Path: utzoo!mnetor!uunet!husc6!sri-unix!quintus!ok
From: ok@quintus.UUCP (Richard A. O'Keefe)
Newsgroups: comp.arch
Subject: Re: RISC data alignment
Message-ID: <669@cresswell.quintus.UUCP>
Date: 20 Feb 88 03:46:15 GMT
References: <2635@calmasd.GE.COM> <28200092@ccvaxa> <496@ecrcvax.UUCP> <20003@bu-cs.BU.EDU>
Organization: Quintus Computer Systems, Mountain View, CA
Lines: 24

In article <20003@bu-cs.BU.EDU>, bzs@bu-cs.BU.EDU (Barry Shein) writes:
: Does anyone have any problems with:
: foo()
:     {
: 	struct { double x; int i; } a;
: 
: 	a.x = 3.1;
: 	a.i = 12;
: 	printf("%g %d\n",a);
: }
: 
: as an example of a legal, portable program (printf isn't necessary,
: any function which takes multiple arguments possibly handed off as a
: struct)? 

Unless I have completely misread the dpANS, this will not be legal
ANSI C, and the reason for that is that it has never been portable.
K&R say that elements of a structure are given increasing addresses
(a.x is lower than a.i), but the order of arguments is NOT defined:
printf() could easily expect its arguments in the opposite order.  What
is more, some C compilers pass struct arguments on another stack; this
is common when "small" arguments are passed in registers.  The Orion C
compiler, for example, allocated arrays and structs in one stack, and
scalars in another.  (I got burned by this once; never again!)