https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100577
Bug ID: 100577
Summary: [11/12 Regression] Unhelpful diagnostics for
ill-formed call to partially applied range adaptor
object
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: ppalka at gcc dot gnu.org
Target Milestone: ---
For the following invalid testcase:
#include <ranges>
int main() {
extern int x[100];
std::views::take(nullptr)(x);
}
GCC 10 emits the following errors:
In file included from <stdin>:1:
/usr/include/c++/10/ranges: In instantiation of
‘std::ranges::views::<lambda(_Range&&, _Tp&&)> [with _Range = int (&)[100]; _Tp
= std::nullptr_t]’:
/usr/include/c++/10/ranges:1142:27: required from
‘std::ranges::views::__adaptor::_RangeAdaptor<_Callable>::operator()<{std::nullptr_t}>::<lambda(_Range&&)>
[with _Range = int (&)[100]]’
/usr/include/c++/10/ranges:1162:44: required from ‘constexpr auto
std::ranges::views::__adaptor::_RangeAdaptorClosure<_Callable>::operator()(_Range&&)
const [with _Range = int (&)[100]; _Callable = std::ranges
::views::__adaptor::_RangeAdaptor<_Callable>::operator()<{std::nullptr_t}>::<lambda(_Range&&)>]’
<stdin>:5:30: required from here
/usr/include/c++/10/ranges:2148:68: error: class template argument deduction
failed:
2148 | return take_view{std::forward<_Range>(__r), std::forward<_Tp>(__n)};
| ^
/usr/include/c++/10/ranges:2148:68: error: no matching function for call to
‘take_view(int [100], std::nullptr_t)’
[...]
/usr/include/c++/10/ranges:2140:5: note: candidate:
‘std::ranges::take_view(_Range&&, std::ranges::range_difference_t<_Range>)->
std::ranges::take_view<std::ranges::views::all_t<_Range> > [with _Range = int
(&)[
100]; std::ranges::views::all_t<_Range> = std::ranges::ref_view<int [100]>;
std::ranges::range_difference_t<_Range> = long int]’
2140 | take_view(_Range&&, range_difference_t<_Range>)
| ^~~~~~~~~
Whereas GCC 11, after r11-8053, emits an almost useless error:
<stdin>:5:28: error: use of deleted function ‘constexpr auto
std::ranges::views::__adaptor::_Partial<_Adaptor, _Arg>::operator()(_Range&&)
const && [with _Range = int (&)[100]; _Adaptor = std::ranges::views::_Take;
_Arg = std::nullptr_t]’
In file included from <stdin>:1:
/home/patrick/code/gcc-master/libstdc++-v3/include/std/ranges:865:9: note:
declared here
865 | operator()(_Range&& __r) const && = delete;
| ^~~~~~~~
