C++0x static asserts cannot be used like so:
#include <cassert>
/// Enumeration for memory_order
typedef enum memory_order
{
memory_order_relaxed,
memory_order_consume,
memory_order_acquire,
memory_order_release,
memory_order_acq_rel,
memory_order_seq_cst
} memory_order;
class a
{
void
store1(void* __v, memory_order __m = memory_order_seq_cst) volatile
{
assert(__m == memory_order_acquire);
assert(__m == memory_order_acq_rel);
assert(__m == memory_order_consume);
}
void
store2(void* __v, const memory_order __m = memory_order_seq_cst)
{
static_assert(__m == memory_order_acquire,
"atomic_address::store requirements not met.");
static_assert(__m == memory_order_acq_rel,
"atomic_address::store requirements not met.");
static_assert(__m == memory_order_consume,
"atomic_address::store requirements not met.");
}
};
g++ -std=gnu++0x says:
<b...@francisco> /home/bkoz
%$bld/H-x86-gcc.20081208/bin/g++ -std=gnu++0x -g teststatic_a.cc
teststatic_a.cc: In member function 'void a::store2(void*, memory_order)':
teststatic_a.cc:27: error: '__m' cannot appear in a constant-expression
teststatic_a.cc:29: error: '__m' cannot appear in a constant-expression
teststatic_a.cc:31: error: '__m' cannot appear in a constant-expression
There is an interesting comment in the originating boost static assert header,
see 'It's not particularly clear how this applies to enum's or typedefs;'
http://www.boost.org/doc/libs/1_37_0/boost/static_assert.hpp
Now for the legalese:
In N2798,
7.1p4:
In a static_assert-declaration the constant-expression shall be a constant
expression (5.19) that can be contextually converted to bool (Clause 4).
5.18p3
A constant expression is an integral constant expression if it is of integral
or enumeration type
>From this, I expect the above code to be valid and compile w/o error.
--
Summary: static_assert vs. enums
Product: gcc
Version: unknown
Status: UNCONFIRMED
Keywords: rejects-valid
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: bkoz at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38502
