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package st1008
import (
"go/types"
"honnef.co/go/tools/analysis/lint"
"honnef.co/go/tools/analysis/report"
"honnef.co/go/tools/internal/passes/buildir"
"golang.org/x/tools/go/analysis"
)
var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
Analyzer: &analysis.Analyzer{
Name: "ST1008",
Run: run,
Requires: []*analysis.Analyzer{buildir.Analyzer},
},
Doc: &lint.RawDocumentation{
Title: `A function's error value should be its last return value`,
Text: `A function's error value should be its last return value.`,
Since: `2019.1`,
MergeIf: lint.MergeIfAny,
},
})
var Analyzer = SCAnalyzer.Analyzer
func run(pass *analysis.Pass) (interface{}, error) {
fnLoop:
for _, fn := range pass.ResultOf[buildir.Analyzer].(*buildir.IR).SrcFuncs {
sig := fn.Type().(*types.Signature)
rets := sig.Results()
if rets == nil || rets.Len() < 2 {
continue
}
if types.Unalias(rets.At(rets.Len()-1).Type()) == types.Universe.Lookup("error").Type() {
// Last return type is error. If the function also returns
// errors in other positions, that's fine.
continue
}
if rets.Len() >= 2 &&
types.Unalias(rets.At(rets.Len()-1).Type()) == types.Universe.Lookup("bool").Type() &&
types.Unalias(rets.At(rets.Len()-2).Type()) == types.Universe.Lookup("error").Type() {
// Accept (..., error, bool) and assume it's a comma-ok function. It's not clear whether the bool should come last or not for these kinds of functions.
continue
}
for i := rets.Len() - 2; i >= 0; i-- {
if types.Unalias(rets.At(i).Type()) == types.Universe.Lookup("error").Type() {
report.Report(pass, rets.At(i), "error should be returned as the last argument", report.ShortRange())
continue fnLoop
}
}
}
return nil, nil
}
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