🚀 go-pugleaf

Paul Long <plong@perf.com> wrote:

>Section 6.5.2.3 says, "If a type specifier of the form _struct-or-union
>identifier_ occurs prior to the declaration that defines the content, the
>structure or union is an incomplete type. It declares a tag that specifies a
>type that may be used only when the size of an object of the specified type is
>not needed."

>What does "the size...is not needed" mean? "Needed" sounds awfully vague. For
>example, is the size needed here?

>   struct S x;
>   void foo() { x; }

>I don't think so, but perhaps this is implementation-dependent.

I think the size is needed, but not because of the reference in foo(),
but because of the way it's defined.  Since x is of static storage
class, the language is obliged to initialize it, and it can't without
knowing the size.

If you used "extern struct S x;" then the size is not needed.  I would
expect the following to be fully legal:

extern struct S x, y;

struct S *pickS(int pick)
{
    if(pick)
        return &x;
    else
        return &y;
}

--
Richard Krehbiel, Kastle Systems, Arlington VA USA
rich@kastle.com (work) or richk@cais.com (personal)