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From: "vogt at linux dot vnet.ibm.com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug go/67976] New: Cgo + Gccgo not working like Cgo + Golang?
Date: Thu, 15 Oct 2015 14:03:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67976

            Bug ID: 67976
           Summary: Cgo + Gccgo not working like Cgo + Golang?
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: go
          Assignee: ian at airs dot com
          Reporter: vogt at linux dot vnet.ibm.com
                CC: cmang at google dot com
  Target Milestone: ---

The authors of the Ethereum project seem to assume that cgo can handle the code
below in a sensible way, but when using the -gccgo option that is not the case.

-- snip --
package foo 

/* 
int foo_cgo(unsigned); 
*/ 
import "C" 
import "unsafe" 

//export foo 
func foo(x C.unsigned) C.int { 
        return 0 
} 

func () bar() { 
        _ = unsafe.Pointer(C.foo_cgo) 
} 
-- snip --

Running this through

  $ mkdir _obj
  $ cgo -objdir _obj -gccgo foo.go

Results in this code in _cgo_main.c:

  extern char foo_cgo[]; 
  void *_cgohack_foo_cgo = foo_cgo; 
  #include "_cgo_export.h"

And this line in _cgo_export.h:

  int foo_cgo(unsigned); 

Redeclaring foo_cgo results in an error message when trying to compile
_cgo_main.c.

Maybe _cgo_export.h should simply be emitted to _cgo_main.c *before* all the
declarations?