Skip links with invalid span context

CHANGELOG.md

@@ -22,6 +22,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - The Metric SDK `Export()` function takes a new two-level reader interface for iterating over results one instrumentation library at a time. (#2197)
   - The former `"go.opentelemetry.io/otel/sdk/export/metric".CheckpointSet` is renamed `Reader`.
   - The new interface is named `"go.opentelemetry.io/otel/sdk/export/metric".InstrumentationLibraryReader`.
+- Skip links with invalid span context. (#2275)
 
 ## [1.0.0] - 2021-09-20
 

sdk/trace/trace_test.go

@@ -670,6 +670,15 @@ func TestLinks(t *testing.T) {
 	if diff := cmpDiff(got, want); diff != "" {
 		t.Errorf("Link: -got +want %s", diff)
 	}
+	sc1 = trace.NewSpanContext(trace.SpanContextConfig{TraceID: trace.TraceID([16]byte{1, 1}), SpanID: trace.SpanID{3}})
+
+	span1 := startSpan(tp, "name", trace.WithLinks([]trace.Link{
+		{SpanContext: trace.SpanContext{}},
+		{SpanContext: sc1},
+	}...))
+
+	sdkspan, _ := span1.(*recordingSpan)
+	require.Len(t, sdkspan.Links(), 1)
 }
 
 func TestLinksOverLimit(t *testing.T) {

sdk/trace/tracer.go

@@ -138,7 +138,9 @@ func (tr *tracer) newRecordingSpan(psc, sc trace.SpanContext, name string, sr Sa
 	}
 
 	for _, l := range config.Links() {
-		s.addLink(l)
+		if l.SpanContext.IsValid() {
+			s.addLink(l)
+		}
 	}
 
 	s.SetAttributes(sr.Attributes...)