Re: The --with-wide-int build and Lisp_Sub_Char_Table assertion

[Eli Zaretskii]

> Date: Mon, 12 Jan 2015 20:03:29 +0300
> From: Dmitry Antipov <address@hidden>
> CC: address@hidden
> 
> On 01/12/2015 07:29 PM, Eli Zaretskii wrote:
> 
> > In the 32-bit MinGW configuration with wide integers, we have:
> >
> >    offsetof (struct Lisp_Sub_Char_Table, contents) = 16
> >    offsetof (struct Lisp_Sub_Char_Table, depth)    =  4
> >    word_size                                       =  8
> 
> OK, but...
> 
> >    header_size                                     =  8
> >    offsetof(struct Lisp_Vector, contents)          =  8
> 
> ==> sizeof(ptrdiff_t) is 8 in a 32-bit configuration?

No, it's 4, of course.

> Or, if sizeof(ptrdiff_t) is 4, what is sizeof(struct vectorlike_header)?

Also 4.

> IIUC it should be 4, and so header_size should be 4 too...

This is exactly the flaw: the assumption that if the size of 'struct
vectorlike_header' is 4, the offset of the next struct member is also
4.  In reality, a compiler can add padding, and evidently here it did,
probably to get that member aligned an a 8-byte boundary.

What I'm saying IOW is that instead of assuming the above, why not
simply use header_size as computed already, since that's what you use
in PSEUDOVECSIZE?