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From: nobody@ism780c.UUCP (Unprivileged user)
Newsgroups: comp.lang.c
Subject: Re: what C needs
Message-ID: <8631@ism780c.UUCP>
Date: 18 Jan 88 21:54:00 GMT
References: <8712241909.AA03710@decwrl.dec.com> <6926@brl-smoke.ARPA> <496@doug.UUCP> <6995@brl-smoke.ARPA> <1128@jenny.cl.cam.ac.uk> <7116@brl-smoke.ARPA>
Reply-To: marv@ism780.UUCP (Marvin Rubenstein)
Organization: Interactive Systems Corp., Santa Monica CA
Lines: 23

In article <7116@brl-smoke.ARPA> gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>) writes:
>In article <1128@jenny.cl.cam.ac.uk> am@cl.cam.ac.uk (Alan Mycroft) writes:
>-What about a machine which initialises its stack with parity errors
>-...  How about
>-    f2() { struct { char a; int b; } x;
>-          x.a = 1, x.b = 1;
>-          g2(x);
>-       }
>
>The implementation is not allowed to cause a trap when passing x to g2().
>If it wants to flag holes specially so they cause a trap when touched,
>then it will have to pass struct arguments member-by-member.

Another thing that a legal implementation may do is to generate code to
assign to the pad bytes (if any) when a reference to a near by variable is
incountered.  For example the assignemt:

	      x.a = 1;

may fill the pad that exists between x.a and x.b.  For most machines this no
more costly than leaving the pad bytes undefined.

    Marv Rubinstein  -- Interactive Systems