115 lines
2.5 KiB
Go
115 lines
2.5 KiB
Go
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package sa4008
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import (
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"go/ast"
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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/ir"
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"honnef.co/go/tools/internal/passes/buildir"
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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: "SA4008",
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Run: run,
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Requires: []*analysis.Analyzer{buildir.Analyzer},
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},
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Doc: &lint.RawDocumentation{
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Title: `The variable in the loop condition never changes, are you incrementing the wrong variable?`,
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Text: `For example:
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for i := 0; i < 10; j++ { ... }
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This may also occur when a loop can only execute once because of unconditional
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control flow that terminates the loop. For example, when a loop body contains an
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unconditional break, return, or panic:
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func f() {
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panic("oops")
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}
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func g() {
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for i := 0; i < 10; i++ {
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// f unconditionally calls panic, which means "i" is
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// never incremented.
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f()
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}
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}`,
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Since: "2017.1",
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Severity: lint.SeverityWarning,
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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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func run(pass *analysis.Pass) (any, error) {
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for _, fn := range pass.ResultOf[buildir.Analyzer].(*buildir.IR).SrcFuncs {
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cb := func(node ast.Node) bool {
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loop, ok := node.(*ast.ForStmt)
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if !ok {
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return true
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}
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if loop.Init == nil || loop.Cond == nil || loop.Post == nil {
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return true
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}
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init, ok := loop.Init.(*ast.AssignStmt)
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if !ok || len(init.Lhs) != 1 || len(init.Rhs) != 1 {
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return true
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}
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cond, ok := loop.Cond.(*ast.BinaryExpr)
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if !ok {
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return true
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}
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x, ok := cond.X.(*ast.Ident)
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if !ok {
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return true
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}
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lhs, ok := init.Lhs[0].(*ast.Ident)
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if !ok {
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return true
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}
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if pass.TypesInfo.ObjectOf(x) != pass.TypesInfo.ObjectOf(lhs) {
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return true
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}
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if _, ok := loop.Post.(*ast.IncDecStmt); !ok {
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return true
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}
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v, isAddr := fn.ValueForExpr(cond.X)
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if v == nil || isAddr {
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return true
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}
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switch v := v.(type) {
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case *ir.Phi:
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ops := v.Operands(nil)
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if len(ops) != 2 {
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return true
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}
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_, ok := (*ops[0]).(*ir.Const)
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if !ok {
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return true
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}
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sigma, ok := (*ops[1]).(*ir.Sigma)
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if !ok {
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return true
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}
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if sigma.X != v {
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return true
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}
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case *ir.Load:
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return true
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}
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report.Report(pass, cond, "variable in loop condition never changes")
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return true
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}
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if source := fn.Source(); source != nil {
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ast.Inspect(source, cb)
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}
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}
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return nil, nil
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}
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