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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/103923] is_invocable<const T &, ...> inexplicably fails
Date: Thu, 06 Jan 2022 09:31:18 +0000	[thread overview]
Message-ID: <bug-103923-4-WX5ahDNetY@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-103923-4@http.gcc.gnu.org/bugzilla/>

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))
      |                     ^~~~

  parent reply	other threads:[~2022-01-06  9:31 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-05 23:16 [Bug c++/103923] New: " jengelh at inai dot de
2022-01-05 23:19 ` [Bug libstdc++/103923] " pinskia at gcc dot gnu.org
2022-01-06  9:23 ` redi at gcc dot gnu.org
2022-01-06  9:31 ` redi at gcc dot gnu.org [this message]
2022-01-06  9:37 ` redi at gcc dot gnu.org
2022-01-06  9:39 ` redi at gcc dot gnu.org
2022-01-06  9:46 ` redi at gcc dot gnu.org
2022-01-06 14:30 ` redi at gcc dot gnu.org
2022-01-06 14:53 ` redi at gcc dot gnu.org
2022-01-06 16:00 ` redi at gcc dot gnu.org

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