🚀 go-pugleaf

In article <MEISSNER.95Sep22121246@tiktok.cygnus.com>,
Michael Meissner <meissner@cygnus.com> wrote:
|In article <43s7k4$j2v@gatekeeper.atml.co.uk> jrr@atml.co.uk (John Rickard) writes:
|
|| Stan Ryckman (sgr@ae-sun01.alden.com) wrote:
|| : All pointers-to-struct must have the same "shape"
|| 
|| Is that so?  I've often written code that makes that assumption, but I
|| can't find any justification for it in the standard.  Can you give
|| references?
|
|Because if they didn't, then you couldn't reliably write code that uses:
|
|	struct unknown_in_this_module *ptr
|
|as an opaque pointer.

I think you actually could as long as size was the same.  A bizarre
implementation could use machine address for all struct pointers
except those whose first element is of type char, and reverse
all the bits on those pointers.  All opaque treatments would work.

The problem would occur when casting the "opaque" pointer to a
specific struct pointer for actual use.

Cheers,
Stan.
-- 
HELP!  I'M BEING HELD PRISONER IN A .SIGNATURE FACTORY!
    Stan Ryckman   sgr@alden.com