59 lines
1.4 KiB
Go
59 lines
1.4 KiB
Go
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package sa4024
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import (
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"fmt"
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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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"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: "SA4024",
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Run: run,
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Requires: code.RequiredAnalyzers,
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},
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Doc: &lint.RawDocumentation{
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Title: `Checking for impossible return value from a builtin function`,
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Text: `Return values of the \'len\' and \'cap\' builtins cannot be negative.
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See https://golang.org/pkg/builtin/#len and https://golang.org/pkg/builtin/#cap.
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Example:
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if len(slice) < 0 {
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fmt.Println("unreachable code")
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}`,
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Since: "2021.1",
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Severity: lint.SeverityWarning,
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MergeIf: lint.MergeIfAny,
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},
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})
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var Analyzer = SCAnalyzer.Analyzer
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var builtinLessThanZeroQ = pattern.MustParse(`
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(Or
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(BinaryExpr
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(IntegerLiteral "0")
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">"
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(CallExpr builtin@(Builtin (Or "len" "cap")) _))
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(BinaryExpr
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(CallExpr builtin@(Builtin (Or "len" "cap")) _)
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"<"
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(IntegerLiteral "0")))
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`)
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func run(pass *analysis.Pass) (any, error) {
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for node, matcher := range code.Matches(pass, builtinLessThanZeroQ) {
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builtin := matcher.State["builtin"].(*ast.Ident)
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report.Report(pass, node, fmt.Sprintf("builtin function %s does not return negative values", builtin.Name))
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}
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return nil, nil
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}
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