sa1010.go raw

   1  package sa1010
   2  
   3  import (
   4  	"fmt"
   5  	"go/constant"
   6  
   7  	"honnef.co/go/tools/analysis/callcheck"
   8  	"honnef.co/go/tools/analysis/lint"
   9  	"honnef.co/go/tools/go/ir"
  10  	"honnef.co/go/tools/internal/passes/buildir"
  11  
  12  	"golang.org/x/tools/go/analysis"
  13  )
  14  
  15  var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
  16  	Analyzer: &analysis.Analyzer{
  17  		Name:     "SA1010",
  18  		Requires: []*analysis.Analyzer{buildir.Analyzer},
  19  		Run:      callcheck.Analyzer(checkRegexpFindAllRules),
  20  	},
  21  	Doc: &lint.RawDocumentation{
  22  		Title: `\'(*regexp.Regexp).FindAll\' called with \'n == 0\', which will always return zero results`,
  23  		Text: `If \'n >= 0\', the function returns at most \'n\' matches/submatches. To
  24  return all results, specify a negative number.`,
  25  		Since:    "2017.1",
  26  		Severity: lint.SeverityWarning,
  27  		MergeIf:  lint.MergeIfAny, // MergeIfAny if we only flag literals, not named constants
  28  	},
  29  })
  30  
  31  var Analyzer = SCAnalyzer.Analyzer
  32  
  33  var checkRegexpFindAllRules = map[string]callcheck.Check{
  34  	"(*regexp.Regexp).FindAll":                    RepeatZeroTimes("a FindAll method", 1),
  35  	"(*regexp.Regexp).FindAllIndex":               RepeatZeroTimes("a FindAll method", 1),
  36  	"(*regexp.Regexp).FindAllString":              RepeatZeroTimes("a FindAll method", 1),
  37  	"(*regexp.Regexp).FindAllStringIndex":         RepeatZeroTimes("a FindAll method", 1),
  38  	"(*regexp.Regexp).FindAllStringSubmatch":      RepeatZeroTimes("a FindAll method", 1),
  39  	"(*regexp.Regexp).FindAllStringSubmatchIndex": RepeatZeroTimes("a FindAll method", 1),
  40  	"(*regexp.Regexp).FindAllSubmatch":            RepeatZeroTimes("a FindAll method", 1),
  41  	"(*regexp.Regexp).FindAllSubmatchIndex":       RepeatZeroTimes("a FindAll method", 1),
  42  }
  43  
  44  func RepeatZeroTimes(name string, arg int) callcheck.Check {
  45  	return func(call *callcheck.Call) {
  46  		arg := call.Args[arg]
  47  		if k, ok := arg.Value.Value.(*ir.Const); ok && k.Value.Kind() == constant.Int {
  48  			if v, ok := constant.Int64Val(k.Value); ok && v == 0 {
  49  				arg.Invalid(fmt.Sprintf("calling %s with n == 0 will return no results, did you mean -1?", name))
  50  			}
  51  		}
  52  	}
  53  }
  54