Add staticcheck tool

vendor/honnef.co/go/tools/staticcheck/sa5005/sa5005.go

@@ -0,0 +1,90 @@
+package sa5005
+
+import (
+	"fmt"
+
+	"honnef.co/go/tools/analysis/lint"
+	"honnef.co/go/tools/analysis/report"
+	"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:     "SA5005",
+		Run:      run,
+		Requires: []*analysis.Analyzer{buildir.Analyzer},
+	},
+	Doc: &lint.RawDocumentation{
+		Title: `The finalizer references the finalized object, preventing garbage collection`,
+		Text: `A finalizer is a function associated with an object that runs when the
+garbage collector is ready to collect said object, that is when the
+object is no longer referenced by anything.
+
+If the finalizer references the object, however, it will always remain
+as the final reference to that object, preventing the garbage
+collector from collecting the object. The finalizer will never run,
+and the object will never be collected, leading to a memory leak. That
+is why the finalizer should instead use its first argument to operate
+on the object. That way, the number of references can temporarily go
+to zero before the object is being passed to the finalizer.`,
+		Since:    "2017.1",
+		Severity: lint.SeverityWarning,
+		MergeIf:  lint.MergeIfAny,
+	},
+})
+
+var Analyzer = SCAnalyzer.Analyzer
+
+func run(pass *analysis.Pass) (any, error) {
+	cb := func(caller *ir.Function, site ir.CallInstruction, callee *ir.Function) {
+		if callee.RelString(nil) != "runtime.SetFinalizer" {
+			return
+		}
+		arg0 := site.Common().Args[knowledge.Arg("runtime.SetFinalizer.obj")]
+		if iface, ok := arg0.(*ir.MakeInterface); ok {
+			arg0 = iface.X
+		}
+		load, ok := arg0.(*ir.Load)
+		if !ok {
+			return
+		}
+		v, ok := load.X.(*ir.Alloc)
+		if !ok {
+			return
+		}
+		arg1 := site.Common().Args[knowledge.Arg("runtime.SetFinalizer.finalizer")]
+		if iface, ok := arg1.(*ir.MakeInterface); ok {
+			arg1 = iface.X
+		}
+		mc, ok := arg1.(*ir.MakeClosure)
+		if !ok {
+			return
+		}
+		for _, b := range mc.Bindings {
+			if b == v {
+				pos := report.DisplayPosition(pass.Fset, mc.Fn.Pos())
+				report.Report(pass, site, fmt.Sprintf("the finalizer closes over the object, preventing the finalizer from ever running (at %s)", pos))
+			}
+		}
+	}
+	for _, fn := range pass.ResultOf[buildir.Analyzer].(*buildir.IR).SrcFuncs {
+		eachCall(fn, cb)
+	}
+	return nil, nil
+}
+
+func eachCall(fn *ir.Function, cb func(caller *ir.Function, site ir.CallInstruction, callee *ir.Function)) {
+	for _, b := range fn.Blocks {
+		for _, instr := range b.Instrs {
+			if site, ok := instr.(ir.CallInstruction); ok {
+				if g := site.Common().StaticCallee(); g != nil {
+					cb(fn, site, g)
+				}
+			}
+		}
+	}
+}