Add staticcheck tool

vendor/honnef.co/go/tools/staticcheck/sa1014/sa1014.go

@@ -0,0 +1,52 @@
+package sa1014
+
+import (
+	"fmt"
+	"go/types"
+
+	"honnef.co/go/tools/analysis/callcheck"
+	"honnef.co/go/tools/analysis/lint"
+	"honnef.co/go/tools/internal/passes/buildir"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
+	Analyzer: &analysis.Analyzer{
+		Name:     "SA1014",
+		Requires: []*analysis.Analyzer{buildir.Analyzer},
+		Run:      callcheck.Analyzer(checkUnmarshalPointerRules),
+	},
+	Doc: &lint.RawDocumentation{
+		Title:    `Non-pointer value passed to \'Unmarshal\' or \'Decode\'`,
+		Since:    "2017.1",
+		Severity: lint.SeverityError,
+		MergeIf:  lint.MergeIfAny,
+	},
+})
+
+var Analyzer = SCAnalyzer.Analyzer
+
+var checkUnmarshalPointerRules = map[string]callcheck.Check{
+	"encoding/xml.Unmarshal":                unmarshalPointer("xml.Unmarshal", 1),
+	"(*encoding/xml.Decoder).Decode":        unmarshalPointer("Decode", 0),
+	"(*encoding/xml.Decoder).DecodeElement": unmarshalPointer("DecodeElement", 0),
+	"encoding/json.Unmarshal":               unmarshalPointer("json.Unmarshal", 1),
+	"(*encoding/json.Decoder).Decode":       unmarshalPointer("Decode", 0),
+}
+
+func unmarshalPointer(name string, arg int) callcheck.Check {
+	return func(call *callcheck.Call) {
+		if !Pointer(call.Args[arg].Value) {
+			call.Args[arg].Invalid(fmt.Sprintf("%s expects to unmarshal into a pointer, but the provided value is not a pointer", name))
+		}
+	}
+}
+
+func Pointer(v callcheck.Value) bool {
+	switch v.Value.Type().Underlying().(type) {
+	case *types.Pointer, *types.Interface:
+		return true
+	}
+	return false
+}