by mcphail_colin@hotmail.com:

If a C header contains a function declaration such as
    extern const char *class_getName(Class cls);
where Class is the typedef name for struct objc_class * then the C wrapper code
generated by cgo uses type struct objc_class * for unmarshalling the function argument
rather than type Class.  Normally this is fine but in this case the definition of struct
objc_class has the 'unavailable' attribute attached to it, so the generated code fails
to compile.

What steps will reproduce the problem?
1. Unzip/untar attached cgo_example.tar.gz and cd to cgo_example.
2. cgo main.go
3. gcc -c -I. _obj/main.cgo2.c

What is the expected output?
No output - compilation succeeds silently.

What do you see instead?
main.go: In function ‘_cgo_451c23f32582_Cfunc_class_getName’:
main.go:30: error: ‘objc_class’ is unavailable (declared at ./c_header.h:1)

Which compiler are you using (5g, 6g, 8g, gccgo)?
cgo

Which operating system are you using?
Mac OS X 10.7.3

Which revision are you using?  (hg identify)
weekly.2012-01-27 11507

Please provide any additional information below.
I produced a modified version of cgo by deleting the *dwarf.TypedefType switch case in
func (c *typeConv) FuncArg() at approx line 1275 in src/cmd/cgo/gcc.go .  This had the
effect of using the argument type as given in the C header and allowed compilation of
the generated wrapper code to succeed.

Attachments:

1. cgo_example.tar.gz (445 bytes)