Rollup merge of #105443 - compiler-errors:move-more, r=oli-obk
Move some queries and methods Each commit's title should be self-explanatory. Motivated to break up some large, general files and move queries into leaf crates.
This commit is contained in:
commit
6111a7345b
13 changed files with 1756 additions and 1095 deletions
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@ -1,88 +0,0 @@
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// This file contains various trait resolution methods used by codegen.
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// They all assume regions can be erased and monomorphic types. It
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// seems likely that they should eventually be merged into more
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// general routines.
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use crate::infer::{DefiningAnchor, TyCtxtInferExt};
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use crate::traits::error_reporting::TypeErrCtxtExt;
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use crate::traits::{
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ImplSource, Obligation, ObligationCause, SelectionContext, TraitEngine, TraitEngineExt,
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Unimplemented,
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};
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use rustc_infer::traits::FulfillmentErrorCode;
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use rustc_middle::traits::CodegenObligationError;
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use rustc_middle::ty::{self, TyCtxt};
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/// Attempts to resolve an obligation to an `ImplSource`. The result is
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/// a shallow `ImplSource` resolution, meaning that we do not
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/// (necessarily) resolve all nested obligations on the impl. Note
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/// that type check should guarantee to us that all nested
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/// obligations *could be* resolved if we wanted to.
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///
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/// This also expects that `trait_ref` is fully normalized.
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pub fn codegen_select_candidate<'tcx>(
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tcx: TyCtxt<'tcx>,
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(param_env, trait_ref): (ty::ParamEnv<'tcx>, ty::PolyTraitRef<'tcx>),
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) -> Result<&'tcx ImplSource<'tcx, ()>, CodegenObligationError> {
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// We expect the input to be fully normalized.
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debug_assert_eq!(trait_ref, tcx.normalize_erasing_regions(param_env, trait_ref));
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// Do the initial selection for the obligation. This yields the
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// shallow result we are looking for -- that is, what specific impl.
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let infcx = tcx
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.infer_ctxt()
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.ignoring_regions()
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.with_opaque_type_inference(DefiningAnchor::Bubble)
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.build();
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//~^ HACK `Bubble` is required for
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// this test to pass: type-alias-impl-trait/assoc-projection-ice.rs
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let mut selcx = SelectionContext::new(&infcx);
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let obligation_cause = ObligationCause::dummy();
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let obligation = Obligation::new(tcx, obligation_cause, param_env, trait_ref);
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let selection = match selcx.select(&obligation) {
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Ok(Some(selection)) => selection,
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Ok(None) => return Err(CodegenObligationError::Ambiguity),
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Err(Unimplemented) => return Err(CodegenObligationError::Unimplemented),
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Err(e) => {
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bug!("Encountered error `{:?}` selecting `{:?}` during codegen", e, trait_ref)
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}
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};
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debug!(?selection);
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// Currently, we use a fulfillment context to completely resolve
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// all nested obligations. This is because they can inform the
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// inference of the impl's type parameters.
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let mut fulfill_cx = <dyn TraitEngine<'tcx>>::new(tcx);
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let impl_source = selection.map(|predicate| {
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fulfill_cx.register_predicate_obligation(&infcx, predicate);
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});
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// In principle, we only need to do this so long as `impl_source`
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// contains unbound type parameters. It could be a slight
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// optimization to stop iterating early.
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let errors = fulfill_cx.select_all_or_error(&infcx);
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if !errors.is_empty() {
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// `rustc_monomorphize::collector` assumes there are no type errors.
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// Cycle errors are the only post-monomorphization errors possible; emit them now so
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// `rustc_ty_utils::resolve_associated_item` doesn't return `None` post-monomorphization.
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for err in errors {
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if let FulfillmentErrorCode::CodeCycle(cycle) = err.code {
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infcx.err_ctxt().report_overflow_obligation_cycle(&cycle);
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}
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}
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return Err(CodegenObligationError::FulfillmentError);
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}
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let impl_source = infcx.resolve_vars_if_possible(impl_source);
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let impl_source = infcx.tcx.erase_regions(impl_source);
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// Opaque types may have gotten their hidden types constrained, but we can ignore them safely
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// as they will get constrained elsewhere, too.
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// (ouz-a) This is required for `type-alias-impl-trait/assoc-projection-ice.rs` to pass
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let _ = infcx.inner.borrow_mut().opaque_type_storage.take_opaque_types();
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Ok(&*tcx.arena.alloc(impl_source))
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}
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@ -4,7 +4,6 @@
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pub mod auto_trait;
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mod chalk_fulfill;
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pub mod codegen;
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mod coherence;
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pub mod const_evaluatable;
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mod engine;
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@ -20,9 +19,9 @@ mod select;
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mod specialize;
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mod structural_match;
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mod util;
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mod vtable;
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pub mod wf;
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use crate::errors::DumpVTableEntries;
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use crate::infer::outlives::env::OutlivesEnvironment;
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use crate::infer::{InferCtxt, TyCtxtInferExt};
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use crate::traits::error_reporting::TypeErrCtxtExt as _;
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@ -30,15 +29,11 @@ use crate::traits::query::evaluate_obligation::InferCtxtExt as _;
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use rustc_errors::ErrorGuaranteed;
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use rustc_hir as hir;
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use rustc_hir::def_id::DefId;
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use rustc_hir::lang_items::LangItem;
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use rustc_middle::ty::fold::TypeFoldable;
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use rustc_middle::ty::visit::TypeVisitable;
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use rustc_middle::ty::{
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self, DefIdTree, GenericParamDefKind, ToPredicate, Ty, TyCtxt, TypeSuperVisitable, VtblEntry,
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};
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use rustc_middle::ty::{self, DefIdTree, ToPredicate, Ty, TyCtxt, TypeSuperVisitable};
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use rustc_middle::ty::{InternalSubsts, SubstsRef};
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use rustc_span::{sym, Span};
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use smallvec::SmallVec;
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use rustc_span::Span;
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use std::fmt::Debug;
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use std::ops::ControlFlow;
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@ -567,369 +562,12 @@ fn is_impossible_method<'tcx>(
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false
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}
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#[derive(Clone, Debug)]
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enum VtblSegment<'tcx> {
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MetadataDSA,
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TraitOwnEntries { trait_ref: ty::PolyTraitRef<'tcx>, emit_vptr: bool },
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}
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/// Prepare the segments for a vtable
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fn prepare_vtable_segments<'tcx, T>(
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tcx: TyCtxt<'tcx>,
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trait_ref: ty::PolyTraitRef<'tcx>,
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mut segment_visitor: impl FnMut(VtblSegment<'tcx>) -> ControlFlow<T>,
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) -> Option<T> {
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// The following constraints holds for the final arrangement.
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// 1. The whole virtual table of the first direct super trait is included as the
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// the prefix. If this trait doesn't have any super traits, then this step
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// consists of the dsa metadata.
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// 2. Then comes the proper pointer metadata(vptr) and all own methods for all
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// other super traits except those already included as part of the first
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// direct super trait virtual table.
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// 3. finally, the own methods of this trait.
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// This has the advantage that trait upcasting to the first direct super trait on each level
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// is zero cost, and to another trait includes only replacing the pointer with one level indirection,
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// while not using too much extra memory.
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// For a single inheritance relationship like this,
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// D --> C --> B --> A
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// The resulting vtable will consists of these segments:
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// DSA, A, B, C, D
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// For a multiple inheritance relationship like this,
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// D --> C --> A
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// \-> B
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// The resulting vtable will consists of these segments:
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// DSA, A, B, B-vptr, C, D
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// For a diamond inheritance relationship like this,
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// D --> B --> A
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// \-> C -/
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// The resulting vtable will consists of these segments:
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// DSA, A, B, C, C-vptr, D
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// For a more complex inheritance relationship like this:
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// O --> G --> C --> A
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// \ \ \-> B
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// | |-> F --> D
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// | \-> E
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// |-> N --> J --> H
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// \ \-> I
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// |-> M --> K
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// \-> L
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// The resulting vtable will consists of these segments:
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// DSA, A, B, B-vptr, C, D, D-vptr, E, E-vptr, F, F-vptr, G,
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// H, H-vptr, I, I-vptr, J, J-vptr, K, K-vptr, L, L-vptr, M, M-vptr,
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// N, N-vptr, O
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// emit dsa segment first.
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if let ControlFlow::Break(v) = (segment_visitor)(VtblSegment::MetadataDSA) {
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return Some(v);
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}
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let mut emit_vptr_on_new_entry = false;
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let mut visited = util::PredicateSet::new(tcx);
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let predicate = trait_ref.without_const().to_predicate(tcx);
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let mut stack: SmallVec<[(ty::PolyTraitRef<'tcx>, _, _); 5]> =
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smallvec![(trait_ref, emit_vptr_on_new_entry, None)];
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visited.insert(predicate);
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// the main traversal loop:
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// basically we want to cut the inheritance directed graph into a few non-overlapping slices of nodes
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// that each node is emitted after all its descendents have been emitted.
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// so we convert the directed graph into a tree by skipping all previously visited nodes using a visited set.
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// this is done on the fly.
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// Each loop run emits a slice - it starts by find a "childless" unvisited node, backtracking upwards, and it
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// stops after it finds a node that has a next-sibling node.
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// This next-sibling node will used as the starting point of next slice.
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// Example:
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// For a diamond inheritance relationship like this,
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// D#1 --> B#0 --> A#0
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// \-> C#1 -/
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// Starting point 0 stack [D]
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// Loop run #0: Stack after diving in is [D B A], A is "childless"
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// after this point, all newly visited nodes won't have a vtable that equals to a prefix of this one.
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// Loop run #0: Emitting the slice [B A] (in reverse order), B has a next-sibling node, so this slice stops here.
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// Loop run #0: Stack after exiting out is [D C], C is the next starting point.
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// Loop run #1: Stack after diving in is [D C], C is "childless", since its child A is skipped(already emitted).
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// Loop run #1: Emitting the slice [D C] (in reverse order). No one has a next-sibling node.
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// Loop run #1: Stack after exiting out is []. Now the function exits.
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loop {
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// dive deeper into the stack, recording the path
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'diving_in: loop {
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if let Some((inner_most_trait_ref, _, _)) = stack.last() {
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let inner_most_trait_ref = *inner_most_trait_ref;
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let mut direct_super_traits_iter = tcx
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.super_predicates_of(inner_most_trait_ref.def_id())
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.predicates
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.into_iter()
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.filter_map(move |(pred, _)| {
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pred.subst_supertrait(tcx, &inner_most_trait_ref).to_opt_poly_trait_pred()
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});
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'diving_in_skip_visited_traits: loop {
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if let Some(next_super_trait) = direct_super_traits_iter.next() {
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if visited.insert(next_super_trait.to_predicate(tcx)) {
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// We're throwing away potential constness of super traits here.
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// FIXME: handle ~const super traits
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let next_super_trait = next_super_trait.map_bound(|t| t.trait_ref);
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stack.push((
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next_super_trait,
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emit_vptr_on_new_entry,
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Some(direct_super_traits_iter),
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));
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break 'diving_in_skip_visited_traits;
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} else {
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continue 'diving_in_skip_visited_traits;
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}
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} else {
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break 'diving_in;
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}
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}
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}
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}
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// Other than the left-most path, vptr should be emitted for each trait.
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emit_vptr_on_new_entry = true;
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// emit innermost item, move to next sibling and stop there if possible, otherwise jump to outer level.
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'exiting_out: loop {
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if let Some((inner_most_trait_ref, emit_vptr, siblings_opt)) = stack.last_mut() {
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if let ControlFlow::Break(v) = (segment_visitor)(VtblSegment::TraitOwnEntries {
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trait_ref: *inner_most_trait_ref,
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emit_vptr: *emit_vptr,
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}) {
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return Some(v);
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}
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'exiting_out_skip_visited_traits: loop {
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if let Some(siblings) = siblings_opt {
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if let Some(next_inner_most_trait_ref) = siblings.next() {
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if visited.insert(next_inner_most_trait_ref.to_predicate(tcx)) {
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// We're throwing away potential constness of super traits here.
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// FIXME: handle ~const super traits
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let next_inner_most_trait_ref =
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next_inner_most_trait_ref.map_bound(|t| t.trait_ref);
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*inner_most_trait_ref = next_inner_most_trait_ref;
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*emit_vptr = emit_vptr_on_new_entry;
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break 'exiting_out;
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} else {
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continue 'exiting_out_skip_visited_traits;
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}
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}
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}
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stack.pop();
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continue 'exiting_out;
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}
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}
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// all done
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return None;
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}
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}
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}
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fn dump_vtable_entries<'tcx>(
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tcx: TyCtxt<'tcx>,
|
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sp: Span,
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trait_ref: ty::PolyTraitRef<'tcx>,
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entries: &[VtblEntry<'tcx>],
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) {
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tcx.sess.emit_err(DumpVTableEntries {
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span: sp,
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trait_ref,
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entries: format!("{:#?}", entries),
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});
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}
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fn own_existential_vtable_entries<'tcx>(tcx: TyCtxt<'tcx>, trait_def_id: DefId) -> &'tcx [DefId] {
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let trait_methods = tcx
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.associated_items(trait_def_id)
|
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.in_definition_order()
|
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.filter(|item| item.kind == ty::AssocKind::Fn);
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// Now list each method's DefId (for within its trait).
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let own_entries = trait_methods.filter_map(move |trait_method| {
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debug!("own_existential_vtable_entry: trait_method={:?}", trait_method);
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let def_id = trait_method.def_id;
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|
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// Some methods cannot be called on an object; skip those.
|
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if !is_vtable_safe_method(tcx, trait_def_id, &trait_method) {
|
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debug!("own_existential_vtable_entry: not vtable safe");
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return None;
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}
|
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|
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Some(def_id)
|
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});
|
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|
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tcx.arena.alloc_from_iter(own_entries.into_iter())
|
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}
|
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|
||||
/// Given a trait `trait_ref`, iterates the vtable entries
|
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/// that come from `trait_ref`, including its supertraits.
|
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fn vtable_entries<'tcx>(
|
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tcx: TyCtxt<'tcx>,
|
||||
trait_ref: ty::PolyTraitRef<'tcx>,
|
||||
) -> &'tcx [VtblEntry<'tcx>] {
|
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debug!("vtable_entries({:?})", trait_ref);
|
||||
|
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let mut entries = vec![];
|
||||
|
||||
let vtable_segment_callback = |segment| -> ControlFlow<()> {
|
||||
match segment {
|
||||
VtblSegment::MetadataDSA => {
|
||||
entries.extend(TyCtxt::COMMON_VTABLE_ENTRIES);
|
||||
}
|
||||
VtblSegment::TraitOwnEntries { trait_ref, emit_vptr } => {
|
||||
let existential_trait_ref = trait_ref
|
||||
.map_bound(|trait_ref| ty::ExistentialTraitRef::erase_self_ty(tcx, trait_ref));
|
||||
|
||||
// Lookup the shape of vtable for the trait.
|
||||
let own_existential_entries =
|
||||
tcx.own_existential_vtable_entries(existential_trait_ref.def_id());
|
||||
|
||||
let own_entries = own_existential_entries.iter().copied().map(|def_id| {
|
||||
debug!("vtable_entries: trait_method={:?}", def_id);
|
||||
|
||||
// The method may have some early-bound lifetimes; add regions for those.
|
||||
let substs = trait_ref.map_bound(|trait_ref| {
|
||||
InternalSubsts::for_item(tcx, def_id, |param, _| match param.kind {
|
||||
GenericParamDefKind::Lifetime => tcx.lifetimes.re_erased.into(),
|
||||
GenericParamDefKind::Type { .. }
|
||||
| GenericParamDefKind::Const { .. } => {
|
||||
trait_ref.substs[param.index as usize]
|
||||
}
|
||||
})
|
||||
});
|
||||
|
||||
// The trait type may have higher-ranked lifetimes in it;
|
||||
// erase them if they appear, so that we get the type
|
||||
// at some particular call site.
|
||||
let substs = tcx
|
||||
.normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), substs);
|
||||
|
||||
// It's possible that the method relies on where-clauses that
|
||||
// do not hold for this particular set of type parameters.
|
||||
// Note that this method could then never be called, so we
|
||||
// do not want to try and codegen it, in that case (see #23435).
|
||||
let predicates = tcx.predicates_of(def_id).instantiate_own(tcx, substs);
|
||||
if impossible_predicates(tcx, predicates.predicates) {
|
||||
debug!("vtable_entries: predicates do not hold");
|
||||
return VtblEntry::Vacant;
|
||||
}
|
||||
|
||||
let instance = ty::Instance::resolve_for_vtable(
|
||||
tcx,
|
||||
ty::ParamEnv::reveal_all(),
|
||||
def_id,
|
||||
substs,
|
||||
)
|
||||
.expect("resolution failed during building vtable representation");
|
||||
VtblEntry::Method(instance)
|
||||
});
|
||||
|
||||
entries.extend(own_entries);
|
||||
|
||||
if emit_vptr {
|
||||
entries.push(VtblEntry::TraitVPtr(trait_ref));
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
ControlFlow::Continue(())
|
||||
};
|
||||
|
||||
let _ = prepare_vtable_segments(tcx, trait_ref, vtable_segment_callback);
|
||||
|
||||
if tcx.has_attr(trait_ref.def_id(), sym::rustc_dump_vtable) {
|
||||
let sp = tcx.def_span(trait_ref.def_id());
|
||||
dump_vtable_entries(tcx, sp, trait_ref, &entries);
|
||||
}
|
||||
|
||||
tcx.arena.alloc_from_iter(entries.into_iter())
|
||||
}
|
||||
|
||||
/// Find slot base for trait methods within vtable entries of another trait
|
||||
fn vtable_trait_first_method_offset<'tcx>(
|
||||
tcx: TyCtxt<'tcx>,
|
||||
key: (
|
||||
ty::PolyTraitRef<'tcx>, // trait_to_be_found
|
||||
ty::PolyTraitRef<'tcx>, // trait_owning_vtable
|
||||
),
|
||||
) -> usize {
|
||||
let (trait_to_be_found, trait_owning_vtable) = key;
|
||||
|
||||
// #90177
|
||||
let trait_to_be_found_erased = tcx.erase_regions(trait_to_be_found);
|
||||
|
||||
let vtable_segment_callback = {
|
||||
let mut vtable_base = 0;
|
||||
|
||||
move |segment| {
|
||||
match segment {
|
||||
VtblSegment::MetadataDSA => {
|
||||
vtable_base += TyCtxt::COMMON_VTABLE_ENTRIES.len();
|
||||
}
|
||||
VtblSegment::TraitOwnEntries { trait_ref, emit_vptr } => {
|
||||
if tcx.erase_regions(trait_ref) == trait_to_be_found_erased {
|
||||
return ControlFlow::Break(vtable_base);
|
||||
}
|
||||
vtable_base += util::count_own_vtable_entries(tcx, trait_ref);
|
||||
if emit_vptr {
|
||||
vtable_base += 1;
|
||||
}
|
||||
}
|
||||
}
|
||||
ControlFlow::Continue(())
|
||||
}
|
||||
};
|
||||
|
||||
if let Some(vtable_base) =
|
||||
prepare_vtable_segments(tcx, trait_owning_vtable, vtable_segment_callback)
|
||||
{
|
||||
vtable_base
|
||||
} else {
|
||||
bug!("Failed to find info for expected trait in vtable");
|
||||
}
|
||||
}
|
||||
|
||||
/// Find slot offset for trait vptr within vtable entries of another trait
|
||||
pub fn vtable_trait_upcasting_coercion_new_vptr_slot<'tcx>(
|
||||
tcx: TyCtxt<'tcx>,
|
||||
key: (
|
||||
Ty<'tcx>, // trait object type whose trait owning vtable
|
||||
Ty<'tcx>, // trait object for supertrait
|
||||
),
|
||||
) -> Option<usize> {
|
||||
let (source, target) = key;
|
||||
assert!(matches!(&source.kind(), &ty::Dynamic(..)) && !source.needs_infer());
|
||||
assert!(matches!(&target.kind(), &ty::Dynamic(..)) && !target.needs_infer());
|
||||
|
||||
// this has been typecked-before, so diagnostics is not really needed.
|
||||
let unsize_trait_did = tcx.require_lang_item(LangItem::Unsize, None);
|
||||
|
||||
let trait_ref = tcx.mk_trait_ref(unsize_trait_did, [source, target]);
|
||||
|
||||
match tcx.codegen_select_candidate((ty::ParamEnv::reveal_all(), ty::Binder::dummy(trait_ref))) {
|
||||
Ok(ImplSource::TraitUpcasting(implsrc_traitcasting)) => {
|
||||
implsrc_traitcasting.vtable_vptr_slot
|
||||
}
|
||||
otherwise => bug!("expected TraitUpcasting candidate, got {otherwise:?}"),
|
||||
}
|
||||
}
|
||||
|
||||
pub fn provide(providers: &mut ty::query::Providers) {
|
||||
object_safety::provide(providers);
|
||||
structural_match::provide(providers);
|
||||
vtable::provide(providers);
|
||||
*providers = ty::query::Providers {
|
||||
specialization_graph_of: specialize::specialization_graph_provider,
|
||||
specializes: specialize::specializes,
|
||||
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,
|
||||
..*providers
|
||||
|
|
|
@ -19,6 +19,10 @@ use rustc_span::def_id::DefId;
|
|||
|
||||
use crate::traits::project::{normalize_with_depth, normalize_with_depth_to};
|
||||
use crate::traits::util::{self, closure_trait_ref_and_return_type, predicate_for_trait_def};
|
||||
use crate::traits::vtable::{
|
||||
count_own_vtable_entries, prepare_vtable_segments, vtable_trait_first_method_offset,
|
||||
VtblSegment,
|
||||
};
|
||||
use crate::traits::{
|
||||
BuiltinDerivedObligation, ImplDerivedObligation, ImplDerivedObligationCause, ImplSource,
|
||||
ImplSourceAutoImplData, ImplSourceBuiltinData, ImplSourceClosureData,
|
||||
|
@ -26,7 +30,7 @@ use crate::traits::{
|
|||
ImplSourceGeneratorData, ImplSourceObjectData, ImplSourceTraitAliasData,
|
||||
ImplSourceTraitUpcastingData, ImplSourceUserDefinedData, Normalized, ObjectCastObligation,
|
||||
Obligation, ObligationCause, OutputTypeParameterMismatch, PredicateObligation, Selection,
|
||||
SelectionError, TraitNotObjectSafe, TraitObligation, Unimplemented, VtblSegment,
|
||||
SelectionError, TraitNotObjectSafe, TraitObligation, Unimplemented,
|
||||
};
|
||||
|
||||
use super::BuiltinImplConditions;
|
||||
|
@ -583,7 +587,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
|
|||
|
||||
debug!(?nested, "object nested obligations");
|
||||
|
||||
let vtable_base = super::super::vtable_trait_first_method_offset(
|
||||
let vtable_base = vtable_trait_first_method_offset(
|
||||
tcx,
|
||||
(unnormalized_upcast_trait_ref, ty::Binder::dummy(object_trait_ref)),
|
||||
);
|
||||
|
@ -904,7 +908,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
|
|||
vptr_offset += TyCtxt::COMMON_VTABLE_ENTRIES.len();
|
||||
}
|
||||
VtblSegment::TraitOwnEntries { trait_ref, emit_vptr } => {
|
||||
vptr_offset += util::count_own_vtable_entries(tcx, trait_ref);
|
||||
vptr_offset += count_own_vtable_entries(tcx, trait_ref);
|
||||
if trait_ref == upcast_trait_ref {
|
||||
if emit_vptr {
|
||||
return ControlFlow::Break(Some(vptr_offset));
|
||||
|
@ -923,8 +927,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
|
|||
};
|
||||
|
||||
let vtable_vptr_slot =
|
||||
super::super::prepare_vtable_segments(tcx, source_trait_ref, vtable_segment_callback)
|
||||
.unwrap();
|
||||
prepare_vtable_segments(tcx, source_trait_ref, vtable_segment_callback).unwrap();
|
||||
|
||||
Ok(ImplSourceTraitUpcastingData { upcast_trait_ref, vtable_vptr_slot, nested })
|
||||
}
|
||||
|
|
|
@ -1,10 +1,5 @@
|
|||
use crate::infer::{InferCtxt, TyCtxtInferExt};
|
||||
use crate::traits::{ObligationCause, ObligationCtxt};
|
||||
|
||||
use rustc_data_structures::fx::FxHashSet;
|
||||
use rustc_hir as hir;
|
||||
use rustc_hir::lang_items::LangItem;
|
||||
use rustc_middle::ty::query::Providers;
|
||||
use rustc_middle::ty::{self, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitor};
|
||||
use rustc_span::Span;
|
||||
use std::ops::ControlFlow;
|
||||
|
@ -59,41 +54,6 @@ pub fn search_for_adt_const_param_violation<'tcx>(
|
|||
.break_value()
|
||||
}
|
||||
|
||||
/// This method returns true if and only if `adt_ty` itself has been marked as
|
||||
/// eligible for structural-match: namely, if it implements both
|
||||
/// `StructuralPartialEq` and `StructuralEq` (which are respectively injected by
|
||||
/// `#[derive(PartialEq)]` and `#[derive(Eq)]`).
|
||||
///
|
||||
/// Note that this does *not* recursively check if the substructure of `adt_ty`
|
||||
/// implements the traits.
|
||||
fn type_marked_structural<'tcx>(
|
||||
infcx: &InferCtxt<'tcx>,
|
||||
adt_ty: Ty<'tcx>,
|
||||
cause: ObligationCause<'tcx>,
|
||||
) -> bool {
|
||||
let ocx = ObligationCtxt::new(infcx);
|
||||
// require `#[derive(PartialEq)]`
|
||||
let structural_peq_def_id =
|
||||
infcx.tcx.require_lang_item(LangItem::StructuralPeq, Some(cause.span));
|
||||
ocx.register_bound(cause.clone(), ty::ParamEnv::empty(), adt_ty, structural_peq_def_id);
|
||||
// for now, require `#[derive(Eq)]`. (Doing so is a hack to work around
|
||||
// the type `for<'a> fn(&'a ())` failing to implement `Eq` itself.)
|
||||
let structural_teq_def_id =
|
||||
infcx.tcx.require_lang_item(LangItem::StructuralTeq, Some(cause.span));
|
||||
ocx.register_bound(cause, ty::ParamEnv::empty(), adt_ty, structural_teq_def_id);
|
||||
|
||||
// We deliberately skip *reporting* fulfillment errors (via
|
||||
// `report_fulfillment_errors`), for two reasons:
|
||||
//
|
||||
// 1. The error messages would mention `std::marker::StructuralPartialEq`
|
||||
// (a trait which is solely meant as an implementation detail
|
||||
// for now), and
|
||||
//
|
||||
// 2. We are sometimes doing future-incompatibility lints for
|
||||
// now, so we do not want unconditional errors here.
|
||||
ocx.select_all_or_error().is_empty()
|
||||
}
|
||||
|
||||
/// This implements the traversal over the structure of a given type to try to
|
||||
/// find instances of ADTs (specifically structs or enums) that do not implement
|
||||
/// the structural-match traits (`StructuralPartialEq` and `StructuralEq`).
|
||||
|
@ -249,11 +209,3 @@ impl<'tcx> TypeVisitor<'tcx> for Search<'tcx> {
|
|||
})
|
||||
}
|
||||
}
|
||||
|
||||
pub fn provide(providers: &mut Providers) {
|
||||
providers.has_structural_eq_impls = |tcx, ty| {
|
||||
let infcx = tcx.infer_ctxt().build();
|
||||
let cause = ObligationCause::dummy();
|
||||
type_marked_structural(&infcx, ty, cause)
|
||||
};
|
||||
}
|
||||
|
|
|
@ -261,16 +261,6 @@ pub fn upcast_choices<'tcx>(
|
|||
supertraits(tcx, source_trait_ref).filter(|r| r.def_id() == target_trait_def_id).collect()
|
||||
}
|
||||
|
||||
/// Given a trait `trait_ref`, returns the number of vtable entries
|
||||
/// that come from `trait_ref`, excluding its supertraits. Used in
|
||||
/// computing the vtable base for an upcast trait of a trait object.
|
||||
pub fn count_own_vtable_entries<'tcx>(
|
||||
tcx: TyCtxt<'tcx>,
|
||||
trait_ref: ty::PolyTraitRef<'tcx>,
|
||||
) -> usize {
|
||||
tcx.own_existential_vtable_entries(trait_ref.def_id()).len()
|
||||
}
|
||||
|
||||
/// Given an upcast trait object described by `object`, returns the
|
||||
/// index of the method `method_def_id` (which should be part of
|
||||
/// `object.upcast_trait_ref`) within the vtable for `object`.
|
||||
|
|
386
compiler/rustc_trait_selection/src/traits/vtable.rs
Normal file
386
compiler/rustc_trait_selection/src/traits/vtable.rs
Normal file
|
@ -0,0 +1,386 @@
|
|||
use crate::errors::DumpVTableEntries;
|
||||
use crate::traits::{impossible_predicates, is_vtable_safe_method};
|
||||
use rustc_hir::def_id::DefId;
|
||||
use rustc_hir::lang_items::LangItem;
|
||||
use rustc_infer::traits::util::PredicateSet;
|
||||
use rustc_infer::traits::ImplSource;
|
||||
use rustc_middle::ty::visit::TypeVisitable;
|
||||
use rustc_middle::ty::InternalSubsts;
|
||||
use rustc_middle::ty::{self, GenericParamDefKind, ToPredicate, Ty, TyCtxt, VtblEntry};
|
||||
use rustc_span::{sym, Span};
|
||||
use smallvec::SmallVec;
|
||||
|
||||
use std::fmt::Debug;
|
||||
use std::ops::ControlFlow;
|
||||
|
||||
#[derive(Clone, Debug)]
|
||||
pub(super) enum VtblSegment<'tcx> {
|
||||
MetadataDSA,
|
||||
TraitOwnEntries { trait_ref: ty::PolyTraitRef<'tcx>, emit_vptr: bool },
|
||||
}
|
||||
|
||||
/// Prepare the segments for a vtable
|
||||
pub(super) fn prepare_vtable_segments<'tcx, T>(
|
||||
tcx: TyCtxt<'tcx>,
|
||||
trait_ref: ty::PolyTraitRef<'tcx>,
|
||||
mut segment_visitor: impl FnMut(VtblSegment<'tcx>) -> ControlFlow<T>,
|
||||
) -> Option<T> {
|
||||
// The following constraints holds for the final arrangement.
|
||||
// 1. The whole virtual table of the first direct super trait is included as the
|
||||
// the prefix. If this trait doesn't have any super traits, then this step
|
||||
// consists of the dsa metadata.
|
||||
// 2. Then comes the proper pointer metadata(vptr) and all own methods for all
|
||||
// other super traits except those already included as part of the first
|
||||
// direct super trait virtual table.
|
||||
// 3. finally, the own methods of this trait.
|
||||
|
||||
// This has the advantage that trait upcasting to the first direct super trait on each level
|
||||
// is zero cost, and to another trait includes only replacing the pointer with one level indirection,
|
||||
// while not using too much extra memory.
|
||||
|
||||
// For a single inheritance relationship like this,
|
||||
// D --> C --> B --> A
|
||||
// The resulting vtable will consists of these segments:
|
||||
// DSA, A, B, C, D
|
||||
|
||||
// For a multiple inheritance relationship like this,
|
||||
// D --> C --> A
|
||||
// \-> B
|
||||
// The resulting vtable will consists of these segments:
|
||||
// DSA, A, B, B-vptr, C, D
|
||||
|
||||
// For a diamond inheritance relationship like this,
|
||||
// D --> B --> A
|
||||
// \-> C -/
|
||||
// The resulting vtable will consists of these segments:
|
||||
// DSA, A, B, C, C-vptr, D
|
||||
|
||||
// For a more complex inheritance relationship like this:
|
||||
// O --> G --> C --> A
|
||||
// \ \ \-> B
|
||||
// | |-> F --> D
|
||||
// | \-> E
|
||||
// |-> N --> J --> H
|
||||
// \ \-> I
|
||||
// |-> M --> K
|
||||
// \-> L
|
||||
// The resulting vtable will consists of these segments:
|
||||
// DSA, A, B, B-vptr, C, D, D-vptr, E, E-vptr, F, F-vptr, G,
|
||||
// H, H-vptr, I, I-vptr, J, J-vptr, K, K-vptr, L, L-vptr, M, M-vptr,
|
||||
// N, N-vptr, O
|
||||
|
||||
// emit dsa segment first.
|
||||
if let ControlFlow::Break(v) = (segment_visitor)(VtblSegment::MetadataDSA) {
|
||||
return Some(v);
|
||||
}
|
||||
|
||||
let mut emit_vptr_on_new_entry = false;
|
||||
let mut visited = PredicateSet::new(tcx);
|
||||
let predicate = trait_ref.without_const().to_predicate(tcx);
|
||||
let mut stack: SmallVec<[(ty::PolyTraitRef<'tcx>, _, _); 5]> =
|
||||
smallvec![(trait_ref, emit_vptr_on_new_entry, None)];
|
||||
visited.insert(predicate);
|
||||
|
||||
// the main traversal loop:
|
||||
// basically we want to cut the inheritance directed graph into a few non-overlapping slices of nodes
|
||||
// that each node is emitted after all its descendents have been emitted.
|
||||
// so we convert the directed graph into a tree by skipping all previously visited nodes using a visited set.
|
||||
// this is done on the fly.
|
||||
// Each loop run emits a slice - it starts by find a "childless" unvisited node, backtracking upwards, and it
|
||||
// stops after it finds a node that has a next-sibling node.
|
||||
// This next-sibling node will used as the starting point of next slice.
|
||||
|
||||
// Example:
|
||||
// For a diamond inheritance relationship like this,
|
||||
// D#1 --> B#0 --> A#0
|
||||
// \-> C#1 -/
|
||||
|
||||
// Starting point 0 stack [D]
|
||||
// Loop run #0: Stack after diving in is [D B A], A is "childless"
|
||||
// after this point, all newly visited nodes won't have a vtable that equals to a prefix of this one.
|
||||
// Loop run #0: Emitting the slice [B A] (in reverse order), B has a next-sibling node, so this slice stops here.
|
||||
// Loop run #0: Stack after exiting out is [D C], C is the next starting point.
|
||||
// Loop run #1: Stack after diving in is [D C], C is "childless", since its child A is skipped(already emitted).
|
||||
// Loop run #1: Emitting the slice [D C] (in reverse order). No one has a next-sibling node.
|
||||
// Loop run #1: Stack after exiting out is []. Now the function exits.
|
||||
|
||||
loop {
|
||||
// dive deeper into the stack, recording the path
|
||||
'diving_in: loop {
|
||||
if let Some((inner_most_trait_ref, _, _)) = stack.last() {
|
||||
let inner_most_trait_ref = *inner_most_trait_ref;
|
||||
let mut direct_super_traits_iter = tcx
|
||||
.super_predicates_of(inner_most_trait_ref.def_id())
|
||||
.predicates
|
||||
.into_iter()
|
||||
.filter_map(move |(pred, _)| {
|
||||
pred.subst_supertrait(tcx, &inner_most_trait_ref).to_opt_poly_trait_pred()
|
||||
});
|
||||
|
||||
'diving_in_skip_visited_traits: loop {
|
||||
if let Some(next_super_trait) = direct_super_traits_iter.next() {
|
||||
if visited.insert(next_super_trait.to_predicate(tcx)) {
|
||||
// We're throwing away potential constness of super traits here.
|
||||
// FIXME: handle ~const super traits
|
||||
let next_super_trait = next_super_trait.map_bound(|t| t.trait_ref);
|
||||
stack.push((
|
||||
next_super_trait,
|
||||
emit_vptr_on_new_entry,
|
||||
Some(direct_super_traits_iter),
|
||||
));
|
||||
break 'diving_in_skip_visited_traits;
|
||||
} else {
|
||||
continue 'diving_in_skip_visited_traits;
|
||||
}
|
||||
} else {
|
||||
break 'diving_in;
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// Other than the left-most path, vptr should be emitted for each trait.
|
||||
emit_vptr_on_new_entry = true;
|
||||
|
||||
// emit innermost item, move to next sibling and stop there if possible, otherwise jump to outer level.
|
||||
'exiting_out: loop {
|
||||
if let Some((inner_most_trait_ref, emit_vptr, siblings_opt)) = stack.last_mut() {
|
||||
if let ControlFlow::Break(v) = (segment_visitor)(VtblSegment::TraitOwnEntries {
|
||||
trait_ref: *inner_most_trait_ref,
|
||||
emit_vptr: *emit_vptr,
|
||||
}) {
|
||||
return Some(v);
|
||||
}
|
||||
|
||||
'exiting_out_skip_visited_traits: loop {
|
||||
if let Some(siblings) = siblings_opt {
|
||||
if let Some(next_inner_most_trait_ref) = siblings.next() {
|
||||
if visited.insert(next_inner_most_trait_ref.to_predicate(tcx)) {
|
||||
// We're throwing away potential constness of super traits here.
|
||||
// FIXME: handle ~const super traits
|
||||
let next_inner_most_trait_ref =
|
||||
next_inner_most_trait_ref.map_bound(|t| t.trait_ref);
|
||||
*inner_most_trait_ref = next_inner_most_trait_ref;
|
||||
*emit_vptr = emit_vptr_on_new_entry;
|
||||
break 'exiting_out;
|
||||
} else {
|
||||
continue 'exiting_out_skip_visited_traits;
|
||||
}
|
||||
}
|
||||
}
|
||||
stack.pop();
|
||||
continue 'exiting_out;
|
||||
}
|
||||
}
|
||||
// all done
|
||||
return None;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
fn dump_vtable_entries<'tcx>(
|
||||
tcx: TyCtxt<'tcx>,
|
||||
sp: Span,
|
||||
trait_ref: ty::PolyTraitRef<'tcx>,
|
||||
entries: &[VtblEntry<'tcx>],
|
||||
) {
|
||||
tcx.sess.emit_err(DumpVTableEntries {
|
||||
span: sp,
|
||||
trait_ref,
|
||||
entries: format!("{:#?}", entries),
|
||||
});
|
||||
}
|
||||
|
||||
fn own_existential_vtable_entries<'tcx>(tcx: TyCtxt<'tcx>, trait_def_id: DefId) -> &'tcx [DefId] {
|
||||
let trait_methods = tcx
|
||||
.associated_items(trait_def_id)
|
||||
.in_definition_order()
|
||||
.filter(|item| item.kind == ty::AssocKind::Fn);
|
||||
// Now list each method's DefId (for within its trait).
|
||||
let own_entries = trait_methods.filter_map(move |trait_method| {
|
||||
debug!("own_existential_vtable_entry: trait_method={:?}", trait_method);
|
||||
let def_id = trait_method.def_id;
|
||||
|
||||
// Some methods cannot be called on an object; skip those.
|
||||
if !is_vtable_safe_method(tcx, trait_def_id, &trait_method) {
|
||||
debug!("own_existential_vtable_entry: not vtable safe");
|
||||
return None;
|
||||
}
|
||||
|
||||
Some(def_id)
|
||||
});
|
||||
|
||||
tcx.arena.alloc_from_iter(own_entries.into_iter())
|
||||
}
|
||||
|
||||
/// Given a trait `trait_ref`, iterates the vtable entries
|
||||
/// that come from `trait_ref`, including its supertraits.
|
||||
fn vtable_entries<'tcx>(
|
||||
tcx: TyCtxt<'tcx>,
|
||||
trait_ref: ty::PolyTraitRef<'tcx>,
|
||||
) -> &'tcx [VtblEntry<'tcx>] {
|
||||
debug!("vtable_entries({:?})", trait_ref);
|
||||
|
||||
let mut entries = vec![];
|
||||
|
||||
let vtable_segment_callback = |segment| -> ControlFlow<()> {
|
||||
match segment {
|
||||
VtblSegment::MetadataDSA => {
|
||||
entries.extend(TyCtxt::COMMON_VTABLE_ENTRIES);
|
||||
}
|
||||
VtblSegment::TraitOwnEntries { trait_ref, emit_vptr } => {
|
||||
let existential_trait_ref = trait_ref
|
||||
.map_bound(|trait_ref| ty::ExistentialTraitRef::erase_self_ty(tcx, trait_ref));
|
||||
|
||||
// Lookup the shape of vtable for the trait.
|
||||
let own_existential_entries =
|
||||
tcx.own_existential_vtable_entries(existential_trait_ref.def_id());
|
||||
|
||||
let own_entries = own_existential_entries.iter().copied().map(|def_id| {
|
||||
debug!("vtable_entries: trait_method={:?}", def_id);
|
||||
|
||||
// The method may have some early-bound lifetimes; add regions for those.
|
||||
let substs = trait_ref.map_bound(|trait_ref| {
|
||||
InternalSubsts::for_item(tcx, def_id, |param, _| match param.kind {
|
||||
GenericParamDefKind::Lifetime => tcx.lifetimes.re_erased.into(),
|
||||
GenericParamDefKind::Type { .. }
|
||||
| GenericParamDefKind::Const { .. } => {
|
||||
trait_ref.substs[param.index as usize]
|
||||
}
|
||||
})
|
||||
});
|
||||
|
||||
// The trait type may have higher-ranked lifetimes in it;
|
||||
// erase them if they appear, so that we get the type
|
||||
// at some particular call site.
|
||||
let substs = tcx
|
||||
.normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), substs);
|
||||
|
||||
// It's possible that the method relies on where-clauses that
|
||||
// do not hold for this particular set of type parameters.
|
||||
// Note that this method could then never be called, so we
|
||||
// do not want to try and codegen it, in that case (see #23435).
|
||||
let predicates = tcx.predicates_of(def_id).instantiate_own(tcx, substs);
|
||||
if impossible_predicates(tcx, predicates.predicates) {
|
||||
debug!("vtable_entries: predicates do not hold");
|
||||
return VtblEntry::Vacant;
|
||||
}
|
||||
|
||||
let instance = ty::Instance::resolve_for_vtable(
|
||||
tcx,
|
||||
ty::ParamEnv::reveal_all(),
|
||||
def_id,
|
||||
substs,
|
||||
)
|
||||
.expect("resolution failed during building vtable representation");
|
||||
VtblEntry::Method(instance)
|
||||
});
|
||||
|
||||
entries.extend(own_entries);
|
||||
|
||||
if emit_vptr {
|
||||
entries.push(VtblEntry::TraitVPtr(trait_ref));
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
ControlFlow::Continue(())
|
||||
};
|
||||
|
||||
let _ = prepare_vtable_segments(tcx, trait_ref, vtable_segment_callback);
|
||||
|
||||
if tcx.has_attr(trait_ref.def_id(), sym::rustc_dump_vtable) {
|
||||
let sp = tcx.def_span(trait_ref.def_id());
|
||||
dump_vtable_entries(tcx, sp, trait_ref, &entries);
|
||||
}
|
||||
|
||||
tcx.arena.alloc_from_iter(entries.into_iter())
|
||||
}
|
||||
|
||||
/// Find slot base for trait methods within vtable entries of another trait
|
||||
pub(super) fn vtable_trait_first_method_offset<'tcx>(
|
||||
tcx: TyCtxt<'tcx>,
|
||||
key: (
|
||||
ty::PolyTraitRef<'tcx>, // trait_to_be_found
|
||||
ty::PolyTraitRef<'tcx>, // trait_owning_vtable
|
||||
),
|
||||
) -> usize {
|
||||
let (trait_to_be_found, trait_owning_vtable) = key;
|
||||
|
||||
// #90177
|
||||
let trait_to_be_found_erased = tcx.erase_regions(trait_to_be_found);
|
||||
|
||||
let vtable_segment_callback = {
|
||||
let mut vtable_base = 0;
|
||||
|
||||
move |segment| {
|
||||
match segment {
|
||||
VtblSegment::MetadataDSA => {
|
||||
vtable_base += TyCtxt::COMMON_VTABLE_ENTRIES.len();
|
||||
}
|
||||
VtblSegment::TraitOwnEntries { trait_ref, emit_vptr } => {
|
||||
if tcx.erase_regions(trait_ref) == trait_to_be_found_erased {
|
||||
return ControlFlow::Break(vtable_base);
|
||||
}
|
||||
vtable_base += count_own_vtable_entries(tcx, trait_ref);
|
||||
if emit_vptr {
|
||||
vtable_base += 1;
|
||||
}
|
||||
}
|
||||
}
|
||||
ControlFlow::Continue(())
|
||||
}
|
||||
};
|
||||
|
||||
if let Some(vtable_base) =
|
||||
prepare_vtable_segments(tcx, trait_owning_vtable, vtable_segment_callback)
|
||||
{
|
||||
vtable_base
|
||||
} else {
|
||||
bug!("Failed to find info for expected trait in vtable");
|
||||
}
|
||||
}
|
||||
|
||||
/// Find slot offset for trait vptr within vtable entries of another trait
|
||||
pub(crate) fn vtable_trait_upcasting_coercion_new_vptr_slot<'tcx>(
|
||||
tcx: TyCtxt<'tcx>,
|
||||
key: (
|
||||
Ty<'tcx>, // trait object type whose trait owning vtable
|
||||
Ty<'tcx>, // trait object for supertrait
|
||||
),
|
||||
) -> Option<usize> {
|
||||
let (source, target) = key;
|
||||
assert!(matches!(&source.kind(), &ty::Dynamic(..)) && !source.needs_infer());
|
||||
assert!(matches!(&target.kind(), &ty::Dynamic(..)) && !target.needs_infer());
|
||||
|
||||
// this has been typecked-before, so diagnostics is not really needed.
|
||||
let unsize_trait_did = tcx.require_lang_item(LangItem::Unsize, None);
|
||||
|
||||
let trait_ref = tcx.mk_trait_ref(unsize_trait_did, [source, target]);
|
||||
|
||||
match tcx.codegen_select_candidate((ty::ParamEnv::reveal_all(), ty::Binder::dummy(trait_ref))) {
|
||||
Ok(ImplSource::TraitUpcasting(implsrc_traitcasting)) => {
|
||||
implsrc_traitcasting.vtable_vptr_slot
|
||||
}
|
||||
otherwise => bug!("expected TraitUpcasting candidate, got {otherwise:?}"),
|
||||
}
|
||||
}
|
||||
|
||||
/// Given a trait `trait_ref`, returns the number of vtable entries
|
||||
/// that come from `trait_ref`, excluding its supertraits. Used in
|
||||
/// computing the vtable base for an upcast trait of a trait object.
|
||||
pub(crate) fn count_own_vtable_entries<'tcx>(
|
||||
tcx: TyCtxt<'tcx>,
|
||||
trait_ref: ty::PolyTraitRef<'tcx>,
|
||||
) -> usize {
|
||||
tcx.own_existential_vtable_entries(trait_ref.def_id()).len()
|
||||
}
|
||||
|
||||
pub(super) fn provide(providers: &mut ty::query::Providers) {
|
||||
*providers = ty::query::Providers {
|
||||
own_existential_vtable_entries,
|
||||
vtable_entries,
|
||||
vtable_trait_upcasting_coercion_new_vptr_slot,
|
||||
..*providers
|
||||
};
|
||||
}
|
Loading…
Add table
Add a link
Reference in a new issue