sa4012.go raw

   1  package sa4012
   2  
   3  import (
   4  	"honnef.co/go/tools/analysis/lint"
   5  	"honnef.co/go/tools/analysis/report"
   6  	"honnef.co/go/tools/go/ir"
   7  	"honnef.co/go/tools/go/ir/irutil"
   8  	"honnef.co/go/tools/internal/passes/buildir"
   9  
  10  	"golang.org/x/tools/go/analysis"
  11  )
  12  
  13  var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
  14  	Analyzer: &analysis.Analyzer{
  15  		Name:     "SA4012",
  16  		Run:      run,
  17  		Requires: []*analysis.Analyzer{buildir.Analyzer},
  18  	},
  19  	Doc: &lint.RawDocumentation{
  20  		Title:    `Comparing a value against NaN even though no value is equal to NaN`,
  21  		Since:    "2017.1",
  22  		Severity: lint.SeverityWarning,
  23  		MergeIf:  lint.MergeIfAny,
  24  	},
  25  })
  26  
  27  var Analyzer = SCAnalyzer.Analyzer
  28  
  29  func run(pass *analysis.Pass) (interface{}, error) {
  30  	isNaN := func(v ir.Value) bool {
  31  		call, ok := v.(*ir.Call)
  32  		if !ok {
  33  			return false
  34  		}
  35  		return irutil.IsCallTo(call.Common(), "math.NaN")
  36  	}
  37  	for _, fn := range pass.ResultOf[buildir.Analyzer].(*buildir.IR).SrcFuncs {
  38  		for _, block := range fn.Blocks {
  39  			for _, ins := range block.Instrs {
  40  				ins, ok := ins.(*ir.BinOp)
  41  				if !ok {
  42  					continue
  43  				}
  44  				if isNaN(irutil.Flatten(ins.X)) || isNaN(irutil.Flatten(ins.Y)) {
  45  					report.Report(pass, ins, "no value is equal to NaN, not even NaN itself")
  46  				}
  47  			}
  48  		}
  49  	}
  50  	return nil, nil
  51  }
  52