https://gcc.gnu.org/g:74605294950e4a49627fb71fdedefea176f5ecf7
commit r16-137-g74605294950e4a49627fb71fdedefea176f5ecf7
Author: Tomasz Kamiński <tkami...@redhat.com>
Date: Thu Apr 24 09:32:24 2025 +0200
libstdc++: Constrain formatter for thread::id [PR119918]
This patch add constraint __formatter::__char to _CharT type parameter
of formatter<thread::id, _CharT> specialization, matching the constraint
of formatting of integer/pointers that are used as native handles.
The dependency on <format> header, is changed to <bits/formatfwd.h>.
To achieve that, formatting of pointers is extracted from void const*
specialization to internal __formatter_ptr<_CharT>, that can be forward
declared.
Finally, the handle representation is now printed directly to __fc.out(),
by the formatter for handle type. To support this, internal formatters
can now be constructed from _Spec object as alternative to invoking parse
method.
PR libstdc++/119918
libstdc++-v3/ChangeLog:
* include/bits/formatfwd.h (__format::_Align): Moved from
std/format.
(std::__throw_format_error, __format::__formatter_str)
(__format::__formatter_ptr): Declare.
* include/std/format (__format::_Align): Moved to bits/formatfwd.h.
(__formatter_int::__formatter_int): Define.
(__format::__formatter_ptr): Extracted from formatter for const
void*.
(std::formatter<const void*, _CharT>, formatter<void*, _CharT>)
(std::formatter<nullptr_t, _CharT>): Delegate to
__formatter_ptr<_CharT>.
* include/std/thread (std::formatter<thread::id, _CharT>): Constrain
_CharT template parameter.
(formatter<thread::id, _CharT>::parse): Specify default aligment,
and
qualify __throw_format_error to disable ADL.
(formatter<thread::id, _CharT>::format): Use formatters to write
directly
to output.
* testsuite/30_threads/thread/id/output.cc: Tests for formatting
thread::id
representing not-a-thread with padding and formattable concept.
Reviewed-by: Jonathan Wakely <jwak...@redhat.com>
Signed-off-by: Tomasz Kamiński <tkami...@redhat.com>
Diff:
---
libstdc++-v3/include/bits/formatfwd.h | 21 +-
libstdc++-v3/include/std/format | 257 +++++++++++----------
libstdc++-v3/include/std/thread | 45 ++--
.../testsuite/30_threads/thread/id/output.cc | 30 +++
4 files changed, 210 insertions(+), 143 deletions(-)
diff --git a/libstdc++-v3/include/bits/formatfwd.h
b/libstdc++-v3/include/bits/formatfwd.h
index 9ba658b078a5..12ae2ad2ac08 100644
--- a/libstdc++-v3/include/bits/formatfwd.h
+++ b/libstdc++-v3/include/bits/formatfwd.h
@@ -57,6 +57,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Tp, typename _CharT = char> struct formatter;
/// @cond undocumented
+ [[noreturn]]
+ inline void
+ __throw_format_error(const char* __what);
+
namespace __format
{
#ifdef _GLIBCXX_USE_WCHAR_T
@@ -67,6 +71,19 @@ namespace __format
concept __char = same_as<_CharT, char>;
#endif
+ enum _Align {
+ _Align_default,
+ _Align_left,
+ _Align_right,
+ _Align_centre,
+ };
+
+ template<typename _CharT> struct _Spec;
+
+ template<__char _CharT> struct __formatter_str;
+ template<__char _CharT> struct __formatter_int;
+ template<__char _CharT> struct __formatter_ptr;
+
template<typename _Tp, typename _Context,
typename _Formatter
= typename _Context::template formatter_type<remove_const_t<_Tp>>,
@@ -107,9 +124,6 @@ namespace __format
{
__f.set_debug_format();
};
-
- template<__char _CharT>
- struct __formatter_int;
} // namespace __format
/// @endcond
@@ -141,7 +155,6 @@ namespace __format
}
#endif // format_ranges
-
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif // __glibcxx_format
diff --git a/libstdc++-v3/include/std/format b/libstdc++-v3/include/std/format
index 7d3067098bef..86c93f0e6ebd 100644
--- a/libstdc++-v3/include/std/format
+++ b/libstdc++-v3/include/std/format
@@ -491,13 +491,6 @@ namespace __format
_Pres_esc = 0xf, // For strings, charT and ranges
};
- enum _Align {
- _Align_default,
- _Align_left,
- _Align_right,
- _Align_centre,
- };
-
enum _Sign {
_Sign_default,
_Sign_plus,
@@ -1440,6 +1433,13 @@ namespace __format
static constexpr _Pres_type _AsBool = _Pres_s;
static constexpr _Pres_type _AsChar = _Pres_c;
+ __formatter_int() = default;
+
+ constexpr
+ __formatter_int(_Spec<_CharT> __spec) noexcept
+ : _M_spec(__spec)
+ { }
+
constexpr typename basic_format_parse_context<_CharT>::iterator
_M_do_parse(basic_format_parse_context<_CharT>& __pc, _Pres_type __type)
{
@@ -2387,6 +2387,134 @@ namespace __format
_Spec<_CharT> _M_spec{};
};
+ template<__format::__char _CharT>
+ struct __formatter_ptr
+ {
+ __formatter_ptr() = default;
+
+ constexpr
+ __formatter_ptr(_Spec<_CharT> __spec) noexcept
+ : _M_spec(__spec)
+ { }
+
+ constexpr typename basic_format_parse_context<_CharT>::iterator
+ parse(basic_format_parse_context<_CharT>& __pc)
+ {
+ __format::_Spec<_CharT> __spec{};
+ const auto __last = __pc.end();
+ auto __first = __pc.begin();
+
+ auto __finalize = [this, &__spec] {
+ _M_spec = __spec;
+ };
+
+ auto __finished = [&] {
+ if (__first == __last || *__first == '}')
+ {
+ __finalize();
+ return true;
+ }
+ return false;
+ };
+
+ if (__finished())
+ return __first;
+
+ __first = __spec._M_parse_fill_and_align(__first, __last);
+ if (__finished())
+ return __first;
+
+// _GLIBCXX_RESOLVE_LIB_DEFECTS
+// P2510R3 Formatting pointers
+#if __glibcxx_format >= 202304L
+ __first = __spec._M_parse_zero_fill(__first, __last);
+ if (__finished())
+ return __first;
+#endif
+
+ __first = __spec._M_parse_width(__first, __last, __pc);
+
+ if (__first != __last)
+ {
+ if (*__first == 'p')
+ ++__first;
+#if __glibcxx_format >= 202304L
+ else if (*__first == 'P')
+ {
+ __spec._M_type = __format::_Pres_P;
+ ++__first;
+ }
+#endif
+ }
+
+ if (__finished())
+ return __first;
+
+ __format::__failed_to_parse_format_spec();
+ }
+
+ template<typename _Out>
+ typename basic_format_context<_Out, _CharT>::iterator
+ format(const void* __v, basic_format_context<_Out, _CharT>& __fc) const
+ {
+ auto __u = reinterpret_cast<__UINTPTR_TYPE__>(__v);
+ char __buf[2 + sizeof(__v) * 2];
+ auto [__ptr, __ec] = std::to_chars(__buf + 2, std::end(__buf),
+ __u, 16);
+ int __n = __ptr - __buf;
+ __buf[0] = '0';
+ __buf[1] = 'x';
+#if __glibcxx_format >= 202304L
+ if (_M_spec._M_type == __format::_Pres_P)
+ {
+ __buf[1] = 'X';
+ for (auto __p = __buf + 2; __p != __ptr; ++__p)
+#if __has_builtin(__builtin_toupper)
+ *__p = __builtin_toupper(*__p);
+#else
+ *__p = std::toupper(*__p);
+#endif
+ }
+#endif
+
+ basic_string_view<_CharT> __str;
+ if constexpr (is_same_v<_CharT, char>)
+ __str = string_view(__buf, __n);
+#ifdef _GLIBCXX_USE_WCHAR_T
+ else
+ {
+ auto __p = (_CharT*)__builtin_alloca(__n * sizeof(_CharT));
+ std::__to_wstring_numeric(__buf, __n, __p);
+ __str = wstring_view(__p, __n);
+ }
+#endif
+
+#if __glibcxx_format >= 202304L
+ if (_M_spec._M_zero_fill)
+ {
+ size_t __width = _M_spec._M_get_width(__fc);
+ if (__width <= __str.size())
+ return __format::__write(__fc.out(), __str);
+
+ auto __out = __fc.out();
+ // Write "0x" or "0X" prefix before zero-filling.
+ __out = __format::__write(std::move(__out), __str.substr(0, 2));
+ __str.remove_prefix(2);
+ size_t __nfill = __width - __n;
+ return __format::__write_padded(std::move(__out), __str,
+ __format::_Align_right,
+ __nfill, _CharT('0'));
+ }
+#endif
+
+ return __format::__write_padded_as_spec(__str, __n, __fc, _M_spec,
+ __format::_Align_right);
+ }
+
+ private:
+ __format::_Spec<_CharT> _M_spec{};
+ };
+
} // namespace __format
/// @endcond
@@ -2851,120 +2979,15 @@ namespace __format
constexpr typename basic_format_parse_context<_CharT>::iterator
parse(basic_format_parse_context<_CharT>& __pc)
- {
- __format::_Spec<_CharT> __spec{};
- const auto __last = __pc.end();
- auto __first = __pc.begin();
-
- auto __finalize = [this, &__spec] {
- _M_spec = __spec;
- };
-
- auto __finished = [&] {
- if (__first == __last || *__first == '}')
- {
- __finalize();
- return true;
- }
- return false;
- };
-
- if (__finished())
- return __first;
-
- __first = __spec._M_parse_fill_and_align(__first, __last);
- if (__finished())
- return __first;
-
-// _GLIBCXX_RESOLVE_LIB_DEFECTS
-// P2510R3 Formatting pointers
-#if __glibcxx_format >= 202304L
- __first = __spec._M_parse_zero_fill(__first, __last);
- if (__finished())
- return __first;
-#endif
-
- __first = __spec._M_parse_width(__first, __last, __pc);
-
- if (__first != __last)
- {
- if (*__first == 'p')
- ++__first;
-#if __glibcxx_format >= 202304L
- else if (*__first == 'P')
- {
- __spec._M_type = __format::_Pres_P;
- ++__first;
- }
-#endif
- }
-
- if (__finished())
- return __first;
-
- __format::__failed_to_parse_format_spec();
- }
+ { return _M_f.parse(__pc); }
template<typename _Out>
typename basic_format_context<_Out, _CharT>::iterator
format(const void* __v, basic_format_context<_Out, _CharT>& __fc) const
- {
- auto __u = reinterpret_cast<__UINTPTR_TYPE__>(__v);
- char __buf[2 + sizeof(__v) * 2];
- auto [__ptr, __ec] = std::to_chars(__buf + 2, std::end(__buf),
- __u, 16);
- int __n = __ptr - __buf;
- __buf[0] = '0';
- __buf[1] = 'x';
-#if __glibcxx_format >= 202304L
- if (_M_spec._M_type == __format::_Pres_P)
- {
- __buf[1] = 'X';
- for (auto __p = __buf + 2; __p != __ptr; ++__p)
-#if __has_builtin(__builtin_toupper)
- *__p = __builtin_toupper(*__p);
-#else
- *__p = std::toupper(*__p);
-#endif
- }
-#endif
-
- basic_string_view<_CharT> __str;
- if constexpr (is_same_v<_CharT, char>)
- __str = string_view(__buf, __n);
-#ifdef _GLIBCXX_USE_WCHAR_T
- else
- {
- auto __p = (_CharT*)__builtin_alloca(__n * sizeof(_CharT));
- std::__to_wstring_numeric(__buf, __n, __p);
- __str = wstring_view(__p, __n);
- }
-#endif
-
-#if __glibcxx_format >= 202304L
- if (_M_spec._M_zero_fill)
- {
- size_t __width = _M_spec._M_get_width(__fc);
- if (__width <= __str.size())
- return __format::__write(__fc.out(), __str);
-
- auto __out = __fc.out();
- // Write "0x" or "0X" prefix before zero-filling.
- __out = __format::__write(std::move(__out), __str.substr(0, 2));
- __str.remove_prefix(2);
- size_t __nfill = __width - __n;
- return __format::__write_padded(std::move(__out), __str,
- __format::_Align_right,
- __nfill, _CharT('0'));
- }
-#endif
-
- return __format::__write_padded_as_spec(__str, __n, __fc, _M_spec,
- __format::_Align_right);
- }
+ { return _M_f.format(__v, __fc); }
private:
- __format::_Spec<_CharT> _M_spec{};
+ __format::__formatter_ptr<_CharT> _M_f;
};
template<__format::__char _CharT>
@@ -2983,7 +3006,7 @@ namespace __format
{ return _M_f.format(__v, __fc); }
private:
- formatter<const void*, _CharT> _M_f;
+ __format::__formatter_ptr<_CharT> _M_f;
};
template<__format::__char _CharT>
@@ -3002,7 +3025,7 @@ namespace __format
{ return _M_f.format(nullptr, __fc); }
private:
- formatter<const void*, _CharT> _M_f;
+ __format::__formatter_ptr<_CharT> _M_f;
};
/// @}
diff --git a/libstdc++-v3/include/std/thread b/libstdc++-v3/include/std/thread
index d2f91ad89953..0de08c0bd3e3 100644
--- a/libstdc++-v3/include/std/thread
+++ b/libstdc++-v3/include/std/thread
@@ -297,7 +297,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
#endif // __cpp_lib_jthread
#ifdef __cpp_lib_formatters // C++ >= 23
- template<typename _CharT>
+ // We deviate from the standard, that does not put requirements
+ // on _CharT here.
+ template<__format::__char _CharT>
requires is_pointer_v<thread::native_handle_type>
|| is_integral_v<thread::native_handle_type>
class formatter<thread::id, _CharT>
@@ -307,6 +309,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
parse(basic_format_parse_context<_CharT>& __pc)
{
__format::_Spec<_CharT> __spec{};
+ __spec._M_align = __format::_Align_right;
const auto __last = __pc.end();
auto __first = __pc.begin();
@@ -334,36 +337,34 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
if (__finished())
return __first;
- __throw_format_error("format error: invalid format-spec for "
- "std::thread::id");
+ std::__throw_format_error("format error: invalid format-spec for "
+ "std::thread::id");
}
template<typename _Out>
typename basic_format_context<_Out, _CharT>::iterator
format(thread::id __id, basic_format_context<_Out, _CharT>& __fc) const
{
- basic_string_view<_CharT> __sv;
- if constexpr (is_same_v<_CharT, char>)
- __sv = "{}thread::id of a non-executing thread";
- else
- __sv = L"{}thread::id of a non-executing thread";
- basic_string<_CharT> __str;
+
if (__id == thread::id())
- __sv.remove_prefix(2);
- else
{
- using _FmtStr = __format::_Runtime_format_string<_CharT>;
- // Convert non-void pointers to const void* for formatted output.
- using __output_type
- = __conditional_t<is_pointer_v<thread::native_handle_type>,
- const void*,
- thread::native_handle_type>;
- auto __o = static_cast<__output_type>(__id._M_thread);
- __sv = __str = std::format(_FmtStr(__sv.substr(0, 2)), __o);
+ const _CharT* __msg;
+ if constexpr (is_same_v<_CharT, char>)
+ __msg = "thread::id of a non-executing thread";
+ else
+ __msg = L"thread::id of a non-executing thread";
+
+ __format::__formatter_str<_CharT> __formatter(_M_spec);
+ return __formatter.format(__msg, __fc);
}
- return __format::__write_padded_as_spec(__sv, __sv.size(),
- __fc, _M_spec,
- __format::_Align_right);
+
+ using _HandleFormatter
+ = __conditional_t<is_pointer_v<thread::native_handle_type>,
+ __format::__formatter_ptr<_CharT>,
+ __format::__formatter_int<_CharT>>;
+
+ _HandleFormatter __formatter(_M_spec);
+ return __formatter.format(__id._M_thread, __fc);
}
private:
diff --git a/libstdc++-v3/testsuite/30_threads/thread/id/output.cc
b/libstdc++-v3/testsuite/30_threads/thread/id/output.cc
index 94a6ff0e2a1d..3d1dd38d998f 100644
--- a/libstdc++-v3/testsuite/30_threads/thread/id/output.cc
+++ b/libstdc++-v3/testsuite/30_threads/thread/id/output.cc
@@ -118,8 +118,38 @@ test02()
VERIFY( ws1.length() == len );
#endif
+ out.str("");
+ out << i;
+ s1 = out.str();
+ len = s1.size();
+ out.str("");
+
+ // with width
+ s2 = std::format("{0:{1}}", i, len + 2);
+ VERIFY( s2 == (" " + s1) );
+ // with align + width
+ s2 = std::format("{0:>{1}}", i, len + 2);
+ VERIFY( s2 == (" " + s1) );
+ s2 = std::format("{0:<{1}}", i, len + 2);
+ VERIFY( s2 == (s1 + " ") );
+ // with fill-and-align + width
+ s2 = std::format("{0:x^{1}}", i, len + 5);
+ VERIFY( s2 == ("xx" + s1 + "xxx") );
+
+#ifdef _GLIBCXX_USE_WCHAR_T
+ static_assert(
std::is_default_constructible_v<std::formatter<std::thread::id, wchar_t>> );
+ ws1 = std::format(L"{}", i);
+ VERIFY( ws1.length() == len );
+#endif
+
t1.join();
t2.join();
+
+ static_assert( std::formattable<std::thread::id, char> );
+ static_assert( std::formattable<std::thread::id, wchar_t> );
+ static_assert( !std::formattable<std::thread::id, char16_t> );
+ static_assert( !std::formattable<std::thread::id, int> );
+
#elif __cplusplus >= 202302L
# error "Feature-test macro for formatters has wrong value in <thread>"
#endif
