collecting lang items thru AST

compiler/rustc_ast_lowering/src/lib.rs

@@ -429,8 +429,10 @@ fn compute_hir_hash(
 }
 
 pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> hir::Crate<'_> {
+    println!("running lower_to_hir");
     let sess = tcx.sess;
     // Queries that borrow `resolver_for_lowering`.
+    tcx.ensure_with_value().get_lang_items(());
     tcx.ensure_with_value().output_filenames(());
     tcx.ensure_with_value().early_lint_checks(());
     tcx.ensure_with_value().debugger_visualizers(LOCAL_CRATE);
@@ -464,6 +466,7 @@ pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> hir::Crate<'_> {
     // Don't hash unless necessary, because it's expensive.
     let opt_hir_hash =
         if tcx.needs_crate_hash() { Some(compute_hir_hash(tcx, &owners)) } else { None };
+    println!("exiting lower_to_hir");
     hir::Crate { owners, opt_hir_hash }
 }
 

compiler/rustc_passes/src/lang_items.rs

@@ -7,21 +7,14 @@
 //! * Traits that represent operators; e.g., `Add`, `Sub`, `Index`.
 //! * Functions called by the compiler itself.
 
-use crate::check_attr::target_from_impl_item;
-use crate::errors::{
-    DuplicateLangItem, IncorrectTarget, LangItemOnIncorrectTarget, UnknownLangItem,
-};
-use crate::weak_lang_items;
+use crate::errors::DuplicateLangItem;
 
-use rustc_hir as hir;
-use rustc_hir::def::DefKind;
-use rustc_hir::def_id::{DefId, LocalDefId};
-use rustc_hir::lang_items::{extract, GenericRequirement};
-use rustc_hir::{LangItem, LanguageItems, Target};
+use rustc_ast::visit::Visitor;
+use rustc_hir::def_id::DefId;
+use rustc_hir::{LangItem, LanguageItems};
 use rustc_middle::ty::TyCtxt;
 use rustc_session::cstore::ExternCrate;
 use rustc_span::symbol::kw::Empty;
-use rustc_span::{sym, Span};
 
 use rustc_middle::query::Providers;
 
@@ -36,36 +29,13 @@ struct LanguageItemCollector<'tcx> {
     tcx: TyCtxt<'tcx>,
 }
 
+impl<'tcx, 'ast> Visitor<'ast> for LanguageItemCollector<'tcx> {}
+
 impl<'tcx> LanguageItemCollector<'tcx> {
     fn new(tcx: TyCtxt<'tcx>) -> LanguageItemCollector<'tcx> {
         LanguageItemCollector { tcx, items: LanguageItems::new() }
     }
 
-    fn check_for_lang(&mut self, actual_target: Target, def_id: LocalDefId) {
-        let attrs = self.tcx.hir().attrs(self.tcx.hir().local_def_id_to_hir_id(def_id));
-        if let Some((name, span)) = extract(&attrs) {
-            match LangItem::from_name(name) {
-                // Known lang item with attribute on correct target.
-                Some(lang_item) if actual_target == lang_item.target() => {
-                    self.collect_item_extended(lang_item, def_id, span);
-                }
-                // Known lang item with attribute on incorrect target.
-                Some(lang_item) => {
-                    self.tcx.sess.emit_err(LangItemOnIncorrectTarget {
-                        span,
-                        name,
-                        expected_target: lang_item.target(),
-                        actual_target,
-                    });
-                }
-                // Unknown lang item.
-                _ => {
-                    self.tcx.sess.emit_err(UnknownLangItem { span, name });
-                }
-            }
-        }
-    }
-
     fn collect_item(&mut self, lang_item: LangItem, item_def_id: DefId) {
         // Check for duplicates.
         if let Some(original_def_id) = self.items.get(lang_item) {
@@ -140,67 +110,6 @@ impl<'tcx> LanguageItemCollector<'tcx> {
         // Matched.
         self.items.set(lang_item, item_def_id);
     }
-
-    // Like collect_item() above, but also checks whether the lang item is declared
-    // with the right number of generic arguments.
-    fn collect_item_extended(&mut self, lang_item: LangItem, item_def_id: LocalDefId, span: Span) {
-        let name = lang_item.name();
-
-        // Now check whether the lang_item has the expected number of generic
-        // arguments. Generally speaking, binary and indexing operations have
-        // one (for the RHS/index), unary operations have none, the closure
-        // traits have one for the argument list, generators have one for the
-        // resume argument, and ordering/equality relations have one for the RHS
-        // Some other types like Box and various functions like drop_in_place
-        // have minimum requirements.
-
-        if let hir::Node::Item(hir::Item { kind, span: item_span, .. }) =
-            self.tcx.hir().get_by_def_id(item_def_id)
-        {
-            let (actual_num, generics_span) = match kind.generics() {
-                Some(generics) => (
-                    generics
-                        .params
-                        .iter()
-                        .filter(|p| !self.tcx.has_attr(p.def_id, sym::rustc_host))
-                        .count(),
-                    generics.span,
-                ),
-                None => (0, *item_span),
-            };
-
-            let mut at_least = false;
-            let required = match lang_item.required_generics() {
-                GenericRequirement::Exact(num) if num != actual_num => Some(num),
-                GenericRequirement::Minimum(num) if actual_num < num => {
-                    at_least = true;
-                    Some(num)}
-                ,
-                // If the number matches, or there is no requirement, handle it normally
-                _ => None,
-            };
-
-            if let Some(num) = required {
-                // We are issuing E0718 "incorrect target" here, because while the
-                // item kind of the target is correct, the target is still wrong
-                // because of the wrong number of generic arguments.
-                self.tcx.sess.emit_err(IncorrectTarget {
-                    span,
-                    generics_span,
-                    name: name.as_str(),
-                    kind: kind.descr(),
-                    num,
-                    actual_num,
-                    at_least,
-                });
-
-                // return early to not collect the lang item
-                return;
-            }
-        }
-
-        self.collect_item(lang_item, item_def_id.to_def_id());
-    }
 }
 
 /// Traverses and collects all the lang items in all crates.
@@ -216,39 +125,13 @@ fn get_lang_items(tcx: TyCtxt<'_>, (): ()) -> LanguageItems {
     }
 
     // Collect lang items in this crate.
-    let crate_items = tcx.hir_crate_items(());
-
-    for id in crate_items.items() {
-        collector
-            .check_for_lang(Target::from_def_kind(tcx.def_kind(id.owner_id)), id.owner_id.def_id);
-
-        if matches!(tcx.def_kind(id.owner_id), DefKind::Enum) {
-            let item = tcx.hir().item(id);
-            if let hir::ItemKind::Enum(def, ..) = &item.kind {
-                for variant in def.variants {
-                    collector.check_for_lang(Target::Variant, variant.def_id);
-                }
-            }
-        }
-    }
-
-    // FIXME: avoid calling trait_item() when possible
-    for id in crate_items.trait_items() {
-        let item = tcx.hir().trait_item(id);
-        collector.check_for_lang(Target::from_trait_item(item), item.owner_id.def_id)
-    }
-
-    // FIXME: avoid calling impl_item() when possible
-    for id in crate_items.impl_items() {
-        let item = tcx.hir().impl_item(id);
-        collector.check_for_lang(target_from_impl_item(tcx, item), item.owner_id.def_id)
-    }
+    let krate = &tcx.resolver_for_lowering(()).borrow().1;
+    println!("running visit_crate");
+    collector.visit_crate(&krate);
+    println!("exiting visit_crate");
 
     // Extract out the found lang items.
-    let LanguageItemCollector { mut items, .. } = collector;
-
-    // Find all required but not-yet-defined lang items.
-    weak_lang_items::check_crate(tcx, &mut items);
+    let LanguageItemCollector { items, .. } = collector;
 
     items
 }

compiler/rustc_passes/src/lib.rs

@@ -43,7 +43,6 @@ mod naked_functions;
 mod reachable;
 pub mod stability;
 mod upvars;
-mod weak_lang_items;
 
 fluent_messages! { "../messages.ftl" }