designated initializers extension and sparc

[Ian Lance Taylor]

On Mon, Jun 17, 2013 at 4:21 AM, Sergey Kljopov <hlodvig@unipro.ru> wrote:
>
> So, I've read the spec about extension
>
> The `[index]' or `.fieldname' is known as a designator. You can also
> use a designator (or the obsolete colon syntax) when initializing a
> union, to specify which element of the union should be used. For
> example,
>      union foo { int i; double d; };
>      union foo f = { .d = 4 };
> will convert 4 to a double to store it in the union using the second
> element. By contrast, casting 4 to type union foo would store it
> into the union as the integer i, since it is an integer. (See Cast
> to Union.)
>
> and wrote the following test:
>
> union foo { int i; double d; };
>
> int main(int argc, char **argv)
> {
>     union foo f = { .d = 4 };
>
>     ASSERT_EQ(0, f.i);
>     ASSERT_FEQ(4.0, f.d);
>
>     return 0;
> }
>
> ASSERT_EQ and ASSERT_FEQ are some macros which checks the value and
> gives some error messages.
>
> But it fails on sparc. I guess int should be equal 0x40100000 since bytes
> are in reverse order.
> As I know now, this extension is not bi-endian.
> So the question is: what shall I do? Does it mean that I just shall forget
> about that extension usage on sparc?

I'm sorry, I don't understand your question.  You're right, SPARC is
big-endian where x86 is little-endian, so if you look at the first
four bytes of a double you will get different results on the two
systems.  That is all normal and expected behaviour.

I think you neglected to explain what you actually want to do.

Ian