With Go 1.21, use clear in set.Clear()

This addresses the edge cases where a set couldn't be fully cleared,
and will be more efficient in cases where the loop isn't optimised
away.

Signed-off-by: Stephen Kitt <[email protected]>

set/set.go

@@ -213,17 +213,3 @@ func (s Set[T]) Clone() Set[T] {
 func (s Set[T]) SymmetricDifference(s2 Set[T]) Set[T] {
 	return s.Difference(s2).Union(s2.Difference(s))
 }
-
-// Clear empties the set.
-// It is preferable to replace the set with a newly constructed set,
-// but not all callers can do that (when there are other references to the map).
-// In some cases the set *won't* be fully cleared, e.g. a Set[float32] containing NaN
-// can't be cleared because NaN can't be removed.
-// For sets containing items of a type that is reflexive for ==,
-// this is optimized to a single call to runtime.mapclear().
-func (s Set[T]) Clear() Set[T] {
-	for key := range s {
-		delete(s, key)
-	}
-	return s
-}

set/set_go_1.20.go

@@ -0,0 +1,33 @@
+//go:build !go1.21
+
+/*
+Copyright 2023 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package set
+
+// Clear empties the set.
+// It is preferable to replace the set with a newly constructed set,
+// but not all callers can do that (when there are other references to the map).
+// In some cases the set *won't* be fully cleared, e.g. a Set[float32] containing NaN
+// can't be cleared because NaN can't be removed.
+// For sets containing items of a type that is reflexive for ==,
+// this is optimized to a single call to runtime.mapclear().
+func (s Set[T]) Clear() Set[T] {
+	for key := range s {
+		delete(s, key)
+	}
+	return s
+}

set/set_go_1.21.go

@@ -0,0 +1,27 @@
+//go:build go1.21
+
+/*
+Copyright 2023 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package set
+
+// Clear empties the set.
+// It is preferable to replace the set with a newly constructed set,
+// but not all callers can do that (when there are other references to the map).
+func (s Set[T]) Clear() Set[T] {
+	clear(s)
+	return s
+}