fix Issue 9931 - Mac OS X ABI not followed when returning structs for extern (C)

[WalterBright]

http://d.puremagic.com/issues/show_bug.cgi?id=9931

[yebblies]

Test case...?

[jacob-carlborg]

Here's a test case. Of course it should be in the pull request. Just compile the C and D code and run the executable. It should not segfault.

C code:

struct Foo
{
    int a;
    int b;
    int c;
};

typedef struct Foo Foo;

Foo foo (int a)
{
    Foo f;
    f.a = 1;
    f.b = 2;
    f.c = 3;
    return f;
}

D code:

struct Foo
{
    int a;
    int b;
    int c;
}

extern (C) Foo foo (int a);

Foo bar ()
{
    return foo(0);
}

void main ()
{
    auto frame = bar();
}

[MartinNowak]

Test case...?

Relies on a particular C compiler.
Of course we should add C-ABI tests, but as that would require to extend the test framework I'm going to merge this now.

[jacob-carlborg]

Awesome, thanks.

[jacob-carlborg]

Unfortunately there's still an issue with 64bit. It doesn't segfault but it doesn't given the correct result for the returned struct. See the original bug report: http://d.puremagic.com/issues/show_bug.cgi?id=9931#c26