src

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git clone git://code.dwrz.net/src
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sa4015.go (1513B)

      1 package sa4015
      2 
      3 import (
      4 	"fmt"
      5 	"go/types"
      6 
      7 	"honnef.co/go/tools/analysis/callcheck"
      8 	"honnef.co/go/tools/analysis/lint"
      9 	"honnef.co/go/tools/go/ir"
     10 	"honnef.co/go/tools/go/ir/irutil"
     11 	"honnef.co/go/tools/go/types/typeutil"
     12 	"honnef.co/go/tools/internal/passes/buildir"
     13 
     14 	"golang.org/x/tools/go/analysis"
     15 )
     16 
     17 var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
     18 	Analyzer: &analysis.Analyzer{
     19 		Name:     "SA4015",
     20 		Requires: []*analysis.Analyzer{buildir.Analyzer},
     21 		Run:      callcheck.Analyzer(checkMathIntRules),
     22 	},
     23 	Doc: &lint.RawDocumentation{
     24 		Title:    `Calling functions like \'math.Ceil\' on floats converted from integers doesn't do anything useful`,
     25 		Since:    "2017.1",
     26 		Severity: lint.SeverityWarning,
     27 		MergeIf:  lint.MergeIfAll,
     28 	},
     29 })
     30 
     31 var Analyzer = SCAnalyzer.Analyzer
     32 
     33 var checkMathIntRules = map[string]callcheck.Check{
     34 	"math.Ceil":  pointlessIntMath,
     35 	"math.Floor": pointlessIntMath,
     36 	"math.IsNaN": pointlessIntMath,
     37 	"math.Trunc": pointlessIntMath,
     38 	"math.IsInf": pointlessIntMath,
     39 }
     40 
     41 func pointlessIntMath(call *callcheck.Call) {
     42 	if ConvertedFromInt(call.Args[0].Value) {
     43 		call.Invalid(fmt.Sprintf("calling %s on a converted integer is pointless", irutil.CallName(call.Instr.Common())))
     44 	}
     45 }
     46 
     47 func ConvertedFromInt(v callcheck.Value) bool {
     48 	conv, ok := v.Value.(*ir.Convert)
     49 	if !ok {
     50 		return false
     51 	}
     52 	return typeutil.NewTypeSet(conv.X.Type()).All(func(t *types.Term) bool {
     53 		b, ok := t.Type().Underlying().(*types.Basic)
     54 		return ok && b.Info()&types.IsInteger != 0
     55 	})
     56 }