sa6006.go raw

   1  package sa6006
   2  
   3  import (
   4  	"go/ast"
   5  
   6  	"honnef.co/go/tools/analysis/code"
   7  	"honnef.co/go/tools/analysis/lint"
   8  	"honnef.co/go/tools/analysis/report"
   9  	"honnef.co/go/tools/pattern"
  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:     "SA6006",
  18  		Run:      run,
  19  		Requires: []*analysis.Analyzer{inspect.Analyzer},
  20  	},
  21  	Doc: &lint.RawDocumentation{
  22  		Title: `Using io.WriteString to write \'[]byte\'`,
  23  		Text: `Using io.WriteString to write a slice of bytes, as in
  24  
  25      io.WriteString(w, string(b))
  26  
  27  is both unnecessary and inefficient. Converting from \'[]byte\' to \'string\'
  28  has to allocate and copy the data, and we could simply use \'w.Write(b)\'
  29  instead.`,
  30  
  31  		Since: "2024.1",
  32  	},
  33  })
  34  
  35  var Analyzer = SCAnalyzer.Analyzer
  36  
  37  var ioWriteStringConversion = pattern.MustParse(`(CallExpr (Symbol "io.WriteString") [_ (CallExpr (Builtin "string") [arg])])`)
  38  
  39  func run(pass *analysis.Pass) (interface{}, error) {
  40  	fn := func(node ast.Node) {
  41  		m, ok := code.Match(pass, ioWriteStringConversion, node)
  42  		if !ok {
  43  			return
  44  		}
  45  		if !code.IsOfStringConvertibleByteSlice(pass, m.State["arg"].(ast.Expr)) {
  46  			return
  47  		}
  48  		report.Report(pass, node, "use io.Writer.Write instead of converting from []byte to string to use io.WriteString")
  49  	}
  50  	code.Preorder(pass, fn, (*ast.CallExpr)(nil))
  51  
  52  	return nil, nil
  53  }
  54