Tested powerpc64le-linux. Pushed to trunk.
-- >8 --
As pointed out in P2641R1, we can use GCC's __builtin_constant_p to
emulate the proposed std::is_active_member. This allows us to detect
which of the union members is active during constant evaluation, so we
don't need the extra bool data member. We still can't support constexpr
until C++20 though, as we need to change the active member during
constant evaluation.
libstdc++-v3/ChangeLog:
* include/experimental/internet (ip::basic_endpoint::_M_if_v6):
Revert change from member function to data member. Fix for
constant evaluation by detecting which union member is active.
(ip::basic_endpoint::resize): Revert changes to update _M_is_v6
flag.
---
libstdc++-v3/include/experimental/internet | 32 ++++++++++------------
1 file changed, 14 insertions(+), 18 deletions(-)
diff --git a/libstdc++-v3/include/experimental/internet
b/libstdc++-v3/include/experimental/internet
index dff81b456ab..eb23ae21cdc 100644
--- a/libstdc++-v3/include/experimental/internet
+++ b/libstdc++-v3/include/experimental/internet
@@ -1531,7 +1531,6 @@ namespace ip
std::_Construct(&_M_data._M_v6);
_M_data._M_v6.sin6_family = __proto.family();
_M_data._M_v6.sin6_port = address_v4::_S_hton_16(__port_num);
- _M_is_v6 = true;
}
else
{
@@ -1560,7 +1559,6 @@ namespace ip
for (int __i = 0; __i < 16; ++__i)
__s6a[__i] = __addr._M_v6._M_bytes[__i];
_M_data._M_v6.sin6_scope_id = __addr._M_v6._M_scope_id;
- _M_is_v6 = true;
}
}
@@ -1568,13 +1566,13 @@ namespace ip
constexpr protocol_type protocol() const noexcept
{
- return _M_is_v6 ? protocol_type::v6() : protocol_type::v4();
+ return _M_is_v6() ? protocol_type::v6() : protocol_type::v4();
}
constexpr ip::address
address() const noexcept
{
- if (_M_is_v6)
+ if (_M_is_v6())
{
address_v6 __v6;
const uint8_t* __s6a = _M_data._M_v6.sin6_addr.s6_addr;
@@ -1601,14 +1599,12 @@ namespace ip
__builtin_memcpy(_M_data._M_v6.sin6_addr.s6_addr,
__addr._M_v6._M_bytes.data(), 16);
_M_data._M_v6.sin6_scope_id = __addr._M_v6._M_scope_id;
- _M_is_v6 = true;
}
else
{
std::_Construct(&_M_data._M_v4);
_M_data._M_v4.sin_family = protocol_type::v4().family();
_M_data._M_v4.sin_addr.s_addr = __addr._M_v4._M_addr;
- _M_is_v6 = false;
}
}
@@ -1616,7 +1612,7 @@ namespace ip
port() const noexcept
{
port_type __p = 0;
- if (_M_is_v6)
+ if (_M_is_v6())
__p = _M_data._M_v6.sin6_port;
else
__p = _M_data._M_v4.sin_port;
@@ -1627,7 +1623,7 @@ namespace ip
port(port_type __port_num) noexcept
{
__port_num = address_v4::_S_hton_16(__port_num);
- if (_M_is_v6)
+ if (_M_is_v6())
_M_data._M_v6.sin6_port = __port_num;
else
_M_data._M_v4.sin_port = __port_num;
@@ -1639,19 +1635,11 @@ namespace ip
constexpr size_t
size() const noexcept
- { return _M_is_v6 ? sizeof(sockaddr_in6) : sizeof(sockaddr_in); }
+ { return _M_is_v6() ? sizeof(sockaddr_in6) : sizeof(sockaddr_in); }
void
resize(size_t __s)
{
- __glibcxx_assert(__s >= 0);
- static_assert(offsetof(sockaddr_in6, sin6_family)
- == offsetof(sockaddr_in, sin_family),
- "sockaddr_in::sin_family and sockaddr_in6::sin6_family "
- "must be at the same offset");
- const sa_family_t __in6 = AF_INET6;
- const auto* __ptr = (char*)&_M_data + offsetof(sockaddr_in, sin_family);
- _M_is_v6 = __builtin_memcmp(&__in6, __ptr, sizeof(__in6)) == 0;
if (__s != size())
__throw_length_error("net::ip::basic_endpoint::resize");
}
@@ -1665,7 +1653,15 @@ namespace ip
sockaddr_in6 _M_v6;
} _M_data;
- bool _M_is_v6 = false;
+ constexpr bool
+ _M_is_v6() const noexcept
+ {
+ // For constexpr eval we can just detect which union member is active.
+ // i.e. emulate P2641R1's std::is_active_member(&_M_data._M_v6)).
+ if (std::__is_constant_evaluated())
+ return __builtin_constant_p(_M_data._M_v6.sin6_family);
+ return _M_data._M_v6.sin6_family == AF_INET6;
+ }
};
/** basic_endpoint comparisons
--
2.39.2
