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nsenter: fix the -Wunused-variable warning 

The change 699429e60f that allows the
constructor attribute to not be optimized out on gccgo has resulted in a
warning when compiling on the golang compiler.

```
./nsenter.go: In function ‘_cgo_51505a0edd5d_Cfunc_init’:
./nsenter.go:40:49: warning: unused variable ‘a’ [-Wunused-variable]
```

the generated code produced an unused struct like:

```
void
_cgo_d6cfae95ae01_Cfunc_init (void *v)
{
  struct
  {
    char unused;
  } __attribute__ ((__packed__, __gcc_struct__)) * a = v;
  init ();
}
```

Truly the "fix" would be upstream in cgo. If it knows it is producing an
unused struct, then it should also include __attribute__ ((unused))

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>
This commit is contained in:
Vincent Batts 2015-03-10 14:43:09 -04:00
parent 43fabe36d1
commit 2a9511a026
2 changed files with 27 additions and 15 deletions
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17
nsenter/nsenter.go
View File

@ -1,25 +1,12 @@
// +build linux
// +build linux,!gccgo
package nsenter
/*
#cgo CFLAGS: -Wall
extern void nsexec();
void __attribute__((constructor)) init() {
void __attribute__((constructor)) init(void) {
nsexec();
}
*/
import "C"
// AlwaysFalse is here to stay false
// (and be exported so the compiler doesn't optimize out its reference)
var AlwaysFalse bool
func init() {
if AlwaysFalse {
// by referencing this C init() in a noop test, it will ensure the compiler
// links in the C function.
// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65134
C.init()
}
}

25
nsenter/nsenter_gccgo.go Normal file
View File

@ -0,0 +1,25 @@
// +build linux,gccgo
package nsenter
/*
#cgo CFLAGS: -Wall
extern void nsexec();
void __attribute__((constructor)) init(void) {
nsexec();
}
*/
import "C"
// AlwaysFalse is here to stay false
// (and be exported so the compiler doesn't optimize out its reference)
var AlwaysFalse bool
func init() {
if AlwaysFalse {
// by referencing this C init() in a noop test, it will ensure the compiler
// links in the C function.
// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65134
C.init()
}
}