Use is_lang_item more

compiler/rustc_hir_typeck/src/check.rs

@@ -160,15 +160,11 @@ pub(super) fn check_fn<'a, 'tcx>(
     fcx.demand_suptype(span, ret_ty, actual_return_ty);
 
     // Check that a function marked as `#[panic_handler]` has signature `fn(&PanicInfo) -> !`
-    if let Some(panic_impl_did) = tcx.lang_items().panic_impl()
-        && panic_impl_did == fn_def_id.to_def_id()
-    {
-        check_panic_info_fn(tcx, panic_impl_did.expect_local(), fn_sig);
+    if tcx.is_lang_item(fn_def_id.to_def_id(), LangItem::PanicImpl) {
+        check_panic_info_fn(tcx, fn_def_id, fn_sig);
     }
 
-    if let Some(lang_start_defid) = tcx.lang_items().start_fn()
-        && lang_start_defid == fn_def_id.to_def_id()
-    {
+    if tcx.is_lang_item(fn_def_id.to_def_id(), LangItem::Start) {
         check_lang_start_fn(tcx, fn_sig, fn_def_id);
     }
 

compiler/rustc_lint/src/for_loops_over_fallibles.rs

@@ -1,5 +1,5 @@
 use hir::{Expr, Pat};
-use rustc_hir as hir;
+use rustc_hir::{self as hir, LangItem};
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_infer::traits::ObligationCause;
 use rustc_middle::ty;
@@ -126,7 +126,10 @@ fn extract_iterator_next_call<'tcx>(
 ) -> Option<&'tcx Expr<'tcx>> {
     // This won't work for `Iterator::next(iter)`, is this an issue?
     if let hir::ExprKind::MethodCall(_, recv, _, _) = expr.kind
-        && cx.typeck_results().type_dependent_def_id(expr.hir_id) == cx.tcx.lang_items().next_fn()
+        && cx
+            .typeck_results()
+            .type_dependent_def_id(expr.hir_id)
+            .is_some_and(|def_id| cx.tcx.is_lang_item(def_id, LangItem::IteratorNext))
     {
         Some(recv)
     } else {

compiler/rustc_lint/src/traits.rs

@@ -114,7 +114,7 @@ impl<'tcx> LateLintPass<'tcx> for DropTraitConstraints {
         let hir::TyKind::TraitObject(bounds, _lifetime, _syntax) = &ty.kind else { return };
         for (bound, modifier) in &bounds[..] {
             let def_id = bound.trait_ref.trait_def_id();
-            if cx.tcx.lang_items().drop_trait() == def_id
+            if def_id.is_some_and(|def_id| cx.tcx.is_lang_item(def_id, LangItem::Drop))
                 && *modifier != hir::TraitBoundModifier::Maybe
             {
                 let Some(def_id) = cx.tcx.get_diagnostic_item(sym::needs_drop) else { return };

compiler/rustc_middle/src/ty/diagnostics.rs

@@ -6,10 +6,9 @@ use std::ops::ControlFlow;
 
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::{into_diag_arg_using_display, Applicability, Diag, DiagArgValue, IntoDiagArg};
-use rustc_hir as hir;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::DefId;
-use rustc_hir::{PredicateOrigin, WherePredicate};
+use rustc_hir::{self as hir, LangItem, PredicateOrigin, WherePredicate};
 use rustc_span::{BytePos, Span};
 use rustc_type_ir::TyKind::*;
 
@@ -290,8 +289,9 @@ pub fn suggest_constraining_type_params<'a>(
         let Some(param) = param else { return false };
 
         {
-            let mut sized_constraints =
-                constraints.extract_if(|(_, def_id)| *def_id == tcx.lang_items().sized_trait());
+            let mut sized_constraints = constraints.extract_if(|(_, def_id)| {
+                def_id.is_some_and(|def_id| tcx.is_lang_item(def_id, LangItem::Sized))
+            });
             if let Some((_, def_id)) = sized_constraints.next() {
                 applicability = Applicability::MaybeIncorrect;
 

compiler/rustc_middle/src/ty/instance.rs

@@ -838,7 +838,7 @@ impl<'tcx> Instance<'tcx> {
             return None;
         };
 
-        if tcx.lang_items().get(coroutine_callable_item) == Some(trait_item_id) {
+        if tcx.is_lang_item(trait_item_id, coroutine_callable_item) {
             let ty::Coroutine(_, id_args) = *tcx.type_of(coroutine_def_id).skip_binder().kind()
             else {
                 bug!()

compiler/rustc_middle/src/ty/print/pretty.rs

@@ -1145,7 +1145,9 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                         let term = if let Some(ty) = term.skip_binder().as_type()
                             && let ty::Alias(ty::Projection, proj) = ty.kind()
                             && let Some(assoc) = tcx.opt_associated_item(proj.def_id)
-                            && assoc.trait_container(tcx) == tcx.lang_items().coroutine_trait()
+                            && assoc
+                                .trait_container(tcx)
+                                .is_some_and(|def_id| tcx.is_lang_item(def_id, LangItem::Coroutine))
                             && assoc.name == rustc_span::sym::Return
                         {
                             if let ty::Coroutine(_, args) = args.type_at(0).kind() {

compiler/rustc_middle/src/ty/sty.rs

@@ -1915,7 +1915,7 @@ impl<'tcx> Ty<'tcx> {
 
     pub fn is_c_void(self, tcx: TyCtxt<'_>) -> bool {
         match self.kind() {
-            ty::Adt(adt, _) => tcx.lang_items().get(LangItem::CVoid) == Some(adt.did()),
+            ty::Adt(adt, _) => tcx.is_lang_item(adt.did(), LangItem::CVoid),
             _ => false,
         }
     }

compiler/rustc_monomorphize/src/partitioning.rs

@@ -648,7 +648,9 @@ fn characteristic_def_id_of_mono_item<'tcx>(
 
             if let Some(impl_def_id) = tcx.impl_of_method(def_id) {
                 if tcx.sess.opts.incremental.is_some()
-                    && tcx.trait_id_of_impl(impl_def_id) == tcx.lang_items().drop_trait()
+                    && tcx
+                        .trait_id_of_impl(impl_def_id)
+                        .is_some_and(|def_id| tcx.is_lang_item(def_id, LangItem::Drop))
                 {
                     // Put `Drop::drop` into the same cgu as `drop_in_place`
                     // since `drop_in_place` is the only thing that can

compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs

@@ -230,8 +230,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                             post_message,
                         );
 
-                        let (err_msg, safe_transmute_explanation) = if Some(main_trait_ref.def_id())
-                            == self.tcx.lang_items().transmute_trait()
+                        let (err_msg, safe_transmute_explanation) = if self.tcx.is_lang_item(main_trait_ref.def_id(), LangItem::TransmuteTrait)
                         {
                             // Recompute the safe transmute reason and use that for the error reporting
                             match self.get_safe_transmute_error_and_reason(

compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs

@@ -2829,7 +2829,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                                     // Do not suggest relaxing if there is an explicit `Sized` obligation.
                                     && !bounds.iter()
                                         .filter_map(|bound| bound.trait_ref())
-                                        .any(|tr| tr.trait_def_id() == tcx.lang_items().sized_trait())
+                                        .any(|tr| tr.trait_def_id().is_some_and(|def_id| tcx.is_lang_item(def_id, LangItem::Sized)))
                                 {
                                     let (span, separator) = if let [.., last] = bounds {
                                         (last.span().shrink_to_hi(), " +")

compiler/rustc_trait_selection/src/traits/query/type_op/prove_predicate.rs

@@ -1,3 +1,4 @@
+use rustc_hir::LangItem;
 use rustc_infer::traits::Obligation;
 pub use rustc_middle::traits::query::type_op::ProvePredicate;
 use rustc_middle::traits::query::NoSolution;
@@ -20,8 +21,7 @@ impl<'tcx> super::QueryTypeOp<'tcx> for ProvePredicate<'tcx> {
         // such cases.
         if let ty::PredicateKind::Clause(ty::ClauseKind::Trait(trait_ref)) =
             key.value.predicate.kind().skip_binder()
-            && let Some(sized_def_id) = tcx.lang_items().sized_trait()
-            && trait_ref.def_id() == sized_def_id
+            && tcx.is_lang_item(trait_ref.def_id(), LangItem::Sized)
             && trait_ref.self_ty().is_trivially_sized(tcx)
         {
             return Some(());

compiler/rustc_ty_utils/src/abi.rs

@@ -621,7 +621,7 @@ fn fn_abi_new_uncached<'tcx>(
     let rust_abi = matches!(sig.abi, RustIntrinsic | Rust | RustCall);
 
     let is_drop_in_place =
-        fn_def_id.is_some() && fn_def_id == cx.tcx.lang_items().drop_in_place_fn();
+        fn_def_id.is_some_and(|def_id| cx.tcx.is_lang_item(def_id, LangItem::DropInPlace));
 
     let arg_of = |ty: Ty<'tcx>, arg_idx: Option<usize>| -> Result<_, &'tcx FnAbiError<'tcx>> {
         let span = tracing::debug_span!("arg_of");