Add staticcheck tool

vendor/honnef.co/go/tools/staticcheck/sa1023/sa1023.go

@@ -0,0 +1,72 @@
+package sa1023
+
+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"
+	"honnef.co/go/tools/knowledge"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
+	Analyzer: &analysis.Analyzer{
+		Name:     "SA1023",
+		Run:      run,
+		Requires: []*analysis.Analyzer{buildir.Analyzer},
+	},
+	Doc: &lint.RawDocumentation{
+		Title:    `Modifying the buffer in an \'io.Writer\' implementation`,
+		Text:     `\'Write\' must not modify the slice data, even temporarily.`,
+		Since:    "2017.1",
+		Severity: lint.SeverityError,
+		MergeIf:  lint.MergeIfAny,
+	},
+})
+
+var Analyzer = SCAnalyzer.Analyzer
+
+func run(pass *analysis.Pass) (any, error) {
+	// TODO(dh): this might be a good candidate for taint analysis.
+	// Taint the argument as MUST_NOT_MODIFY, then propagate that
+	// through functions like bytes.Split
+
+	for _, fn := range pass.ResultOf[buildir.Analyzer].(*buildir.IR).SrcFuncs {
+		sig := fn.Signature
+		if fn.Name() != "Write" || sig.Recv() == nil {
+			continue
+		}
+		if !types.Identical(sig, knowledge.Signatures["(io.Writer).Write"]) {
+			continue
+		}
+
+		for _, block := range fn.Blocks {
+			for _, ins := range block.Instrs {
+				switch ins := ins.(type) {
+				case *ir.Store:
+					addr, ok := ins.Addr.(*ir.IndexAddr)
+					if !ok {
+						continue
+					}
+					if addr.X != fn.Params[1] {
+						continue
+					}
+					report.Report(pass, ins, "io.Writer.Write must not modify the provided buffer, not even temporarily")
+				case *ir.Call:
+					if !irutil.IsCallTo(ins.Common(), "append") {
+						continue
+					}
+					if ins.Common().Args[0] != fn.Params[1] {
+						continue
+					}
+					report.Report(pass, ins, "io.Writer.Write must not modify the provided buffer, not even temporarily")
+				}
+			}
+		}
+	}
+	return nil, nil
+}