Encode LangItem directly

compiler/rustc_hir/src/lang_items.rs

@@ -42,7 +42,7 @@ macro_rules! expand_group {
 pub struct LanguageItems {
     /// Mappings from lang items to their possibly found [`DefId`]s.
     /// The index corresponds to the order in [`LangItem`].
-    pub items: Vec<Option<DefId>>,
+    items: Vec<Option<DefId>>,
     /// Lang items that were not found during collection.
     pub missing: Vec<LangItem>,
     /// Mapping from [`LangItemGroup`] discriminants to all
@@ -133,11 +133,6 @@ macro_rules! language_item_table {
                 }
             }
 
-            /// Returns the mappings to the possibly found `DefId`s for each lang item.
-            pub fn items(&self) -> &[Option<DefId>] {
-                &*self.items
-            }
-
             /// Returns the [`DefId`]s of all lang items in a group.
             pub fn group(&self, group: LangItemGroup) -> &[DefId] {
                 self.groups[group as usize].as_ref()

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -15,7 +15,6 @@ use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
 use rustc_hir::def_id::{CrateNum, DefId, DefIndex, CRATE_DEF_INDEX, LOCAL_CRATE};
 use rustc_hir::definitions::{DefKey, DefPath, DefPathData, DefPathHash};
 use rustc_hir::diagnostic_items::DiagnosticItems;
-use rustc_hir::lang_items;
 use rustc_index::vec::{Idx, IndexVec};
 use rustc_middle::metadata::ModChild;
 use rustc_middle::middle::exported_symbols::{ExportedSymbol, SymbolExportInfo};
@@ -967,7 +966,7 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
     }
 
     /// Iterates over the language items in the given crate.
-    fn get_lang_items(self, tcx: TyCtxt<'tcx>) -> &'tcx [(DefId, usize)] {
+    fn get_lang_items(self, tcx: TyCtxt<'tcx>) -> &'tcx [(DefId, LangItem)] {
         tcx.arena.alloc_from_iter(
             self.root
                 .lang_items
@@ -1319,7 +1318,7 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
         )
     }
 
-    fn get_missing_lang_items(self, tcx: TyCtxt<'tcx>) -> &'tcx [lang_items::LangItem] {
+    fn get_missing_lang_items(self, tcx: TyCtxt<'tcx>) -> &'tcx [LangItem] {
         tcx.arena.alloc_from_iter(self.root.lang_items_missing.decode(self))
     }
 

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -17,7 +17,7 @@ use rustc_hir::def_id::{
 };
 use rustc_hir::definitions::DefPathData;
 use rustc_hir::intravisit::{self, Visitor};
-use rustc_hir::lang_items;
+use rustc_hir::lang_items::LangItem;
 use rustc_middle::hir::nested_filter;
 use rustc_middle::middle::dependency_format::Linkage;
 use rustc_middle::middle::exported_symbols::{
@@ -1905,22 +1905,15 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         self.lazy_array(diagnostic_items.iter().map(|(&name, def_id)| (name, def_id.index)))
     }
 
-    fn encode_lang_items(&mut self) -> LazyArray<(DefIndex, usize)> {
+    fn encode_lang_items(&mut self) -> LazyArray<(DefIndex, LangItem)> {
         empty_proc_macro!(self);
-        let tcx = self.tcx;
+        let lang_items = self.tcx.lang_items().iter();
-        let lang_items = tcx.lang_items();
+        self.lazy_array(lang_items.filter_map(|(lang_item, def_id)| {
-        let lang_items = lang_items.items().iter();
+            def_id.as_local().map(|id| (id.local_def_index, lang_item))
-        self.lazy_array(lang_items.enumerate().filter_map(|(i, &opt_def_id)| {
-            if let Some(def_id) = opt_def_id {
-                if def_id.is_local() {
-                    return Some((def_id.index, i));
-                }
-            }
-            None
         }))
     }
 
-    fn encode_lang_items_missing(&mut self) -> LazyArray<lang_items::LangItem> {
+    fn encode_lang_items_missing(&mut self) -> LazyArray<LangItem> {
         empty_proc_macro!(self);
         let tcx = self.tcx;
         self.lazy_array(&tcx.lang_items().missing)

compiler/rustc_metadata/src/rmeta/mod.rs

@@ -12,7 +12,7 @@ use rustc_hir as hir;
 use rustc_hir::def::{CtorKind, DefKind};
 use rustc_hir::def_id::{CrateNum, DefId, DefIndex, DefPathHash, StableCrateId};
 use rustc_hir::definitions::DefKey;
-use rustc_hir::lang_items;
+use rustc_hir::lang_items::LangItem;
 use rustc_index::bit_set::{BitSet, FiniteBitSet};
 use rustc_index::vec::IndexVec;
 use rustc_middle::metadata::ModChild;
@@ -230,8 +230,8 @@ pub(crate) struct CrateRoot {
     dylib_dependency_formats: LazyArray<Option<LinkagePreference>>,
     lib_features: LazyArray<(Symbol, Option<Symbol>)>,
     stability_implications: LazyArray<(Symbol, Symbol)>,
-    lang_items: LazyArray<(DefIndex, usize)>,
+    lang_items: LazyArray<(DefIndex, LangItem)>,
-    lang_items_missing: LazyArray<lang_items::LangItem>,
+    lang_items_missing: LazyArray<LangItem>,
     diagnostic_items: LazyArray<(Symbol, DefIndex)>,
     native_libraries: LazyArray<NativeLib>,
     foreign_modules: LazyArray<ForeignModule>,

compiler/rustc_middle/src/query/mod.rs

@@ -1705,7 +1705,7 @@ rustc_queries! {
     }
 
     /// Returns the lang items defined in another crate by loading it from metadata.
-    query defined_lang_items(_: CrateNum) -> &'tcx [(DefId, usize)] {
+    query defined_lang_items(_: CrateNum) -> &'tcx [(DefId, LangItem)] {
         desc { "calculating the lang items defined in a crate" }
         separate_provide_extern
     }

compiler/rustc_passes/src/lang_items.rs

@@ -65,12 +65,12 @@ impl<'tcx> LanguageItemCollector<'tcx> {
         }
     }
 
-    fn collect_item(&mut self, item_index: usize, item_def_id: DefId) {
+    fn collect_item(&mut self, lang_item: LangItem, item_def_id: DefId) {
         // Check for duplicates.
-        if let Some(original_def_id) = self.items.items[item_index] {
+        if let Some(original_def_id) = self.items.get(lang_item) {
             if original_def_id != item_def_id {
                 let local_span = self.tcx.hir().span_if_local(item_def_id);
-                let lang_item_name = LangItem::from_u32(item_index as u32).unwrap().name();
+                let lang_item_name = lang_item.name();
                 let crate_name = self.tcx.crate_name(item_def_id.krate);
                 let mut dependency_of = Empty;
                 let is_local = item_def_id.is_local();
@@ -139,8 +139,8 @@ impl<'tcx> LanguageItemCollector<'tcx> {
         }
 
         // Matched.
-        self.items.items[item_index] = Some(item_def_id);
+        self.items.set(lang_item, item_def_id);
-        if let Some(group) = LangItem::from_u32(item_index as u32).unwrap().group() {
+        if let Some(group) = lang_item.group() {
             self.items.groups[group as usize].push(item_def_id);
         }
     }
@@ -197,7 +197,7 @@ impl<'tcx> LanguageItemCollector<'tcx> {
             }
         }
 
-        self.collect_item(item_index, item_def_id);
+        self.collect_item(lang_item, item_def_id);
     }
 }
 
@@ -208,8 +208,8 @@ fn get_lang_items(tcx: TyCtxt<'_>, (): ()) -> LanguageItems {
 
     // Collect lang items in other crates.
     for &cnum in tcx.crates(()).iter() {
-        for &(def_id, item_index) in tcx.defined_lang_items(cnum).iter() {
+        for &(def_id, lang_item) in tcx.defined_lang_items(cnum).iter() {
-            collector.collect_item(item_index, def_id);
+            collector.collect_item(lang_item, def_id);
         }
     }