Remove //nolint: gas directives from fmt.Fprintf #590 (#656)

Summary:
Filter out gas linter error checks for fmt.Fprintf commands. This required defining a custom linter around gas that additionally included the offending code.

Notes:

Gas format, without piping it through gometalinter, gives output like this:

$ gas -fmt=csv geth/jail/console/console.go
geth/jail/console/console.go,21,Errors unhandled.,LOW,HIGH,"fmt.Fprintf(w, ""%s: %s"", consoleEventName, formatForConsole(fn.ArgumentList))"
Gometalinter, by default, does not grab the line of code when it filters gas errors. To resolve this, I created a wrapper around gas (I wasn't sure what to call this "gas wrapper", I opted for gasv2, open to other names).

The first part of the regular expression was taken directly from gometalinter (see https://github.com/alecthomas/gometalinter/blob/master/linters.go#L236), and I then appended ,\".*\" to additionally grab the line of code of the offending line. Lastly, I excluded ".*Errors unhandled.*fmt.Fprintf.*" to filter out only fmt.Fprintf errors around omitted errors.

Also as a result of this change, gas lint output will now include the offending code.

Closes #590

.gometalinter.json

@@ -1,15 +1,22 @@
 {
     "Exclude": [
         ".*_mock.go",
-        "geth/jail/doc.go"
+        "geth/jail/doc.go",
+        ".*Errors unhandled.*fmt.Fprint.*gasv2.*"
     ],
     "Skip": ["helpers", "static"],
     "Vendor": true,
     "Test": true,
+    "Linters": {
+        "gasv2": {
+          "Command": "gas -fmt=csv",
+          "Pattern": "^(?P<path>.*?\\.go),(?P<line>\\d+),(?P<message>[^,]+,[^,]+,[^,]+,\".*\")"
+        }
+    },
     "Enable": [
         "deadcode",
         "errcheck",
-        "gas",
+        "gasv2",
         "goconst",
         "gocyclo",
         "gofmt",

cmd/statusd/main.go

@@ -276,7 +276,7 @@ Examples:
 
 Options:
 `
-	fmt.Fprint(os.Stderr, usage) // nolint: gas
+	fmt.Fprintf(os.Stderr, usage)
 	flag.PrintDefaults()
 }
 

geth/common/utils.go

@@ -131,9 +131,9 @@ func Fatalf(reason interface{}, args ...interface{}) {
 	// find out whether error or string has been passed as a reason
 	r := reflect.ValueOf(reason)
 	if r.Kind() == reflect.String {
-		fmt.Fprintf(w, "Fatal Failure: %v\n%v\n", reason.(string), args) //nolint: gas
+		fmt.Fprintf(w, "Fatal Failure: %v\n%v\n", reason.(string), args)
 	} else {
-		fmt.Fprintf(w, "Fatal Failure: %v\n", reason.(error)) //nolint: gas
+		fmt.Fprintf(w, "Fatal Failure: %v\n", reason.(error))
 	}
 
 	debug.PrintStack()

geth/jail/console/console.go

@@ -18,7 +18,7 @@ func Write(fn otto.FunctionCall, w io.Writer, consoleEventName string) otto.Valu
 	})
 
 	// Next print out the giving values.
-	fmt.Fprintf(w, "%s: %s", consoleEventName, formatForConsole(fn.ArgumentList)) // nolint: gas
+	fmt.Fprintf(w, "%s: %s", consoleEventName, formatForConsole(fn.ArgumentList))
 
 	return otto.UndefinedValue()
 }

geth/log/log.go

@@ -91,7 +91,7 @@ func SetLogFile(filename string) error {
 func levelFromString(level string) log.Lvl {
 	lvl, err := log.LvlFromString(strings.ToLower(level))
 	if err != nil {
-		fmt.Fprintf(os.Stderr, "Incorrect log level: %s, using defaults\n", level) // nolint: gas
+		fmt.Fprintf(os.Stderr, "Incorrect log level: %s, using defaults\n", level)
 		lvl = log.LvlInfo
 	}
 	return lvl