[chore]: enable perfsprint linter (#1676)

.golangci.yml

@@ -25,6 +25,7 @@ linters:
     - ineffassign
     - misspell
     - nolintlint
+    - perfsprint
     - predeclared
     - revive
     - staticcheck
@@ -66,6 +67,17 @@ linters-settings:
     local-prefixes: github.com/prometheus/client_golang
   gofumpt:
     extra-rules: true
+  perfsprint:
+    # Optimizes even if it requires an int or uint type cast.
+    int-conversion: true
+    # Optimizes into `err.Error()` even if it is only equivalent for non-nil errors.
+    err-error: true
+    # Optimizes `fmt.Errorf`.
+    errorf: true
+    # Optimizes `fmt.Sprintf` with only one argument.
+    sprintf1: true
+    # Optimizes into strings concatenation.
+    strconcat: true
   revive:
     rules:
       # https://github.com/mgechev/revive/blob/master/RULES_DESCRIPTIONS.md#unused-parameter

api/prometheus/v1/api_test.go

@@ -16,13 +16,13 @@ package v1
 import (
 	"context"
 	"errors"
-	"fmt"
 	"io"
 	"math"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
 	"reflect"
+	"strconv"
 	"strings"
 	"testing"
 	"time"
@@ -260,7 +260,7 @@ func TestAPIs(t *testing.T) {
 		},
 		{
 			do:    doQuery("2", testTime),
-			inErr: fmt.Errorf("some error"),
+			inErr: errors.New("some error"),
 
 			reqMethod: "POST",
 			reqPath:   "/api/v1/query",
@@ -336,7 +336,7 @@ func TestAPIs(t *testing.T) {
 				End:   testTime,
 				Step:  1 * time.Minute,
 			}, WithTimeout(5*time.Second)),
-			inErr: fmt.Errorf("some error"),
+			inErr: errors.New("some error"),
 
 			reqMethod: "POST",
 			reqPath:   "/api/v1/query_range",
@@ -361,14 +361,14 @@ func TestAPIs(t *testing.T) {
 
 		{
 			do:        doLabelNames(nil, testTime.Add(-100*time.Hour), testTime),
-			inErr:     fmt.Errorf("some error"),
+			inErr:     errors.New("some error"),
 			reqMethod: "POST",
 			reqPath:   "/api/v1/labels",
 			err:       errors.New("some error"),
 		},
 		{
 			do:         doLabelNames(nil, testTime.Add(-100*time.Hour), testTime),
-			inErr:      fmt.Errorf("some error"),
+			inErr:      errors.New("some error"),
 			inWarnings: []string{"a"},
 			reqMethod:  "POST",
 			reqPath:    "/api/v1/labels",
@@ -400,14 +400,14 @@ func TestAPIs(t *testing.T) {
 
 		{
 			do:        doLabelValues(nil, "mylabel", testTime.Add(-100*time.Hour), testTime),
-			inErr:     fmt.Errorf("some error"),
+			inErr:     errors.New("some error"),
 			reqMethod: "GET",
 			reqPath:   "/api/v1/label/mylabel/values",
 			err:       errors.New("some error"),
 		},
 		{
 			do:         doLabelValues(nil, "mylabel", testTime.Add(-100*time.Hour), testTime),
-			inErr:      fmt.Errorf("some error"),
+			inErr:      errors.New("some error"),
 			inWarnings: []string{"a"},
 			reqMethod:  "GET",
 			reqPath:    "/api/v1/label/mylabel/values",
@@ -464,7 +464,7 @@ func TestAPIs(t *testing.T) {
 
 		{
 			do:        doSeries("up", testTime.Add(-time.Minute), testTime),
-			inErr:     fmt.Errorf("some error"),
+			inErr:     errors.New("some error"),
 			reqMethod: "POST",
 			reqPath:   "/api/v1/series",
 			err:       errors.New("some error"),
@@ -472,7 +472,7 @@ func TestAPIs(t *testing.T) {
 		// Series with error and warning.
 		{
 			do:         doSeries("up", testTime.Add(-time.Minute), testTime),
-			inErr:      fmt.Errorf("some error"),
+			inErr:      errors.New("some error"),
 			inWarnings: []string{"a"},
 			reqMethod:  "POST",
 			reqPath:    "/api/v1/series",
@@ -493,7 +493,7 @@ func TestAPIs(t *testing.T) {
 
 		{
 			do:        doSnapshot(true),
-			inErr:     fmt.Errorf("some error"),
+			inErr:     errors.New("some error"),
 			reqMethod: "POST",
 			reqPath:   "/api/v1/admin/tsdb/snapshot",
 			err:       errors.New("some error"),
@@ -507,7 +507,7 @@ func TestAPIs(t *testing.T) {
 
 		{
 			do:        doCleanTombstones(),
-			inErr:     fmt.Errorf("some error"),
+			inErr:     errors.New("some error"),
 			reqMethod: "POST",
 			reqPath:   "/api/v1/admin/tsdb/clean_tombstones",
 			err:       errors.New("some error"),
@@ -528,7 +528,7 @@ func TestAPIs(t *testing.T) {
 
 		{
 			do:        doDeleteSeries("up", testTime.Add(-time.Minute), testTime),
-			inErr:     fmt.Errorf("some error"),
+			inErr:     errors.New("some error"),
 			reqMethod: "POST",
 			reqPath:   "/api/v1/admin/tsdb/delete_series",
 			err:       errors.New("some error"),
@@ -550,8 +550,8 @@ func TestAPIs(t *testing.T) {
 			do:        doConfig(),
 			reqMethod: "GET",
 			reqPath:   "/api/v1/status/config",
-			inErr:     fmt.Errorf("some error"),
-			err:       fmt.Errorf("some error"),
+			inErr:     errors.New("some error"),
+			err:       errors.New("some error"),
 		},
 
 		{
@@ -578,16 +578,16 @@ func TestAPIs(t *testing.T) {
 			do:        doFlags(),
 			reqMethod: "GET",
 			reqPath:   "/api/v1/status/flags",
-			inErr:     fmt.Errorf("some error"),
-			err:       fmt.Errorf("some error"),
+			inErr:     errors.New("some error"),
+			err:       errors.New("some error"),
 		},
 
 		{
 			do:        doBuildinfo(),
 			reqMethod: "GET",
 			reqPath:   "/api/v1/status/buildinfo",
-			inErr:     fmt.Errorf("some error"),
-			err:       fmt.Errorf("some error"),
+			inErr:     errors.New("some error"),
+			err:       errors.New("some error"),
 		},
 
 		{
@@ -616,8 +616,8 @@ func TestAPIs(t *testing.T) {
 			do:        doRuntimeinfo(),
 			reqMethod: "GET",
 			reqPath:   "/api/v1/status/runtimeinfo",
-			inErr:     fmt.Errorf("some error"),
-			err:       fmt.Errorf("some error"),
+			inErr:     errors.New("some error"),
+			err:       errors.New("some error"),
 		},
 
 		{
@@ -684,8 +684,8 @@ func TestAPIs(t *testing.T) {
 			do:        doAlertManagers(),
 			reqMethod: "GET",
 			reqPath:   "/api/v1/alertmanagers",
-			inErr:     fmt.Errorf("some error"),
-			err:       fmt.Errorf("some error"),
+			inErr:     errors.New("some error"),
+			err:       errors.New("some error"),
 		},
 
 		{
@@ -891,8 +891,8 @@ func TestAPIs(t *testing.T) {
 			do:        doRules(),
 			reqMethod: "GET",
 			reqPath:   "/api/v1/rules",
-			inErr:     fmt.Errorf("some error"),
-			err:       fmt.Errorf("some error"),
+			inErr:     errors.New("some error"),
+			err:       errors.New("some error"),
 		},
 
 		{
@@ -971,8 +971,8 @@ func TestAPIs(t *testing.T) {
 			do:        doTargets(),
 			reqMethod: "GET",
 			reqPath:   "/api/v1/targets",
-			inErr:     fmt.Errorf("some error"),
-			err:       fmt.Errorf("some error"),
+			inErr:     errors.New("some error"),
+			err:       errors.New("some error"),
 		},
 
 		{
@@ -1005,7 +1005,7 @@ func TestAPIs(t *testing.T) {
 
 		{
 			do:        doTargetsMetadata("{job=\"prometheus\"}", "go_goroutines", "1"),
-			inErr:     fmt.Errorf("some error"),
+			inErr:     errors.New("some error"),
 			reqMethod: "GET",
 			reqPath:   "/api/v1/targets/metadata",
 			err:       errors.New("some error"),
@@ -1037,7 +1037,7 @@ func TestAPIs(t *testing.T) {
 
 		{
 			do:        doMetadata("", "1"),
-			inErr:     fmt.Errorf("some error"),
+			inErr:     errors.New("some error"),
 			reqMethod: "GET",
 			reqPath:   "/api/v1/metadata",
 			err:       errors.New("some error"),
@@ -1047,8 +1047,8 @@ func TestAPIs(t *testing.T) {
 			do:        doTSDB(),
 			reqMethod: "GET",
 			reqPath:   "/api/v1/status/tsdb",
-			inErr:     fmt.Errorf("some error"),
-			err:       fmt.Errorf("some error"),
+			inErr:     errors.New("some error"),
+			err:       errors.New("some error"),
 		},
 
 		{
@@ -1127,8 +1127,8 @@ func TestAPIs(t *testing.T) {
 			do:        doWalReply(),
 			reqMethod: "GET",
 			reqPath:   "/api/v1/status/walreplay",
-			inErr:     fmt.Errorf("some error"),
-			err:       fmt.Errorf("some error"),
+			inErr:     errors.New("some error"),
+			err:       errors.New("some error"),
 		},
 
 		{
@@ -1212,7 +1212,7 @@ func TestAPIs(t *testing.T) {
 	tests = append(tests, queryTests...)
 
 	for i, test := range tests {
-		t.Run(fmt.Sprintf("%d", i), func(t *testing.T) {
+		t.Run(strconv.Itoa(i), func(t *testing.T) {
 			tc.curTest = test
 
 			res, warnings, err := test.do()
@@ -1430,7 +1430,7 @@ func TestAPIClientDo(t *testing.T) {
 	}
 
 	for i, test := range tests {
-		t.Run(fmt.Sprintf("%d", i), func(t *testing.T) {
+		t.Run(strconv.Itoa(i), func(t *testing.T) {
 			tc.ch <- test
 
 			_, body, warnings, err := client.Do(context.Background(), tc.req)

examples/exemplars/main.go

@@ -17,10 +17,10 @@
 package main
 
 import (
-	"fmt"
 	"log"
 	"math/rand"
 	"net/http"
+	"strconv"
 	"time"
 
 	"github.com/prometheus/client_golang/prometheus"
@@ -50,7 +50,7 @@ func main() {
 			// Record fictional latency.
 			now := time.Now()
 			requestDurations.(prometheus.ExemplarObserver).ObserveWithExemplar(
-				time.Since(now).Seconds(), prometheus.Labels{"dummyID": fmt.Sprint(rand.Intn(100000))},
+				time.Since(now).Seconds(), prometheus.Labels{"dummyID": strconv.Itoa(rand.Intn(100000))},
 			)
 			time.Sleep(600 * time.Millisecond)
 		}

examples/random/main.go

@@ -18,11 +18,11 @@ package main
 
 import (
 	"flag"
-	"fmt"
 	"log"
 	"math"
 	"math/rand"
 	"net/http"
+	"strconv"
 	"time"
 
 	"github.com/prometheus/client_golang/prometheus"
@@ -116,7 +116,7 @@ func main() {
 			// the ExemplarObserver interface and thus don't need to
 			// check the outcome of the type assertion.
 			m.rpcDurationsHistogram.(prometheus.ExemplarObserver).ObserveWithExemplar(
-				v, prometheus.Labels{"dummyID": fmt.Sprint(rand.Intn(100000))},
+				v, prometheus.Labels{"dummyID": strconv.Itoa(rand.Intn(100000))},
 			)
 			time.Sleep(time.Duration(75*oscillationFactor()) * time.Millisecond)
 		}

prometheus/counter_test.go

@@ -14,7 +14,6 @@
 package prometheus
 
 import (
-	"fmt"
 	"math"
 	"strings"
 	"testing"
@@ -120,10 +119,10 @@ func TestCounterVecGetMetricWithInvalidLabelValues(t *testing.T) {
 
 		expectPanic(t, func() {
 			counterVec.WithLabelValues(labelValues...)
-		}, fmt.Sprintf("WithLabelValues: expected panic because: %s", test.desc))
+		}, "WithLabelValues: expected panic because: "+test.desc)
 		expectPanic(t, func() {
 			counterVec.With(test.labels)
-		}, fmt.Sprintf("WithLabelValues: expected panic because: %s", test.desc))
+		}, "WithLabelValues: expected panic because: "+test.desc)
 
 		if _, err := counterVec.GetMetricWithLabelValues(labelValues...); err == nil {
 			t.Errorf("GetMetricWithLabelValues: expected error because: %s", test.desc)

prometheus/internal/difflib.go

@@ -22,6 +22,7 @@ import (
 	"bytes"
 	"fmt"
 	"io"
+	"strconv"
 	"strings"
 )
 
@@ -524,7 +525,7 @@ func formatRangeUnified(start, stop int) string {
 	beginning := start + 1 // lines start numbering with one
 	length := stop - start
 	if length == 1 {
-		return fmt.Sprintf("%d", beginning)
+		return strconv.Itoa(beginning)
 	}
 	if length == 0 {
 		beginning-- // empty ranges begin at line just before the range

prometheus/process_collector_cgo_darwin.go

@@ -22,9 +22,7 @@ import "C"
 import "fmt"
 
 func getMemory() (*memoryInfo, error) {
-	var (
-		rss, vsize C.ulonglong
-	)
+	var rss, vsize C.ulonglong
 
 	if err := C.get_memory_info(&rss, &vsize); err != 0 {
 		return nil, fmt.Errorf("task_info() failed with 0x%x", int(err))

prometheus/promhttp/http_test.go

@@ -98,7 +98,7 @@ func readCompressedBody(r io.Reader, comp Compression) (string, error) {
 		got, err := io.ReadAll(reader)
 		return string(got), err
 	}
-	return "", fmt.Errorf("Unsupported compression")
+	return "", errors.New("Unsupported compression")
 }
 
 func TestHandlerErrorHandling(t *testing.T) {

prometheus/registry_test.go

@@ -27,6 +27,7 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"os"
+	"strconv"
 	"sync"
 	"testing"
 	"time"
@@ -1282,7 +1283,7 @@ func ExampleRegistry_grouping() {
 				ConstLabels: prometheus.Labels{
 					// Generate a label unique to this worker so its metric doesn't
 					// collide with the metrics from other workers.
-					"worker_id": fmt.Sprintf("%d", workerID),
+					"worker_id": strconv.Itoa(workerID),
 				},
 			})
 			workerReg.MustRegister(workTime)

prometheus/testutil/promlint/promlint_test.go

@@ -14,6 +14,7 @@
 package promlint_test
 
 import (
+	"errors"
 	"fmt"
 	"reflect"
 	"strings"
@@ -733,7 +734,7 @@ request_duration_seconds{httpService="foo"} 10
 func TestLintUnitAbbreviations(t *testing.T) {
 	genTest := func(n string) test {
 		return test{
-			name: fmt.Sprintf("%s with abbreviated unit", n),
+			name: n + " with abbreviated unit",
 			in: fmt.Sprintf(`
 # HELP %s Test metric.
 # TYPE %s gauge
@@ -820,7 +821,7 @@ mc_something_total 10
 
 	prefixValidation := func(mf *dto.MetricFamily) []error {
 		if !strings.HasPrefix(mf.GetName(), "memcached_") {
-			return []error{fmt.Errorf("expected metric name to start with 'memcached_'")}
+			return []error{errors.New("expected metric name to start with 'memcached_'")}
 		}
 		return nil
 	}

prometheus/testutil/promlint/validations/duplicate_validations.go

@@ -14,7 +14,7 @@
 package validations
 
 import (
-	"fmt"
+	"errors"
 	"reflect"
 
 	dto "github.com/prometheus/client_model/go"
@@ -27,7 +27,7 @@ func LintDuplicateMetric(mf *dto.MetricFamily) []error {
 	for i, m := range mf.Metric {
 		for _, k := range mf.Metric[i+1:] {
 			if reflect.DeepEqual(m.Label, k.Label) {
-				problems = append(problems, fmt.Errorf("metric not unique"))
+				problems = append(problems, errors.New("metric not unique"))
 				break
 			}
 		}

prometheus/value_test.go

@@ -14,7 +14,6 @@
 package prometheus
 
 import (
-	"fmt"
 	"testing"
 	"time"
 
@@ -51,7 +50,7 @@ func TestNewConstMetricInvalidLabelValues(t *testing.T) {
 
 		expectPanic(t, func() {
 			MustNewConstMetric(metricDesc, CounterValue, 0.3, "\xFF")
-		}, fmt.Sprintf("WithLabelValues: expected panic because: %s", test.desc))
+		}, "WithLabelValues: expected panic because: "+test.desc)
 
 		if _, err := NewConstMetric(metricDesc, CounterValue, 0.3, "\xFF"); err == nil {
 			t.Errorf("NewConstMetric: expected error because: %s", test.desc)

prometheus/vec_test.go

@@ -16,6 +16,7 @@ package prometheus
 import (
 	"fmt"
 	"reflect"
+	"strconv"
 	"testing"
 
 	dto "github.com/prometheus/client_model/go"
@@ -291,7 +292,7 @@ func testMetricVec(t *testing.T, vec *GaugeVec) {
 	expected := map[[2]string]int{}
 
 	for i := 0; i < 1000; i++ {
-		pair[0], pair[1] = fmt.Sprint(i%4), fmt.Sprint(i%5) // Varying combinations multiples.
+		pair[0], pair[1] = strconv.Itoa(i%4), strconv.Itoa(i%5) // Varying combinations multiples.
 		expected[pair]++
 		vec.WithLabelValues(pair[0], pair[1]).Inc()
 
@@ -363,7 +364,7 @@ func testConstrainedMetricVec(t *testing.T, vec *GaugeVec, constrain func(string
 	expected := map[[2]string]int{}
 
 	for i := 0; i < 1000; i++ {
-		pair[0], pair[1] = fmt.Sprint(i%4), fmt.Sprint(i%5) // Varying combinations multiples.
+		pair[0], pair[1] = strconv.Itoa(i%4), strconv.Itoa(i%5) // Varying combinations multiples.
 		expected[[2]string{pair[0], constrain(pair[1])}]++
 		vec.WithLabelValues(pair[0], pair[1]).Inc()