https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103923
--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
If I change the __cache_default trait to be:
template<typename _Tp, typename _Hash>
using __cache_default
= __bool_constant<!(__is_fast_hash<_Hash>::value // Do not cache for fast
hasher.
// Mandatory to have erase not throwing.
&& noexcept(std::declval<const _Hash&>()(std::declval<const
_Tp&>())))>;
Then you get an error from the instantiation of std::unordered_map, confirming
what I said above:
In file included from /home/jwakely/gcc/12/include/c++/12.0.0/unordered_map:46,
from 103923.C:4:
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h: In instantiation of
'class std::unordered_map<T::K, int, T::H>':
103923.C:13:45: required from here
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
50 | && noexcept(std::declval<const _Hash&>()(std::declval<const
_Tp&>())))>;
| ~~~~~~~~~~~~~~~~~~~~~~~~~~^~
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
In file included from /home/jwakely/gcc/12/include/c++/12.0.0/unordered_map:47,
from 103923.C:4:
/home/jwakely/gcc/12/include/c++/12.0.0/bits/unordered_map.h:874:42: error:
using invalid field 'std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::_M_h'
874 | find(const _Kt& __x) -> decltype(_M_h._M_find_tr(__x))
| ^~~~
/home/jwakely/gcc/12/include/c++/12.0.0/bits/unordered_map.h:885:48: error:
using invalid field 'std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::_M_h'
885 | find(const _Kt& __x) const -> decltype(_M_h._M_find_tr(__x))
| ^~~~
/home/jwakely/gcc/12/include/c++/12.0.0/bits/unordered_map.h:907:49: error:
using invalid field 'std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::_M_h'
907 | count(const _Kt& __x) const -> decltype(_M_h._M_count_tr(__x))
| ^~~~
/home/jwakely/gcc/12/include/c++/12.0.0/bits/unordered_map.h:926:21: error:
using invalid field 'std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::_M_h'
926 | -> decltype(_M_h._M_find_tr(__x), void(), true)
| ^~~~
In file included from /home/jwakely/gcc/12/include/c++/12.0.0/unordered_map:46,
from 103923.C:4:
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
50 | && noexcept(std::declval<const _Hash&>()(std::declval<const
_Tp&>())))>;
| ~~~~~~~~~~~~~~~~~~~~~~~~~~^~
In file included from /home/jwakely/gcc/12/include/c++/12.0.0/unordered_map:47,
from 103923.C:4:
/home/jwakely/gcc/12/include/c++/12.0.0/bits/unordered_map.h:948:21: error:
using invalid field 'std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::_M_h'
948 | -> decltype(_M_h._M_equal_range_tr(__x))
| ^~~~
In file included from /home/jwakely/gcc/12/include/c++/12.0.0/unordered_map:46,
from 103923.C:4:
/home/jwakely/gcc/12/include/c++/12.0.0/bits/hashtable.h:50:50: error: use of
'auto T::H::operator()(const T::K&) const' before deduction of 'auto'
50 | && noexcept(std::declval<const _Hash&>()(std::declval<const
_Tp&>())))>;
| ~~~~~~~~~~~~~~~~~~~~~~~~~~^~
In file included from /home/jwakely/gcc/12/include/c++/12.0.0/unordered_map:47,
from 103923.C:4:
/home/jwakely/gcc/12/include/c++/12.0.0/bits/unordered_map.h:960:21: error:
using invalid field 'std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::_M_h'
960 | -> decltype(_M_h._M_equal_range_tr(__x))
| ^~~~
