Add staticcheck tool

vendor/honnef.co/go/tools/staticcheck/sa1025/sa1025.go

@@ -0,0 +1,92 @@
+package sa1025
+
+import (
+	"go/types"
+
+	"honnef.co/go/tools/analysis/lint"
+	"honnef.co/go/tools/analysis/report"
+	"honnef.co/go/tools/go/ir"
+	"honnef.co/go/tools/go/ir/irutil"
+	"honnef.co/go/tools/internal/passes/buildir"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
+	Analyzer: &analysis.Analyzer{
+		Name:     "SA1025",
+		Run:      run,
+		Requires: []*analysis.Analyzer{buildir.Analyzer},
+	},
+	Doc: &lint.RawDocumentation{
+		Title:    `It is not possible to use \'(*time.Timer).Reset\''s return value correctly`,
+		Since:    "2019.1",
+		Severity: lint.SeverityWarning,
+		MergeIf:  lint.MergeIfAny,
+	},
+})
+
+var Analyzer = SCAnalyzer.Analyzer
+
+func run(pass *analysis.Pass) (any, error) {
+	for _, fn := range pass.ResultOf[buildir.Analyzer].(*buildir.IR).SrcFuncs {
+		for _, block := range fn.Blocks {
+			for _, ins := range block.Instrs {
+				call, ok := ins.(*ir.Call)
+				if !ok {
+					continue
+				}
+				if !irutil.IsCallTo(call.Common(), "(*time.Timer).Reset") {
+					continue
+				}
+				refs := call.Referrers()
+				if refs == nil {
+					continue
+				}
+				for _, ref := range irutil.FilterDebug(*refs) {
+					ifstmt, ok := ref.(*ir.If)
+					if !ok {
+						continue
+					}
+
+					found := false
+					for _, succ := range ifstmt.Block().Succs {
+						if len(succ.Preds) != 1 {
+							// Merge point, not a branch in the
+							// syntactical sense.
+
+							// FIXME(dh): this is broken for if
+							// statements a la "if x || y"
+							continue
+						}
+						irutil.Walk(succ, func(b *ir.BasicBlock) bool {
+							if !succ.Dominates(b) {
+								// We've reached the end of the branch
+								return false
+							}
+							for _, ins := range b.Instrs {
+								// TODO(dh): we should check that we're receiving from the
+								// channel of a time.Timer to further reduce false
+								// positives. Not a key priority, considering the rarity
+								// of Reset and the tiny likeliness of a false positive
+								//
+								// We intentionally don't handle aliases here, because
+								// we're only interested in time.Timer.C.
+								if ins, ok := ins.(*ir.Recv); ok && types.TypeString(ins.Chan.Type(), nil) == "<-chan time.Time" {
+									found = true
+									return false
+								}
+							}
+							return true
+						})
+					}
+
+					if found {
+						report.Report(pass, call, "it is not possible to use Reset's return value correctly, as there is a race condition between draining the channel and the new timer expiring")
+					}
+				}
+			}
+		}
+	}
+	return nil, nil
+}