fix: spancheck default StartSpanMatchersSlice values (#5324)

Author: ldez

Diff for: pkg/golinters/spancheck/spancheck.go

@@ -12,16 +12,16 @@ func New(settings *config.SpancheckSettings) *goanalysis.Linter {
 	cfg := spancheck.NewDefaultConfig()
 
 	if settings != nil {
-		if settings.Checks != nil {
+		if len(settings.Checks) > 0 {
 			cfg.EnabledChecks = settings.Checks
 		}
 
-		if settings.IgnoreCheckSignatures != nil {
+		if len(settings.IgnoreCheckSignatures) > 0 {
 			cfg.IgnoreChecksSignaturesSlice = settings.IgnoreCheckSignatures
 		}
 
-		if settings.ExtraStartSpanSignatures != nil {
-			cfg.StartSpanMatchersSlice = settings.ExtraStartSpanSignatures
+		if len(settings.ExtraStartSpanSignatures) > 0 {
+			cfg.StartSpanMatchersSlice = append(cfg.StartSpanMatchersSlice, settings.ExtraStartSpanSignatures...)
 		}
 	}
 

Diff for: pkg/golinters/spancheck/testdata/spancheck_default.go renamed to pkg/golinters/spancheck/testdata/spancheck.go

@@ -0,0 +1,18 @@
+//golangcitest:args -Espancheck
+//golangcitest:config_path testdata/spancheck_keep_default.yml
+package spancheck
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/trace"
+)
+
+func StartTrace() (context.Context, trace.Span) {
+	return otel.Tracer("example.com/main").Start(context.Background(), "span name") // want "span is unassigned, probable memory leak"
+}
+
+func _() {
+	_, _ = StartTrace()
+}

Diff for: pkg/golinters/spancheck/testdata/spancheck_keep_default.go

@@ -0,0 +1,4 @@
+linters-settings:
+  spancheck:
+    extra-start-span-signatures:
+      - dummy:opentelemetry