rustc_typeck to rustc_hir_analysis
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lcnr
parent
de0b511daa
commit
1fc86a63f4
140 changed files with 101 additions and 102 deletions
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@ -0,0 +1,307 @@
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use rustc_data_structures::fx::{FxHashMap, FxHashSet};
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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::DefId;
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use rustc_index::vec::IndexVec;
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use rustc_middle::traits::specialization_graph::OverlapMode;
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use rustc_middle::ty::{self, TyCtxt};
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use rustc_span::Symbol;
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use rustc_trait_selection::traits::{self, SkipLeakCheck};
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use smallvec::SmallVec;
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use std::collections::hash_map::Entry;
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pub fn crate_inherent_impls_overlap_check(tcx: TyCtxt<'_>, (): ()) {
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let mut inherent_overlap_checker = InherentOverlapChecker { tcx };
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for id in tcx.hir().items() {
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inherent_overlap_checker.check_item(id);
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}
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}
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struct InherentOverlapChecker<'tcx> {
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tcx: TyCtxt<'tcx>,
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}
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impl<'tcx> InherentOverlapChecker<'tcx> {
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/// Checks whether any associated items in impls 1 and 2 share the same identifier and
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/// namespace.
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fn impls_have_common_items(
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&self,
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impl_items1: &ty::AssocItems<'_>,
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impl_items2: &ty::AssocItems<'_>,
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) -> bool {
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let mut impl_items1 = &impl_items1;
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let mut impl_items2 = &impl_items2;
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// Performance optimization: iterate over the smaller list
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if impl_items1.len() > impl_items2.len() {
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std::mem::swap(&mut impl_items1, &mut impl_items2);
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}
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for item1 in impl_items1.in_definition_order() {
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let collision = impl_items2
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.filter_by_name_unhygienic(item1.name)
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.any(|item2| self.compare_hygienically(item1, item2));
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if collision {
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return true;
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}
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}
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false
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}
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fn compare_hygienically(&self, item1: &ty::AssocItem, item2: &ty::AssocItem) -> bool {
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// Symbols and namespace match, compare hygienically.
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item1.kind.namespace() == item2.kind.namespace()
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&& item1.ident(self.tcx).normalize_to_macros_2_0()
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== item2.ident(self.tcx).normalize_to_macros_2_0()
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}
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fn check_for_common_items_in_impls(
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&self,
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impl1: DefId,
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impl2: DefId,
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overlap: traits::OverlapResult<'_>,
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) {
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let impl_items1 = self.tcx.associated_items(impl1);
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let impl_items2 = self.tcx.associated_items(impl2);
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for item1 in impl_items1.in_definition_order() {
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let collision = impl_items2
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.filter_by_name_unhygienic(item1.name)
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.find(|item2| self.compare_hygienically(item1, item2));
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if let Some(item2) = collision {
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let name = item1.ident(self.tcx).normalize_to_macros_2_0();
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let mut err = struct_span_err!(
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self.tcx.sess,
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self.tcx.def_span(item1.def_id),
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E0592,
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"duplicate definitions with name `{}`",
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name
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);
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err.span_label(
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self.tcx.def_span(item1.def_id),
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format!("duplicate definitions for `{}`", name),
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);
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err.span_label(
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self.tcx.def_span(item2.def_id),
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format!("other definition for `{}`", name),
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);
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for cause in &overlap.intercrate_ambiguity_causes {
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cause.add_intercrate_ambiguity_hint(&mut err);
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}
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if overlap.involves_placeholder {
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traits::add_placeholder_note(&mut err);
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}
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err.emit();
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}
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}
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}
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fn check_for_overlapping_inherent_impls(
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&self,
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overlap_mode: OverlapMode,
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impl1_def_id: DefId,
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impl2_def_id: DefId,
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) {
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traits::overlapping_impls(
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self.tcx,
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impl1_def_id,
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impl2_def_id,
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// We go ahead and just skip the leak check for
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// inherent impls without warning.
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SkipLeakCheck::Yes,
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overlap_mode,
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|overlap| {
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self.check_for_common_items_in_impls(impl1_def_id, impl2_def_id, overlap);
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false
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},
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|| true,
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);
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}
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fn check_item(&mut self, id: hir::ItemId) {
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let def_kind = self.tcx.def_kind(id.def_id);
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if !matches!(def_kind, DefKind::Enum | DefKind::Struct | DefKind::Trait | DefKind::Union) {
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return;
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}
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let impls = self.tcx.inherent_impls(id.def_id);
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// If there is only one inherent impl block,
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// there is nothing to overlap check it with
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if impls.len() <= 1 {
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return;
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}
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let overlap_mode = OverlapMode::get(self.tcx, id.def_id.to_def_id());
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let impls_items = impls
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.iter()
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.map(|impl_def_id| (impl_def_id, self.tcx.associated_items(*impl_def_id)))
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.collect::<SmallVec<[_; 8]>>();
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// Perform a O(n^2) algorithm for small n,
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// otherwise switch to an allocating algorithm with
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// faster asymptotic runtime.
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const ALLOCATING_ALGO_THRESHOLD: usize = 500;
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if impls.len() < ALLOCATING_ALGO_THRESHOLD {
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for (i, &(&impl1_def_id, impl_items1)) in impls_items.iter().enumerate() {
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for &(&impl2_def_id, impl_items2) in &impls_items[(i + 1)..] {
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if self.impls_have_common_items(impl_items1, impl_items2) {
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self.check_for_overlapping_inherent_impls(
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overlap_mode,
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impl1_def_id,
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impl2_def_id,
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);
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}
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}
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}
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} else {
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// Build a set of connected regions of impl blocks.
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// Two impl blocks are regarded as connected if they share
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// an item with the same unhygienic identifier.
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// After we have assembled the connected regions,
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// run the O(n^2) algorithm on each connected region.
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// This is advantageous to running the algorithm over the
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// entire graph when there are many connected regions.
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rustc_index::newtype_index! {
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pub struct RegionId {
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ENCODABLE = custom
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}
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}
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struct ConnectedRegion {
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idents: SmallVec<[Symbol; 8]>,
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impl_blocks: FxHashSet<usize>,
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}
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let mut connected_regions: IndexVec<RegionId, _> = Default::default();
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// Reverse map from the Symbol to the connected region id.
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let mut connected_region_ids = FxHashMap::default();
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for (i, &(&_impl_def_id, impl_items)) in impls_items.iter().enumerate() {
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if impl_items.len() == 0 {
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continue;
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}
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// First obtain a list of existing connected region ids
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let mut idents_to_add = SmallVec::<[Symbol; 8]>::new();
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let mut ids = impl_items
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.in_definition_order()
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.filter_map(|item| {
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let entry = connected_region_ids.entry(item.name);
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if let Entry::Occupied(e) = &entry {
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Some(*e.get())
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} else {
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idents_to_add.push(item.name);
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None
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}
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})
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.collect::<SmallVec<[RegionId; 8]>>();
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// Sort the id list so that the algorithm is deterministic
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ids.sort_unstable();
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ids.dedup();
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let ids = ids;
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match &ids[..] {
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// Create a new connected region
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[] => {
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let id_to_set = connected_regions.next_index();
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// Update the connected region ids
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for ident in &idents_to_add {
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connected_region_ids.insert(*ident, id_to_set);
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}
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connected_regions.insert(
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id_to_set,
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ConnectedRegion {
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idents: idents_to_add,
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impl_blocks: std::iter::once(i).collect(),
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},
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);
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}
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// Take the only id inside the list
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&[id_to_set] => {
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let region = connected_regions[id_to_set].as_mut().unwrap();
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region.impl_blocks.insert(i);
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region.idents.extend_from_slice(&idents_to_add);
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// Update the connected region ids
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for ident in &idents_to_add {
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connected_region_ids.insert(*ident, id_to_set);
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}
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}
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// We have multiple connected regions to merge.
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// In the worst case this might add impl blocks
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// one by one and can thus be O(n^2) in the size
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// of the resulting final connected region, but
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// this is no issue as the final step to check
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// for overlaps runs in O(n^2) as well.
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&[id_to_set, ..] => {
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let mut region = connected_regions.remove(id_to_set).unwrap();
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region.impl_blocks.insert(i);
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region.idents.extend_from_slice(&idents_to_add);
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// Update the connected region ids
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for ident in &idents_to_add {
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connected_region_ids.insert(*ident, id_to_set);
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}
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// Remove other regions from ids.
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for &id in ids.iter() {
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if id == id_to_set {
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continue;
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}
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let r = connected_regions.remove(id).unwrap();
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for ident in r.idents.iter() {
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connected_region_ids.insert(*ident, id_to_set);
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}
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region.idents.extend_from_slice(&r.idents);
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region.impl_blocks.extend(r.impl_blocks);
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}
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connected_regions.insert(id_to_set, region);
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}
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}
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}
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debug!(
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"churning through {} components (sum={}, avg={}, var={}, max={})",
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connected_regions.len(),
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impls.len(),
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impls.len() / connected_regions.len(),
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{
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let avg = impls.len() / connected_regions.len();
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let s = connected_regions
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.iter()
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.flatten()
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.map(|r| r.impl_blocks.len() as isize - avg as isize)
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.map(|v| v.abs() as usize)
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.sum::<usize>();
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s / connected_regions.len()
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},
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connected_regions.iter().flatten().map(|r| r.impl_blocks.len()).max().unwrap()
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);
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// List of connected regions is built. Now, run the overlap check
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// for each pair of impl blocks in the same connected region.
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for region in connected_regions.into_iter().flatten() {
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let mut impl_blocks =
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region.impl_blocks.into_iter().collect::<SmallVec<[usize; 8]>>();
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impl_blocks.sort_unstable();
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for (i, &impl1_items_idx) in impl_blocks.iter().enumerate() {
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let &(&impl1_def_id, impl_items1) = &impls_items[impl1_items_idx];
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for &impl2_items_idx in impl_blocks[(i + 1)..].iter() {
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let &(&impl2_def_id, impl_items2) = &impls_items[impl2_items_idx];
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if self.impls_have_common_items(impl_items1, impl_items2) {
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self.check_for_overlapping_inherent_impls(
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overlap_mode,
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impl1_def_id,
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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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}
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}
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}
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