72 lines
1.8 KiB
Go
72 lines
1.8 KiB
Go
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package s1031
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import (
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"go/types"
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"honnef.co/go/tools/analysis/code"
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"honnef.co/go/tools/analysis/facts/generated"
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"honnef.co/go/tools/analysis/lint"
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"honnef.co/go/tools/analysis/report"
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"honnef.co/go/tools/go/types/typeutil"
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"honnef.co/go/tools/pattern"
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"golang.org/x/tools/go/analysis"
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)
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var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
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Analyzer: &analysis.Analyzer{
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Name: "S1031",
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Run: run,
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Requires: append([]*analysis.Analyzer{generated.Analyzer}, code.RequiredAnalyzers...),
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},
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Doc: &lint.RawDocumentation{
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Title: `Omit redundant nil check around loop`,
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Text: `You can use range on nil slices and maps, the loop will simply never
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execute. This makes an additional nil check around the loop
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unnecessary.`,
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Before: `
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if s != nil {
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for _, x := range s {
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...
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}
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}`,
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After: `
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for _, x := range s {
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...
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}`,
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Since: "2017.1",
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// MergeIfAll because x might be a channel under some build tags.
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// you shouldn't write code like that…
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MergeIf: lint.MergeIfAll,
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},
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})
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var Analyzer = SCAnalyzer.Analyzer
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var checkNilCheckAroundRangeQ = pattern.MustParse(`
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(IfStmt
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nil
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(BinaryExpr x@(Object _) "!=" (Builtin "nil"))
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[(RangeStmt _ _ _ x _)]
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nil)`)
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func run(pass *analysis.Pass) (any, error) {
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for node, m := range code.Matches(pass, checkNilCheckAroundRangeQ) {
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ok := typeutil.All(m.State["x"].(types.Object).Type(), func(term *types.Term) bool {
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switch term.Type().Underlying().(type) {
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case *types.Slice, *types.Map:
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return true
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case *types.TypeParam, *types.Chan, *types.Pointer, *types.Signature:
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return false
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default:
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lint.ExhaustiveTypeSwitch(term.Type().Underlying())
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return false
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}
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})
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if ok {
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report.Report(pass, node, "unnecessary nil check around range", report.ShortRange(), report.FilterGenerated())
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}
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}
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return nil, nil
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}
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