70 lines
2.1 KiB
Go
70 lines
2.1 KiB
Go
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package sa4025
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import (
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"fmt"
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"go/ast"
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"go/constant"
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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: "SA4025",
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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: "Integer division of literals that results in zero",
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Text: `When dividing two integer constants, the result will
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also be an integer. Thus, a division such as \'2 / 3\' results in \'0\'.
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This is true for all of the following examples:
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_ = 2 / 3
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const _ = 2 / 3
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const _ float64 = 2 / 3
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_ = float64(2 / 3)
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Staticcheck will flag such divisions if both sides of the division are
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integer literals, as it is highly unlikely that the division was
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intended to truncate to zero. Staticcheck will not flag integer
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division involving named constants, to avoid noisy positives.
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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 integerDivisionQ = pattern.MustParse(`(BinaryExpr (IntegerLiteral _) "/" (IntegerLiteral _))`)
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func run(pass *analysis.Pass) (any, error) {
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for node := range code.Matches(pass, integerDivisionQ) {
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val := constant.ToInt(pass.TypesInfo.Types[node.(ast.Expr)].Value)
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if v, ok := constant.Uint64Val(val); ok && v == 0 {
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report.Report(pass, node, fmt.Sprintf("the integer division '%s' results in zero", report.Render(pass, node)))
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}
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// TODO: we could offer a suggested fix here, but I am not
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// sure what it should be. There are many options to choose
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// from.
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// Note: we experimented with flagging divisions that truncate
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// (e.g. 4 / 3), but it ran into false positives in Go's
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// 'time' package, which does this, deliberately:
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//
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// unixToInternal int64 = (1969*365 + 1969/4 - 1969/100 + 1969/400) * secondsPerDay
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//
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// The check also found a real bug in other code, but I don't
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// think we can outright ban this kind of division.
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}
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return nil, nil
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}
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