*: fix some varcheck lint warnings

ddl/error.go

@@ -21,6 +21,7 @@ import (
 	"github.com/pingcap/tidb/util/dbterror"
 )
 
+// nolint:varcheck
 var (
 	// errWorkerClosed means we have already closed the DDL worker.
 	errInvalidWorker = dbterror.ClassDDL.NewStd(mysql.ErrInvalidDDLWorker)

domain/infosync/info.go

@@ -82,6 +82,7 @@ const (
 // ErrPrometheusAddrIsNotSet is the error that Prometheus address is not set in PD and etcd
 var ErrPrometheusAddrIsNotSet = dbterror.ClassDomain.NewStd(errno.ErrPrometheusAddrIsNotSet)
 
+// nolint:varcheck
 // errPlacementRulesDisabled is exported for internal usage, indicating PD rejected the request due to disabled placement feature.
 var errPlacementRulesDisabled = errors.New("placement rules feature is disabled")
 

executor/hash_table.go

@@ -32,18 +32,21 @@ import (
 )
 
 const (
+	// nolint:varcheck
 	// estCountMaxFactor defines the factor of estCountMax with maxChunkSize.
 	// estCountMax is maxChunkSize * estCountMaxFactor, the maximum threshold of estCount.
 	// if estCount is larger than estCountMax, set estCount to estCountMax.
 	// Set this threshold to prevent buildSideEstCount being too large and causing a performance and memory regression.
 	estCountMaxFactor = 10 * 1024
 
+	// nolint:varcheck
 	// estCountMinFactor defines the factor of estCountMin with maxChunkSize.
 	// estCountMin is maxChunkSize * estCountMinFactor, the minimum threshold of estCount.
 	// If estCount is smaller than estCountMin, set estCount to 0.
 	// Set this threshold to prevent buildSideEstCount being too small and causing a performance regression.
 	estCountMinFactor = 8
 
+	// nolint:varcheck
 	// estCountDivisor defines the divisor of buildSideEstCount.
 	// Set this divisor to prevent buildSideEstCount being too large and causing a performance regression.
 	estCountDivisor = 8

executor/merge_join.go

@@ -15,7 +15,6 @@ package executor
 
 import (
 	"context"
-	"fmt"
 
 	"github.com/pingcap/failpoint"
 	"github.com/pingcap/tidb/config"
@@ -24,7 +23,6 @@ import (
 	"github.com/pingcap/tidb/util/chunk"
 	"github.com/pingcap/tidb/util/disk"
 	"github.com/pingcap/tidb/util/memory"
-	"github.com/pingcap/tidb/util/stringutil"
 )
 
 // MergeJoinExec implements the merge join algorithm.
@@ -53,11 +51,6 @@ type MergeJoinExec struct {
 	diskTracker *disk.Tracker
 }
 
-var (
-	innerTableLabel fmt.Stringer = stringutil.StringerStr("innerTable")
-	outerTableLabel fmt.Stringer = stringutil.StringerStr("outerTable")
-)
-
 type mergeJoinTable struct {
 	isInner    bool
 	childIndex int

expression/errors.go

@@ -21,6 +21,7 @@ import (
 	"github.com/pingcap/tidb/util/dbterror"
 )
 
+// nolint:varcheck
 // Error instances.
 var (
 	// All the exported errors are defined here:

planner/core/find_best_task.go

@@ -90,6 +90,7 @@ func (c *PlanCounterTp) IsForce() bool {
 	return *c != -1
 }
 
+// nolint:varcheck
 // wholeTaskTypes records all possible kinds of task that a plan can return. For Agg, TopN and Limit, we will try to get
 // these tasks one by one.
 var wholeTaskTypes = [...]property.TaskType{property.CopSingleReadTaskType, property.CopDoubleReadTaskType, property.RootTaskType}

server/server.go

@@ -698,10 +698,3 @@ func setSystemTimeZoneVariable() {
 		variable.SetSysVar("system_time_zone", tz)
 	})
 }
-
-// Server error codes.
-const (
-	codeUnknownFieldType = 1
-	codeInvalidSequence  = 3
-	codeInvalidType      = 4
-)

sessionctx/binloginfo/binloginfo.go

@@ -46,6 +46,8 @@ var pumpsClient *pumpcli.PumpsClient
 var pumpsClientLock sync.RWMutex
 var shardPat = regexp.MustCompile(`SHARD_ROW_ID_BITS\s*=\s*\d+\s*`)
 var preSplitPat = regexp.MustCompile(`PRE_SPLIT_REGIONS\s*=\s*\d+\s*`)
+
+// nolint:varcheck
 var autoRandomPat = regexp.MustCompile(`AUTO_RANDOM\s*\(\s*\d+\s*\)\s*`)
 
 // BinlogInfo contains binlog data and binlog client.

store/mockstore/unistore/cophandler/mpp.go

@@ -43,6 +43,7 @@ const (
 	MPPErrEstablishConnMultiTimes
 )
 
+// nolint:varcheck
 const (
 	taskInit int32 = iota
 	taskRunning

util/chunk/list.go

@@ -14,12 +14,9 @@
 package chunk
 
 import (
-	"fmt"
-
 	"github.com/pingcap/errors"
 	"github.com/pingcap/tidb/types"
 	"github.com/pingcap/tidb/util/memory"
-	"github.com/pingcap/tidb/util/stringutil"
 )
 
 // List holds a slice of chunks, use to append rows with max chunk size properly handled.
@@ -42,8 +39,6 @@ type RowPtr struct {
 	RowIdx uint32
 }
 
-var chunkListLabel fmt.Stringer = stringutil.StringerStr("chunk.List")
-
 // NewList creates a new List with field types, init chunk size and max chunk size.
 func NewList(fieldTypes []*types.FieldType, initChunkSize, maxChunkSize int) *List {
 	l := &List{