cmd/cgo: with -compiler=gccgo can't compile function pointer type with cgo exported feature

[gopherbot]

by Snyh1010:

What does 'go version' print?
go version devel +a622a4ff09da Fri Jul 18 13:05:21 2014 +0400 linux/amd64               
    
and
go version go1.3.1 linux/amd64

What steps reproduce the problem?
use go build -compiler=gccgo to compile below code
http://play.golang.org/p/77fSej3teX


What happened?
snyh:xx$go build -compiler=gccgo 
# _/run/shm/xx
In file included from $WORK/_/run/shm/xx/_obj/_cgo_main.c:8:0:
./a.go:4:7: error: conflicting types for ‘success_cb’
 //PFunc success_cb;
       ^
/tmp/go-build297076724/_/run/shm/xx/_obj/_cgo_main.c:5:13: note: previous declaration of
‘success_cb’ was here
 extern char success_cb[];
             ^


Please provide any additional information below.

[gopherbot]

Comment 1 by Snyh1010:

src/cmd/cgo/out.go:105  
write the error prototype for the function pointer type.

[gopherbot]

Comment 2 by Snyh1010:

Is the _cgohack_ still useful?  I can't find any information about the "void *_cgohack_"
which caused this issues.
remove this hack can fix this issues.

[ianlancetaylor]

Comment 3:

The _cgohack_ code is for issue #1334.  The change that committed it
(http://golang.org/cl/3746041) included a test case, so it should be
straightforward to determine whether it is still needed.
In any case I'm fairly certain it's not needed for gccgo, and could be omitted when
*gccgo is true.

Labels changed: added repo-main, release-go1.5.

Status changed to Accepted.

[gopherbot]

Comment 4 by Snyh1010:

I have request a simple CL with a test case to fix this. 
https://golang.org/cl/154360045/
I have test it with gcc and clang and it's ok, but how can I run build script  with
gccgo test enable?

[ianlancetaylor]

Comment 5:

If I understand what you are asking, you can't.  The run.sh script is for gc, not gccgo.
 But that's OK: if your CL fixes the go build -compiler=gccgo case, go ahead and mail it.

[gopherbot]

CL https://golang.org/cl/11658 mentions this issue.