Add staticcheck tool

vendor/honnef.co/go/tools/staticcheck/sa5001/sa5001.go

@@ -0,0 +1,109 @@
+package sa5001
+
+import (
+	"fmt"
+	"go/ast"
+	"go/types"
+
+	"honnef.co/go/tools/analysis/code"
+	"honnef.co/go/tools/analysis/lint"
+	"honnef.co/go/tools/analysis/report"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+)
+
+var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
+	Analyzer: &analysis.Analyzer{
+		Name:     "SA5001",
+		Run:      run,
+		Requires: []*analysis.Analyzer{inspect.Analyzer},
+	},
+	Doc: &lint.RawDocumentation{
+		Title:    `Deferring \'Close\' before checking for a possible error`,
+		Since:    "2017.1",
+		Severity: lint.SeverityWarning,
+		MergeIf:  lint.MergeIfAny,
+	},
+})
+
+var Analyzer = SCAnalyzer.Analyzer
+
+func run(pass *analysis.Pass) (any, error) {
+	fn := func(node ast.Node) {
+		block := node.(*ast.BlockStmt)
+		if len(block.List) < 2 {
+			return
+		}
+		for i, stmt := range block.List {
+			if i == len(block.List)-1 {
+				break
+			}
+			assign, ok := stmt.(*ast.AssignStmt)
+			if !ok {
+				continue
+			}
+			if len(assign.Rhs) != 1 {
+				continue
+			}
+			if len(assign.Lhs) < 2 {
+				continue
+			}
+			if lhs, ok := assign.Lhs[len(assign.Lhs)-1].(*ast.Ident); ok && lhs.Name == "_" {
+				continue
+			}
+			call, ok := assign.Rhs[0].(*ast.CallExpr)
+			if !ok {
+				continue
+			}
+			sig, ok := pass.TypesInfo.TypeOf(call.Fun).(*types.Signature)
+			if !ok {
+				continue
+			}
+			if sig.Results().Len() < 2 {
+				continue
+			}
+			last := sig.Results().At(sig.Results().Len() - 1)
+			// FIXME(dh): check that it's error from universe, not
+			// another type of the same name
+			if last.Type().String() != "error" {
+				continue
+			}
+			lhs, ok := assign.Lhs[0].(*ast.Ident)
+			if !ok {
+				continue
+			}
+			def, ok := block.List[i+1].(*ast.DeferStmt)
+			if !ok {
+				continue
+			}
+			sel, ok := def.Call.Fun.(*ast.SelectorExpr)
+			if !ok {
+				continue
+			}
+			ident, ok := selectorX(sel).(*ast.Ident)
+			if !ok {
+				continue
+			}
+			if pass.TypesInfo.ObjectOf(ident) != pass.TypesInfo.ObjectOf(lhs) {
+				continue
+			}
+			if sel.Sel.Name != "Close" {
+				continue
+			}
+			report.Report(pass, def, fmt.Sprintf("should check error returned from %s() before deferring %s",
+				report.Render(pass, call.Fun), report.Render(pass, def.Call)))
+		}
+	}
+	code.Preorder(pass, fn, (*ast.BlockStmt)(nil))
+	return nil, nil
+}
+
+func selectorX(sel *ast.SelectorExpr) ast.Node {
+	switch x := sel.X.(type) {
+	case *ast.SelectorExpr:
+		return selectorX(x)
+	default:
+		return x
+	}
+}