[cfe-dev] Implementation of the CGRecordLayoutBuilder for Microsoft ABI.

[David Blaikie]

On Mon, Sep 26, 2011 at 4:36 PM, Francois Pichet <pichet2000 at gmail.com>wrote:

> On Mon, Sep 26, 2011 at 6:52 PM, Eli Friedman <eli.friedman at gmail.com>
> wrote:
> > On Mon, Sep 26, 2011 at 6:09 AM, r4start <r4start at gmail.com> wrote:
> >> I really don't understand why align=4 isn't correct.
> >> I always thought that #pragma pack only affects members of the
> structure.
> >> And __declspec(align(n)) specifies the alignment for objects of type.
> >> In MSVS align for B is 4 and for A is 1.
> >
> > The only answer I can come up with is the model MSVC uses is simply
> insane.
> >
> > One more attempt to get some sanity: does the following compile with
> > MSVC?  If so, what is the output?
> >
> > #include <cstdio>
> > class A {
> >  char c;
> > };
> > class B : public virtual A {
> >  public:
> >  void *p;
> > };
> > B* x = new B[10];
> > int main() { std::printf("%d\n", (int)(x[1].p)); }
> >
>
> it compiles and the output is 0.
> not sure what you are trying to test here.


I'll guess that Eli meant to print &x[1].p (to see whether the void* pointer
was aligned or not), perhaps. I modified the program to print:

    std::printf("%d\n", (int)(&x[0].p));
    std::printf("%d\n", (int)(&x[1].p));

& the result I got (in debug) was:

1077836
1077845
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