sa4013.go raw

   1  package sa4013
   2  
   3  import (
   4  	"go/ast"
   5  
   6  	"honnef.co/go/tools/analysis/code"
   7  	"honnef.co/go/tools/analysis/edit"
   8  	"honnef.co/go/tools/analysis/lint"
   9  	"honnef.co/go/tools/analysis/report"
  10  	"honnef.co/go/tools/pattern"
  11  
  12  	"golang.org/x/tools/go/analysis"
  13  	"golang.org/x/tools/go/analysis/passes/inspect"
  14  )
  15  
  16  var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
  17  	Analyzer: &analysis.Analyzer{
  18  		Name:     "SA4013",
  19  		Run:      run,
  20  		Requires: []*analysis.Analyzer{inspect.Analyzer},
  21  	},
  22  	Doc: &lint.RawDocumentation{
  23  		Title:    `Negating a boolean twice (\'!!b\') is the same as writing \'b\'. This is either redundant, or a typo.`,
  24  		Since:    "2017.1",
  25  		Severity: lint.SeverityWarning,
  26  		MergeIf:  lint.MergeIfAny,
  27  	},
  28  })
  29  
  30  var Analyzer = SCAnalyzer.Analyzer
  31  
  32  var checkDoubleNegationQ = pattern.MustParse(`(UnaryExpr "!" single@(UnaryExpr "!" x))`)
  33  
  34  func run(pass *analysis.Pass) (interface{}, error) {
  35  	fn := func(node ast.Node) {
  36  		if m, ok := code.Match(pass, checkDoubleNegationQ, node); ok {
  37  			report.Report(pass, node, "negating a boolean twice has no effect; is this a typo?", report.Fixes(
  38  				edit.Fix("turn into single negation", edit.ReplaceWithNode(pass.Fset, node, m.State["single"].(ast.Node))),
  39  				edit.Fix("remove double negation", edit.ReplaceWithNode(pass.Fset, node, m.State["x"].(ast.Node)))))
  40  		}
  41  	}
  42  	code.Preorder(pass, fn, (*ast.UnaryExpr)(nil))
  43  	return nil, nil
  44  }
  45