diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/infer/expr.rs b/src/tools/rust-analyzer/crates/hir-ty/src/infer/expr.rs
index ae69e5176ae5..dc4d34f7b5d2 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/infer/expr.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/infer/expr.rs
@@ -780,7 +780,7 @@ impl<'db> InferenceContext<'_, 'db> {
                     Ty::new_adt(
                         self.interner(),
                         adt,
-                        GenericArgs::new_from_iter(self.interner(), [GenericArg::from(ty)]),
+                        GenericArgs::new_from_slice(&[GenericArg::from(ty)]),
                     )
                 };
                 match (range_type, lhs_ty, rhs_ty) {
@@ -2164,10 +2164,8 @@ impl<'db> InferenceContext<'_, 'db> {
                     if let ItemContainerId::TraitId(trait_) = f.lookup(self.db).container {
                         // construct a TraitRef
                         let trait_params_len = generics(self.db, trait_.into()).len();
-                        let substs = GenericArgs::new_from_iter(
-                            self.interner(),
-                            parameters.as_slice()[..trait_params_len].iter().copied(),
-                        );
+                        let substs =
+                            GenericArgs::new_from_slice(&parameters.as_slice()[..trait_params_len]);
                         self.table.register_predicate(Obligation::new(
                             self.interner(),
                             ObligationCause::new(),
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/infer/path.rs b/src/tools/rust-analyzer/crates/hir-ty/src/infer/path.rs
index 69e6b40a091a..98a2a2ddc049 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/infer/path.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/infer/path.rs
@@ -240,10 +240,7 @@ impl<'db> InferenceContext<'_, 'db> {
 
         if let ItemContainerId::TraitId(trait_) = container {
             let parent_len = generics(self.db, def).parent_generics().map_or(0, |g| g.len_self());
-            let parent_subst = GenericArgs::new_from_iter(
-                interner,
-                subst.as_slice()[..parent_len].iter().copied(),
-            );
+            let parent_subst = GenericArgs::new_from_slice(&subst.as_slice()[..parent_len]);
             let trait_ref = TraitRef::new(interner, trait_.into(), parent_subst);
             self.table.register_predicate(Obligation::new(
                 interner,
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/lib.rs b/src/tools/rust-analyzer/crates/hir-ty/src/lib.rs
index 012fd8a10abd..407657299333 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/lib.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/lib.rs
@@ -469,7 +469,7 @@ where
     Canonical {
         value,
         max_universe: rustc_type_ir::UniverseIndex::ZERO,
-        variables: CanonicalVars::new_from_iter(interner, error_replacer.vars),
+        variables: CanonicalVars::new_from_slice(&error_replacer.vars),
     }
 }
 
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/lower.rs b/src/tools/rust-analyzer/crates/hir-ty/src/lower.rs
index 7c38c83628fa..62a5837f349d 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/lower.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/lower.rs
@@ -2336,10 +2336,7 @@ pub(crate) fn associated_ty_item_bounds<'db>(
                             Some(ExistentialPredicate::Trait(ExistentialTraitRef::new_from_args(
                                 interner,
                                 t.def_id(),
-                                GenericArgs::new_from_iter(
-                                    interner,
-                                    t.trait_ref.args.iter().skip(1),
-                                ),
+                                GenericArgs::new_from_slice(&t.trait_ref.args[1..]),
                             )))
                         }
                     }
@@ -2347,10 +2344,7 @@ pub(crate) fn associated_ty_item_bounds<'db>(
                         ExistentialPredicate::Projection(ExistentialProjection::new_from_args(
                             interner,
                             p.def_id(),
-                            GenericArgs::new_from_iter(
-                                interner,
-                                p.projection_term.args.iter().skip(1),
-                            ),
+                            GenericArgs::new_from_slice(&p.projection_term.args[1..]),
                             p.term,
                         )),
                     ),
@@ -2380,7 +2374,7 @@ pub(crate) fn associated_ty_item_bounds<'db>(
         bounds.push(sized_clause);
     }
 
-    EarlyBinder::bind(BoundExistentialPredicates::new_from_iter(interner, bounds))
+    EarlyBinder::bind(BoundExistentialPredicates::new_from_slice(&bounds))
 }
 
 pub(crate) fn associated_type_by_name_including_super_traits<'db>(
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/lower/path.rs b/src/tools/rust-analyzer/crates/hir-ty/src/lower/path.rs
index fba176bcb1ab..54ce1f740246 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/lower/path.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/lower/path.rs
@@ -1283,7 +1283,7 @@ pub(crate) fn substs_from_args_and_bindings<'db>(
         }
     }
 
-    GenericArgs::new_from_iter(interner, substs)
+    GenericArgs::new_from_slice(&substs)
 }
 
 fn type_looks_like_const(
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/method_resolution.rs b/src/tools/rust-analyzer/crates/hir-ty/src/method_resolution.rs
index aaa3cce4fad9..fee3f664095e 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/method_resolution.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/method_resolution.rs
@@ -392,10 +392,10 @@ pub fn is_dyn_method<'db>(
     };
     let trait_params = db.generic_params(trait_id.into()).len();
     let fn_params = fn_subst.len() - trait_params;
-    let trait_ref = TraitRef::new(
+    let trait_ref = TraitRef::new_from_args(
         interner,
         trait_id.into(),
-        GenericArgs::new_from_iter(interner, fn_subst.iter().take(trait_params)),
+        GenericArgs::new_from_slice(&fn_subst[..trait_params]),
     );
     let self_ty = trait_ref.self_ty();
     if let TyKind::Dynamic(d, _) = self_ty.kind() {
@@ -427,10 +427,10 @@ pub(crate) fn lookup_impl_method_query<'db>(
         return (func, fn_subst);
     };
     let trait_params = db.generic_params(trait_id.into()).len();
-    let trait_ref = TraitRef::new(
+    let trait_ref = TraitRef::new_from_args(
         interner,
         trait_id.into(),
-        GenericArgs::new_from_iter(interner, fn_subst.iter().take(trait_params)),
+        GenericArgs::new_from_slice(&fn_subst[..trait_params]),
     );
 
     let name = &db.function_signature(func).name;
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/generic_arg.rs b/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/generic_arg.rs
index 6eee7cc27a0e..9936e443210a 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/generic_arg.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/generic_arg.rs
@@ -698,10 +698,7 @@ impl<'db> rustc_type_ir::inherent::GenericArgs<DbInterner<'db>> for GenericArgs<
                                 let inputs = Ty::new_tup(interner, s.inputs());
                                 let output = s.output();
                                 FnSigTys {
-                                    inputs_and_output: Tys::new_from_iter(
-                                        interner,
-                                        [inputs, output],
-                                    ),
+                                    inputs_and_output: Tys::new_from_slice(&[inputs, output]),
                                 }
                             }),
                             header,
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/infer/canonical/canonicalizer.rs b/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/infer/canonical/canonicalizer.rs
index 4422eeaa9a4b..ccd93590107f 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/infer/canonical/canonicalizer.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/infer/canonical/canonicalizer.rs
@@ -562,7 +562,7 @@ impl<'cx, 'db> Canonicalizer<'cx, 'db> {
         debug_assert!(!out_value.has_infer() && !out_value.has_placeholders());
 
         let canonical_variables =
-            CanonicalVars::new_from_iter(tcx, canonicalizer.universe_canonicalized_variables());
+            CanonicalVars::new_from_slice(&canonicalizer.universe_canonicalized_variables());
 
         let max_universe = canonical_variables
             .iter()
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/interner.rs b/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/interner.rs
index fcda02b1faeb..2ebc5b81ba5c 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/interner.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/interner.rs
@@ -21,9 +21,9 @@ use rustc_abi::{ReprFlags, ReprOptions};
 use rustc_hash::FxHashSet;
 use rustc_index::bit_set::DenseBitSet;
 use rustc_type_ir::{
-    AliasTermKind, AliasTyKind, BoundVar, CollectAndApply, CoroutineWitnessTypes, DebruijnIndex,
-    EarlyBinder, FlagComputation, Flags, GenericArgKind, GenericTypeVisitable, ImplPolarity,
-    InferTy, Interner, TraitRef, TypeFlags, TypeVisitableExt, UniverseIndex, Upcast, Variance,
+    AliasTermKind, AliasTyKind, BoundVar, CoroutineWitnessTypes, DebruijnIndex, EarlyBinder,
+    FlagComputation, Flags, GenericArgKind, GenericTypeVisitable, ImplPolarity, InferTy, Interner,
+    TraitRef, TypeFlags, TypeVisitableExt, UniverseIndex, Upcast, Variance,
     elaborate::elaborate,
     error::TypeError,
     fast_reject,
@@ -1270,10 +1270,8 @@ impl<'db> Interner for DbInterner<'db> {
     ) -> (rustc_type_ir::TraitRef<Self>, Self::GenericArgsSlice) {
         let trait_def_id = self.parent(def_id);
         let trait_generics = self.generics_of(trait_def_id);
-        let trait_args = GenericArgs::new_from_iter(
-            self,
-            args.as_slice()[0..trait_generics.own_params.len()].iter().cloned(),
-        );
+        let trait_args =
+            GenericArgs::new_from_slice(&args.as_slice()[0..trait_generics.own_params.len()]);
         let alias_args = &args.as_slice()[trait_generics.own_params.len()..];
         (TraitRef::new_from_args(self, trait_def_id.try_into().unwrap(), trait_args), alias_args)
     }
@@ -2105,9 +2103,7 @@ impl<'db> Interner for DbInterner<'db> {
         let mut map = Default::default();
         let delegate = Anonymize { interner: self, map: &mut map };
         let inner = self.replace_escaping_bound_vars_uncached(value.skip_binder(), delegate);
-        let bound_vars = CollectAndApply::collect_and_apply(map.into_values(), |xs| {
-            BoundVarKinds::new_from_iter(self, xs.iter().cloned())
-        });
+        let bound_vars = BoundVarKinds::new_from_iter(self, map.into_values());
         Binder::bind_with_vars(inner, bound_vars)
     }
 
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/variance.rs b/src/tools/rust-analyzer/crates/hir-ty/src/variance.rs
index a050124c90b7..5b8122a0a5df 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/variance.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/variance.rs
@@ -82,7 +82,7 @@ fn variances_of_query(db: &dyn HirDatabase, def: GenericDefId) -> StoredVariance
         }
     }
 
-    VariancesOf::new_from_iter(interner, variances).store()
+    VariancesOf::new_from_slice(&variances).store()
 }
 
 // pub(crate) fn variances_of_cycle_fn(