stabilize feature(trait_upcasting)
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Waffle Lapkin
parent
942db6782f
commit
da9a85a1a6
6 changed files with 6 additions and 90 deletions
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@ -400,6 +400,9 @@ declare_features! (
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/// Allows `#[track_caller]` to be used which provides
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/// accurate caller location reporting during panic (RFC 2091).
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(accepted, track_caller, "1.46.0", Some(47809)),
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/// Allows dyn upcasting trait objects via supertraits.
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/// Dyn upcasting is casting, e.g., `dyn Foo -> dyn Bar` where `Foo: Bar`.
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(accepted, trait_upcasting, "CURRENT_RUSTC_VERSION", Some(65991)),
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/// Allows #[repr(transparent)] on univariant enums (RFC 2645).
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(accepted, transparent_enums, "1.42.0", Some(60405)),
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/// Allows indexing tuples.
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@ -634,9 +634,6 @@ declare_features! (
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(unstable, thread_local, "1.0.0", Some(29594)),
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/// Allows defining `trait X = A + B;` alias items.
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(unstable, trait_alias, "1.24.0", Some(41517)),
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/// Allows dyn upcasting trait objects via supertraits.
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/// Dyn upcasting is casting, e.g., `dyn Foo -> dyn Bar` where `Foo: Bar`.
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(unstable, trait_upcasting, "1.56.0", Some(65991)),
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/// Allows for transmuting between arrays with sizes that contain generic consts.
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(unstable, transmute_generic_consts, "1.70.0", Some(109929)),
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/// Allows #[repr(transparent)] on unions (RFC 2645).
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@ -605,7 +605,6 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
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)];
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let mut has_unsized_tuple_coercion = false;
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let mut has_trait_upcasting_coercion = None;
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// Keep resolving `CoerceUnsized` and `Unsize` predicates to avoid
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// emitting a coercion in cases like `Foo<$1>` -> `Foo<$2>`, where
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@ -690,13 +689,6 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
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// these here and emit a feature error if coercion doesn't fail
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// due to another reason.
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match impl_source {
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traits::ImplSource::Builtin(
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BuiltinImplSource::TraitUpcasting { .. },
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_,
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) => {
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has_trait_upcasting_coercion =
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Some((trait_pred.self_ty(), trait_pred.trait_ref.args.type_at(1)));
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}
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traits::ImplSource::Builtin(BuiltinImplSource::TupleUnsizing, _) => {
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has_unsized_tuple_coercion = true;
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}
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@ -707,21 +699,6 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
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}
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}
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if let Some((sub, sup)) = has_trait_upcasting_coercion
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&& !self.tcx().features().trait_upcasting()
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{
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// Renders better when we erase regions, since they're not really the point here.
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let (sub, sup) = self.tcx.erase_regions((sub, sup));
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let mut err = feature_err(
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&self.tcx.sess,
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sym::trait_upcasting,
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self.cause.span,
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format!("cannot cast `{sub}` to `{sup}`, trait upcasting coercion is experimental"),
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);
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err.note(format!("required when coercing `{source}` into `{target}`"));
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err.emit();
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}
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if has_unsized_tuple_coercion && !self.tcx.features().unsized_tuple_coercion() {
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feature_err(
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&self.tcx.sess,
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@ -21,6 +21,7 @@
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// tidy-alphabetical-start
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#![allow(internal_features)]
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#![cfg_attr(bootstrap, feature(trait_upcasting))]
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#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
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#![doc(rust_logo)]
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#![feature(array_windows)]
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@ -32,7 +33,6 @@
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#![feature(let_chains)]
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#![feature(rustc_attrs)]
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#![feature(rustdoc_internals)]
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#![feature(trait_upcasting)]
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#![warn(unreachable_pub)]
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// tidy-alphabetical-end
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@ -29,6 +29,7 @@
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#![allow(rustc::diagnostic_outside_of_impl)]
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#![allow(rustc::potential_query_instability)]
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#![allow(rustc::untranslatable_diagnostic)]
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#![cfg_attr(bootstrap, feature(trait_upcasting))]
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#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
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#![doc(rust_logo)]
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#![feature(allocator_api)]
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@ -56,7 +57,6 @@
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#![feature(ptr_alignment_type)]
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#![feature(rustc_attrs)]
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#![feature(rustdoc_internals)]
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#![feature(trait_upcasting)]
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#![feature(trusted_len)]
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#![feature(try_blocks)]
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#![feature(try_trait_v2)]
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@ -12,9 +12,7 @@ use hir::LangItem;
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use hir::def_id::DefId;
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use rustc_data_structures::fx::{FxHashSet, FxIndexSet};
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use rustc_hir as hir;
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use rustc_infer::traits::{
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Obligation, ObligationCause, PolyTraitObligation, PredicateObligations, SelectionError,
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};
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use rustc_infer::traits::{Obligation, PolyTraitObligation, SelectionError};
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use rustc_middle::ty::fast_reject::DeepRejectCtxt;
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use rustc_middle::ty::{self, Ty, TypeVisitableExt, TypingMode};
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use rustc_middle::{bug, span_bug};
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@ -23,8 +21,6 @@ use tracing::{debug, instrument, trace};
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use super::SelectionCandidate::*;
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use super::{BuiltinImplConditions, SelectionCandidateSet, SelectionContext, TraitObligationStack};
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use crate::traits;
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use crate::traits::query::evaluate_obligation::InferCtxtExt;
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use crate::traits::util;
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impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
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@ -904,54 +900,6 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
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})
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}
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/// Temporary migration for #89190
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fn need_migrate_deref_output_trait_object(
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&mut self,
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ty: Ty<'tcx>,
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param_env: ty::ParamEnv<'tcx>,
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cause: &ObligationCause<'tcx>,
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) -> Option<ty::PolyExistentialTraitRef<'tcx>> {
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// Don't drop any candidates in intercrate mode, as it's incomplete.
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// (Not that it matters, since `Unsize` is not a stable trait.)
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//
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// FIXME(@lcnr): This should probably only trigger during analysis,
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// disabling candidates during codegen is also questionable.
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if let TypingMode::Coherence = self.infcx.typing_mode() {
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return None;
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}
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let tcx = self.tcx();
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if tcx.features().trait_upcasting() {
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return None;
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}
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// <ty as Deref>
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let trait_ref = ty::TraitRef::new(tcx, tcx.lang_items().deref_trait()?, [ty]);
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let obligation =
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traits::Obligation::new(tcx, cause.clone(), param_env, ty::Binder::dummy(trait_ref));
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if !self.infcx.predicate_may_hold(&obligation) {
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return None;
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}
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self.infcx.probe(|_| {
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let ty = traits::normalize_projection_ty(
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self,
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param_env,
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ty::AliasTy::new_from_args(tcx, tcx.lang_items().deref_target()?, trait_ref.args),
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cause.clone(),
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0,
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// We're *intentionally* throwing these away,
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// since we don't actually use them.
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&mut PredicateObligations::new(),
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)
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.as_type()
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.unwrap();
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if let ty::Dynamic(data, ..) = ty.kind() { data.principal() } else { None }
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})
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}
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/// Searches for unsizing that might apply to `obligation`.
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fn assemble_candidates_for_unsizing(
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&mut self,
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@ -1019,15 +967,6 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
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let principal_a = a_data.principal().unwrap();
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let target_trait_did = principal_def_id_b.unwrap();
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let source_trait_ref = principal_a.with_self_ty(self.tcx(), source);
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if let Some(deref_trait_ref) = self.need_migrate_deref_output_trait_object(
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source,
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obligation.param_env,
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&obligation.cause,
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) {
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if deref_trait_ref.def_id() == target_trait_did {
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return;
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}
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}
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for (idx, upcast_trait_ref) in
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util::supertraits(self.tcx(), source_trait_ref).enumerate()
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