Add staticcheck tool

vendor/honnef.co/go/tools/staticcheck/sa4011/sa4011.go

@@ -0,0 +1,88 @@
+package sa4011
+
+import (
+	"go/ast"
+	"go/token"
+
+	"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:     "SA4011",
+		Run:      run,
+		Requires: []*analysis.Analyzer{inspect.Analyzer},
+	},
+	Doc: &lint.RawDocumentation{
+		Title:    `Break statement with no effect. Did you mean to break out of an outer loop?`,
+		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) {
+		var body *ast.BlockStmt
+		switch node := node.(type) {
+		case *ast.ForStmt:
+			body = node.Body
+		case *ast.RangeStmt:
+			body = node.Body
+		default:
+			lint.ExhaustiveTypeSwitch(node)
+		}
+		for _, stmt := range body.List {
+			var blocks [][]ast.Stmt
+			switch stmt := stmt.(type) {
+			case *ast.SwitchStmt:
+				for _, c := range stmt.Body.List {
+					blocks = append(blocks, c.(*ast.CaseClause).Body)
+				}
+			case *ast.SelectStmt:
+				for _, c := range stmt.Body.List {
+					blocks = append(blocks, c.(*ast.CommClause).Body)
+				}
+			default:
+				continue
+			}
+
+			for _, body := range blocks {
+				if len(body) == 0 {
+					continue
+				}
+				lasts := []ast.Stmt{body[len(body)-1]}
+				// TODO(dh): unfold all levels of nested block
+				// statements, not just a single level if statement
+				if ifs, ok := lasts[0].(*ast.IfStmt); ok {
+					if len(ifs.Body.List) == 0 {
+						continue
+					}
+					lasts[0] = ifs.Body.List[len(ifs.Body.List)-1]
+
+					if block, ok := ifs.Else.(*ast.BlockStmt); ok {
+						if len(block.List) != 0 {
+							lasts = append(lasts, block.List[len(block.List)-1])
+						}
+					}
+				}
+				for _, last := range lasts {
+					branch, ok := last.(*ast.BranchStmt)
+					if !ok || branch.Tok != token.BREAK || branch.Label != nil {
+						continue
+					}
+					report.Report(pass, branch, "ineffective break statement. Did you mean to break out of the outer loop?")
+				}
+			}
+		}
+	}
+	code.Preorder(pass, fn, (*ast.ForStmt)(nil), (*ast.RangeStmt)(nil))
+	return nil, nil
+}