non-local function...uses anonymous type

[lilydjwg]

I have the following code:

#include<cstdio>
typedef struct{
  int  exp;
}MyType[10];
void func(MyType a){
  return;
}
int main(){
  return(0);
}

When I use g++ to compile it, it said:

test.cpp:5: error: non-local function ‘void func(<anonymous struct>*)’ uses anonymous type

Add 'static' to the function it'll be fine. But anyone can tell me why?

[kbw]

You haven't named your struct, so MyType is an array of 10 elements of an anonymous struct that has an int named exp.

C treats structs differently. you'll find this code compiles in C, but not C++.

[lilydjwg]

But if I define MyType as an anonymous struct (not an array), it'll be fine. And if I use static, no error either. So can you explain that why C++ treats this as error. In other words, why can't a non-local function use a pointer of anonymous type as parameter?
Thanks.

[kbw]

It doesn't complain using Microsoft VS2005. It does using gcc 4.3.2. I see no reason why it should complain myself.

Here are some links that discuss the matter. It looks like a GCC specific issue.
http://gcc.gnu.org/ml/gcc-bugs/2000-05/msg00909.html
http://archives.devshed.com/forums/development-94/gcc-4-0-non-local-variable-uses-anonymous-type-warning-129952.html

[lilydjwg]

The links help a lot. Thank you.