Newsgroups: comp.std.c
Path: utzoo!henry
From: henry@zoo.toronto.edu (Henry Spencer)
Subject: Re: Interaction between storage class and qualifiers
Message-ID: <1991Jan8.000756.24432@zoo.toronto.edu>
Organization: U of Toronto Zoology
References: <2760@charon.cwi.nl>
Date: Tue, 8 Jan 1991 00:07:56 GMT

In article <2760@charon.cwi.nl> jack@cwi.nl (Jack Jansen) writes:
>The SGI C compiler treats the following two pointers as unequal:
>	register volatile struct foo *p1;
>	volatile register struct foo *p2;
>p1 is a pointer (in a register) to a volatile struct foo, while
>p2 is a volatile pointer (in a register) to a struct foo.

This is incorrect.  The standard attributes no significance to the order
of storage class specifiers, type specifiers, and type qualifiers in the
declaration-specifiers list beginning a declaration.  The type specifiers
(in this case `struct foo') and type qualifiers (`volatile') all go to
forming the "base type", so to speak, for the declaration.

The way to declare a volatile pointer (in a register) to a struct foo is

	register struct foo * volatile p3;

See the pointer-declarator rules in 3.5.4.1.

>... I haven't been able to find anything in
>the standard about the interaction of storage classes and type
>qualifiers.

That's because there is none.  The storage class is completely independent
of the type.
-- 
If the Space Shuttle was the answer,   | Henry Spencer at U of Toronto Zoology
what was the question?                 |  henry@zoo.toronto.edu   utzoo!henry