Add staticcheck tool

vendor/honnef.co/go/tools/staticcheck/sa6003/sa6003.go

@@ -0,0 +1,42 @@
+package sa6003
+
+import (
+	"honnef.co/go/tools/analysis/lint"
+	"honnef.co/go/tools/internal/passes/buildir"
+	"honnef.co/go/tools/internal/sharedcheck"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
+	Analyzer: &analysis.Analyzer{
+		Name:     "SA6003",
+		Run:      sharedcheck.CheckRangeStringRunes,
+		Requires: []*analysis.Analyzer{buildir.Analyzer},
+	},
+	Doc: &lint.RawDocumentation{
+		Title: `Converting a string to a slice of runes before ranging over it`,
+		Text: `You may want to loop over the runes in a string. Instead of converting
+the string to a slice of runes and looping over that, you can loop
+over the string itself. That is,
+
+    for _, r := range s {}
+
+and
+
+    for _, r := range []rune(s) {}
+
+will yield the same values. The first version, however, will be faster
+and avoid unnecessary memory allocations.
+
+Do note that if you are interested in the indices, ranging over a
+string and over a slice of runes will yield different indices. The
+first one yields byte offsets, while the second one yields indices in
+the slice of runes.`,
+		Since:    "2017.1",
+		Severity: lint.SeverityWarning,
+		MergeIf:  lint.MergeIfAny,
+	},
+})
+
+var Analyzer = SCAnalyzer.Analyzer