On 13/10/21 20:41 +0100, Jonathan Wakely wrote:
Adjust the __detail::__effective_range overloads so they always return a
string or string view using std::char_traits, because we don't care
about the traits of an incoming string.
Use std::contiguous_iterator in the __effective_range(const Source&)
overload, to allow returning a basic_string_view in more cases. For the
non-contiguous cases in both __effective_range and __string_from_range,
return a std::string instead of std::u8string when the value type of the
range is char8_t. These changes avoid unnecessary basic_string
temporaries.
Also simplify __string_from_range(Iter, Iter) to not need
std::__to_address for the contiguous case.
Combine the _S_convert(string_type) and _S_convert(const T&) overloads
into a single _S_convert(T) function which also avoids the dangling
view problem of PR 102592 (should that recur somehow).
libstdc++-v3/ChangeLog:
* include/bits/fs_path.h (__detail::__is_contiguous): New
variable template to identify contiguous iterators.
(__detail::__unified_char8_t): New alias template to decide when
to treat char8_t as char without encoding conversion.
(__detail::__effective_range(const basic_string<C,T>&)): Use
std::char_traits<C> for returned string view.
(__detail::__effective_range(const basic_string_view<C,T>&)):
Likewise.
(__detail::__effective_range(const Source&)): Use
__is_contiguous to detect mode cases of contiguous iterators.
Use __unified_char8_t to return a std::string instead of
std::u8string.
Tested powerpc64le-linux. Committed to trunk.
template<typename _Tp>
static auto
- _S_convert(const _Tp& __str)
+ _S_convert(_Tp __str)
{
- if constexpr (is_same_v<_Tp, string_type>)
- return __str;
- else if constexpr (is_same_v<_Tp, basic_string_view<value_type>>)
- return __str;
- else if constexpr (is_same_v<typename _Tp::value_type, value_type>)
- return basic_string_view<value_type>(__str.data(), __str.size());
+ if constexpr (is_same_v<_Tp, typename _Tp::value_type>)
+ return __str; // No conversion needed.
Yikes, this condition is wrong! Causing PR 102743 on Windows.
Fixed by the attached patch, tested x86_64-linux and x86_64-mingw32,
pushed to trunk.
commit 5e3f88838994b67580594c4679c839fff7cdeba0
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Thu Oct 14 13:20:57 2021
libstdc++: Fix brainwrong in path::_S_convert(T) [PR102743]
This function was supposed to check whether the parameter's value type
is the same as path::value_type, and therefore needs no conversion.
Instead it checks whether the parameter is the same as its own value
type, which is never true. This means we incorrectly return a string
view for the case where T is path::string_type, instead of just
returning the string itself. The only place that happens is
path::_S_convert_loc for Windows, where we call _S_convert with a
std::wstring rvalue.
This fixes the condition in _S_convert(T).
libstdc++-v3/ChangeLog:
PR libstdc++/102743
* include/bits/fs_path.h (path::_S_convert(T)): Fix condition
for returning the same string unchanged.
diff --git a/libstdc++-v3/include/bits/fs_path.h b/libstdc++-v3/include/bits/fs_path.h
index c51bfa3095a..a63e4b9ab07 100644
--- a/libstdc++-v3/include/bits/fs_path.h
+++ b/libstdc++-v3/include/bits/fs_path.h
@@ -625,7 +625,7 @@ namespace __detail
static auto
_S_convert(_Tp __str)
{
- if constexpr (is_same_v<_Tp, typename _Tp::value_type>)
+ if constexpr (is_same_v<typename _Tp::value_type, value_type>)
return __str; // No conversion needed.
#if !defined _GLIBCXX_FILESYSTEM_IS_WINDOWS && defined _GLIBCXX_USE_CHAR8_T
else if constexpr (is_same_v<_Tp, std::u8string>)
