const qualifiers on function returns type

const qualifiers on function returns type

[Benoit Boissinot]

Hi,

there are some function who are declared this way:

include/linux/cpuset.h:21
extern const cpumask_t cpuset_cpus_allowed(const struct task_struct *p);

I was wondering what means const for a function returns type.
K&R doesn't say anything about this and gcc-4 warns (warning: type
qualifiers ignored on function return type)

If it is a mistake, there are a few functions who should be modified.

Regards,

Benoit

Re: const qualifiers on function returns type

[Bodo Eggert]

Benoit Boissinot <bboissin@gmail.com> wrote:

> extern const cpumask_t cpuset_cpus_allowed(const struct task_struct *p);
> 
> I was wondering what means const for a function returns type.
> K&R doesn't say anything about this and gcc-4 warns (warning: type
> qualifiers ignored on function return type)

It used to be a hint that the function has no side effect nor depends on
any variable besides the parameters. Calls to those functions may be cached
or omitted.
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