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| author | Jonathan Wakely <jwakely@redhat.com> | 2021-05-06 13:44:36 +0100 |
|---|---|---|
| committer | Jonathan Wakely <jwakely@redhat.com> | 2021-10-01 20:34:48 +0100 |
| commit | fb4d55ef61ca3191ec946d4d41e0e715f4cc4197 (patch) | |
| tree | bb8483706c5a4ceb0663a4c79dc4e087c253dfd6 | |
| parent | 10b6d89baddd86139480ba902f491903fcb464a6 (diff) | |
| download | gcc-fb4d55ef61ca3191ec946d4d41e0e715f4cc4197.zip gcc-fb4d55ef61ca3191ec946d4d41e0e715f4cc4197.tar.gz gcc-fb4d55ef61ca3191ec946d4d41e0e715f4cc4197.tar.bz2 | |
libstdc++: Simplify __normal_iterator converting constructor
This uses C++11 features to simplify the definition of the
__normal_iterator constructor that allows converting from iterator to
const_iterator. The previous definition relied on _Container::pointer
which is present in std::vector and std::basic_string, but is not
actually part of the container requirements.
Removing the use of _Container::pointer and defining it in terms of
is_convertible allows __normal_iterator to be used with new container
types which do not define a pointer member. Specifically, this will
allow it to be used in std::basic_stacktrace.
In theory this will enable some conversions which were not previously
permitted, for example __normal_iterator<volatile T*, vector<T>> can
now be converted to __normal_iterator<const volatile T*, vector<T>>.
In practice this doesn't matter because the library never uses such
types. In any case, allowing those conversions is consistent with
the corresponding constructors of std::reverse_iterator and
std::move_iterator.
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
* include/bits/stl_iterator.h (__normal_iterator): Simplify
converting constructor and do not require _Container::pointer.
| -rw-r--r-- | libstdc++-v3/include/bits/stl_iterator.h | 20 |
1 files changed, 17 insertions, 3 deletions
diff --git a/libstdc++-v3/include/bits/stl_iterator.h b/libstdc++-v3/include/bits/stl_iterator.h index 8517652..df774ee 100644 --- a/libstdc++-v3/include/bits/stl_iterator.h +++ b/libstdc++-v3/include/bits/stl_iterator.h @@ -1022,6 +1022,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION typedef std::iterator_traits<_Iterator> __traits_type; +#if __cplusplus >= 201103L + template<typename _Iter> + using __convertible_from + = std::__enable_if_t<std::is_convertible<_Iter, _Iterator>::value>; +#endif + public: typedef _Iterator iterator_type; typedef typename __traits_type::iterator_category iterator_category; @@ -1042,12 +1048,20 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION : _M_current(__i) { } // Allow iterator to const_iterator conversion +#if __cplusplus >= 201103L + template<typename _Iter, typename = __convertible_from<_Iter>> + _GLIBCXX20_CONSTEXPR + __normal_iterator(const __normal_iterator<_Iter, _Container>& __i) + noexcept +#else + // N.B. _Container::pointer is not actually in container requirements, + // but is present in std::vector and std::basic_string. template<typename _Iter> - _GLIBCXX20_CONSTEXPR __normal_iterator(const __normal_iterator<_Iter, typename __enable_if< - (std::__are_same<_Iter, typename _Container::pointer>::__value), - _Container>::__type>& __i) _GLIBCXX_NOEXCEPT + (std::__are_same<_Iter, typename _Container::pointer>::__value), + _Container>::__type>& __i) +#endif : _M_current(__i.base()) { } // Forward iterator requirements |