sql/specutil: use interface instead of generic for ColumnByRef

sql/internal/specutil/convert.go

@@ -1089,29 +1089,26 @@ func SchemaName(ref *schemahcl.Ref) (string, error) {
 }
 
 // ColumnByRef returns a column from the table by its reference.
-func ColumnByRef[T *schema.View | *schema.Table](tv T, ref *schemahcl.Ref) (*schema.Column, error) {
+func ColumnByRef(tv interface {
+	Column(string) (*schema.Column, bool)
+}, ref *schemahcl.Ref) (*schema.Column, error) {
 	vs, err := ref.ByType(typeColumn)
 	if err != nil {
 		return nil, err
 	}
 	if len(vs) != 1 {
 		return nil, fmt.Errorf("expected 1 column ref, got %d", len(vs))
 	}
-	switch tv := any(tv).(type) {
-	case *schema.Table:
-		c, ok := tv.Column(vs[0])
-		if !ok {
-			return nil, fmt.Errorf("column %q was not found in table %s", vs[0], tv.Name)
-		}
+	if c, ok := tv.Column(vs[0]); ok {
 		return c, nil
+	}
+	switch tv := tv.(type) {
+	case *schema.Table:
+		return nil, fmt.Errorf("column %q was not found in table %s", vs[0], tv.Name)
 	case *schema.View:
-		c, ok := tv.Column(vs[0])
-		if !ok {
-			return nil, fmt.Errorf("column %q was not found in view %s", vs[0], tv.Name)
-		}
-		return c, nil
+		return nil, fmt.Errorf("column %q was not found in view %s", vs[0], tv.Name)
 	default:
-		return nil, fmt.Errorf("unreachable %T", tv)
+		return nil, fmt.Errorf("column %q was not found in %T", vs[0], tv)
 	}
 }