Re: On alignment

[Tom Tromey <tromey at redhat dot com>]

>>>>> "Gabriel" == Gabriel Dos Reis <gdr at integrable-solutions dot net> writes:

Gabriel> #define FIELD_ALIGNOF(TYPE) __alignof (((struct { TYPE t; } *)0)->t)

Gabriel>     j.C: In function `int main()':
Gabriel>     j.C:7: error: types may not be defined in casts

I got that too, but I worked around it like so:

template<typename T>
struct aligner
{
  T field;
};

#define ALIGNOF(TYPE) (__alignof__ (((aligner<TYPE> *) 0)->field))


Gabriel> I think the template-based solution I posted in another
Gabriel> message solves the problem...

In that message you said that you got "8" as the answer for a double
field on x86.  That's not the answer I'm looking for :-(.  On x86, a
double field has alignment 4, while a non-field double has alignment
8.  In the libgcj context, we're only ever laying out structures, so
we need to get "4" as the answer.  The above does do that.

Tom