passing POD by value with const qualifiers. Silly or not?

[André Wöbbeking]

On Friday 22 February 2008, Stefan Teleman wrote:
> On Fri, Feb 22, 2008 at 8:28 AM, André Wöbbeking <Woebbeking at kde.org> 
wrote:
> >  Did you try it? According to the C++ standard e.g.
> >
> >  void foo(int);
> >  void foo(const int);
> >
> >  are equivalent.
>
> Tried it and dealt with it many many times.
>
> ISO/IEC:14882:2003:13.1
>
> Overloadable declarations
>
> [ ... ] const and volatile type-specifiers buried within a parameter
> type specification are significant and can be used to distinguish
> overloaded function declarations. [ ... ]

Either the context of that paragraph changed or you oversaw it. In 
ISO/IEC 14882:1998 it is:

Only the const and volatile type-specifiers at the outermost level of 
the parameter type specification are ignored in this fashion; const and 
volatile type-specifiers buried within a parameter type specification 
are significant and can be used to distinguish overloaded function 
declarations. In particular, for any type T, “pointer to T,” “pointer 
to const T,” and “pointer to volatile T” are considered distinct 
parameter types, as are “reference to T,” “reference to const T,” 
and “reference to volatile T.”

> One could argue that overloading on the const or volatile type
> specifier was intended for pointer or reference types only [hi,
> comp.std.c++.moderated!], but Sun Studio has enforced the overloading
> distinction between void foo(int) and void foo(const int) since i can
> remember.
>
> The question still remains (in my mind): why is void foo(const int)
> useful ? It's not like there are any amazing assembler optimizations
> possible when saying void foo(const int) as opposed to just void
> foo(int).

As I wrote before, it isn't useful in the API.


Cheers,
André