sa4011.go raw

   1  package sa4011
   2  
   3  import (
   4  	"go/ast"
   5  	"go/token"
   6  
   7  	"honnef.co/go/tools/analysis/code"
   8  	"honnef.co/go/tools/analysis/lint"
   9  	"honnef.co/go/tools/analysis/report"
  10  
  11  	"golang.org/x/tools/go/analysis"
  12  	"golang.org/x/tools/go/analysis/passes/inspect"
  13  )
  14  
  15  var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
  16  	Analyzer: &analysis.Analyzer{
  17  		Name:     "SA4011",
  18  		Run:      run,
  19  		Requires: []*analysis.Analyzer{inspect.Analyzer},
  20  	},
  21  	Doc: &lint.RawDocumentation{
  22  		Title:    `Break statement with no effect. Did you mean to break out of an outer loop?`,
  23  		Since:    "2017.1",
  24  		Severity: lint.SeverityWarning,
  25  		MergeIf:  lint.MergeIfAny,
  26  	},
  27  })
  28  
  29  var Analyzer = SCAnalyzer.Analyzer
  30  
  31  func run(pass *analysis.Pass) (interface{}, error) {
  32  	fn := func(node ast.Node) {
  33  		var body *ast.BlockStmt
  34  		switch node := node.(type) {
  35  		case *ast.ForStmt:
  36  			body = node.Body
  37  		case *ast.RangeStmt:
  38  			body = node.Body
  39  		default:
  40  			lint.ExhaustiveTypeSwitch(node)
  41  		}
  42  		for _, stmt := range body.List {
  43  			var blocks [][]ast.Stmt
  44  			switch stmt := stmt.(type) {
  45  			case *ast.SwitchStmt:
  46  				for _, c := range stmt.Body.List {
  47  					blocks = append(blocks, c.(*ast.CaseClause).Body)
  48  				}
  49  			case *ast.SelectStmt:
  50  				for _, c := range stmt.Body.List {
  51  					blocks = append(blocks, c.(*ast.CommClause).Body)
  52  				}
  53  			default:
  54  				continue
  55  			}
  56  
  57  			for _, body := range blocks {
  58  				if len(body) == 0 {
  59  					continue
  60  				}
  61  				lasts := []ast.Stmt{body[len(body)-1]}
  62  				// TODO(dh): unfold all levels of nested block
  63  				// statements, not just a single level if statement
  64  				if ifs, ok := lasts[0].(*ast.IfStmt); ok {
  65  					if len(ifs.Body.List) == 0 {
  66  						continue
  67  					}
  68  					lasts[0] = ifs.Body.List[len(ifs.Body.List)-1]
  69  
  70  					if block, ok := ifs.Else.(*ast.BlockStmt); ok {
  71  						if len(block.List) != 0 {
  72  							lasts = append(lasts, block.List[len(block.List)-1])
  73  						}
  74  					}
  75  				}
  76  				for _, last := range lasts {
  77  					branch, ok := last.(*ast.BranchStmt)
  78  					if !ok || branch.Tok != token.BREAK || branch.Label != nil {
  79  						continue
  80  					}
  81  					report.Report(pass, branch, "ineffective break statement. Did you mean to break out of the outer loop?")
  82  				}
  83  			}
  84  		}
  85  	}
  86  	code.Preorder(pass, fn, (*ast.ForStmt)(nil), (*ast.RangeStmt)(nil))
  87  	return nil, nil
  88  }
  89