s1033.go raw

   1  package s1033
   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/facts/generated"
   9  	"honnef.co/go/tools/analysis/lint"
  10  	"honnef.co/go/tools/analysis/report"
  11  	"honnef.co/go/tools/pattern"
  12  
  13  	"golang.org/x/tools/go/analysis"
  14  	"golang.org/x/tools/go/analysis/passes/inspect"
  15  )
  16  
  17  var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
  18  	Analyzer: &analysis.Analyzer{
  19  		Name:     "S1033",
  20  		Run:      run,
  21  		Requires: []*analysis.Analyzer{inspect.Analyzer, generated.Analyzer},
  22  	},
  23  	Doc: &lint.RawDocumentation{
  24  		Title:   `Unnecessary guard around call to \"delete\"`,
  25  		Text:    `Calling \'delete\' on a nil map is a no-op.`,
  26  		Since:   "2019.2",
  27  		MergeIf: lint.MergeIfAny,
  28  	},
  29  })
  30  
  31  var Analyzer = SCAnalyzer.Analyzer
  32  
  33  var checkGuardedDeleteQ = pattern.MustParse(`
  34  	(IfStmt
  35  		(AssignStmt
  36  			[(Ident "_") ok@(Ident _)]
  37  			":="
  38  			(IndexExpr m key))
  39  		ok
  40  		[call@(CallExpr (Builtin "delete") [m key])]
  41  		nil)`)
  42  
  43  func run(pass *analysis.Pass) (interface{}, error) {
  44  	fn := func(node ast.Node) {
  45  		if m, ok := code.Match(pass, checkGuardedDeleteQ, node); ok {
  46  			report.Report(pass, node, "unnecessary guard around call to delete",
  47  				report.ShortRange(),
  48  				report.FilterGenerated(),
  49  				report.Fixes(edit.Fix("remove guard", edit.ReplaceWithNode(pass.Fset, node, m.State["call"].(ast.Node)))))
  50  		}
  51  	}
  52  
  53  	code.Preorder(pass, fn, (*ast.IfStmt)(nil))
  54  	return nil, nil
  55  }
  56