Normalizes the predicates and checks whether they hold in an empty environment. If this
/// returns true, then either normalize encountered an error or one of the predicates did not
/// hold. Used when creating vtables to check for unsatisfiable methods.
debug!("impossible_predicates(predicates={:?})", predicates);
let result = tcx.infer_ctxt().enter(|infcx| {
- // HACK: Set tainted by errors to gracefully exit in case of overflow.
- infcx.set_tainted_by_errors();
-
let param_env = ty::ParamEnv::reveal_all();
- let mut selcx = SelectionContext::new(&infcx);
- let mut fulfill_cx = FulfillmentContext::new();
- let cause = ObligationCause::dummy();
- let Normalized { value: predicates, obligations } =
- normalize(&mut selcx, param_env, cause.clone(), predicates);
- for obligation in obligations {
- fulfill_cx.register_predicate_obligation(&infcx, obligation);
- }
+ let ocx = ObligationCtxt::new(&infcx);
+ let predicates = ocx.normalize(ObligationCause::dummy(), param_env, predicates);
for predicate in predicates {
- let obligation = Obligation::new(cause.clone(), param_env, predicate);
- fulfill_cx.register_predicate_obligation(&infcx, obligation);
+ let obligation = Obligation::new(ObligationCause::dummy(), param_env, predicate);
+ ocx.register_obligation(obligation);
}
-
- let errors = fulfill_cx.select_all_or_error(&infcx);
+ let errors = ocx.select_all_or_error();
// Clean up after ourselves
let _ = infcx.inner.borrow_mut().opaque_type_storage.take_opaque_types();
result
}
+/// Checks whether a trait's method is impossible to call on a given impl.
+///
+/// This only considers predicates that reference the impl's generics, and not
+/// those that reference the method's generics.
+fn is_impossible_method<'tcx>(
+ tcx: TyCtxt<'tcx>,
+ (impl_def_id, trait_item_def_id): (DefId, DefId),
+) -> bool {
+ struct ReferencesOnlyParentGenerics<'tcx> {
+ tcx: TyCtxt<'tcx>,
+ generics: &'tcx ty::Generics,
+ trait_item_def_id: DefId,
+ }
+ impl<'tcx> ty::TypeVisitor<'tcx> for ReferencesOnlyParentGenerics<'tcx> {
+ type BreakTy = ();
+ fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
+ // If this is a parameter from the trait item's own generics, then bail
+ if let ty::Param(param) = t.kind()
+ && let param_def_id = self.generics.type_param(param, self.tcx).def_id
+ && self.tcx.parent(param_def_id) == self.trait_item_def_id
+ {
+ return ControlFlow::BREAK;
+ }
+ t.super_visit_with(self)
+ }
+ fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
+ if let ty::ReEarlyBound(param) = r.kind()
+ && let param_def_id = self.generics.region_param(¶m, self.tcx).def_id
+ && self.tcx.parent(param_def_id) == self.trait_item_def_id
+ {
+ return ControlFlow::BREAK;
+ }
+ r.super_visit_with(self)
+ }
+ fn visit_const(&mut self, ct: ty::Const<'tcx>) -> ControlFlow<Self::BreakTy> {
+ if let ty::ConstKind::Param(param) = ct.kind()
+ && let param_def_id = self.generics.const_param(¶m, self.tcx).def_id
+ && self.tcx.parent(param_def_id) == self.trait_item_def_id
+ {
+ return ControlFlow::BREAK;
+ }
+ ct.super_visit_with(self)
+ }
+ }
+
+ let generics = tcx.generics_of(trait_item_def_id);
+ let predicates = tcx.predicates_of(trait_item_def_id);
+ let impl_trait_ref =
+ tcx.impl_trait_ref(impl_def_id).expect("expected impl to correspond to trait");
+ let param_env = tcx.param_env(impl_def_id);
+
+ let mut visitor = ReferencesOnlyParentGenerics { tcx, generics, trait_item_def_id };
+ let predicates_for_trait = predicates.predicates.iter().filter_map(|(pred, span)| {
+ if pred.visit_with(&mut visitor).is_continue() {
+ Some(Obligation::new(
+ ObligationCause::dummy_with_span(*span),
+ param_env,
+ ty::EarlyBinder(*pred).subst(tcx, impl_trait_ref.substs),
+ ))
+ } else {
+ None
+ }
+ });
+
+ tcx.infer_ctxt().ignoring_regions().enter(|ref infcx| {
+ for obligation in predicates_for_trait {
+ // Ignore overflow error, to be conservative.
+ if let Ok(result) = infcx.evaluate_obligation(&obligation)
+ && !result.may_apply()
+ {
+ return true;
+ }
+ }
+
+ false
+ })
+}
+
#[derive(Clone, Debug)]
enum VtblSegment<'tcx> {
MetadataDSA,
trait_ref: ty::PolyTraitRef<'tcx>,
entries: &[VtblEntry<'tcx>],
) {
- let msg = format!("vtable entries for `{}`: {:#?}", trait_ref, entries);
- tcx.sess.struct_span_err(sp, &msg).emit();
+ tcx.sess.emit_err(DumpVTableEntries {
+ span: sp,
+ trait_ref,
+ entries: format!("{:#?}", entries),
+ });
}
fn own_existential_vtable_entries<'tcx>(
*providers = ty::query::Providers {
specialization_graph_of: specialize::specialization_graph_provider,
specializes: specialize::specializes,
- codegen_fulfill_obligation: codegen::codegen_fulfill_obligation,
+ codegen_select_candidate: codegen::codegen_select_candidate,
own_existential_vtable_entries,
vtable_entries,
vtable_trait_upcasting_coercion_new_vptr_slot,
subst_and_check_impossible_predicates,
+ is_impossible_method,
try_unify_abstract_consts: |tcx, param_env_and| {
let (param_env, (a, b)) = param_env_and.into_parts();
const_evaluatable::try_unify_abstract_consts(tcx, (a, b), param_env)
projects / rustc.git / blobdiff