115 lines
2.3 KiB
Go
115 lines
2.3 KiB
Go
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package rule
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import (
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"go/ast"
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"github.com/mgechev/revive/lint"
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)
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// UnreachableCodeRule lints unreachable code.
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type UnreachableCodeRule struct{}
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// Apply applies the rule to given file.
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func (r *UnreachableCodeRule) Apply(file *lint.File, _ lint.Arguments) []lint.Failure {
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var failures []lint.Failure
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onFailure := func(failure lint.Failure) {
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failures = append(failures, failure)
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}
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var branchingFunctions = map[string]map[string]bool{
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"os": map[string]bool{"Exit": true},
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"log": map[string]bool{
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"Fatal": true,
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"Fatalf": true,
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"Fatalln": true,
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"Panic": true,
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"Panicf": true,
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"Panicln": true,
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},
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}
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w := lintUnreachableCode{onFailure, branchingFunctions}
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ast.Walk(w, file.AST)
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return failures
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}
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// Name returns the rule name.
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func (r *UnreachableCodeRule) Name() string {
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return "unreachable-code"
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}
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type lintUnreachableCode struct {
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onFailure func(lint.Failure)
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branchingFunctions map[string]map[string]bool
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}
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func (w lintUnreachableCode) Visit(node ast.Node) ast.Visitor {
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blk, ok := node.(*ast.BlockStmt)
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if !ok {
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return w
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}
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if len(blk.List) < 2 {
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return w
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}
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loop:
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for i, stmt := range blk.List[:len(blk.List)-1] {
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// println("iterating ", len(blk.List))
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next := blk.List[i+1]
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if _, ok := next.(*ast.LabeledStmt); ok {
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continue // skip if next statement is labeled
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}
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switch s := stmt.(type) {
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case *ast.ReturnStmt:
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w.onFailure(newUnreachableCodeFailure(s))
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break loop
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case *ast.BranchStmt:
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token := s.Tok.String()
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if token != "fallthrough" {
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w.onFailure(newUnreachableCodeFailure(s))
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break loop
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}
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case *ast.ExprStmt:
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ce, ok := s.X.(*ast.CallExpr)
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if !ok {
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continue
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}
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// it's a function call
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fc, ok := ce.Fun.(*ast.SelectorExpr)
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if !ok {
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continue
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}
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id, ok := fc.X.(*ast.Ident)
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if !ok {
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continue
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}
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fn := fc.Sel.Name
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pkg := id.Name
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if !w.branchingFunctions[pkg][fn] { // it isn't a call to a branching function
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continue
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}
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if _, ok := next.(*ast.ReturnStmt); ok { // return statement needed to satisfy function signature
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continue
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}
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w.onFailure(newUnreachableCodeFailure(s))
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break loop
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}
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}
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return w
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}
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func newUnreachableCodeFailure(node ast.Node) lint.Failure {
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return lint.Failure{
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Confidence: 1,
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Node: node,
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Category: "logic",
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Failure: "unreachable code after this statement",
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}
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}
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