Misc Metrics Fixes

src/libraries/Microsoft.Extensions.Diagnostics/src/Metrics/DefaultMeterFactory.cs

@@ -55,7 +55,7 @@ public Meter Create(MeterOptions options)
 
                 object? scope = options.Scope;
                 options.Scope = this;
-                FactoryMeter m = new FactoryMeter(options.Name, options.Version, options.Tags, scope: this);
+                FactoryMeter m = new FactoryMeter(options);
                 options.Scope = scope;
 
                 meterList.Add(m);
@@ -89,8 +89,7 @@ public void Dispose()
 
     internal sealed class FactoryMeter : Meter
     {
-        public FactoryMeter(string name, string? version, IEnumerable<KeyValuePair<string, object?>>? tags, object? scope)
-            : base(name, version, tags, scope)
+        public FactoryMeter(MeterOptions options) : base(options)
         {
         }
 

src/libraries/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/Metrics/Instrument.netfx.cs

@@ -93,7 +93,7 @@ protected void RecordMeasurement(T measurement, in TagList tagList)
                 case 3: tags[2] = tagList.Tag3; goto case 2;
                 case 2: tags[1] = tagList.Tag2; goto case 1;
                 case 1: tags[0] = tagList.Tag1; break;
-                case 0: return; // no need to report anything
+                case 0: break;
                 default:
                     Debug.Assert(false);
                     return;

src/libraries/System.Diagnostics.DiagnosticSource/tests/MetricsTests.cs

@@ -1707,6 +1707,29 @@ public void TestHistogramCreationWithAdvice()
            }).Dispose();
         }
 
+        [ConditionalFact(typeof(RemoteExecutor), nameof(RemoteExecutor.IsSupported))]
+        public void TestRecordingWithEmptyTagList()
+        {
+           RemoteExecutor.Invoke(() =>
+           {
+                using MeterListener meterListener = new MeterListener();
+                using Meter meter = new Meter("demo");
+
+                int count = 0;
+
+                Counter<int> counter = meter.CreateCounter<int>("counter");
+                meterListener.SetMeasurementEventCallback<int>((instrument, measurement, tags,state) => count += measurement);
+                meterListener.EnableMeasurementEvents(counter);
+
+                counter.Add(1);
+                counter.Add(1, new TagList());
+                counter.Add(1, Array.Empty<KeyValuePair<string, object>>());
+                counter.Add(1, new TagList(Array.Empty<KeyValuePair<string, object>>()));
+
+                Assert.Equal(4, count);
+           }).Dispose();
+        }
+
         private void PublishCounterMeasurement<T>(Counter<T> counter, T value, KeyValuePair<string, object?>[] tags) where T : struct
         {
             switch (tags.Length)