Add staticcheck tool

vendor/honnef.co/go/tools/staticcheck/sa4001/sa4001.go

@@ -0,0 +1,52 @@
+package sa4001
+
+import (
+	"go/ast"
+	"regexp"
+
+	"honnef.co/go/tools/analysis/code"
+	"honnef.co/go/tools/analysis/lint"
+	"honnef.co/go/tools/analysis/report"
+	"honnef.co/go/tools/pattern"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+)
+
+var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
+	Analyzer: &analysis.Analyzer{
+		Name:     "SA4001",
+		Run:      run,
+		Requires: []*analysis.Analyzer{inspect.Analyzer},
+	},
+	Doc: &lint.RawDocumentation{
+		Title:    `\'&*x\' gets simplified to \'x\', it does not copy \'x\'`,
+		Since:    "2017.1",
+		Severity: lint.SeverityWarning,
+		MergeIf:  lint.MergeIfAny,
+	},
+})
+
+var Analyzer = SCAnalyzer.Analyzer
+
+var (
+	// cgo produces code like fn(&*_Cvar_kSomeCallbacks) which we don't
+	// want to flag.
+	cgoIdent               = regexp.MustCompile(`^_C(func|var)_.+$`)
+	checkIneffectiveCopyQ1 = pattern.MustParse(`(UnaryExpr "&" (StarExpr obj))`)
+	checkIneffectiveCopyQ2 = pattern.MustParse(`(StarExpr (UnaryExpr "&" _))`)
+)
+
+func run(pass *analysis.Pass) (any, error) {
+	fn := func(node ast.Node) {
+		if m, ok := code.Match(pass, checkIneffectiveCopyQ1, node); ok {
+			if ident, ok := m.State["obj"].(*ast.Ident); !ok || !cgoIdent.MatchString(ident.Name) {
+				report.Report(pass, node, "&*x will be simplified to x. It will not copy x.")
+			}
+		} else if _, ok := code.Match(pass, checkIneffectiveCopyQ2, node); ok {
+			report.Report(pass, node, "*&x will be simplified to x. It will not copy x.")
+		}
+	}
+	code.Preorder(pass, fn, (*ast.UnaryExpr)(nil), (*ast.StarExpr)(nil))
+	return nil, nil
+}