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Re: [std-proposals] Small C compatibility extensions for array

From: Bo Persson <bo_at_[hidden]>
Date: Sun, 23 Oct 2022 21:28:41 +0200
On 2022-10-23 at 14:23, blacktea hamburger via Std-Proposals wrote:
> cppreference <https://en.cppreference.com/w/c/language/array>:
> |*[*| |*static*|(optional) qualifiers(optional) expression(optional)
> |*]*| attr-spec-seq(optional) (1)
> |*[*| qualifiers(optional) |*static*|(optional) expression(optional)
> |*]*| attr-spec-seq(optional) (2)
> expression - any expression other than comma operator
> <https://en.cppreference.com/w/c/language/operator_other#Comma_operator>, designates the number of elements in the array
> qualifiers - any combination of |const|
> <https://en.cppreference.com/w/c/language/const>, |restrict|
> <https://en.cppreference.com/w/c/language/restrict>, or |volatile|
> <https://en.cppreference.com/w/c/language/volatile> qualifiers, only
> allowed in function parameter lists; this qualifies the pointer type to
> which this array parameter is transformed
> In function parameter lists, additional syntax elements are allowed
> within the array declarators: the keyword |*static*| and qualifiers,
> which may appear in any order before the size expression (they may also
> appear even when the size expression is omitted).
> In each function call
> <https://en.cppreference.com/w/c/language/operator_other#Function_call> to a function where an array parameter uses the keyword |*static*| between |*[*| and |*]*|, the value of the actual parameter must be a valid pointer to the first element of an array with at least as many elements as specified by expression:
> If qualifiers are present, they qualify the pointer type to which the
> array parameter type is transformed
> They are also useful for C++ and improve C compatibility.

 From the very start, the C++ committee has declined proposals to fix C
arrays, because they were deemed not fixable.

So instead of f(int [static 42]) you could use f(std::array<int, 42>&).

Being C compatible is a very minor convenience here.

Received on 2022-10-23 19:28:51