[Bug libstdc++/48101] obscure error message with std::set
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48101 --- Comment #13 from Jonathan Wakely --- Nice!
[Bug libstdc++/48101] obscure error message with std::set
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48101 Louis Dionne changed: What|Removed |Added CC||ldionne.2 at gmail dot com --- Comment #12 from Louis Dionne --- FWIW, we now consider it a bug in libc++ that we accept std::allocator, and we're trying to remove that "extension".
[Bug libstdc++/48101] obscure error message with std::set
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48101 --- Comment #11 from Jonathan Wakely --- Author: redi Date: Tue May 7 15:46:05 2019 New Revision: 270960 URL: https://gcc.gnu.org/viewcvs?rev=270960&root=gcc&view=rev Log: PR libstdc++/85965 delay static assertions until types are complete The static assertions added for PR libstdc++/48101 were at class scope and so were evaluated too eagerly, when it might not be possible to determine whether the function objects are invocable with the key types. The problematic cases are where the key type is not known to be convertible to the argument type(s) of the function object until later, after a type has been completed. Specifically, if the key type is a pointer to a derived class and the function object's argument type is a pointer to a base class, then the derived-to-base conversion is only valid once the derived type is complete. By moving the static assertions to the destructor they will only be evaluated when the destructor is instantiated, at which point whether the key type can be passed to the function object should be knowable. The ideal place to do the checks would be only when the function objects are actually invoked, but that would mean adding the checks in numerous places, so the destructor is used instead. The tests need to be adjusted because the "required from here" line is now the location of the destructor, not the point of instantiation in the test file. For the map and multimap tests which check two specializations, the dg-error matching the assertion text matches both cases. Also check the diagnostic output for the template arguments, to ensure both specializations trigger the assertion. Backport from mainline 2019-03-26 Jonathan Wakely PR libstdc++/85965 * include/bits/hashtable.h (_Hashtable): Move static assertions to destructor so they are not evaluated until the _Key type is complete. * include/bits/stl_tree.h (_Rb_tree): Likewise. * testsuite/23_containers/set/85965.cc: New test. * testsuite/23_containers/unordered_set/85965.cc: New test. * testsuite/23_containers/map/48101_neg.cc: Replace "here" errors with regexp matching the corresponding _Rb_tree specialization. * testsuite/23_containers/multimap/48101_neg.cc: Likewise. * testsuite/23_containers/multiset/48101_neg.cc: Remove "here" error. * testsuite/23_containers/set/48101_neg.cc: Likewise. * testsuite/23_containers/unordered_map/48101_neg.cc: Likewise. * testsuite/23_containers/unordered_multimap/48101_neg.cc: Likewise. * testsuite/23_containers/unordered_multiset/48101_neg.cc: Likewise. * testsuite/23_containers/unordered_set/48101_neg.cc: Likewise. Added: branches/gcc-8-branch/libstdc++-v3/testsuite/23_containers/set/85965.cc - copied, changed from r270959, branches/gcc-8-branch/libstdc++-v3/testsuite/23_containers/map/48101_neg.cc branches/gcc-8-branch/libstdc++-v3/testsuite/23_containers/unordered_set/85965.cc - copied, changed from r270959, branches/gcc-8-branch/libstdc++-v3/testsuite/23_containers/map/48101_neg.cc Modified: branches/gcc-8-branch/libstdc++-v3/ChangeLog branches/gcc-8-branch/libstdc++-v3/include/bits/hashtable.h branches/gcc-8-branch/libstdc++-v3/include/bits/stl_tree.h branches/gcc-8-branch/libstdc++-v3/testsuite/23_containers/map/48101_neg.cc branches/gcc-8-branch/libstdc++-v3/testsuite/23_containers/multimap/48101_neg.cc branches/gcc-8-branch/libstdc++-v3/testsuite/23_containers/multiset/48101_neg.cc branches/gcc-8-branch/libstdc++-v3/testsuite/23_containers/set/48101_neg.cc branches/gcc-8-branch/libstdc++-v3/testsuite/23_containers/unordered_map/48101_neg.cc branches/gcc-8-branch/libstdc++-v3/testsuite/23_containers/unordered_multimap/48101_neg.cc branches/gcc-8-branch/libstdc++-v3/testsuite/23_containers/unordered_multiset/48101_neg.cc branches/gcc-8-branch/libstdc++-v3/testsuite/23_containers/unordered_set/48101_neg.cc
[Bug libstdc++/48101] obscure error message with std::set
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48101 --- Comment #10 from Jonathan Wakely --- Author: redi Date: Tue Mar 26 15:28:48 2019 New Revision: 269949 URL: https://gcc.gnu.org/viewcvs?rev=269949&root=gcc&view=rev Log: PR libstdc++/85965 delay static assertions until types are complete The static assertions added for PR libstdc++/48101 were at class scope and so were evaluated too eagerly, when it might not be possible to determine whether the function objects are invocable with the key types. The problematic cases are where the key type is not known to be convertible to the argument type(s) of the function object until later, after a type has been completed. Specifically, if the key type is a pointer to a derived class and the function object's argument type is a pointer to a base class, then the derived-to-base conversion is only valid once the derived type is complete. By moving the static assertions to the destructor they will only be evaluated when the destructor is instantiated, at which point whether the key type can be passed to the function object should be knowable. The ideal place to do the checks would be only when the function objects are actually invoked, but that would mean adding the checks in numerous places, so the destructor is used instead. The tests need to be adjusted because the "required from here" line is now the location of the destructor, not the point of instantiation in the test file. For the map and multimap tests which check two specializations, the dg-error matching the assertion text matches both cases. Also check the diagnostic output for the template arguments, to ensure both specializations trigger the assertion. PR libstdc++/85965 * include/bits/hashtable.h (_Hashtable): Move static assertions to destructor so they are not evaluated until the _Key type is complete. * include/bits/stl_tree.h (_Rb_tree): Likewise. * testsuite/23_containers/set/85965.cc: New test. * testsuite/23_containers/unordered_set/85965.cc: New test. * testsuite/23_containers/map/48101_neg.cc: Replace "here" errors with regexp matching the corresponding _Rb_tree specialization. * testsuite/23_containers/multimap/48101_neg.cc: Likewise. * testsuite/23_containers/multiset/48101_neg.cc: Remove "here" error. * testsuite/23_containers/set/48101_neg.cc: Likewise. * testsuite/23_containers/unordered_map/48101_neg.cc: Likewise. * testsuite/23_containers/unordered_multimap/48101_neg.cc: Likewise. * testsuite/23_containers/unordered_multiset/48101_neg.cc: Likewise. * testsuite/23_containers/unordered_set/48101_neg.cc: Likewise. Added: trunk/libstdc++-v3/testsuite/23_containers/set/85965.cc - copied, changed from r269947, trunk/libstdc++-v3/testsuite/23_containers/map/48101_neg.cc trunk/libstdc++-v3/testsuite/23_containers/unordered_set/85965.cc - copied, changed from r269947, trunk/libstdc++-v3/testsuite/23_containers/map/48101_neg.cc Modified: trunk/libstdc++-v3/ChangeLog trunk/libstdc++-v3/include/bits/hashtable.h trunk/libstdc++-v3/include/bits/stl_tree.h trunk/libstdc++-v3/testsuite/23_containers/map/48101_neg.cc trunk/libstdc++-v3/testsuite/23_containers/multimap/48101_neg.cc trunk/libstdc++-v3/testsuite/23_containers/multiset/48101_neg.cc trunk/libstdc++-v3/testsuite/23_containers/set/48101_neg.cc trunk/libstdc++-v3/testsuite/23_containers/unordered_map/48101_neg.cc trunk/libstdc++-v3/testsuite/23_containers/unordered_multimap/48101_neg.cc trunk/libstdc++-v3/testsuite/23_containers/unordered_multiset/48101_neg.cc trunk/libstdc++-v3/testsuite/23_containers/unordered_set/48101_neg.cc
[Bug libstdc++/48101] obscure error message with std::set
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48101 Jonathan Wakely changed: What|Removed |Added Keywords||diagnostic Status|NEW |RESOLVED Resolution|--- |FIXED Target Milestone|--- |8.0 --- Comment #9 from Jonathan Wakely --- Gaby's original testcase now prints simply: In file included from /home/jwakely/gcc/8/include/c++/8.0.0/set:61:0, from const.cc:1: /home/jwakely/gcc/8/include/c++/8.0.0/bits/stl_set.h: In instantiation of ‘class std::set’: const.cc:4:23: required from here /home/jwakely/gcc/8/include/c++/8.0.0/bits/stl_set.h:108:7: error: static assertion failed: std::set must have a non-const, non-volatile value_type static_assert(is_same::type, _Key>::value, ^
[Bug libstdc++/48101] obscure error message with std::set
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48101 --- Comment #8 from Jonathan Wakely --- Author: redi Date: Tue Nov 21 20:47:09 2017 New Revision: 255035 URL: https://gcc.gnu.org/viewcvs?rev=255035&root=gcc&view=rev Log: PR libstdc++/48101 improve errors for invalid container specializations PR libstdc++/48101 * include/bits/allocator.h (allocator) (allocator, allocator): Add partial specializations. * include/bits/forward_list.h (forward_list): Add static assertions. * include/bits/hashtable.h (__cache_default): Use __is_nothrow_invocable instead of __is_noexcept_hash. (_Hashtable): Add static assertions. * include/bits/hashtable_policy.h (__is_noexcept_hash): Remove. * include/bits/stl_deque.h (deque): Add static assertions. * include/bits/stl_function.h (_Identity): Add partial specialization. * include/bits/stl_list.h (list): Add static assertions. * include/bits/stl_map.h (map): Likewise. * include/bits/stl_multimap.h (multimap): Likewise. * include/bits/stl_multiset.h (multiset): Likewise. * include/bits/stl_set.h (set): Likewise. * include/bits/stl_tree.h (_Rb_tree): Likewise. * include/bits/stl_vector.h (vector): Likewise. * include/bits/unordered_map.h (unordered_map, unordered_multimap): Use typename instead of class in template-parameter-list and remove spaces. * include/bits/unordered_set.h (unordered_set, unordered_multiset): Likewise. * testsuite/23_containers/deque/48101-2_neg.cc: New test. * testsuite/23_containers/deque/48101_neg.cc: New test. * testsuite/23_containers/forward_list/48101-2_neg.cc: New test. * testsuite/23_containers/forward_list/48101_neg.cc: New test. * testsuite/23_containers/list/48101-2_neg.cc: New test. * testsuite/23_containers/list/48101_neg.cc: New test. * testsuite/23_containers/map/48101-2_neg.cc: New test. * testsuite/23_containers/map/48101_neg.cc: New test. * testsuite/23_containers/map/operations/31440.cc: Fix comparison object to have const-qualified call operator. * testsuite/23_containers/multimap/48101-2_neg.cc: New test. * testsuite/23_containers/multimap/48101_neg.cc: New test. * testsuite/23_containers/multiset/48101-2_neg.cc: New test. * testsuite/23_containers/multiset/48101_neg.cc: New test. * testsuite/23_containers/set/48101-2_neg.cc: New test. * testsuite/23_containers/set/48101_neg.cc: New test. * testsuite/23_containers/unordered_map/48101-2_neg.cc: New test. * testsuite/23_containers/unordered_map/48101_neg.cc: New test. * testsuite/23_containers/unordered_multimap/48101-2_neg.cc: New test. * testsuite/23_containers/unordered_multimap/48101_neg.cc: New test. * testsuite/23_containers/unordered_multiset/48101-2_neg.cc: New test. * testsuite/23_containers/unordered_multiset/48101_neg.cc: New test. * testsuite/23_containers/unordered_set/48101-2_neg.cc: New test. * testsuite/23_containers/unordered_set/48101_neg.cc: New test. * testsuite/23_containers/unordered_set/instantiation_neg.cc: Adjust dg-error line number. * testsuite/23_containers/vector/48101-2_neg.cc: New test. * testsuite/23_containers/vector/48101_neg.cc: New test. Added: trunk/libstdc++-v3/testsuite/23_containers/deque/48101-2_neg.cc - copied, changed from r255023, trunk/libstdc++-v3/testsuite/23_containers/map/operations/31440.cc trunk/libstdc++-v3/testsuite/23_containers/deque/48101_neg.cc - copied, changed from r255023, trunk/libstdc++-v3/testsuite/23_containers/unordered_set/instantiation_neg.cc trunk/libstdc++-v3/testsuite/23_containers/forward_list/48101-2_neg.cc - copied, changed from r255023, trunk/libstdc++-v3/testsuite/23_containers/map/operations/31440.cc trunk/libstdc++-v3/testsuite/23_containers/forward_list/48101_neg.cc - copied, changed from r255023, trunk/libstdc++-v3/testsuite/23_containers/unordered_set/instantiation_neg.cc trunk/libstdc++-v3/testsuite/23_containers/list/48101-2_neg.cc - copied, changed from r255023, trunk/libstdc++-v3/testsuite/23_containers/map/operations/31440.cc trunk/libstdc++-v3/testsuite/23_containers/list/48101_neg.cc - copied, changed from r255023, trunk/libstdc++-v3/testsuite/23_containers/unordered_set/instantiation_neg.cc trunk/libstdc++-v3/testsuite/23_containers/map/48101-2_neg.cc - copied, changed from r255023, trunk/libstdc++-v3/testsuite/23_containers/map/operations/31440.cc trunk/libstdc++-v3/testsuite/23_containers/map/48101_neg.cc - copied, changed from r255023, trunk/libstdc++-v3/testsuite/23_containers/map/operations/31440.cc trunk/libstdc++-v3/testsuite/23_containers/multimap/48101-2_neg.cc - copied, changed from r255023,
[Bug libstdc++/48101] obscure error message with std::set
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48101 --- Comment #7 from Jonathan Wakely --- Even if we allowed allocator you still can't use std::set because the container code assumes a non-const value type in several places.
[Bug libstdc++/48101] obscure error message with std::set
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48101 --- Comment #6 from Jonathan Wakely --- You can't allocate const memory, but in essence yes, that's the reason. The standard says that an allocator's value type must be a non-const, non-volatile object type, so std::allocator is undefined behaviour.
[Bug libstdc++/48101] obscure error message with std::set
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48101 --- Comment #5 from gccbugs at jbapple dot com --- What is the virtue of making std::allocator an error? Is this required by the standard? Is it because calls to construct are writing to const memory?
[Bug libstdc++/48101] obscure error message with std::set
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48101 --- Comment #4 from Jonathan Wakely --- Which causes the code to be accepted. I'd rather do: template class allocator; // undefined so there's an error.
[Bug libstdc++/48101] obscure error message with std::set
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48101
gccbugs at jbapple dot com changed:
What|Removed |Added
CC||gccbugs at jbapple dot com
--- Comment #3 from gccbugs at jbapple dot com ---
libc++ handles this with a partial template specialization like
template
class allocator {
...
See
https://github.com/llvm-mirror/libcxx/blob/b4a34c08ac01146141a9940bcfb0a680d24dc092/include/memory#L1817
[Bug libstdc++/48101] obscure error message with std::set
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48101 Jonathan Wakely changed: What|Removed |Added CC||corey at octayn dot net --- Comment #2 from Jonathan Wakely --- *** Bug 55963 has been marked as a duplicate of this bug. ***
[Bug libstdc++/48101] obscure error message with std::set
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48101 Jonathan Wakely changed: What|Removed |Added Status|UNCONFIRMED |NEW Last reconfirmed||2014-09-19 Ever confirmed|0 |1 Severity|normal |enhancement
[Bug libstdc++/48101] obscure error message with std::set
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48101 --- Comment #1 from Jonathan Wakely 2011-03-13 12:24:13 UTC --- Do you have a suggestion for a better error? We could use a static_assert in std::allocator to reject const T As far as I can see, the reason the code is invalid is exactly the reason given: std::allocator can't be instantiated with const T. I don't think it's invalid to default construct a set::set with a const value_type, as long as don't use std::allocator.
