hir: consistent use and naming of lang items

This commit adjusts the naming of various lang items so that they are
consistent and don't include prefixes containing the target or
"LangItem". In addition, lang item variants are no longer exported from
the `lang_items` module.

Signed-off-by: David Wood <david@davidtw.co>

Author: davidtwco

src/librustc_ast_lowering/lib.rs

@@ -2058,7 +2058,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
 
         hir::GenericBound::LangItemTrait(
             // ::std::future::Future<future_params>
-            hir::LangItem::FutureTraitLangItem,
+            hir::LangItem::Future,
             span,
             self.next_id(),
             future_args,

src/librustc_codegen_ssa/base.rs

@@ -31,7 +31,7 @@ use rustc_data_structures::profiling::print_time_passes_entry;
 use rustc_data_structures::sync::{par_iter, Lock, ParallelIterator};
 use rustc_hir as hir;
 use rustc_hir::def_id::{LocalDefId, LOCAL_CRATE};
-use rustc_hir::lang_items::StartFnLangItem;
+use rustc_hir::lang_items::LangItem;
 use rustc_index::vec::Idx;
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
 use rustc_middle::middle::cstore::EncodedMetadata;
@@ -458,7 +458,7 @@ pub fn maybe_create_entry_wrapper<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
         let (arg_argc, arg_argv) = get_argc_argv(cx, &mut bx);
 
         let (start_fn, args) = if use_start_lang_item {
-            let start_def_id = cx.tcx().require_lang_item(StartFnLangItem, None);
+            let start_def_id = cx.tcx().require_lang_item(LangItem::Start, None);
             let start_fn = cx.get_fn_addr(
                 ty::Instance::resolve(
                     cx.tcx(),

src/librustc_codegen_ssa/mir/block.rs

@@ -10,7 +10,7 @@ use crate::traits::*;
 use crate::MemFlags;
 
 use rustc_ast as ast;
-use rustc_hir::lang_items;
+use rustc_hir::lang_items::LangItem;
 use rustc_index::vec::Idx;
 use rustc_middle::mir;
 use rustc_middle::mir::interpret::{AllocId, ConstValue, Pointer, Scalar};
@@ -420,14 +420,14 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 let index = self.codegen_operand(&mut bx, index).immediate();
                 // It's `fn panic_bounds_check(index: usize, len: usize)`,
                 // and `#[track_caller]` adds an implicit third argument.
-                (lang_items::PanicBoundsCheckFnLangItem, vec![index, len, location])
+                (LangItem::PanicBoundsCheck, vec![index, len, location])
             }
             _ => {
                 let msg_str = Symbol::intern(msg.description());
                 let msg = bx.const_str(msg_str);
                 // It's `pub fn panic(expr: &str)`, with the wide reference being passed
                 // as two arguments, and `#[track_caller]` adds an implicit third argument.
-                (lang_items::PanicFnLangItem, vec![msg.0, msg.1, location])
+                (LangItem::Panic, vec![msg.0, msg.1, location])
             }
         };
 
@@ -492,8 +492,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
 
                 // Obtain the panic entry point.
                 // FIXME: dedup this with `codegen_assert_terminator` above.
-                let def_id =
-                    common::langcall(bx.tcx(), Some(span), "", lang_items::PanicFnLangItem);
+                let def_id = common::langcall(bx.tcx(), Some(span), "", LangItem::Panic);
                 let instance = ty::Instance::mono(bx.tcx(), def_id);
                 let fn_abi = FnAbi::of_instance(bx, instance, &[]);
                 let llfn = bx.get_fn_addr(instance);

src/librustc_codegen_ssa/mir/rvalue.rs

@@ -8,7 +8,7 @@ use crate::traits::*;
 use crate::MemFlags;
 
 use rustc_apfloat::{ieee, Float, Round, Status};
-use rustc_hir::lang_items::ExchangeMallocFnLangItem;
+use rustc_hir::lang_items::LangItem;
 use rustc_middle::mir;
 use rustc_middle::ty::cast::{CastTy, IntTy};
 use rustc_middle::ty::layout::{HasTyCtxt, TyAndLayout};
@@ -507,7 +507,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 let llty_ptr = bx.cx().backend_type(box_layout);
 
                 // Allocate space:
-                let def_id = match bx.tcx().lang_items().require(ExchangeMallocFnLangItem) {
+                let def_id = match bx.tcx().lang_items().require(LangItem::ExchangeMalloc) {
                     Ok(id) => id,
                     Err(s) => {
                         bx.cx().sess().fatal(&format!("allocation of `{}` {}", box_layout.ty, s));

src/librustc_hir/lang_items.rs

@@ -15,7 +15,7 @@ macro_rules! weak_lang_items {
 lazy_static! {
     pub static ref WEAK_ITEMS_REFS: FxHashMap<Symbol, LangItem> = {
         let mut map = FxHashMap::default();
-        $(map.insert(sym::$name, lang_items::$item);)*
+        $(map.insert(sym::$name, LangItem::$item);)*
         map
     };
 }
@@ -46,7 +46,7 @@ impl LanguageItems {
 ) }
 
 weak_lang_items! {
-    panic_impl,         PanicImplLangItem,          rust_begin_unwind;
-    eh_personality,     EhPersonalityLangItem,      rust_eh_personality;
-    oom,                OomLangItem,                rust_oom;
+    panic_impl,         PanicImpl,          rust_begin_unwind;
+    eh_personality,     EhPersonality,      rust_eh_personality;
+    oom,                Oom,                rust_oom;
 }

src/librustc_hir/weak_lang_items.rs

@@ -53,7 +53,7 @@ pub fn required(tcx: TyCtxt<'_>, lang_item: LangItem) -> bool {
     // symbols. Other panic runtimes ensure that the relevant symbols are
     // available to link things together, but they're never exercised.
     match tcx.sess.panic_strategy() {
-        PanicStrategy::Abort => lang_item != LangItem::EhPersonalityLangItem,
+        PanicStrategy::Abort => lang_item != LangItem::EhPersonality,
         PanicStrategy::Unwind => true,
     }
 }

src/librustc_middle/middle/lang_items.rs

@@ -2,7 +2,7 @@ use crate::ty::subst::SubstsRef;
 use crate::ty::{self, Ty, TyCtxt};
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
-use rustc_hir::lang_items::{DerefMutTraitLangItem, DerefTraitLangItem};
+use rustc_hir::lang_items::LangItem;
 use rustc_macros::HashStable;
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
@@ -118,8 +118,8 @@ pub struct OverloadedDeref<'tcx> {
 impl<'tcx> OverloadedDeref<'tcx> {
     pub fn method_call(&self, tcx: TyCtxt<'tcx>, source: Ty<'tcx>) -> (DefId, SubstsRef<'tcx>) {
         let trait_def_id = match self.mutbl {
-            hir::Mutability::Not => tcx.require_lang_item(DerefTraitLangItem, None),
-            hir::Mutability::Mut => tcx.require_lang_item(DerefMutTraitLangItem, None),
+            hir::Mutability::Not => tcx.require_lang_item(LangItem::Deref, None),
+            hir::Mutability::Mut => tcx.require_lang_item(LangItem::DerefMut, None),
         };
         let method_def_id = tcx
             .associated_items(trait_def_id)

src/librustc_middle/ty/adjustment.rs

@@ -40,7 +40,7 @@ use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LocalDefId, LOCAL_CRATE};
 use rustc_hir::definitions::{DefPathHash, Definitions};
 use rustc_hir::intravisit::Visitor;
-use rustc_hir::lang_items::{self, PanicLocationLangItem};
+use rustc_hir::lang_items::LangItem;
 use rustc_hir::{HirId, ItemKind, ItemLocalId, ItemLocalMap, ItemLocalSet, Node, TraitCandidate};
 use rustc_index::vec::{Idx, IndexVec};
 use rustc_macros::HashStable;
@@ -1538,7 +1538,7 @@ impl<'tcx> TyCtxt<'tcx> {
     pub fn caller_location_ty(&self) -> Ty<'tcx> {
         self.mk_imm_ref(
             self.lifetimes.re_static,
-            self.type_of(self.require_lang_item(PanicLocationLangItem, None))
+            self.type_of(self.require_lang_item(LangItem::PanicLocation, None))
                 .subst(*self, self.mk_substs([self.lifetimes.re_static.into()].iter())),
         )
     }
@@ -2185,12 +2185,12 @@ impl<'tcx> TyCtxt<'tcx> {
 
     #[inline]
     pub fn mk_box(self, ty: Ty<'tcx>) -> Ty<'tcx> {
-        let def_id = self.require_lang_item(lang_items::OwnedBoxLangItem, None);
+        let def_id = self.require_lang_item(LangItem::OwnedBox, None);
         self.mk_generic_adt(def_id, ty)
     }
 
     #[inline]
-    pub fn mk_lang_item(self, ty: Ty<'tcx>, item: lang_items::LangItem) -> Option<Ty<'tcx>> {
+    pub fn mk_lang_item(self, ty: Ty<'tcx>, item: LangItem) -> Option<Ty<'tcx>> {
         let def_id = self.lang_items().require(item).ok()?;
         Some(self.mk_generic_adt(def_id, ty))
     }
@@ -2203,7 +2203,7 @@ impl<'tcx> TyCtxt<'tcx> {
 
     #[inline]
     pub fn mk_maybe_uninit(self, ty: Ty<'tcx>) -> Ty<'tcx> {
-        let def_id = self.require_lang_item(lang_items::MaybeUninitLangItem, None);
+        let def_id = self.require_lang_item(LangItem::MaybeUninit, None);
         self.mk_generic_adt(def_id, ty)
     }
 

src/librustc_middle/ty/context.rs

@@ -5,7 +5,7 @@ use crate::ty::{self, SubstsRef, Ty, TyCtxt, TypeFoldable};
 use rustc_errors::ErrorReported;
 use rustc_hir::def::Namespace;
 use rustc_hir::def_id::{CrateNum, DefId};
-use rustc_hir::lang_items::{DropInPlaceFnLangItem, FnOnceTraitLangItem};
+use rustc_hir::lang_items::LangItem;
 use rustc_macros::HashStable;
 
 use std::fmt;
@@ -408,7 +408,7 @@ impl<'tcx> Instance<'tcx> {
     }
 
     pub fn resolve_drop_in_place(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> ty::Instance<'tcx> {
-        let def_id = tcx.require_lang_item(DropInPlaceFnLangItem, None);
+        let def_id = tcx.require_lang_item(LangItem::DropInPlace, None);
         let substs = tcx.intern_substs(&[ty.into()]);
         Instance::resolve(tcx, ty::ParamEnv::reveal_all(), def_id, substs).unwrap().unwrap()
     }
@@ -419,7 +419,7 @@ impl<'tcx> Instance<'tcx> {
         substs: ty::SubstsRef<'tcx>,
     ) -> Instance<'tcx> {
         debug!("fn_once_adapter_shim({:?}, {:?})", closure_did, substs);
-        let fn_once = tcx.require_lang_item(FnOnceTraitLangItem, None);
+        let fn_once = tcx.require_lang_item(LangItem::FnOnce, None);
         let call_once = tcx
             .associated_items(fn_once)
             .in_definition_order()