251 lines
9.4 KiB
Rust
251 lines
9.4 KiB
Rust
//! The code in this module gathers up all of the inherent impls in
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//! the current crate and organizes them in a map. It winds up
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//! touching the whole crate and thus must be recomputed completely
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//! for any change, but it is very cheap to compute. In practice, most
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//! code in the compiler never *directly* requests this map. Instead,
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//! it requests the inherent impls specific to some type (via
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//! `tcx.inherent_impls(def_id)`). That value, however,
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//! is computed by selecting an idea from this table.
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use rustc_errors::struct_span_err;
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use rustc_hir as hir;
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use rustc_hir::def::DefKind;
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use rustc_hir::def_id::{CrateNum, DefId, LocalDefId};
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use rustc_middle::ty::fast_reject::{simplify_type, SimplifiedType, TreatParams};
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use rustc_middle::ty::{self, CrateInherentImpls, Ty, TyCtxt};
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use rustc_span::symbol::sym;
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use rustc_span::Span;
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/// On-demand query: yields a map containing all types mapped to their inherent impls.
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pub fn crate_inherent_impls(tcx: TyCtxt<'_>, (): ()) -> CrateInherentImpls {
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let mut collect = InherentCollect { tcx, impls_map: Default::default() };
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for id in tcx.hir().items() {
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collect.check_item(id);
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}
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collect.impls_map
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}
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pub fn crate_incoherent_impls(tcx: TyCtxt<'_>, (_, simp): (CrateNum, SimplifiedType)) -> &[DefId] {
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let crate_map = tcx.crate_inherent_impls(());
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tcx.arena.alloc_from_iter(
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crate_map.incoherent_impls.get(&simp).unwrap_or(&Vec::new()).iter().map(|d| d.to_def_id()),
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)
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}
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/// On-demand query: yields a vector of the inherent impls for a specific type.
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pub fn inherent_impls(tcx: TyCtxt<'_>, ty_def_id: DefId) -> &[DefId] {
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let ty_def_id = ty_def_id.expect_local();
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let crate_map = tcx.crate_inherent_impls(());
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match crate_map.inherent_impls.get(&ty_def_id) {
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Some(v) => &v[..],
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None => &[],
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}
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}
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struct InherentCollect<'tcx> {
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tcx: TyCtxt<'tcx>,
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impls_map: CrateInherentImpls,
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}
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const INTO_CORE: &str = "consider moving this inherent impl into `core` if possible";
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const INTO_DEFINING_CRATE: &str =
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"consider moving this inherent impl into the crate defining the type if possible";
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const ADD_ATTR_TO_TY: &str = "alternatively add `#[rustc_has_incoherent_inherent_impls]` to the type \
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and `#[rustc_allow_incoherent_impl]` to the relevant impl items";
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const ADD_ATTR: &str =
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"alternatively add `#[rustc_allow_incoherent_impl]` to the relevant impl items";
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impl<'tcx> InherentCollect<'tcx> {
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fn check_def_id(&mut self, item: &hir::Item<'_>, self_ty: Ty<'tcx>, def_id: DefId) {
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let impl_def_id = item.def_id;
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if let Some(def_id) = def_id.as_local() {
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// Add the implementation to the mapping from implementation to base
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// type def ID, if there is a base type for this implementation and
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// the implementation does not have any associated traits.
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let vec = self.impls_map.inherent_impls.entry(def_id).or_default();
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vec.push(impl_def_id.to_def_id());
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return;
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}
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if self.tcx.features().rustc_attrs {
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let hir::ItemKind::Impl(&hir::Impl { items, .. }) = item.kind else {
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bug!("expected `impl` item: {:?}", item);
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};
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if !self.tcx.has_attr(def_id, sym::rustc_has_incoherent_inherent_impls) {
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struct_span_err!(
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self.tcx.sess,
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item.span,
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E0390,
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"cannot define inherent `impl` for a type outside of the crate where the type is defined",
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)
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.help(INTO_DEFINING_CRATE)
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.span_help(item.span, ADD_ATTR_TO_TY)
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.emit();
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return;
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}
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for impl_item in items {
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if !self
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.tcx
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.has_attr(impl_item.id.def_id.to_def_id(), sym::rustc_allow_incoherent_impl)
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{
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struct_span_err!(
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self.tcx.sess,
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item.span,
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E0390,
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"cannot define inherent `impl` for a type outside of the crate where the type is defined",
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)
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.help(INTO_DEFINING_CRATE)
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.span_help(impl_item.span, ADD_ATTR)
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.emit();
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return;
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}
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}
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if let Some(simp) = simplify_type(self.tcx, self_ty, TreatParams::AsInfer) {
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self.impls_map.incoherent_impls.entry(simp).or_default().push(impl_def_id.def_id);
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} else {
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bug!("unexpected self type: {:?}", self_ty);
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}
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} else {
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struct_span_err!(
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self.tcx.sess,
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item.span,
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E0116,
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"cannot define inherent `impl` for a type outside of the crate \
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where the type is defined"
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)
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.span_label(item.span, "impl for type defined outside of crate.")
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.note("define and implement a trait or new type instead")
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.emit();
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}
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}
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fn check_primitive_impl(
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&mut self,
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impl_def_id: LocalDefId,
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ty: Ty<'tcx>,
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items: &[hir::ImplItemRef],
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span: Span,
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) {
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if !self.tcx.hir().rustc_coherence_is_core() {
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if self.tcx.features().rustc_attrs {
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for item in items {
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if !self
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.tcx
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.has_attr(item.id.def_id.to_def_id(), sym::rustc_allow_incoherent_impl)
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{
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struct_span_err!(
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self.tcx.sess,
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span,
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E0390,
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"cannot define inherent `impl` for primitive types outside of `core`",
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)
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.help(INTO_CORE)
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.span_help(item.span, ADD_ATTR)
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.emit();
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return;
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}
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}
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} else {
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let mut err = struct_span_err!(
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self.tcx.sess,
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span,
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E0390,
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"cannot define inherent `impl` for primitive types",
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);
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err.help("consider using an extension trait instead");
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if let ty::Ref(_, subty, _) = ty.kind() {
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err.note(&format!(
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"you could also try moving the reference to \
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uses of `{}` (such as `self`) within the implementation",
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subty
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));
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}
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err.emit();
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return;
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}
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}
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if let Some(simp) = simplify_type(self.tcx, ty, TreatParams::AsInfer) {
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self.impls_map.incoherent_impls.entry(simp).or_default().push(impl_def_id);
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} else {
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bug!("unexpected primitive type: {:?}", ty);
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}
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}
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fn check_item(&mut self, id: hir::ItemId) {
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if !matches!(self.tcx.def_kind(id.def_id), DefKind::Impl) {
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return;
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}
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let item = self.tcx.hir().item(id);
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let hir::ItemKind::Impl(hir::Impl { of_trait: None, self_ty: ty, ref items, .. }) = item.kind else {
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return;
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};
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let self_ty = self.tcx.type_of(item.def_id);
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match *self_ty.kind() {
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ty::Adt(def, _) => {
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self.check_def_id(item, self_ty, def.did());
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}
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ty::Foreign(did) => {
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self.check_def_id(item, self_ty, did);
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}
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ty::Dynamic(data, ..) if data.principal_def_id().is_some() => {
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self.check_def_id(item, self_ty, data.principal_def_id().unwrap());
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}
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ty::Dynamic(..) => {
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struct_span_err!(
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self.tcx.sess,
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ty.span,
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E0785,
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"cannot define inherent `impl` for a dyn auto trait"
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)
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.span_label(ty.span, "impl requires at least one non-auto trait")
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.note("define and implement a new trait or type instead")
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.emit();
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}
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ty::Bool
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| ty::Char
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| ty::Int(_)
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| ty::Uint(_)
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| ty::Float(_)
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| ty::Str
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| ty::Array(..)
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| ty::Slice(_)
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| ty::RawPtr(_)
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| ty::Ref(..)
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| ty::Never
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| ty::FnPtr(_)
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| ty::Tuple(..) => {
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self.check_primitive_impl(item.def_id.def_id, self_ty, items, ty.span)
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}
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ty::Projection(..) | ty::Opaque(..) | ty::Param(_) => {
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let mut err = struct_span_err!(
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self.tcx.sess,
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ty.span,
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E0118,
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"no nominal type found for inherent implementation"
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);
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err.span_label(ty.span, "impl requires a nominal type")
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.note("either implement a trait on it or create a newtype to wrap it instead");
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err.emit();
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}
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ty::FnDef(..)
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| ty::Closure(..)
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| ty::Generator(..)
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| ty::GeneratorWitness(..)
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| ty::Bound(..)
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| ty::Placeholder(_)
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| ty::Infer(_) => {
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bug!("unexpected impl self type of impl: {:?} {:?}", item.def_id, self_ty);
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}
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ty::Error(_) => {}
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}
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}
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}
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