251 lines
9.3 KiB
Rust
251 lines
9.3 KiB
Rust
//! Detecting language items.
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//!
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//! Language items are items that represent concepts intrinsic to the language
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//! itself. Examples are:
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//!
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//! * Traits that specify "kinds"; e.g., `Sync`, `Send`.
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//! * Traits that represent operators; e.g., `Add`, `Sub`, `Index`.
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//! * Functions called by the compiler itself.
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use crate::check_attr::target_from_impl_item;
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use crate::errors::{
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DuplicateLangItem, IncorrectTarget, LangItemOnIncorrectTarget, UnknownLangItem,
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};
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use crate::weak_lang_items;
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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, LocalDefId};
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use rustc_hir::lang_items::{extract, GenericRequirement};
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use rustc_hir::{LangItem, LanguageItems, Target};
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use rustc_middle::ty::TyCtxt;
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use rustc_session::cstore::ExternCrate;
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use rustc_span::{symbol::kw::Empty, Span};
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use rustc_middle::ty::query::Providers;
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pub(crate) enum Duplicate {
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Plain,
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Crate,
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CrateDepends,
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}
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struct LanguageItemCollector<'tcx> {
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items: LanguageItems,
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tcx: TyCtxt<'tcx>,
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}
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impl<'tcx> LanguageItemCollector<'tcx> {
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fn new(tcx: TyCtxt<'tcx>) -> LanguageItemCollector<'tcx> {
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LanguageItemCollector { tcx, items: LanguageItems::new() }
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}
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fn check_for_lang(&mut self, actual_target: Target, def_id: LocalDefId) {
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let attrs = self.tcx.hir().attrs(self.tcx.hir().local_def_id_to_hir_id(def_id));
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if let Some((name, span)) = extract(&attrs) {
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match LangItem::from_name(name) {
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// Known lang item with attribute on correct target.
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Some(lang_item) if actual_target == lang_item.target() => {
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self.collect_item_extended(lang_item, def_id, span);
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}
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// Known lang item with attribute on incorrect target.
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Some(lang_item) => {
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self.tcx.sess.emit_err(LangItemOnIncorrectTarget {
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span,
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name,
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expected_target: lang_item.target(),
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actual_target,
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});
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}
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// Unknown lang item.
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_ => {
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self.tcx.sess.emit_err(UnknownLangItem { span, name });
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}
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}
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}
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}
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fn collect_item(&mut self, lang_item: LangItem, item_def_id: DefId) {
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// Check for duplicates.
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if let Some(original_def_id) = self.items.get(lang_item) {
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if original_def_id != item_def_id {
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let local_span = self.tcx.hir().span_if_local(item_def_id);
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let lang_item_name = lang_item.name();
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let crate_name = self.tcx.crate_name(item_def_id.krate);
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let mut dependency_of = Empty;
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let is_local = item_def_id.is_local();
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let path = if is_local {
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String::new()
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} else {
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self.tcx
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.crate_extern_paths(item_def_id.krate)
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.iter()
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.map(|p| p.display().to_string())
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.collect::<Vec<_>>()
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.join(", ")
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};
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let first_defined_span = self.tcx.hir().span_if_local(original_def_id);
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let mut orig_crate_name = Empty;
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let mut orig_dependency_of = Empty;
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let orig_is_local = original_def_id.is_local();
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let orig_path = if orig_is_local {
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String::new()
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} else {
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self.tcx
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.crate_extern_paths(original_def_id.krate)
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.iter()
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.map(|p| p.display().to_string())
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.collect::<Vec<_>>()
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.join(", ")
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};
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if first_defined_span.is_none() {
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orig_crate_name = self.tcx.crate_name(original_def_id.krate);
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if let Some(ExternCrate { dependency_of: inner_dependency_of, .. }) =
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self.tcx.extern_crate(original_def_id)
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{
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orig_dependency_of = self.tcx.crate_name(*inner_dependency_of);
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}
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}
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let duplicate = if local_span.is_some() {
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Duplicate::Plain
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} else {
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match self.tcx.extern_crate(item_def_id) {
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Some(ExternCrate { dependency_of: inner_dependency_of, .. }) => {
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dependency_of = self.tcx.crate_name(*inner_dependency_of);
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Duplicate::CrateDepends
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}
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_ => Duplicate::Crate,
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}
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};
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self.tcx.sess.emit_err(DuplicateLangItem {
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local_span,
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lang_item_name,
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crate_name,
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dependency_of,
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is_local,
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path,
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first_defined_span,
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orig_crate_name,
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orig_dependency_of,
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orig_is_local,
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orig_path,
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duplicate,
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});
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}
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}
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// Matched.
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self.items.set(lang_item, item_def_id);
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}
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// Like collect_item() above, but also checks whether the lang item is declared
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// with the right number of generic arguments.
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fn collect_item_extended(&mut self, lang_item: LangItem, item_def_id: LocalDefId, span: Span) {
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let name = lang_item.name();
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// Now check whether the lang_item has the expected number of generic
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// arguments. Generally speaking, binary and indexing operations have
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// one (for the RHS/index), unary operations have none, the closure
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// traits have one for the argument list, generators have one for the
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// resume argument, and ordering/equality relations have one for the RHS
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// Some other types like Box and various functions like drop_in_place
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// have minimum requirements.
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if let hir::Node::Item(hir::Item { kind, span: item_span, .. }) =
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self.tcx.hir().get_by_def_id(item_def_id)
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{
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let (actual_num, generics_span) = match kind.generics() {
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Some(generics) => (generics.params.len(), generics.span),
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None => (0, *item_span),
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};
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let mut at_least = false;
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let required = match lang_item.required_generics() {
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GenericRequirement::Exact(num) if num != actual_num => Some(num),
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GenericRequirement::Minimum(num) if actual_num < num => {
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at_least = true;
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Some(num)}
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,
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// If the number matches, or there is no requirement, handle it normally
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_ => None,
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};
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if let Some(num) = required {
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// We are issuing E0718 "incorrect target" here, because while the
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// item kind of the target is correct, the target is still wrong
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// because of the wrong number of generic arguments.
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self.tcx.sess.emit_err(IncorrectTarget {
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span,
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generics_span,
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name: name.as_str(),
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kind: kind.descr(),
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num,
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actual_num,
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at_least,
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});
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// return early to not collect the lang item
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return;
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}
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}
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self.collect_item(lang_item, item_def_id.to_def_id());
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}
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}
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/// Traverses and collects all the lang items in all crates.
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fn get_lang_items(tcx: TyCtxt<'_>, (): ()) -> LanguageItems {
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// Initialize the collector.
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let mut collector = LanguageItemCollector::new(tcx);
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// Collect lang items in other crates.
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for &cnum in tcx.crates(()).iter() {
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for &(def_id, lang_item) in tcx.defined_lang_items(cnum).iter() {
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collector.collect_item(lang_item, def_id);
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}
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}
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// Collect lang items in this crate.
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let crate_items = tcx.hir_crate_items(());
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for id in crate_items.items() {
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collector
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.check_for_lang(Target::from_def_kind(tcx.def_kind(id.owner_id)), id.owner_id.def_id);
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if matches!(tcx.def_kind(id.owner_id), DefKind::Enum) {
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let item = tcx.hir().item(id);
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if let hir::ItemKind::Enum(def, ..) = &item.kind {
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for variant in def.variants {
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collector.check_for_lang(Target::Variant, variant.def_id);
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}
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}
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}
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}
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// FIXME: avoid calling trait_item() when possible
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for id in crate_items.trait_items() {
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let item = tcx.hir().trait_item(id);
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collector.check_for_lang(Target::from_trait_item(item), item.owner_id.def_id)
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}
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// FIXME: avoid calling impl_item() when possible
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for id in crate_items.impl_items() {
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let item = tcx.hir().impl_item(id);
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collector.check_for_lang(target_from_impl_item(tcx, item), item.owner_id.def_id)
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}
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// Extract out the found lang items.
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let LanguageItemCollector { mut items, .. } = collector;
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// Find all required but not-yet-defined lang items.
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weak_lang_items::check_crate(tcx, &mut items);
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items
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}
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pub fn provide(providers: &mut Providers) {
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providers.get_lang_items = get_lang_items;
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}
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