79 lines
2.0 KiB
Go
79 lines
2.0 KiB
Go
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package sa4014
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import (
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"go/ast"
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"honnef.co/go/tools/analysis/code"
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"honnef.co/go/tools/analysis/lint"
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"honnef.co/go/tools/analysis/report"
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"golang.org/x/tools/go/analysis"
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"golang.org/x/tools/go/analysis/passes/inspect"
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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: "SA4014",
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Run: run,
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Requires: []*analysis.Analyzer{inspect.Analyzer},
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},
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Doc: &lint.RawDocumentation{
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Title: `An if/else if chain has repeated conditions and no side-effects; if the condition didn't match the first time, it won't match the second time, either`,
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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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seen := map[ast.Node]bool{}
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var collectConds func(ifstmt *ast.IfStmt, conds []ast.Expr) ([]ast.Expr, bool)
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collectConds = func(ifstmt *ast.IfStmt, conds []ast.Expr) ([]ast.Expr, bool) {
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seen[ifstmt] = true
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// Bail if any if-statement has an Init statement or side effects in its condition
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if ifstmt.Init != nil {
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return nil, false
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}
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if code.MayHaveSideEffects(pass, ifstmt.Cond, nil) {
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return nil, false
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}
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conds = append(conds, ifstmt.Cond)
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if elsestmt, ok := ifstmt.Else.(*ast.IfStmt); ok {
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return collectConds(elsestmt, conds)
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}
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return conds, true
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}
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fn := func(node ast.Node) {
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ifstmt := node.(*ast.IfStmt)
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if seen[ifstmt] {
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// this if-statement is part of an if/else-if chain that we've already processed
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return
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}
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if ifstmt.Else == nil {
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// there can be at most one condition
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return
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}
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conds, ok := collectConds(ifstmt, nil)
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if !ok {
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return
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}
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if len(conds) < 2 {
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return
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}
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counts := map[string]int{}
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for _, cond := range conds {
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s := report.Render(pass, cond)
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counts[s]++
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if counts[s] == 2 {
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report.Report(pass, cond, "this condition occurs multiple times in this if/else if chain")
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}
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}
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}
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code.Preorder(pass, fn, (*ast.IfStmt)(nil))
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return nil, nil
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}
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