https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104098
Bug ID: 104098
Summary: bits/stl_iterator.h fails to compile for __cplusplus >
201703L but with __cpp_concepts undefined
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: richard.corden at gmail dot com
Target Milestone: ---
Hi,
The following commit changed a preprocessor condition, removing a check for
__cpp_lib_concepts:
https://github.com/gcc-mirror/gcc/commit/d5cbe0f0d4b7bc11f80b2236521f90ec94e95767#diff-d1fe6b9164baa7e8e1119a4d194b6b2481439be0cdf5da5794e8001537db4e84
The result being that this header cannot be used with __cplusplus after 201703L
unless "__cpp_concepts" is defined.
Compiling the following with "g++ -std=c++20 sample.cpp" reproduces the issue:
{code:c++}
// sample.cpp
#undef __cpp_concepts
#include <vector>
{code}
{noformat}
> g++-11 -std=c++20 sample.cpp
In file included from /usr/include/c++/11/bits/stl_algobase.h:67,
from /usr/include/c++/11/vector:60,
from sample.cpp:3:
/usr/include/c++/11/bits/stl_iterator.h:158:25: error: ‘random_access_iterator’
was not declared in this scope; did you mean ‘random_access_iterator_tag’?
158 | = conditional_t<random_access_iterator<_Iterator>,
| ^~~~~~~~~~~~~~~~~~~~~~
| random_access_iterator_tag
/usr/include/c++/11/bits/stl_iterator.h:158:57: error: wrong number of template
arguments (1, should be 3)
158 | = conditional_t<random_access_iterator<_Iterator>,
| ^
In file included from /usr/include/c++/11/bits/move.h:57,
from /usr/include/c++/11/bits/stl_pair.h:59,
from /usr/include/c++/11/bits/stl_algobase.h:64,
from /usr/include/c++/11/vector:60,
from sample.cpp:3:
{noformat}
The following addresses the issue for me locally:
{code:c++}
#if __cplusplus <= 201703L || ! defined (__cpp_lib_concepts)
{code}
Cheers,
Richard
