Forbid items with the same name being defined in overlapping inherent
impl blocks. For example, the following is now correctly illegal: ```rust struct Foo; impl Foo { fn id() {} } impl Foo { fn id() {} } ``` "Overlapping" here is determined the same way it is for traits (and in fact shares the same code path): roughly, there must be some way of substituting any generic types to unify the impls, such that none of the `where` clauses are provably unsatisfiable under such a unification. Closes #22889
This commit is contained in:
parent
9cc3bfcceb
commit
21df87f515
9 changed files with 113 additions and 45 deletions
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@ -58,6 +58,7 @@ pub enum DepNode {
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CoherenceCheckImpl(DefId),
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CoherenceOverlapCheck(DefId),
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CoherenceOverlapCheckSpecial(DefId),
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CoherenceOverlapInherentCheck(DefId),
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CoherenceOrphanCheck(DefId),
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Variance,
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WfCheck(DefId),
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@ -482,14 +482,14 @@ pub fn mk_sub_poly_trait_refs<'a, 'tcx>(cx: &InferCtxt<'a, 'tcx>,
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pub fn mk_eq_impl_headers<'a, 'tcx>(cx: &InferCtxt<'a, 'tcx>,
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a_is_expected: bool,
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origin: TypeOrigin,
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a: ty::ImplHeader<'tcx>,
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b: ty::ImplHeader<'tcx>)
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a: &ty::ImplHeader<'tcx>,
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b: &ty::ImplHeader<'tcx>)
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-> UnitResult<'tcx>
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{
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debug!("mk_eq_impl_header({:?} = {:?})", a, b);
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match (a.trait_ref, b.trait_ref) {
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(Some(a_ref), Some(b_ref)) => mk_eq_trait_refs(cx, a_is_expected, a_ref, b_ref),
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(None, None) => mk_eqty(cx, a_is_expected, a.self_ty, b.self_ty),
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(Some(a_ref), Some(b_ref)) => mk_eq_trait_refs(cx, a_is_expected, origin, a_ref, b_ref),
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(None, None) => mk_eqty(cx, a_is_expected, origin, a.self_ty, b.self_ty),
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_ => cx.tcx.sess.bug("mk_eq_impl_headers given mismatched impl kinds"),
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}
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}
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@ -10,18 +10,15 @@
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//! See `README.md` for high-level documentation
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use super::{Normalized, SelectionContext};
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use super::{Obligation, ObligationCause, PredicateObligation};
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use super::project;
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use super::util;
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use super::{SelectionContext};
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use super::{Obligation, ObligationCause};
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use middle::cstore::LOCAL_CRATE;
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use middle::def_id::DefId;
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use middle::subst::{Subst, Substs, TypeSpace};
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use middle::subst::TypeSpace;
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use middle::ty::{self, Ty, TyCtxt};
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use middle::ty::error::TypeError;
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use middle::infer::{self, InferCtxt, TypeOrigin};
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use syntax::codemap::{DUMMY_SP, Span};
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use syntax::codemap::DUMMY_SP;
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#[derive(Copy, Clone)]
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struct InferIsLocal(bool);
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@ -31,7 +28,7 @@ struct InferIsLocal(bool);
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pub fn overlapping_impls<'cx, 'tcx>(infcx: &InferCtxt<'cx, 'tcx>,
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impl1_def_id: DefId,
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impl2_def_id: DefId)
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-> Option<ImplTy<'tcx>>
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-> Option<ty::ImplHeader<'tcx>>
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{
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debug!("impl_can_satisfy(\
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impl1_def_id={:?}, \
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@ -48,7 +45,7 @@ pub fn overlapping_impls<'cx, 'tcx>(infcx: &InferCtxt<'cx, 'tcx>,
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fn overlap<'cx, 'tcx>(selcx: &mut SelectionContext<'cx, 'tcx>,
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a_def_id: DefId,
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b_def_id: DefId)
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-> Option<ImplHeader<'tcx>>
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-> Option<ty::ImplHeader<'tcx>>
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{
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debug!("overlap(a_def_id={:?}, b_def_id={:?})",
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a_def_id,
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@ -64,8 +61,8 @@ fn overlap<'cx, 'tcx>(selcx: &mut SelectionContext<'cx, 'tcx>,
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if let Err(_) = infer::mk_eq_impl_headers(selcx.infcx(),
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true,
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TypeOrigin::Misc(DUMMY_SP),
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a_impl_header,
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b_impl_header) {
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&a_impl_header,
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&b_impl_header) {
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return None;
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}
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@ -74,7 +71,7 @@ fn overlap<'cx, 'tcx>(selcx: &mut SelectionContext<'cx, 'tcx>,
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// Are any of the obligations unsatisfiable? If so, no overlap.
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let infcx = selcx.infcx();
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let opt_failing_obligation =
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a_impl_header.prediates
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a_impl_header.predicates
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.iter()
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.chain(&b_impl_header.predicates)
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.map(|p| infcx.resolve_type_vars_if_possible(p))
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@ -164,7 +164,7 @@ pub struct ImplHeader<'tcx> {
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}
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impl<'tcx> ImplHeader<'tcx> {
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pub fn with_fresh_ty_vars<'a,'tcx>(selcx: &mut traits::SelectionContext<'a,'tcx>,
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pub fn with_fresh_ty_vars<'a>(selcx: &mut traits::SelectionContext<'a, 'tcx>,
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impl_def_id: DefId)
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-> ImplHeader<'tcx>
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{
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@ -174,13 +174,13 @@ impl<'tcx> ImplHeader<'tcx> {
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let header = ImplHeader {
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impl_def_id: impl_def_id,
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self_ty: tcx.lookup_item_type(impl_def_id),
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self_ty: tcx.lookup_item_type(impl_def_id).ty,
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trait_ref: tcx.impl_trait_ref(impl_def_id),
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predicates: tcx.lookup_predicates(impl_def_id),
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}.subst(tcx, impl_substs);
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predicates: tcx.lookup_predicates(impl_def_id).predicates.into_vec(),
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}.subst(tcx, &impl_substs);
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let Normalized { value: mut header, obligations: obligations } =
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proect::normalize(selcx, ObligationCause::dummy(), &header);
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let traits::Normalized { value: mut header, obligations } =
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traits::normalize(selcx, traits::ObligationCause::dummy(), &header);
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header.predicates.extend(obligations.into_iter().map(|o| o.predicate));
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header
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@ -452,8 +452,7 @@ impl<'tcx> TypeFoldable<'tcx> for ty::ImplHeader<'tcx> {
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impl_def_id: self.impl_def_id,
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self_ty: self.self_ty.fold_with(folder),
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trait_ref: self.trait_ref.map(|t| t.fold_with(folder)),
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predicates: self.predicates.into_iter().map(|p| p.fold_with(folder)).collect(),
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polarity: self.polarity,
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predicates: self.predicates.iter().map(|p| p.fold_with(folder)).collect(),
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}
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}
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@ -35,7 +35,9 @@ use CrateCtxt;
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use middle::infer::{self, InferCtxt, TypeOrigin, new_infer_ctxt};
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use std::cell::RefCell;
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use std::rc::Rc;
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use syntax::ast;
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use syntax::codemap::Span;
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use syntax::errors::DiagnosticBuilder;
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use util::nodemap::{DefIdMap, FnvHashMap};
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use rustc::dep_graph::DepNode;
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use rustc::front::map as hir_map;
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@ -519,6 +521,13 @@ fn enforce_trait_manually_implementable(tcx: &TyCtxt, sp: Span, trait_def_id: De
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err.emit();
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}
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// Factored out into helper because the error cannot be defined in multiple locations.
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pub fn report_duplicate_item<'tcx>(tcx: &TyCtxt<'tcx>, sp: Span, name: ast::Name)
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-> DiagnosticBuilder<'tcx>
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{
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struct_span_err!(tcx.sess, sp, E0201, "duplicate definitions with name `{}`:", name)
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}
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pub fn check_coherence(crate_context: &CrateCtxt) {
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let _task = crate_context.tcx.dep_graph.in_task(DepNode::Coherence);
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let infcx = new_infer_ctxt(crate_context.tcx, &crate_context.tcx.tables, None);
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@ -9,7 +9,8 @@
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// except according to those terms.
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//! Overlap: No two impls for the same trait are implemented for the
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//! same type.
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//! same type. Likewise, no two inherent impls for a given type
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//! constructor provide a method with the same name.
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use middle::cstore::{CrateStore, LOCAL_CRATE};
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use middle::def_id::DefId;
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@ -115,7 +116,6 @@ impl<'cx, 'tcx> OverlapChecker<'cx, 'tcx> {
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}
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}
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fn check_if_impls_overlap(&self,
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impl1_def_id: DefId,
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impl2_def_id: DefId)
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@ -128,8 +128,8 @@ impl<'cx, 'tcx> OverlapChecker<'cx, 'tcx> {
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impl2_def_id);
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let infcx = infer::new_infer_ctxt(self.tcx, &self.tcx.tables, None);
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if let Some(trait_ref) = traits::overlapping_impls(&infcx, impl1_def_id, impl2_def_id) {
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self.report_overlap_error(impl1_def_id, impl2_def_id, trait_ref);
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if let Some(header) = traits::overlapping_impls(&infcx, impl1_def_id, impl2_def_id) {
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self.report_overlap_error(impl1_def_id, impl2_def_id, header.trait_ref.unwrap());
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}
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}
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}
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@ -150,13 +150,13 @@ impl<'cx, 'tcx> OverlapChecker<'cx, 'tcx> {
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}).unwrap_or(String::new())
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};
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let mut err = struct_span_err!(self.tcx.sess, self.span_of_impl(impl1), E0119,
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let mut err = struct_span_err!(self.tcx.sess, self.span_of_def_id(impl1), E0119,
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"conflicting implementations of trait `{}`{}:",
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trait_ref,
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self_type);
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if impl2.is_local() {
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span_note!(&mut err, self.span_of_impl(impl2),
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span_note!(&mut err, self.span_of_def_id(impl2),
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"conflicting implementation is here:");
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} else {
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let cname = self.tcx.sess.cstore.crate_name(impl2.krate);
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err.emit();
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}
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fn span_of_impl(&self, impl_did: DefId) -> Span {
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let node_id = self.tcx.map.as_local_node_id(impl_did).unwrap();
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fn span_of_def_id(&self, did: DefId) -> Span {
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let node_id = self.tcx.map.as_local_node_id(did).unwrap();
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self.tcx.map.span(node_id)
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}
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fn check_for_common_items_in_impls(&self, impl1: DefId, impl2: DefId) {
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#[derive(Copy, Clone, PartialEq)]
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enum Namespace { Type, Value }
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fn name_and_namespace(tcx: &TyCtxt, item: &ty::ImplOrTraitItemId)
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-> (ast::Name, Namespace)
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{
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let name = tcx.impl_or_trait_item(item.def_id()).name();
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(name, match *item {
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ty::TypeTraitItemId(..) => Namespace::Type,
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ty::ConstTraitItemId(..) => Namespace::Value,
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ty::MethodTraitItemId(..) => Namespace::Value,
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})
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}
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let impl_items = self.tcx.impl_items.borrow();
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for item1 in &impl_items[&impl1] {
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let (name, namespace) = name_and_namespace(&self.tcx, item1);
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for item2 in &impl_items[&impl2] {
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if (name, namespace) == name_and_namespace(&self.tcx, item2) {
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let mut err = super::report_duplicate_item(
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&self.tcx, self.span_of_def_id(item1.def_id()), name);
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span_note!(&mut err, self.span_of_def_id(item2.def_id()),
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"conflicting definition is here:");
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err.emit();
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}
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}
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}
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}
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fn check_for_overlapping_inherent_impls(&self, ty_def_id: DefId) {
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let _task = self.tcx.dep_graph.in_task(DepNode::CoherenceOverlapInherentCheck(ty_def_id));
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let inherent_impls = self.tcx.inherent_impls.borrow();
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let impls = match inherent_impls.get(&ty_def_id) {
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Some(impls) => impls,
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None => return
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};
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for (i, &impl1_def_id) in impls.iter().enumerate() {
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for &impl2_def_id in &impls[(i+1)..] {
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let infcx = infer::new_infer_ctxt(self.tcx, &self.tcx.tables, None);
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if traits::overlapping_impls(&infcx, impl1_def_id, impl2_def_id).is_some() {
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self.check_for_common_items_in_impls(impl1_def_id, impl2_def_id)
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}
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}
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}
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}
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}
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@ -180,6 +231,11 @@ impl<'cx, 'tcx,'v> intravisit::Visitor<'v> for OverlapChecker<'cx, 'tcx> {
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self.check_for_overlapping_impls_of_trait(trait_def_id);
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}
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hir::ItemEnum(..) | hir::ItemStruct(..) => {
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let type_def_id = self.tcx.map.local_def_id(item.id);
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self.check_for_overlapping_inherent_impls(type_def_id);
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}
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hir::ItemDefaultImpl(..) => {
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// look for another default impl; note that due to the
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// general orphan/coherence rules, it must always be
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@ -63,6 +63,7 @@ use lint;
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use middle::def::Def;
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use middle::def_id::DefId;
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use constrained_type_params as ctp;
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use coherence;
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use middle::lang_items::SizedTraitLangItem;
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use middle::resolve_lifetime;
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use middle::const_eval::{self, ConstVal};
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@ -750,17 +751,7 @@ fn convert_item(ccx: &CrateCtxt, it: &hir::Item) {
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_ => &mut seen_value_items,
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};
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if !seen_items.insert(impl_item.name) {
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let desc = match impl_item.node {
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hir::ImplItemKind::Const(_, _) => "associated constant",
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hir::ImplItemKind::Type(_) => "associated type",
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hir::ImplItemKind::Method(ref sig, _) =>
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match sig.explicit_self.node {
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hir::SelfStatic => "associated function",
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_ => "method",
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},
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};
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span_err!(tcx.sess, impl_item.span, E0201, "duplicate {}", desc);
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coherence::report_duplicate_item(tcx, impl_item.span, impl_item.name).emit();
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}
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if let hir::ImplItemKind::Const(ref ty, _) = impl_item.node {
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@ -2285,6 +2285,21 @@ impl Baz for Foo {
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type Quux = u32;
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}
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```
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Note, however, that items with the same name are allowed for inherent `impl`
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blocks that don't overlap:
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```
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struct Foo<T>(T);
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impl Foo<u8> {
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fn bar(&self) -> bool { self.0 > 5 }
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}
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impl Foo<bool> {
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fn bar(&self) -> bool { self.0 }
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}
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```
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"##,
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E0202: r##"
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Loading…
Add table
Add a link
Reference in a new issue