Add staticcheck tool

vendor/honnef.co/go/tools/staticcheck/sa1017/sa1017.go

@@ -0,0 +1,64 @@
+package sa1017
+
+import (
+	"go/constant"
+
+	"honnef.co/go/tools/analysis/callcheck"
+	"honnef.co/go/tools/analysis/lint"
+	"honnef.co/go/tools/go/ir"
+	"honnef.co/go/tools/internal/passes/buildir"
+	"honnef.co/go/tools/knowledge"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
+	Analyzer: &analysis.Analyzer{
+		Name:     "SA1017",
+		Requires: []*analysis.Analyzer{buildir.Analyzer},
+		Run:      callcheck.Analyzer(rules),
+	},
+	Doc: &lint.RawDocumentation{
+		Title: `Channels used with \'os/signal.Notify\' should be buffered`,
+		Text: `The \'os/signal\' package uses non-blocking channel sends when delivering
+signals. If the receiving end of the channel isn't ready and the
+channel is either unbuffered or full, the signal will be dropped. To
+avoid missing signals, the channel should be buffered and of the
+appropriate size. For a channel used for notification of just one
+signal value, a buffer of size 1 is sufficient.`,
+		Since:    "2017.1",
+		Severity: lint.SeverityWarning,
+		MergeIf:  lint.MergeIfAny,
+	},
+})
+
+var Analyzer = SCAnalyzer.Analyzer
+
+var rules = map[string]callcheck.Check{
+	"os/signal.Notify": func(call *callcheck.Call) {
+		arg := call.Args[knowledge.Arg("os/signal.Notify.c")]
+		if isUnbufferedChannel(arg.Value) {
+			arg.Invalid("the channel used with signal.Notify should be buffered")
+		}
+	},
+}
+
+func isUnbufferedChannel(v callcheck.Value) bool {
+	// TODO(dh): this check of course misses many cases of unbuffered
+	// channels, such as any in phi or sigma nodes. We'll eventually
+	// replace this function.
+	val := v.Value
+	if ct, ok := val.(*ir.ChangeType); ok {
+		val = ct.X
+	}
+	mk, ok := val.(*ir.MakeChan)
+	if !ok {
+		return false
+	}
+	if k, ok := mk.Size.(*ir.Const); ok && k.Value.Kind() == constant.Int {
+		if v, ok := constant.Int64Val(k.Value); ok && v == 0 {
+			return true
+		}
+	}
+	return false
+}