buld: enable goconst linter (#15566)

build/ci.go

@@ -323,7 +323,15 @@ func doLint(cmdline []string) {
 	build.MustRunCommand(filepath.Join(GOBIN, "gometalinter.v1"), "--install")
 
 	// Run fast linters batched together
-	configs := []string{"--vendor", "--disable-all", "--enable=vet", "--enable=gofmt", "--enable=misspell"}
+	configs := []string{
+		"--vendor",
+		"--disable-all",
+		"--enable=vet",
+		"--enable=gofmt",
+		"--enable=misspell",
+		"--enable=goconst",
+		"--min-occurrences=6", // for goconst
+	}
 	build.MustRunCommand(filepath.Join(GOBIN, "gometalinter.v1"), append(configs, packages...)...)
 
 	// Run slow linters one by one

cmd/swarm/manifest.go

@@ -30,6 +30,8 @@ import (
 	"gopkg.in/urfave/cli.v1"
 )
 
+const bzzManifestJSON = "application/bzz-manifest+json"
+
 func add(ctx *cli.Context) {
 	args := ctx.Args()
 	if len(args) < 3 {
@@ -145,7 +147,7 @@ func addEntryToManifest(ctx *cli.Context, mhash, path, hash, ctype string) strin
 		if path == entry.Path {
 			utils.Fatalf("Path %s already present, not adding anything", path)
 		} else {
-			if entry.ContentType == "application/bzz-manifest+json" {
+			if entry.ContentType == bzzManifestJSON {
 				prfxlen := strings.HasPrefix(path, entry.Path)
 				if prfxlen && len(path) > len(longestPathEntry.Path) {
 					longestPathEntry = entry
@@ -207,7 +209,7 @@ func updateEntryInManifest(ctx *cli.Context, mhash, path, hash, ctype string) st
 		if path == entry.Path {
 			newEntry = entry
 		} else {
-			if entry.ContentType == "application/bzz-manifest+json" {
+			if entry.ContentType == bzzManifestJSON {
 				prfxlen := strings.HasPrefix(path, entry.Path)
 				if prfxlen && len(path) > len(longestPathEntry.Path) {
 					longestPathEntry = entry
@@ -281,7 +283,7 @@ func removeEntryFromManifest(ctx *cli.Context, mhash, path string) string {
 		if path == entry.Path {
 			entryToRemove = entry
 		} else {
-			if entry.ContentType == "application/bzz-manifest+json" {
+			if entry.ContentType == bzzManifestJSON {
 				prfxlen := strings.HasPrefix(path, entry.Path)
 				if prfxlen && len(path) > len(longestPathEntry.Path) {
 					longestPathEntry = entry