[gcc(refs/users/guojiufu/heads/guojiufu-branch)] libstdc++: Simplify filesystem::path SFINAE constraints
Jiu Fu Guo
guojiufu@gcc.gnu.org
Wed Jun 10 03:04:54 GMT 2020
https://gcc.gnu.org/g:988b853f9c829742907ae22ac66de56facfc7bc5
commit 988b853f9c829742907ae22ac66de56facfc7bc5
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Sat May 23 07:28:40 2020 +0100
libstdc++: Simplify filesystem::path SFINAE constraints
This replaces the filesystem::__detail::_Path SFINAE helper with two
separate helpers, _Path and _Path2. This avoids having one helper which
tries to check two different sets of requirements.
The _Path helper now uses variable templates instead of a set of
overloaded functions to detect specializations of basic_string or
basic_string_view.
The __not_<is_void<remove_pointer_t<_Tp1>> check is not necessary in
C++20 because iterator_traits<void*> is now empty. For C++17 replace
that check with a __safe_iterator_traits helper with partial
specializations for void pointers.
Finally, the __is_encoded_char check no longer uses remove_const_t,
which means that iterators with a const value_type will no longer be
accepted as arguments for path creation. Such iterators resulted in
undefined behaviour anyway, so it's still conforming to reject them in
the constraint checks.
* include/bits/fs_path.h (filesystem::__detail::__is_encoded_char):
Replace alias template with variable template. Don't remove const.
(filesystem::__detail::__is_path_src): Replace overloaded function
template with variable template and specializations.
(filesystem::__detail::__is_path_iter_src): Replace alias template
with class template.
(filesystem::__detail::_Path): Use __is_path_src. Remove support for
iterator pairs.
(filesystem::__detail::_Path2): New alias template for checking
InputIterator requirements.
(filesystem::__detail::__constructible_from): Remove.
(filesystem::path): Replace _Path<Iter, Iter> with _Path2<Iter>.
* testsuite/27_io/filesystem/path/construct/80762.cc: Check with two
constructor arguments of void and void* types.
Diff:
---
libstdc++-v3/ChangeLog | 17 +++
libstdc++-v3/include/bits/fs_path.h | 125 +++++++++++++--------
.../27_io/filesystem/path/construct/80762.cc | 6 +
3 files changed, 100 insertions(+), 48 deletions(-)
diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index d19cd51db35..b82479f0ed6 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,20 @@
+2020-05-23 Jonathan Wakely <jwakely@redhat.com>
+
+ * include/bits/fs_path.h (filesystem::__detail::__is_encoded_char):
+ Replace alias template with variable template. Don't remove const.
+ (filesystem::__detail::__is_path_src): Replace overloaded function
+ template with variable template and specializations.
+ (filesystem::__detail::__is_path_iter_src): Replace alias template
+ with class template.
+ (filesystem::__detail::_Path): Use __is_path_src. Remove support for
+ iterator pairs.
+ (filesystem::__detail::_Path2): New alias template for checking
+ InputIterator requirements.
+ (filesystem::__detail::__constructible_from): Remove.
+ (filesystem::path): Replace _Path<Iter, Iter> with _Path2<Iter>.
+ * testsuite/27_io/filesystem/path/construct/80762.cc: Check with two
+ constructor arguments of void and void* types.
+
2020-05-21 Matthias Kretz <kretz@kde.org>
* testsuite/Makefile.am: Remove dup target_triplet and set tool,
diff --git a/libstdc++-v3/include/bits/fs_path.h b/libstdc++-v3/include/bits/fs_path.h
index ee6ab15cc4c..5a998284a99 100644
--- a/libstdc++-v3/include/bits/fs_path.h
+++ b/libstdc++-v3/include/bits/fs_path.h
@@ -73,58 +73,87 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
namespace __detail
{
template<typename _CharT>
- using __is_encoded_char = __is_one_of<remove_const_t<_CharT>,
- char,
+ inline constexpr bool __is_encoded_char = false;
+ template<>
+ inline constexpr bool __is_encoded_char<char> = true;
#ifdef _GLIBCXX_USE_CHAR8_T
- char8_t,
+ template<>
+ inline constexpr bool __is_encoded_char<char8_t> = true;
#endif
#if _GLIBCXX_USE_WCHAR_T
- wchar_t,
+ template<>
+ inline constexpr bool __is_encoded_char<wchar_t> = true;
#endif
- char16_t, char32_t>;
-
- template<typename _Iter,
- typename _Iter_traits = std::iterator_traits<_Iter>>
- using __is_path_iter_src
- = __and_<__is_encoded_char<typename _Iter_traits::value_type>,
- std::is_base_of<std::input_iterator_tag,
- typename _Iter_traits::iterator_category>>;
+ template<>
+ inline constexpr bool __is_encoded_char<char16_t> = true;
+ template<>
+ inline constexpr bool __is_encoded_char<char32_t> = true;
+#if __cpp_concepts >= 201907L
template<typename _Iter>
- static __is_path_iter_src<_Iter>
- __is_path_src(_Iter, int);
-
- template<typename _CharT, typename _Traits, typename _Alloc>
- static __is_encoded_char<_CharT>
- __is_path_src(const basic_string<_CharT, _Traits, _Alloc>&, int);
-
- template<typename _CharT, typename _Traits>
- static __is_encoded_char<_CharT>
- __is_path_src(const basic_string_view<_CharT, _Traits>&, int);
+ using __safe_iterator_traits = std::iterator_traits<_Iter>;
+#else
+ template<typename _Iter>
+ struct __safe_iterator_traits : std::iterator_traits<_Iter>
+ { };
- template<typename _Unknown>
- static std::false_type
- __is_path_src(const _Unknown&, ...);
+ // Protect against ill-formed iterator_traits specializations in C++17
+ template<> struct __safe_iterator_traits<void*> { };
+ template<> struct __safe_iterator_traits<const void*> { };
+ template<> struct __safe_iterator_traits<volatile void*> { };
+ template<> struct __safe_iterator_traits<const volatile void*> { };
+#endif
- template<typename _Tp1, typename _Tp2>
- struct __constructible_from;
+ template<typename _Iter_traits, typename = void>
+ struct __is_path_iter_src
+ : false_type
+ { };
- template<typename _Iter>
- struct __constructible_from<_Iter, _Iter>
- : __is_path_iter_src<_Iter>
+ template<typename _Iter_traits>
+ struct __is_path_iter_src<_Iter_traits,
+ void_t<typename _Iter_traits::value_type>>
+ : bool_constant<__is_encoded_char<typename _Iter_traits::value_type>>
{ };
template<typename _Source>
- struct __constructible_from<_Source, void>
- : decltype(__is_path_src(std::declval<_Source>(), 0))
- { };
+ inline constexpr bool __is_path_src
+ = __is_path_iter_src<iterator_traits<decay_t<_Source>>>::value;
+
+ template<>
+ inline constexpr bool __is_path_src<path> = false;
+
+ template<>
+ inline constexpr bool __is_path_src<volatile path> = false;
+
+ template<>
+ inline constexpr bool __is_path_src<void*> = false;
+
+ template<>
+ inline constexpr bool __is_path_src<const void*> = false;
+
+ template<>
+ inline constexpr bool __is_path_src<volatile void*> = false;
+
+ template<>
+ inline constexpr bool __is_path_src<const volatile void*> = false;
+
+ template<typename _CharT, typename _Traits, typename _Alloc>
+ inline constexpr bool
+ __is_path_src<basic_string<_CharT, _Traits, _Alloc>>
+ = __is_encoded_char<_CharT>;
+
+ template<typename _CharT, typename _Traits>
+ inline constexpr bool
+ __is_path_src<basic_string_view<_CharT, _Traits>>
+ = __is_encoded_char<_CharT>;
+
+ // SFINAE constraint for Source parameters as required by [fs.path.req].
+ template<typename _Tp>
+ using _Path = enable_if_t<__is_path_src<_Tp>, path>;
- template<typename _Tp1, typename _Tp2 = void>
- using _Path = typename
- std::enable_if<__and_<__not_<is_same<remove_cv_t<_Tp1>, path>>,
- __not_<is_void<remove_pointer_t<_Tp1>>>,
- __constructible_from<_Tp1, _Tp2>>::value,
- path>::type;
+ // SFINAE constraint for InputIterator parameters as required by [fs.req].
+ template<typename _Iter, typename _Tr = __safe_iterator_traits<_Iter>>
+ using _Path2 = enable_if_t<__is_path_iter_src<_Tr>::value, path>;
template<typename _Source>
static _Source
@@ -227,7 +256,7 @@ namespace __detail
{ _M_split_cmpts(); }
template<typename _InputIterator,
- typename _Require = __detail::_Path<_InputIterator, _InputIterator>>
+ typename _Require = __detail::_Path2<_InputIterator>>
path(_InputIterator __first, _InputIterator __last, format = auto_format)
: _M_pathname(_S_convert(__first, __last))
{ _M_split_cmpts(); }
@@ -241,8 +270,8 @@ namespace __detail
{ _M_split_cmpts(); }
template<typename _InputIterator,
- typename _Require = __detail::_Path<_InputIterator, _InputIterator>,
- typename _Require2 = __detail::__value_type_is_char<_InputIterator>>
+ typename _Require = __detail::_Path2<_InputIterator>,
+ typename _Req2 = __detail::__value_type_is_char<_InputIterator>>
path(_InputIterator __first, _InputIterator __last, const locale& __loc,
format = auto_format)
: _M_pathname(_S_convert_loc(__first, __last, __loc))
@@ -268,7 +297,7 @@ namespace __detail
{ return *this = path(__source); }
template<typename _InputIterator>
- __detail::_Path<_InputIterator, _InputIterator>&
+ __detail::_Path2<_InputIterator>&
assign(_InputIterator __first, _InputIterator __last)
{ return *this = path(__first, __last); }
@@ -295,7 +324,7 @@ namespace __detail
}
template<typename _InputIterator>
- __detail::_Path<_InputIterator, _InputIterator>&
+ __detail::_Path2<_InputIterator>&
append(_InputIterator __first, _InputIterator __last)
{
_M_append(_S_convert(__first, __last));
@@ -315,7 +344,7 @@ namespace __detail
operator+=(_Source const& __x) { return concat(__x); }
template<typename _CharT>
- __detail::_Path<_CharT*, _CharT*>&
+ __detail::_Path2<_CharT*>&
operator+=(_CharT __x);
template<typename _Source>
@@ -328,7 +357,7 @@ namespace __detail
}
template<typename _InputIterator>
- __detail::_Path<_InputIterator, _InputIterator>&
+ __detail::_Path2<_InputIterator>&
concat(_InputIterator __first, _InputIterator __last)
{
_M_concat(_S_convert(__first, __last));
@@ -695,7 +724,7 @@ namespace __detail
* @relates std::filesystem::path
*/
template<typename _InputIterator,
- typename _Require = __detail::_Path<_InputIterator, _InputIterator>,
+ typename _Require = __detail::_Path2<_InputIterator>,
typename _CharT
= __detail::__value_type_is_char_or_char8_t<_InputIterator>>
inline path
@@ -1000,7 +1029,7 @@ namespace __detail
}
template<typename _CharT>
- inline __detail::_Path<_CharT*, _CharT*>&
+ inline __detail::_Path2<_CharT*>&
path::operator+=(_CharT __x)
{
auto* __addr = std::__addressof(__x);
diff --git a/libstdc++-v3/testsuite/27_io/filesystem/path/construct/80762.cc b/libstdc++-v3/testsuite/27_io/filesystem/path/construct/80762.cc
index bfc1e125e0c..2f37b663f26 100644
--- a/libstdc++-v3/testsuite/27_io/filesystem/path/construct/80762.cc
+++ b/libstdc++-v3/testsuite/27_io/filesystem/path/construct/80762.cc
@@ -37,3 +37,9 @@ static_assert( !std::is_constructible_v<path, const volatile void*> );
static_assert( !std::is_constructible_v<path, void*&> );
static_assert( !std::is_constructible_v<path, void* const&> );
static_assert( !std::is_constructible_v<path, const void* const&> );
+
+static_assert( !std::is_constructible_v<path, void, void> );
+static_assert( !std::is_constructible_v<path, void*, void*> );
+static_assert( !std::is_constructible_v<path, const void*, void*> );
+static_assert( !std::is_constructible_v<path, volatile void*, void*> );
+static_assert( !std::is_constructible_v<path, const volatile void*, void*> );
More information about the Libstdc++-cvs
mailing list