Submitter: Martin Sebor
Submission Date: 2014-03-22
Source: WG14
Reference Document: N1807
Version: 1.0
Date: April 2014
Subject: atomic_load missing const qualifier
Summary
The synopsis of the atomic_load pair of generic functions specified in 7.17.7.2 shows that they accept pointers to a volatile- (bot not const-) qualified type:
#include <stdatomic.h>
C atomic_load(volatile A *object);
C atomic_load_explicit(volatile A *object,
memory_order order);
The absence of the const qualifier implies that the functions cannot be called with an argument of type const A* since there is no such conversion.
However, since neither function modifies its argument, there is no need to prevent it from being called with an argument of type const A*. And, in fact, the latest draft C++ standard as of this writing, N3936, does provide an overload of each function that takes a const volatile pointer.
Suggested Technical CorrigendumIn section 7.17.7.2, paragraph 1, Synopsis, modify the declarations of the atomic_load pair of generic functions as indicated below:
#include <stdatomic.h>
C atomic_load(const volatile A *object);
C atomic_load_explicit(const volatile A *object,
memory_order order);
Proposed Technical Corrigendum
In section 7.17.7.2, paragraph 1, Synopsis, modify the declarations of the atomic_load pair of generic functions from:
#include <stdatomic.h>
C atomic_load(volatile A *object);
C atomic_load_explicit(volatile A *object,
memory_order order);
to:
#include <stdatomic.h>
C atomic_load(const volatile A *object);
C atomic_load_explicit(const volatile A *object,
memory_order order);