[PATCH 0/4]: C++ P1423R3 char8_t remediation implementation
Jonathan Wakely
jwakely@redhat.com
Sat Nov 30 01:04:00 GMT 2019
On 29/11/19 21:45 +0000, Jonathan Wakely wrote:
>On 29/11/19 19:48 +0000, Jonathan Wakely wrote:
>>On 29/11/19 17:45 +0000, Jonathan Wakely wrote:
>>>On 15/09/19 15:39 -0400, Tom Honermann wrote:
>>>>This series of patches provides an implementation of the changes
>>>>for C++ proposal P1423R3 [1].
>>>>
>>>>These changes do not impact default libstdc++ behavior for C++17
>>>>and earlier; they are only active for C++2a or when the
>>>>-fchar8_t option is specified.
>>>>
>>>>Tested x86_64-linux.
>>>>
>>>>Patch 1: Decouple constraints for u8path from path constructors.
>>>>Patch 2: Update __cpp_lib_char8_t feature test macro value, add
>>>>deleted operators, update u8path.
>>>>Patch 3: Updates to existing tests.
>>>>Patch 4: New tests.
>>>>
>>>>Tom.
>>>>
>>>>[1]: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1423r3.html
>>>
>>>It took a while, but I've committed these four patches, with just some
>>>minor whitespace changes and changelog tweaks.
>>
>>Running the new tests revealed a latent bug on Windows, where
>>experimental::filesystem::u8path(const Source&) assumed the input
>>was an iterator over a NTCTS. That worked for a const char* but not a
>>std::string or experimental::string_view.
>>
>>The attached patch fixes that (and simplifies the #if and if-constexpr
>>conditions for Windows) but there's a remaining bug. Constructing a
>>experimental::filesystem::path from a char8_t string doesn't do the
>>right thing on Windows, so these cases fails:
>>
>>fs::path p(u8"\xf0\x9d\x84\x9e");
>>VERIFY( p.u8string() == u8"\U0001D11E" );
>>
>>p = fs::u8path(u8"\xf0\x9d\x84\x9e");
>>VERIFY( p.u8string() == u8"\U0001D11E" );
>>
>>It works correctly for std::filesystem::path, just not the TS version.
>
>I think this is the fix needed for the TS code:
>
>--- a/libstdc++-v3/include/experimental/bits/fs_path.h
>+++ b/libstdc++-v3/include/experimental/bits/fs_path.h
>@@ -765,7 +765,14 @@ namespace __detail
> {
>#ifdef _GLIBCXX_USE_CHAR8_T
> if constexpr (is_same<_CharT, char8_t>::value)
>- return _S_wconvert((const char*)__f, (const char*)__l, true_type());
>+ {
>+ const char* __f2 = (const char*)__f;
>+ const char* __l2 = (const char*)__l;
>+ std::wstring __wstr;
>+ std::codecvt_utf8_utf16<wchar_t> __wcvt;
>+ if (__str_codecvt_in_all(__f2, __l2, __wstr, __wcvt))
>+ return __wstr;
>+ }
> else
>#endif
> {
>
>The current code uses std::codecvt<wchar_t, char, mbstate_t> but when
>we know the input is UTF-8 encoded we should use codecvt_utf8_utf16
>(which is what the C++17 code already does for char8_t input).
>
>I'll add that the patch I'm testing.
Here's the final patch I'm committing. Tested powerpc64le-linux and
x86_64-w64-mingw, committed to trunk.
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