Some require_lang_item -> is_lang_item replacements

Author: oli-obk

compiler/rustc_hir_analysis/src/coherence/builtin.rs

@@ -214,11 +214,9 @@ fn visit_implementation_of_dispatch_from_dyn(checker: &Checker<'_>) -> Result<()
     let span = tcx.def_span(impl_did);
     let trait_name = "DispatchFromDyn";
 
-    let dispatch_from_dyn_trait = tcx.require_lang_item(LangItem::DispatchFromDyn, Some(span));
-
     let source = trait_ref.self_ty();
     let target = {
-        assert_eq!(trait_ref.def_id, dispatch_from_dyn_trait);
+        assert!(tcx.is_lang_item(trait_ref.def_id, LangItem::DispatchFromDyn));
 
         trait_ref.args.type_at(1)
     };
@@ -339,7 +337,7 @@ fn visit_implementation_of_dispatch_from_dyn(checker: &Checker<'_>) -> Result<()
                     tcx,
                     cause.clone(),
                     param_env,
-                    ty::TraitRef::new(tcx, dispatch_from_dyn_trait, [ty_a, ty_b]),
+                    ty::TraitRef::new(tcx, trait_ref.def_id, [ty_a, ty_b]),
                 ));
                 let errors = ocx.select_all_or_error();
                 if !errors.is_empty() {

compiler/rustc_hir_typeck/src/closure.rs

@@ -1080,15 +1080,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         // Check that this is a projection from the `Future` trait.
         let trait_def_id = predicate.projection_term.trait_def_id(self.tcx);
-        let future_trait = self.tcx.require_lang_item(LangItem::Future, Some(cause_span));
-        if trait_def_id != future_trait {
+        if !self.tcx.is_lang_item(trait_def_id, LangItem::Future) {
             debug!("deduce_future_output_from_projection: not a future");
             return None;
         }
 
         // The `Future` trait has only one associated item, `Output`,
         // so check that this is what we see.
-        let output_assoc_item = self.tcx.associated_item_def_ids(future_trait)[0];
+        let output_assoc_item = self.tcx.associated_item_def_ids(trait_def_id)[0];
         if output_assoc_item != predicate.projection_term.def_id {
             span_bug!(
                 cause_span,

compiler/rustc_middle/src/ty/sty.rs

@@ -1260,8 +1260,7 @@ impl<'tcx> Ty<'tcx> {
                     return true;
                 };
                 alloc.expect_ty().ty_adt_def().is_some_and(|alloc_adt| {
-                    let global_alloc = tcx.require_lang_item(LangItem::GlobalAlloc, None);
-                    alloc_adt.did() == global_alloc
+                    tcx.is_lang_item(alloc_adt.did(), LangItem::GlobalAlloc)
                 })
             }
             _ => false,