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go/cmd/vet/testdata/nilfunc.go
Andrew Gerrand 74ecc2c09b go.tools/cmd/vet: detect useless function comparisons
Also fix bug in types.go discovered by this check.

Fixes golang/go#5347.

R=golang-dev, dsymonds, r
CC=golang-dev
https://golang.org/cl/13102043
2013-08-20 16:11:01 +10:00

38 lines
799 B
Go

// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package testdata
import "os"
func F() {}
type T struct {
F func()
}
func (T) M() {}
var Fv = F
func Comparison() {
var t T
var fn func()
if fn == nil || Fv == nil || t.F == nil {
// no error; these func vars or fields may be nil
}
if F == nil { // ERROR "comparison of function F == nil is always false"
panic("can't happen")
}
if t.M == nil { // ERROR "comparison of function M == nil is always false"
panic("can't happen")
}
if F != nil { // ERROR "comparison of function F != nil is always true"
if t.M != nil { // ERROR "comparison of function M != nil is always true"
return
}
}
panic("can't happen")
}