pkg/apis/nfd: specify a dedicated type for regexp cache

Having a dedicated type makes it possible to specify deepcopy functions
for it. We need to do this manually as deepcopy-gen doesn't know how to
create copies of regexps.

pkg/apis/nfd/v1alpha1/expression.go

@@ -43,6 +43,8 @@ var matchOps = map[MatchOp]struct{}{
 	MatchIsFalse:      struct{}{},
 }
 
+type valueRegexpCache []*regexp.Regexp
+
 // NewMatchExpressionSet returns a new MatchExpressionSet instance.
 func NewMatchExpressionSet() *MatchExpressionSet {
 	return &MatchExpressionSet{Expressions: make(Expressions)}
@@ -432,3 +434,22 @@ func (m *MatchValue) UnmarshalJSON(data []byte) error {
 
 	return nil
 }
+
+// DeepCopy supplements the auto-generated code
+func (in *valueRegexpCache) DeepCopy() *valueRegexpCache {
+	if in == nil {
+		return nil
+	}
+	out := new(valueRegexpCache)
+	in.DeepCopyInto(out)
+	return out
+}
+
+// DeepCopyInto is a stub to augment the auto-generated code
+//nolint:staticcheck  // re.Copy is deprecated but we want to use  it here
+func (in *valueRegexpCache) DeepCopyInto(out *valueRegexpCache) {
+	*out = make(valueRegexpCache, len(*in))
+	for i, re := range *in {
+		(*out)[i] = re.Copy()
+	}
+}

pkg/apis/nfd/v1alpha1/types.go

@@ -17,8 +17,6 @@ limitations under the License.
 package v1alpha1
 
 import (
-	"regexp"
-
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
 
@@ -121,7 +119,7 @@ type MatchExpression struct {
 	Value MatchValue `json:"value,omitempty"`
 
 	// valueRe caches compiled regexps for "InRegexp" operator
-	valueRe []*regexp.Regexp `json:"-"`
+	valueRe valueRegexpCache `json:"-"`
 }
 
 // MatchOp is the match operator that is applied on values when evaluating a