Add unparam linter (#5803)

This is the contrib counterpart of
open-telemetry/opentelemetry-go#5531, adding the
unparam linter.

.golangci.yml

@@ -24,6 +24,7 @@ linters:
     - staticcheck
     - typecheck
     - unconvert
+    - unparam
     - unused
 
 issues:

detectors/gcp/cloud-function.go

@@ -41,7 +41,7 @@ func (f *cloudFunction) Detect(ctx context.Context) (*resource.Resource, error)
 	if err != nil {
 		return nil, err
 	}
-	region, err := f.cloudRun.cloudRegion(ctx)
+	region, err := f.cloudRun.cloudRegion()
 	if err != nil {
 		return nil, err
 	}

detectors/gcp/cloud-run.go

@@ -50,7 +50,7 @@ func NewCloudRun() *CloudRun {
 	}
 }
 
-func (c *CloudRun) cloudRegion(ctx context.Context) (string, error) {
+func (c *CloudRun) cloudRegion() (string, error) {
 	region, err := c.mc.Get("instance/region")
 	if err != nil {
 		return "", err
@@ -84,7 +84,7 @@ func (c *CloudRun) Detect(ctx context.Context) (*resource.Resource, error) {
 		attributes = append(attributes, semconv.CloudAccountID(projectID))
 	}
 
-	if region, err := c.cloudRegion(ctx); hasProblem(err) {
+	if region, err := c.cloudRegion(); hasProblem(err) {
 		errInfo = append(errInfo, err.Error())
 	} else if region != "" {
 		attributes = append(attributes, semconv.CloudRegion(region))

instrgen/lib/context_propagation.go

@@ -41,7 +41,7 @@ func (pass *ContextPropagationPass) Execute(
 	// when callexpr is inside var decl
 	// instead of functiondecl
 	currentFun := FuncDescriptor{}
-	emitEmptyContext := func(callExpr *ast.CallExpr, fun FuncDescriptor, ctxArg *ast.Ident) {
+	emitEmptyContext := func(callExpr *ast.CallExpr, ctxArg *ast.Ident) {
 		addImports = true
 		if currentFun != (FuncDescriptor{}) {
 			visited := map[FuncDescriptor]bool{}
@@ -96,7 +96,7 @@ func (pass *ContextPropagationPass) Execute(
 				visited := map[FuncDescriptor]bool{}
 				if isPath(analysis.Callgraph, fun, analysis.RootFunctions[0], visited) {
 					fmt.Println("\t\t\tContextPropagation FuncCall:", funId, pkg.TypesInfo.Uses[ident].Type().String())
-					emitEmptyContext(callExpr, fun, ctxArg)
+					emitEmptyContext(callExpr, ctxArg)
 				}
 			}
 		}

instrumentation/github.com/gorilla/mux/otelmux/test/mux_test.go

@@ -138,7 +138,7 @@ func TestNotFoundIsNotError(t *testing.T) {
 
 func assertSpan(t *testing.T, span sdktrace.ReadOnlySpan, name string, kind trace.SpanKind, attrs ...attribute.KeyValue) {
 	assert.Equal(t, name, span.Name())
-	assert.Equal(t, trace.SpanKindServer, span.SpanKind())
+	assert.Equal(t, kind, span.SpanKind())
 
 	got := make(map[attribute.Key]attribute.Value, len(span.Attributes()))
 	for _, a := range span.Attributes() {

instrumentation/google.golang.org/grpc/otelgrpc/test/grpc_test.go

@@ -635,7 +635,7 @@ func checkUnaryServerSpans(t *testing.T, spans []trace.ReadOnlySpan) {
 	}, largeSpan.Attributes())
 }
 
-func assertEvents(t *testing.T, expected, actual []trace.Event) bool {
+func assertEvents(t *testing.T, expected, actual []trace.Event) bool { //nolint:unparam
 	if !assert.Len(t, actual, len(expected)) {
 		return false
 	}
@@ -694,7 +694,7 @@ func checkUnaryServerRecords(t *testing.T, reader metric.Reader) {
 	metricdatatest.AssertEqual(t, want, rm.ScopeMetrics[0], metricdatatest.IgnoreTimestamp(), metricdatatest.IgnoreValue())
 }
 
-func findAttribute(kvs []attribute.KeyValue, key attribute.Key) (attribute.KeyValue, bool) {
+func findAttribute(kvs []attribute.KeyValue, key attribute.Key) (attribute.KeyValue, bool) { //nolint:unparam
 	for _, kv := range kvs {
 		if kv.Key == key {
 			return kv, true

instrumentation/runtime/internal/x/x_test.go

@@ -33,7 +33,7 @@ func run(steps ...func(*testing.T)) func(*testing.T) {
 	}
 }
 
-func setenv(k, v string) func(t *testing.T) {
+func setenv(k, v string) func(t *testing.T) { //nolint:unparam
 	return func(t *testing.T) { t.Setenv(k, v) }
 }
 

samplers/aws/xray/fallback_sampler.go

@@ -50,7 +50,7 @@ func (fs *FallbackSampler) Description() string {
 }
 
 // take consumes quota from reservoir, if any remains, then returns true. False otherwise.
-func (fs *FallbackSampler) take(now time.Time, itemCost float64) bool {
+func (fs *FallbackSampler) take(now time.Time, itemCost float64) bool { //nolint:unparam
 	fs.mu.Lock()
 	defer fs.mu.Unlock()
 

samplers/aws/xray/internal/client.go

@@ -107,7 +107,7 @@ type xrayClient struct {
 }
 
 // newClient returns an HTTP client with proxy endpoint.
-func newClient(endpoint url.URL) (client *xrayClient, err error) {
+func newClient(endpoint url.URL) (client *xrayClient, err error) { //nolint:unparam
 	// Construct resolved URLs for getSamplingRules and getSamplingTargets API calls.
 	endpoint.Path = "/GetSamplingRules"
 	samplingRulesURL := endpoint

samplers/aws/xray/internal/manifest.go

@@ -289,7 +289,7 @@ func (m *Manifest) updateReservoir(t *samplingTargetDocument) (err error) {
 
 // snapshots takes a snapshot of sampling statistics from all rules, resetting
 // statistics counters in the process.
-func (m *Manifest) snapshots() ([]*samplingStatisticsDocument, error) {
+func (m *Manifest) snapshots() ([]*samplingStatisticsDocument, error) { //nolint:unparam
 	statistics := make([]*samplingStatisticsDocument, 0, len(m.Rules))
 
 	// Generate sampling statistics for user-defined rules.

samplers/aws/xray/internal/manifest_test.go

@@ -20,7 +20,7 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func createSamplingTargetDocument(name string, interval int64, rate, quota, ttl float64) *samplingTargetDocument {
+func createSamplingTargetDocument(name string, interval int64, rate, quota, ttl float64) *samplingTargetDocument { //nolint:unparam
 	return &samplingTargetDocument{
 		FixedRate:         &rate,
 		Interval:          &interval,

samplers/aws/xray/internal/reservoir.go

@@ -44,7 +44,7 @@ func (r *reservoir) expired(now time.Time) bool {
 }
 
 // take consumes quota from reservoir, if any remains, then returns true. False otherwise.
-func (r *reservoir) take(now time.Time, borrowed bool, itemCost float64) bool { // nolint: revive  // borrowed is not a control flag.
+func (r *reservoir) take(now time.Time, borrowed bool, itemCost float64) bool { // nolint:unparam,revive  // borrowed is not a control flag.
 	r.mu.Lock()
 	defer r.mu.Unlock()