move empty id to constexpr in header

2 files changed, 5 insertions, 0 deletions

diff --git a/staging_vespalib/src/vespa/vespalib/metrics/handle.h b/staging_vespalib/src/vespa/vespalib/metrics/handle.h
index ddae0b1b6d2..3e32945ceed 100644
--- a/staging_vespalib/src/vespa/vespalib/metrics/handle.h
+++ b/staging_vespalib/src/vespa/vespalib/metrics/handle.h
@@ -15,9 +15,12 @@ template <typename T>
 class Handle {
 private:
     size_t _id;
+    constexpr Handle() : _id(0) {}
 public:
     explicit Handle(size_t id) : _id(id) {}
     size_t id() const { return _id; }
+
+    static constexpr Handle empty_handle = Handle();
 };
 
 template <typename T>
diff --git a/staging_vespalib/src/vespa/vespalib/metrics/name_collection.h b/staging_vespalib/src/vespa/vespalib/metrics/name_collection.h
index 6a91c2d4a9d..6e939cd372d 100644
--- a/staging_vespalib/src/vespa/vespalib/metrics/name_collection.h
+++ b/staging_vespalib/src/vespa/vespalib/metrics/name_collection.h
@@ -23,6 +23,8 @@ public:
 
     NameCollection();
     ~NameCollection() {}
+
+    static constexpr size_t empty_id = 0;
 };
 
 } // namespace vespalib::metrics