build: make errcheck works correctly (pingcap#12381)

Makefile

@@ -94,7 +94,7 @@ check-slow:tools/bin/gometalinter tools/bin/gosec
 
 errcheck:tools/bin/errcheck
 	@echo "errcheck"
-	@GO111MODULE=on tools/bin/errcheck -exclude ./tools/check/errcheck_excludes.txt -blank $(PACKAGES) | grep -v "_test\.go" | awk '{print} END{if(NR>0) {exit 1}}'
+	@GO111MODULE=on tools/bin/errcheck -exclude ./tools/check/errcheck_excludes.txt -ignoretests -blank $(PACKAGES)
 
 gogenerate:
 	@echo "go generate ./..."

planner/core/rule_max_min_eliminate.go

@@ -143,7 +143,9 @@ func (a *maxMinEliminator) splitAggFuncAndCheckIndices(agg *LogicalAggregation)
 		newAgg := LogicalAggregation{AggFuncs: []*aggregation.AggFuncDesc{f}}.Init(agg.ctx, agg.blockOffset)
 		newAgg.SetChildren(a.cloneSubPlans(agg.children[0]))
 		newAgg.schema = expression.NewSchema(agg.schema.Columns[i])
-		newAgg.PruneColumns([]*expression.Column{newAgg.schema.Columns[0]})
+		if err := newAgg.PruneColumns([]*expression.Column{newAgg.schema.Columns[0]}); err != nil {
+			return nil, false
+		}
 		aggs = append(aggs, newAgg)
 	}
 	return aggs, true

statistics/histogram.go

@@ -227,7 +227,9 @@ func ValueToString(value *types.Datum, idxCols int) (string, error) {
 		return value.ToString()
 	}
 	// Ignore the error and treat remaining part that cannot decode successfully as bytes.
-	decodedVals, remained, _ := codec.DecodeRange(value.GetBytes(), idxCols)
+	decodedVals, remained, err := codec.DecodeRange(value.GetBytes(), idxCols)
+	// Ignore err explicit to pass errcheck.
+	_ = err
 	if len(remained) > 0 {
 		decodedVals = append(decodedVals, types.NewBytesDatum(remained))
 	}

store/mockstore/mocktikv/mvcc_leveldb.go

@@ -1498,14 +1498,13 @@ func (mvcc *MVCCLevelDB) MvccGetByStartTS(starTS uint64) (*kvrpcpb.MvccInfo, []b
 		var value mvccValue
 		err := value.UnmarshalBinary(iter.Value())
 		if err == nil && value.startTS == starTS {
-			_, key, _ = codec.DecodeBytes(iter.Key(), nil)
+			if _, key, err = codec.DecodeBytes(iter.Key(), nil); err != nil {
+				return nil, nil
+			}
 			break
 		}
 		iter.Next()
 	}
-	if key == nil {
-		return nil, nil
-	}
 
 	return mvcc.MvccGetByKey(key), key
 }

tools/check/go.mod

@@ -13,6 +13,7 @@ require (
 	github.com/nicksnyder/go-i18n v1.10.0 // indirect
 	github.com/pelletier/go-toml v1.2.0 // indirect
 	github.com/securego/gosec v0.0.0-20181211171558-12400f9a1ca7
+	golang.org/x/tools v0.0.0-20190925020647-22afafe3322a // indirect
 	gopkg.in/alecthomas/gometalinter.v2 v2.0.12 // indirect
 	gopkg.in/alecthomas/gometalinter.v3 v3.0.0 // indirect
 	gopkg.in/alecthomas/kingpin.v2 v2.2.6 // indirect

tools/check/go.sum

@@ -51,15 +51,23 @@ github.com/ryanuber/go-glob v0.0.0-20170128012129-256dc444b735/go.mod h1:807d1WS
 github.com/securego/gosec v0.0.0-20181211171558-12400f9a1ca7 h1:Ca7U7/rZ+caxjW2na7wbmgmaPsoSCIlpc6sm0aWtFg0=
 github.com/securego/gosec v0.0.0-20181211171558-12400f9a1ca7/go.mod h1:m3KbCTwh9vLhm6AKBjE+ALesKilKcQHezI1uVOti0Ks=
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/net v0.0.0-20170915142106-8351a756f30f/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20171026204733-164713f0dfce/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20180909124046-d0be0721c37e/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/text v0.0.0-20170915090833-1cbadb444a80/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/tools v0.0.0-20170915040203-e531a2a1c15f/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20180911133044-677d2ff680c1/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20181030221726-6c7e314b6563 h1:NIou6eNFigscvKJmsbyez16S2cIS6idossORlFtSt2E=
 golang.org/x/tools v0.0.0-20181030221726-6c7e314b6563/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/tools v0.0.0-20190925020647-22afafe3322a h1:3GxqzBPBt1O2dIiPnzldQ5d25CAMWJFBZTpqxLPfjs8=
+golang.org/x/tools v0.0.0-20190925020647-22afafe3322a/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gopkg.in/alecthomas/gometalinter.v2 v2.0.12 h1:/xBWwtjmOmVxn8FXfIk9noV8m2E2Id9jFfUY/Mh9QAI=
 gopkg.in/alecthomas/gometalinter.v2 v2.0.12/go.mod h1:NDRytsqEZyolNuAgTzJkZMkSQM7FIKyzVzGhjB/qfYo=
 gopkg.in/alecthomas/gometalinter.v3 v3.0.0 h1:tKnpLD70cWDacxrv9JZ4atld7RPoPiHOBfad6mPmyBw=

util/chunk/disk.go

@@ -47,8 +47,11 @@ var bufReaderPool = sync.Pool{
 var tmpDir = path.Join(os.TempDir(), "tidb-server-"+path.Base(os.Args[0]))
 
 func init() {
-	_ = os.RemoveAll(tmpDir) // clean the uncleared temp file during the last run.
-	err := os.Mkdir(tmpDir, 0755)
+	err := os.RemoveAll(tmpDir) // clean the uncleared temp file during the last run.
+	if err != nil {
+		log.Warn("Remove temporary file error", zap.String("tmpDir", tmpDir), zap.Error(err))
+	}
+	err = os.Mkdir(tmpDir, 0755)
 	if err != nil {
 		log.Warn("Mkdir temporary file error", zap.String("tmpDir", tmpDir), zap.Error(err))
 	}