On Feb 16, 2006, at 2:32 PM, Andrew Pinski wrote:
Even more important:
http://gcc.gnu.org/ml/gcc/2005-02/msg00026.html
Which is the answer you are looking for:
But the constraint in C99 is on array declarators, "The element type
shall
not be an incomplete or function type.". This applies to the syntax
whenever it describes an array type even that array type then gets
adjusted to a pointer type. In C90, without the constraint, there was
undefined behavior for an array of incomplete type, even in parameter
context: DR#047 example 3 is almost exactly this case
/* 3 */ struct S *g(struct S a[]) {return a; }
and was said to involve undefined behavior. "However, there is
nothing to
suggest that a not-strictly-conforming array type can magically be
transformed into a strictly conforming pointer parameter via this
rule."
And this was a documented change too:
http://gcc.gnu.org/gcc-4.0/changes.html
Arrays of incomplete element type are invalid in C. GCC now issues an
error for such arrays. Declarations such as extern struct s x[]; (where
struct s has not been defined) can be moved after the definition of
struct s. Function parameters declared as arrays of incomplete type can
instead be declared as pointers
-- Pinski
