https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95289
Bug ID: 95289
Summary: __gnu_debug::__get_distance is not C++11 constexpr
compliant
Product: gcc
Version: 10.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: andysem at mail dot ru
Target Milestone: ---
The following test case fails to compile in C++11 mode:
#include <vector>
#include <fstream>
#include <iterator>
void foo()
{
typedef std::istream_iterator<char> is_iter;
std::ifstream ifs1("test.dat");
std::vector<char> data1;
is_iter it1(ifs1), it_end;
std::copy(it1, it_end, std::back_inserter(data1));
}
$ g++ -std=c++11 -D_GLIBCXX_DEBUG
/opt/compiler-explorer/gcc-10.1.0/include/c++/10.1.0/debug/helper_functions.h:108:5:
error: body of 'constexpr' function 'constexpr typename
__gnu_debug::_Distance_traits<_Iterator>::__type
__gnu_debug::__get_distance(_Iterator, _Iterator, std::input_iterator_tag)
[with _Iterator = std::istream_iterator<char>; typename
__gnu_debug::_Distance_traits<_Iterator>::__type = std::pair<long int,
__gnu_debug::_Distance_precision>]' not a return-statement
https://gcc.godbolt.org/z/6Aa1ce
This is a regression since gcc 9.
