src

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sa4018.go (1550B)

      1 package sa4018
      2 
      3 import (
      4 	"fmt"
      5 	"go/ast"
      6 	"go/token"
      7 	"reflect"
      8 
      9 	"honnef.co/go/tools/analysis/code"
     10 	"honnef.co/go/tools/analysis/facts/generated"
     11 	"honnef.co/go/tools/analysis/facts/purity"
     12 	"honnef.co/go/tools/analysis/lint"
     13 	"honnef.co/go/tools/analysis/report"
     14 
     15 	"golang.org/x/tools/go/analysis"
     16 	"golang.org/x/tools/go/analysis/passes/inspect"
     17 )
     18 
     19 var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
     20 	Analyzer: &analysis.Analyzer{
     21 		Name:     "SA4018",
     22 		Run:      run,
     23 		Requires: []*analysis.Analyzer{inspect.Analyzer, generated.Analyzer, purity.Analyzer},
     24 	},
     25 	Doc: &lint.RawDocumentation{
     26 		Title:    `Self-assignment of variables`,
     27 		Since:    "2017.1",
     28 		Severity: lint.SeverityWarning,
     29 		MergeIf:  lint.MergeIfAny,
     30 	},
     31 })
     32 
     33 var Analyzer = SCAnalyzer.Analyzer
     34 
     35 func run(pass *analysis.Pass) (any, error) {
     36 	pure := pass.ResultOf[purity.Analyzer].(purity.Result)
     37 
     38 	fn := func(node ast.Node) {
     39 		assign := node.(*ast.AssignStmt)
     40 		if assign.Tok != token.ASSIGN || len(assign.Lhs) != len(assign.Rhs) {
     41 			return
     42 		}
     43 		for i, lhs := range assign.Lhs {
     44 			rhs := assign.Rhs[i]
     45 			if reflect.TypeOf(lhs) != reflect.TypeOf(rhs) {
     46 				continue
     47 			}
     48 			if code.MayHaveSideEffects(pass, lhs, pure) || code.MayHaveSideEffects(pass, rhs, pure) {
     49 				continue
     50 			}
     51 
     52 			rlh := report.Render(pass, lhs)
     53 			rrh := report.Render(pass, rhs)
     54 			if rlh == rrh {
     55 				report.Report(pass, assign, fmt.Sprintf("self-assignment of %s to %s", rrh, rlh), report.FilterGenerated())
     56 			}
     57 		}
     58 	}
     59 	code.Preorder(pass, fn, (*ast.AssignStmt)(nil))
     60 	return nil, nil
     61 }