honnef.co/go/tools@v0.5.0-0.dev.0.20240520180541-dcae280a5e87/staticcheck/sa6006/sa6006.go (about)

     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.Documentation{
    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: "Unreleased",
    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  }