build: add Travis job to lint Go code #15372 (#15416)

* build: [finishes #15372] implements generalized linter and travis job

* .travis, build: minor polishes, disable deadcode

2 files changed, 35 insertions, 32 deletions

diff --git a/.travis.yml b/.travis.yml
index 8a7f65e3d..fe3b04cd2 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -38,7 +38,7 @@ matrix:
         - sudo chmod 666 /dev/fuse
         - sudo chown root:$USER /etc/fuse.conf
         - go run build/ci.go install
-        - go run build/ci.go test -coverage -misspell
+        - go run build/ci.go test -coverage
 
     - os: osx
       go: 1.9.x
@@ -48,7 +48,21 @@ matrix:
         - brew install caskroom/cask/brew-cask
         - brew cask install osxfuse
         - go run build/ci.go install
-        - go run build/ci.go test -coverage -misspell
+        - go run build/ci.go test -coverage
+
+    # This builder only tests code linters on latest version of Go
+    - os: linux
+      dist: trusty
+      sudo: required
+      go: 1.9.x
+      env:
+        - lint
+      script:
+        - sudo -E apt-get -yq --no-install-suggests --no-install-recommends --force-yes install fuse
+        - sudo modprobe fuse
+        - sudo chmod 666 /dev/fuse
+        - sudo chown root:$USER /etc/fuse.conf
+        - go run build/ci.go lint
 
     # This builder does the Ubuntu PPA and Linux Azure uploads
     - os: linux
diff --git a/build/ci.go b/build/ci.go
index a4f5616bc..5d52fad87 100644
--- a/build/ci.go
+++ b/build/ci.go
@@ -24,7 +24,8 @@ Usage: go run ci.go <command> <command flags/arguments>
 Available commands are:
 
    install    [ -arch architecture ] [ packages... ]                                           -- builds packages and executables
-   test       [ -coverage ] [ -misspell ] [ packages... ]                                      -- runs the tests
+   test       [ -coverage ] [ packages... ]                                                    -- runs the tests
+   lint                                                                                        -- runs certain pre-selected linters
    archive    [ -arch architecture ] [ -type zip|tar ] [ -signer key-envvar ] [ -upload dest ] -- archives build artefacts
    importkeys                                                                                  -- imports signing keys from env
    debsrc     [ -signer key-id ] [ -upload dest ]                                              -- creates a debian source package
@@ -146,6 +147,8 @@ func main() {
 		doInstall(os.Args[2:])
 	case "test":
 		doTest(os.Args[2:])
+	case "lint":
+		doLint(os.Args[2:])
 	case "archive":
 		doArchive(os.Args[2:])
 	case "debsrc":
@@ -280,7 +283,6 @@ func goToolArch(arch string, subcmd string, args ...string) *exec.Cmd {
 
 func doTest(cmdline []string) {
 	var (
-		misspell = flag.Bool("misspell", false, "Whether to run the spell checker")
 		coverage = flag.Bool("coverage", false, "Whether to record code coverage")
 	)
 	flag.CommandLine.Parse(cmdline)
@@ -294,10 +296,7 @@ func doTest(cmdline []string) {
 
 	// Run analysis tools before the tests.
 	build.MustRun(goTool("vet", packages...))
-	if *misspell {
-		// TODO(karalabe): Reenable after false detection is fixed: https://github.com/client9/misspell/issues/105
-		// spellcheck(packages)
-	}
+
 	// Run the actual tests.
 	gotest := goTool("test", buildFlags(env)...)
 	// Test a single package at a time. CI builders are slow
@@ -306,36 +305,26 @@ func doTest(cmdline []string) {
 	if *coverage {
 		gotest.Args = append(gotest.Args, "-covermode=atomic", "-cover")
 	}
+
 	gotest.Args = append(gotest.Args, packages...)
 	build.MustRun(gotest)
 }
 
-// spellcheck runs the client9/misspell spellchecker package on all Go, Cgo and
-// test files in the requested packages.
-func spellcheck(packages []string) {
-	// Ensure the spellchecker is available
-	build.MustRun(goTool("get", "github.com/client9/misspell/cmd/misspell"))
+// runs gometalinter on requested packages
+func doLint(cmdline []string) {
+	flag.CommandLine.Parse(cmdline)
 
-	// Windows chokes on long argument lists, check packages individually
-	for _, pkg := range packages {
-		// The spell checker doesn't work on packages, gather all .go files for it
-		out, err := goTool("list", "-f", "{{.Dir}}{{range .GoFiles}}\n{{.}}{{end}}{{range .CgoFiles}}\n{{.}}{{end}}{{range .TestGoFiles}}\n{{.}}{{end}}", pkg).CombinedOutput()
-		if err != nil {
-			log.Fatalf("source file listing failed: %v\n%s", err, string(out))
-		}
-		// Retrieve the folder and assemble the source list
-		lines := strings.Split(string(out), "\n")
-		root := lines[0]
-
-		sources := make([]string, 0, len(lines)-1)
-		for _, line := range lines[1:] {
-			if line = strings.TrimSpace(line); line != "" {
-				sources = append(sources, filepath.Join(root, line))
-			}
-		}
-		// Run the spell checker for this particular package
-		build.MustRunCommand(filepath.Join(GOBIN, "misspell"), append([]string{"-error"}, sources...)...)
+	packages := []string{"./..."}
+	if len(flag.CommandLine.Args()) > 0 {
+		packages = flag.CommandLine.Args()
 	}
+	// Get metalinter and install all supported linters
+	build.MustRun(goTool("get", "gopkg.in/alecthomas/gometalinter.v1"))
+	build.MustRunCommand(filepath.Join(GOBIN, "gometalinter.v1"), "--install")
+
+	configs := []string{"--vendor", "--disable-all", "--enable=vet"} // Add additional linters to the slice with "--enable=linter-name"
+
+	build.MustRunCommand(filepath.Join(GOBIN, "gometalinter.v1"), append(configs, packages...)...)
 }
 
 // Release Packaging