sa4018.go raw

   1  package sa4018
   2  
   3  import (
   4  	"fmt"
   5  	"go/ast"
   6  	"go/token"
   7  	"reflect"
   8  
   9  	"honnef.co/go/tools/analysis/code"
  10  	"honnef.co/go/tools/analysis/facts/generated"
  11  	"honnef.co/go/tools/analysis/facts/purity"
  12  	"honnef.co/go/tools/analysis/lint"
  13  	"honnef.co/go/tools/analysis/report"
  14  
  15  	"golang.org/x/tools/go/analysis"
  16  	"golang.org/x/tools/go/analysis/passes/inspect"
  17  )
  18  
  19  var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
  20  	Analyzer: &analysis.Analyzer{
  21  		Name:     "SA4018",
  22  		Run:      run,
  23  		Requires: []*analysis.Analyzer{inspect.Analyzer, generated.Analyzer, purity.Analyzer},
  24  	},
  25  	Doc: &lint.RawDocumentation{
  26  		Title:    `Self-assignment of variables`,
  27  		Since:    "2017.1",
  28  		Severity: lint.SeverityWarning,
  29  		MergeIf:  lint.MergeIfAny,
  30  	},
  31  })
  32  
  33  var Analyzer = SCAnalyzer.Analyzer
  34  
  35  func run(pass *analysis.Pass) (interface{}, error) {
  36  	pure := pass.ResultOf[purity.Analyzer].(purity.Result)
  37  
  38  	fn := func(node ast.Node) {
  39  		assign := node.(*ast.AssignStmt)
  40  		if assign.Tok != token.ASSIGN || len(assign.Lhs) != len(assign.Rhs) {
  41  			return
  42  		}
  43  		for i, lhs := range assign.Lhs {
  44  			rhs := assign.Rhs[i]
  45  			if reflect.TypeOf(lhs) != reflect.TypeOf(rhs) {
  46  				continue
  47  			}
  48  			if code.MayHaveSideEffects(pass, lhs, pure) || code.MayHaveSideEffects(pass, rhs, pure) {
  49  				continue
  50  			}
  51  
  52  			rlh := report.Render(pass, lhs)
  53  			rrh := report.Render(pass, rhs)
  54  			if rlh == rrh {
  55  				report.Report(pass, assign, fmt.Sprintf("self-assignment of %s to %s", rrh, rlh), report.FilterGenerated())
  56  			}
  57  		}
  58  	}
  59  	code.Preorder(pass, fn, (*ast.AssignStmt)(nil))
  60  	return nil, nil
  61  }
  62