[libc++] Complete <charconv> for 64-bit long double platforms
#117125
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@llvm/pr-subscribers-libcxx Author: A. Jiang (frederick-vs-ja) ChangesTowards #99940 and #99952. Implementation of P0067R5 + P0682R1 becomes complete for these platforms. Full diff: https://github.com/llvm/llvm-project/pull/117125.diff 11 Files Affected:
diff --git a/libcxx/docs/FeatureTestMacroTable.rst b/libcxx/docs/FeatureTestMacroTable.rst
index 3c4a13332661ee..597d0ddf3ff299 100644
--- a/libcxx/docs/FeatureTestMacroTable.rst
+++ b/libcxx/docs/FeatureTestMacroTable.rst
@@ -152,7 +152,7 @@ Status
---------------------------------------------------------- -----------------
``__cpp_lib_string_view`` ``201606L``
---------------------------------------------------------- -----------------
- ``__cpp_lib_to_chars`` *unimplemented*
+ ``__cpp_lib_to_chars`` ``201611L``
---------------------------------------------------------- -----------------
``__cpp_lib_transparent_operators`` ``201510L``
---------------------------------------------------------- -----------------
@@ -490,7 +490,7 @@ Status
---------------------------------------------------------- -----------------
``__cpp_lib_text_encoding`` *unimplemented*
---------------------------------------------------------- -----------------
- ``__cpp_lib_to_chars`` *unimplemented*
+ ``__cpp_lib_to_chars`` ``202306L``
---------------------------------------------------------- -----------------
``__cpp_lib_to_string`` *unimplemented*
---------------------------------------------------------- -----------------
diff --git a/libcxx/docs/ReleaseNotes/20.rst b/libcxx/docs/ReleaseNotes/20.rst
index 9039c6f046445b..89c803d3b836bf 100644
--- a/libcxx/docs/ReleaseNotes/20.rst
+++ b/libcxx/docs/ReleaseNotes/20.rst
@@ -38,7 +38,11 @@ What's New in Libc++ 20.0.0?
Implemented Papers
------------------
+- P0067R5: Elementary string conversions is implemented for platforms
+ where ``long double`` has the same format as ``double`` (`Github <https://github.com/llvm/llvm-project/issues/99940>`__)
- P0619R4: Reviewing Deprecated Facilities of C++17 for C++20 (`Github <https://github.com/llvm/llvm-project/issues/99985>`__)
+- P0682R1: Repairing elementary string conversions is implemented for platforms
+ where ``long double`` has the same format as ``double`` (`Github <https://github.com/llvm/llvm-project/issues/99952>`__)
- P2747R2: ``constexpr`` placement new (`Github <https://github.com/llvm/llvm-project/issues/105427>`__)
- P2609R3: Relaxing Ranges Just A Smidge (`Github <https://github.com/llvm/llvm-project/issues/105253>`__)
- P2985R0: A type trait for detecting virtual base classes (`Github <https://github.com/llvm/llvm-project/issues/105432>`__)
diff --git a/libcxx/docs/Status/Cxx17Papers.csv b/libcxx/docs/Status/Cxx17Papers.csv
index a589207085d36f..69f6ccc1db9844 100644
--- a/libcxx/docs/Status/Cxx17Papers.csv
+++ b/libcxx/docs/Status/Cxx17Papers.csv
@@ -71,7 +71,7 @@
"`P0394R4 <https://wg21.link/P0394R4>`__","Hotel Parallelifornia: terminate() for Parallel Algorithms Exception Handling","2016-06 (Oulu)","|Complete|","17",""
"","","","","",""
"`P0003R5 <https://wg21.link/P0003R5>`__","Removing Deprecated Exception Specifications from C++17","2016-11 (Issaquah)","|Complete|","5",""
-"`P0067R5 <https://wg21.link/P0067R5>`__","Elementary string conversions, revision 5","2016-11 (Issaquah)","|Partial|","","For integer types, ``std::(to|from)_chars`` has been available since v7; for ``float`` and ``double``, ``std::to_chars`` since v14 and ``std::from_chars`` since v20. Support is complete except for ``long double``."
+"`P0067R5 <https://wg21.link/P0067R5>`__","Elementary string conversions, revision 5","2016-11 (Issaquah)","|Partial|","","For integer types, ``std::(to|from)_chars`` has been available since v7; for ``float`` and ``double``, ``std::to_chars`` since v14 and ``std::from_chars`` since v20. Support is complete except for ``long double`` on platforms where its format is different ``double``."
"`P0403R1 <https://wg21.link/P0403R1>`__","Literal suffixes for ``basic_string_view``\ ","2016-11 (Issaquah)","|Complete|","4",""
"`P0414R2 <https://wg21.link/P0414R2>`__","Merging shared_ptr changes from Library Fundamentals to C++17","2016-11 (Issaquah)","|Complete|","11",""
"`P0418R2 <https://wg21.link/P0418R2>`__","Fail or succeed: there is no atomic lattice","2016-11 (Issaquah)","","",""
@@ -109,5 +109,5 @@
"`P0618R0 <https://wg21.link/P0618R0>`__","Deprecating <codecvt>","2017-02 (Kona)","|Complete|","15",""
"`P0623R0 <https://wg21.link/P0623R0>`__","Final C++17 Parallel Algorithms Fixes","2017-02 (Kona)","|Nothing To Do|","",""
"","","","","",""
-"`P0682R1 <https://wg21.link/P0682R1>`__","Repairing elementary string conversions","2017-07 (Toronto)","","",""
+"`P0682R1 <https://wg21.link/P0682R1>`__","Repairing elementary string conversions","2017-07 (Toronto)","|Partial|","","Support is complete in v20 on platforms where ``long double`` has the same format as ``double``."
"`P0739R0 <https://wg21.link/P0739R0>`__","Some improvements to class template argument deduction integration into the standard library","2017-07 (Toronto)","|Complete|","5",""
diff --git a/libcxx/include/__charconv/from_chars_floating_point.h b/libcxx/include/__charconv/from_chars_floating_point.h
index 811e518a81db70..62152a392f51b5 100644
--- a/libcxx/include/__charconv/from_chars_floating_point.h
+++ b/libcxx/include/__charconv/from_chars_floating_point.h
@@ -64,6 +64,18 @@ from_chars(const char* __first, const char* __last, double& __value, chars_forma
return std::__from_chars<double>(__first, __last, __value, __fmt);
}
+# if _LIBCPP_LONG_DOUBLE_IS_DOUBLE
+_LIBCPP_AVAILABILITY_FROM_CHARS_FLOATING_POINT _LIBCPP_HIDE_FROM_ABI inline from_chars_result
+from_chars(const char* __first, const char* __last, long double& __value, chars_format __fmt = chars_format::general) {
+ double __dval;
+ const auto __result = std::__from_chars<double>(__first, __last, __dval, __fmt);
+ if (__result.ec == errc{})
+ __value = __dval;
+ return __result;
+}
+// TODO: Complete the implementation for platforms where long double has a different format from double.
+# endif
+
#endif // _LIBCPP_STD_VER >= 17
_LIBCPP_END_NAMESPACE_STD
diff --git a/libcxx/include/__config b/libcxx/include/__config
index 9db00cd0c9fb93..8e8759a073e741 100644
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -1231,6 +1231,12 @@ typedef __char32_t char32_t;
# define _LIBCPP_HAS_EXPLICIT_THIS_PARAMETER 0
# endif
+# if defined(_MSC_VER) || __SIZEOF_LONG_DOUBLE__ == __SIZEOF_DOUBLE__
+# define _LIBCPP_LONG_DOUBLE_IS_DOUBLE 1
+# else
+# define _LIBCPP_LONG_DOUBLE_IS_DOUBLE 0
+# endif
+
#endif // __cplusplus
#endif // _LIBCPP___CONFIG
diff --git a/libcxx/include/version b/libcxx/include/version
index fc57aeade9daf2..c57f391e3f5dc7 100644
--- a/libcxx/include/version
+++ b/libcxx/include/version
@@ -357,7 +357,9 @@ __cpp_lib_void_t 201411L <type_traits>
# define __cpp_lib_shared_ptr_arrays 201611L
# define __cpp_lib_shared_ptr_weak_type 201606L
# define __cpp_lib_string_view 201606L
-// # define __cpp_lib_to_chars 201611L
+# if _LIBCPP_LONG_DOUBLE_IS_DOUBLE
+# define __cpp_lib_to_chars 201611L
+# endif
# undef __cpp_lib_transparent_operators
# define __cpp_lib_transparent_operators 201510L
# define __cpp_lib_type_trait_variable_templates 201510L
@@ -572,8 +574,10 @@ __cpp_lib_void_t 201411L <type_traits>
# define __cpp_lib_string_view 202403L
// # define __cpp_lib_submdspan 202306L
// # define __cpp_lib_text_encoding 202306L
+# if _LIBCPP_LONG_DOUBLE_IS_DOUBLE
# undef __cpp_lib_to_chars
-// # define __cpp_lib_to_chars 202306L
+# define __cpp_lib_to_chars 202306L
+# endif
// # define __cpp_lib_to_string 202306L
# undef __cpp_lib_tuple_like
// # define __cpp_lib_tuple_like 202311L
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/charconv.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/charconv.version.compile.pass.cpp
index cc38cbacd51b73..cd83a5740c5fb5 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/charconv.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/charconv.version.compile.pass.cpp
@@ -50,16 +50,16 @@
# error "__cpp_lib_constexpr_charconv should not be defined before c++23"
# endif
-# if !defined(_LIBCPP_VERSION)
+# if defined(TEST_LONG_DOUBLE_IS_DOUBLE)
# ifndef __cpp_lib_to_chars
# error "__cpp_lib_to_chars should be defined in c++17"
# endif
# if __cpp_lib_to_chars != 201611L
# error "__cpp_lib_to_chars should have the value 201611L in c++17"
# endif
-# else // _LIBCPP_VERSION
+# else
# ifdef __cpp_lib_to_chars
-# error "__cpp_lib_to_chars should not be defined because it is unimplemented in libc++!"
+# error "__cpp_lib_to_chars should not be defined when the requirement 'defined(TEST_LONG_DOUBLE_IS_DOUBLE)' is not met!"
# endif
# endif
@@ -69,16 +69,16 @@
# error "__cpp_lib_constexpr_charconv should not be defined before c++23"
# endif
-# if !defined(_LIBCPP_VERSION)
+# if defined(TEST_LONG_DOUBLE_IS_DOUBLE)
# ifndef __cpp_lib_to_chars
# error "__cpp_lib_to_chars should be defined in c++20"
# endif
# if __cpp_lib_to_chars != 201611L
# error "__cpp_lib_to_chars should have the value 201611L in c++20"
# endif
-# else // _LIBCPP_VERSION
+# else
# ifdef __cpp_lib_to_chars
-# error "__cpp_lib_to_chars should not be defined because it is unimplemented in libc++!"
+# error "__cpp_lib_to_chars should not be defined when the requirement 'defined(TEST_LONG_DOUBLE_IS_DOUBLE)' is not met!"
# endif
# endif
@@ -91,16 +91,16 @@
# error "__cpp_lib_constexpr_charconv should have the value 202207L in c++23"
# endif
-# if !defined(_LIBCPP_VERSION)
+# if defined(TEST_LONG_DOUBLE_IS_DOUBLE)
# ifndef __cpp_lib_to_chars
# error "__cpp_lib_to_chars should be defined in c++23"
# endif
# if __cpp_lib_to_chars != 201611L
# error "__cpp_lib_to_chars should have the value 201611L in c++23"
# endif
-# else // _LIBCPP_VERSION
+# else
# ifdef __cpp_lib_to_chars
-# error "__cpp_lib_to_chars should not be defined because it is unimplemented in libc++!"
+# error "__cpp_lib_to_chars should not be defined when the requirement 'defined(TEST_LONG_DOUBLE_IS_DOUBLE)' is not met!"
# endif
# endif
@@ -113,16 +113,16 @@
# error "__cpp_lib_constexpr_charconv should have the value 202207L in c++26"
# endif
-# if !defined(_LIBCPP_VERSION)
+# if defined(TEST_LONG_DOUBLE_IS_DOUBLE)
# ifndef __cpp_lib_to_chars
# error "__cpp_lib_to_chars should be defined in c++26"
# endif
# if __cpp_lib_to_chars != 202306L
# error "__cpp_lib_to_chars should have the value 202306L in c++26"
# endif
-# else // _LIBCPP_VERSION
+# else
# ifdef __cpp_lib_to_chars
-# error "__cpp_lib_to_chars should not be defined because it is unimplemented in libc++!"
+# error "__cpp_lib_to_chars should not be defined when the requirement 'defined(TEST_LONG_DOUBLE_IS_DOUBLE)' is not met!"
# endif
# endif
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
index b0f8b2f80067d5..215a9ecd4a83e9 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
@@ -3081,16 +3081,16 @@
# error "__cpp_lib_to_array should not be defined before c++20"
# endif
-# if !defined(_LIBCPP_VERSION)
+# if defined(TEST_LONG_DOUBLE_IS_DOUBLE)
# ifndef __cpp_lib_to_chars
# error "__cpp_lib_to_chars should be defined in c++17"
# endif
# if __cpp_lib_to_chars != 201611L
# error "__cpp_lib_to_chars should have the value 201611L in c++17"
# endif
-# else // _LIBCPP_VERSION
+# else
# ifdef __cpp_lib_to_chars
-# error "__cpp_lib_to_chars should not be defined because it is unimplemented in libc++!"
+# error "__cpp_lib_to_chars should not be defined when the requirement 'defined(TEST_LONG_DOUBLE_IS_DOUBLE)' is not met!"
# endif
# endif
@@ -4471,16 +4471,16 @@
# error "__cpp_lib_to_array should have the value 201907L in c++20"
# endif
-# if !defined(_LIBCPP_VERSION)
+# if defined(TEST_LONG_DOUBLE_IS_DOUBLE)
# ifndef __cpp_lib_to_chars
# error "__cpp_lib_to_chars should be defined in c++20"
# endif
# if __cpp_lib_to_chars != 201611L
# error "__cpp_lib_to_chars should have the value 201611L in c++20"
# endif
-# else // _LIBCPP_VERSION
+# else
# ifdef __cpp_lib_to_chars
-# error "__cpp_lib_to_chars should not be defined because it is unimplemented in libc++!"
+# error "__cpp_lib_to_chars should not be defined when the requirement 'defined(TEST_LONG_DOUBLE_IS_DOUBLE)' is not met!"
# endif
# endif
@@ -6077,16 +6077,16 @@
# error "__cpp_lib_to_array should have the value 201907L in c++23"
# endif
-# if !defined(_LIBCPP_VERSION)
+# if defined(TEST_LONG_DOUBLE_IS_DOUBLE)
# ifndef __cpp_lib_to_chars
# error "__cpp_lib_to_chars should be defined in c++23"
# endif
# if __cpp_lib_to_chars != 201611L
# error "__cpp_lib_to_chars should have the value 201611L in c++23"
# endif
-# else // _LIBCPP_VERSION
+# else
# ifdef __cpp_lib_to_chars
-# error "__cpp_lib_to_chars should not be defined because it is unimplemented in libc++!"
+# error "__cpp_lib_to_chars should not be defined when the requirement 'defined(TEST_LONG_DOUBLE_IS_DOUBLE)' is not met!"
# endif
# endif
@@ -8007,16 +8007,16 @@
# error "__cpp_lib_to_array should have the value 201907L in c++26"
# endif
-# if !defined(_LIBCPP_VERSION)
+# if defined(TEST_LONG_DOUBLE_IS_DOUBLE)
# ifndef __cpp_lib_to_chars
# error "__cpp_lib_to_chars should be defined in c++26"
# endif
# if __cpp_lib_to_chars != 202306L
# error "__cpp_lib_to_chars should have the value 202306L in c++26"
# endif
-# else // _LIBCPP_VERSION
+# else
# ifdef __cpp_lib_to_chars
-# error "__cpp_lib_to_chars should not be defined because it is unimplemented in libc++!"
+# error "__cpp_lib_to_chars should not be defined when the requirement 'defined(TEST_LONG_DOUBLE_IS_DOUBLE)' is not met!"
# endif
# endif
diff --git a/libcxx/test/std/utilities/charconv/charconv.from.chars/floating_point.pass.cpp b/libcxx/test/std/utilities/charconv/charconv.from.chars/floating_point.pass.cpp
index 6faf0499c4c9bb..95b04214aa8824 100644
--- a/libcxx/test/std/utilities/charconv/charconv.from.chars/floating_point.pass.cpp
+++ b/libcxx/test/std/utilities/charconv/charconv.from.chars/floating_point.pass.cpp
@@ -15,6 +15,9 @@
//
// from_chars_result from_chars(const char* first, const char* last,
// double& value, chars_format fmt = chars_format::general)
+//
+// from_chars_result from_chars(const char* first, const char* last,
+// long double& value, chars_format fmt = chars_format::general)
#include <array>
#include <charconv>
@@ -1518,6 +1521,25 @@ struct test_hex {
// test/std/utilities/charconv/charconv.msvc/test.cpp
// uses random values. This tests contains errors found by this test.
void test_random_errors() {
+#ifdef TEST_LONG_DOUBLE_IS_DOUBLE
+ {
+ const char* s = "4.219902180869891e-2788";
+ const char* last = s + std::strlen(s) - 1;
+
+ // last + 1 contains a digit. When that value is parsed the exponent is
+ // e-2788 which returns std::errc::result_out_of_range and the value 0.
+ // the proper exponent is e-278, which can be represented by a
+ // long double whose format is same as double.
+
+ long double value = 0.25L;
+ std::from_chars_result result = std::from_chars(s, last, value);
+
+ assert(result.ec == std::errc{});
+ assert(result.ptr == last);
+ assert(value == 4.219902180869891e-278L);
+ }
+ // TODO: Add more precise cases when the implementation for long double is complete.
+#endif
{
const char* s = "4.219902180869891e-2788";
const char* last = s + std::strlen(s) - 1;
diff --git a/libcxx/test/support/charconv_test_helpers.h b/libcxx/test/support/charconv_test_helpers.h
index fcae09478457b6..0ae7a66f421730 100644
--- a/libcxx/test/support/charconv_test_helpers.h
+++ b/libcxx/test/support/charconv_test_helpers.h
@@ -317,7 +317,11 @@ auto all_unsigned = type_list<
>();
auto integrals = concat(all_signed, all_unsigned);
-auto all_floats = type_list< float, double >(); //TODO: Add long double
+#ifdef TEST_LONG_DOUBLE_IS_DOUBLE // TODO: Remove this condition when the implementation for long double is complete.
+auto all_floats = type_list< float, double, long double >();
+#else
+auto all_floats = type_list< float, double >();
+#endif
template <template <typename> class Fn, typename... Ts>
TEST_CONSTEXPR_CXX23 void
diff --git a/libcxx/utils/generate_feature_test_macro_components.py b/libcxx/utils/generate_feature_test_macro_components.py
index 53fd44291b216a..b66ffd9723e72b 100755
--- a/libcxx/utils/generate_feature_test_macro_components.py
+++ b/libcxx/utils/generate_feature_test_macro_components.py
@@ -1333,7 +1333,8 @@ def add_version_header(tc):
"c++26": 202306, # P2497R0 Testing for success or failure of <charconv> functions
},
"headers": ["charconv"],
- "unimplemented": True,
+ "test_suite_guard": "defined(TEST_LONG_DOUBLE_IS_DOUBLE)",
+ "libcxx_guard": "_LIBCPP_LONG_DOUBLE_IS_DOUBLE",
},
{
"name": "__cpp_lib_to_string",
@@ -1532,7 +1533,9 @@ def produce_macros_definition_for_std(std):
result += "# if %s\n" % tc["libcxx_guard"]
inner_indent += 2
if get_value_before(tc["values"], std) is not None:
- assert "test_suite_guard" not in tc.keys()
+ # TRANSITION, __cpp_lib_to_chars has different values
+ # but needs to be guarded.
+ # assert "test_suite_guard" not in tc.keys()
result += "# undef %s\n" % tc["name"]
line = "#%sdefine %s" % ((" " * inner_indent), tc["name"])
line += " " * (indent - len(line))
|
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philnik777
requested changes
Nov 21, 2024
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I'm not convinced this is a good idea. We're essentially adding a bunch of conditionals where we should really just implement the long double overload. Also, IMO we should just provide the symbol for long double on every platform and not just on ones where long double and double have different representations. It's not like we're saving much by providing it only sometimes.
| @@ -1231,6 +1231,12 @@ typedef __char32_t char32_t; | |||
| # define _LIBCPP_HAS_EXPLICIT_THIS_PARAMETER 0 | |||
| # endif | |||
|
|
|||
| # if defined(_MSC_VER) || __SIZEOF_LONG_DOUBLE__ == __SIZEOF_DOUBLE__ | |||
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Is it guaranteed that if they have the same size they have the same representation?
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We're already using such condition in the test suite. I don't think we support any platform where their sizes are equal but their representations are not.
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I'm much less concerned about such a check in our test suite than in our ABI.
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Towards #99940 and #99952. Implementation of P0067R5 + P0682R1 becomes complete for these platforms.