Comment 1:

The callback.* files are not required.
If the variables have an explicit initialiser, the problem does not occur.

Comment 2:

I tell a lie - in another example, adding an explicit initialiser did not remedy the
problem.

Comment 3:

For linux/386 (Ubuntu 10.04) at Go hg id 8d78d5e69093 tip,
/tstcgo$ gotest
rm -f _test/tst-go.nowhere.com/tst.a _gotest_.8
8g -o _gotest_.8  tst.cgo1.go _cgo_gotypes.go tst_test.go
8c -FVw -I/home/peter/go/pkg/linux_386 _cgo_defun.c
8c -FVw _cgo_import.c
rm -f _test/tst-go.nowhere.com/tst.a
gopack grc _test/tst-go.nowhere.com/tst.a _gotest_.8  _cgo_defun.8 _cgo_import.8
callback.o  tst.cgo2.o _cgo_export.o
    (nil)
    (nil)
    (nil)
    (nil)
    (nil)
    (nil)
    (nil)
    (nil)
    (nil)
    (nil)
PASS

Comment 4:

For linux/386 (Ubuntu 10.04) at Go hg id 8d78d5e69093 tip,
/tstcgo$ gotest
rm -f _test/tst-go.nowhere.com/tst.a _gotest_.8
8g -o _gotest_.8  tst.cgo1.go _cgo_gotypes.go tst_test.go
8c -FVw -I/home/peter/go/pkg/linux_386 _cgo_defun.c
8c -FVw _cgo_import.c
rm -f _test/tst-go.nowhere.com/tst.a
gopack grc _test/tst-go.nowhere.com/tst.a _gotest_.8  _cgo_defun.8 _cgo_import.8
callback.o  tst.cgo2.o _cgo_export.o
    (nil)
    (nil)
    (nil)
    (nil)
    (nil)
    (nil)
    (nil)
    (nil)
    (nil)
    (nil)
PASS

Comment 5:

For linux/amd64 (Ubuntu 10.04) at Go hg id b5479d8005d6 tip,
tstcgo$ gotest
rm -f _test/tst-go.nowhere.com/tst.a _gotest_.6
CGOPKGPATH=tst-go.nowhere.com cgo --  tst.go 
touch _cgo_run
6g -o _gotest_.6  tst.cgo1.go _cgo_gotypes.go tst_test.go
6c -FVw -I/home/peter/go/pkg/linux_amd64 _cgo_defun.c
gcc -m64 -g -fPIC -O2 -o _cgo_main.o -c   _cgo_main.c
gcc -m64 -g -fPIC -O2 -o callback.o -c   callback.c
gcc -m64 -g -fPIC -O2 -o tst.cgo2.o -c   tst.cgo2.c
gcc -m64 -g -fPIC -O2 -o _cgo_export.o -c   _cgo_export.c
gcc -m64 -g -fPIC -O2 -o _cgo1_.o _cgo_main.o callback.o tst.cgo2.o _cgo_export.o  
cgo -dynimport _cgo1_.o >__cgo_import.c && mv -f __cgo_import.c _cgo_import.c
6c -FVw _cgo_import.c
rm -f _test/tst-go.nowhere.com/tst.a
gopack grc _test/tst-go.nowhere.com/tst.a _gotest_.6  _cgo_defun.6 _cgo_import.6
callback.o  tst.cgo2.o _cgo_export.o
    (nil)
    (nil)
    (nil)
    (nil)
    (nil)
    (nil)
    (nil)
    (nil)
    (nil)
    (nil)
PASS

Comment 6:

Owner changed to r...@golang.org.

Status changed to Accepted.

Comment 7:

This issue was closed by revision cf3323f.

Status changed to Fixed.