[libcxx-commits] [libcxx] [libc++][format] P2637R3: Member `visit` (PR #76449)
via libcxx-commits
libcxx-commits at lists.llvm.org
Wed Dec 27 08:30:34 PST 2023
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-libcxx
Author: Hristo Hristov (H-G-Hristov)
<details>
<summary>Changes</summary>
Implements parts of: https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2023/p2637r3.html (https://eel.is/c++draft/variant.visit)
Adds member `visit` tests and (NFC) refactors + reformats the non-member `visit` tests to accomodate the member `visit` additions for consistency.
---
Patch is 33.84 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/76449.diff
8 Files Affected:
- (modified) libcxx/docs/Status/Cxx2cPapers.csv (+1-1)
- (modified) libcxx/include/__config (+6)
- (modified) libcxx/include/__format/format_arg.h (+66-2)
- (modified) libcxx/include/format (+1-1)
- (renamed) libcxx/test/std/utilities/format/format.arguments/format.arg/visit.pass.cpp (+68-60)
- (added) libcxx/test/std/utilities/format/format.arguments/format.arg/visit.return_type.pass.cpp (+326)
- (added) libcxx/test/std/utilities/format/format.arguments/format.arg/visit_format_arg.deprecated.verify.cpp (+64)
- (modified) libcxx/utils/generate_feature_test_macro_components.py (+1)
``````````diff
diff --git a/libcxx/docs/Status/Cxx2cPapers.csv b/libcxx/docs/Status/Cxx2cPapers.csv
index ff83648aa76830..b33543aad8b945 100644
--- a/libcxx/docs/Status/Cxx2cPapers.csv
+++ b/libcxx/docs/Status/Cxx2cPapers.csv
@@ -17,7 +17,7 @@
"`P0792R14 <https://wg21.link/P0792R14>`__","LWG","``function_ref``: a type-erased callable reference","Varna June 2023","","",""
"`P2874R2 <https://wg21.link/P2874R2>`__","LWG","Mandating Annex D Require No More","Varna June 2023","","",""
"`P2757R3 <https://wg21.link/P2757R3>`__","LWG","Type-checking format args","Varna June 2023","","","|format|"
-"`P2637R3 <https://wg21.link/P2637R3>`__","LWG","Member ``visit``","Varna June 2023","","","|format|"
+"`P2637R3 <https://wg21.link/P2637R3>`__","LWG","Member ``visit``","Varna June 2023","|Complete|","18.0",""
"`P2641R4 <https://wg21.link/P2641R4>`__","CWG, LWG","Checking if a ``union`` alternative is active","Varna June 2023","","",""
"`P1759R6 <https://wg21.link/P1759R6>`__","LWG","Native handles and file streams","Varna June 2023","","",""
"`P2697R1 <https://wg21.link/P2697R1>`__","LWG","Interfacing ``bitset`` with ``string_view``","Varna June 2023","|Complete|","18.0",""
diff --git a/libcxx/include/__config b/libcxx/include/__config
index adff13e714cb64..ee85b73c2e4cfe 100644
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -956,6 +956,12 @@ typedef __char32_t char32_t;
# define _LIBCPP_DEPRECATED_IN_CXX23
# endif
+# if _LIBCPP_STD_VER >= 26
+# define _LIBCPP_DEPRECATED_IN_CXX26 _LIBCPP_DEPRECATED
+# else
+# define _LIBCPP_DEPRECATED_IN_CXX26
+# endif
+
# if !defined(_LIBCPP_HAS_NO_CHAR8_T)
# define _LIBCPP_DEPRECATED_WITH_CHAR8_T _LIBCPP_DEPRECATED
# else
diff --git a/libcxx/include/__format/format_arg.h b/libcxx/include/__format/format_arg.h
index 280c9108241754..bc9e13eb9029a5 100644
--- a/libcxx/include/__format/format_arg.h
+++ b/libcxx/include/__format/format_arg.h
@@ -93,7 +93,7 @@ _LIBCPP_HIDE_FROM_ABI constexpr __arg_t __get_packed_type(uint64_t __types, size
} // namespace __format
-// This function is not user obervable, so it can directly use the non-standard
+// This function is not user observable, so it can directly use the non-standard
// types of the "variant". See __arg_t for more details.
template <class _Visitor, class _Context>
_LIBCPP_HIDE_FROM_ABI decltype(auto) __visit_format_arg(_Visitor&& __vis, basic_format_arg<_Context> __arg) {
@@ -144,6 +144,57 @@ _LIBCPP_HIDE_FROM_ABI decltype(auto) __visit_format_arg(_Visitor&& __vis, basic_
__libcpp_unreachable();
}
+# if _LIBCPP_STD_VER >= 26
+template <class _Rp, class _Visitor, class _Context>
+_LIBCPP_HIDE_FROM_ABI _Rp __visit_format_arg(_Visitor&& __vis, basic_format_arg<_Context> __arg) {
+ switch (__arg.__type_) {
+ case __format::__arg_t::__none:
+ return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__monostate_);
+ case __format::__arg_t::__boolean:
+ return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__boolean_);
+ case __format::__arg_t::__char_type:
+ return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__char_type_);
+ case __format::__arg_t::__int:
+ return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__int_);
+ case __format::__arg_t::__long_long:
+ return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__long_long_);
+ case __format::__arg_t::__i128:
+# ifndef _LIBCPP_HAS_NO_INT128
+ return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__i128_);
+# else
+ __libcpp_unreachable();
+# endif
+ case __format::__arg_t::__unsigned:
+ return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__unsigned_);
+ case __format::__arg_t::__unsigned_long_long:
+ return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__unsigned_long_long_);
+ case __format::__arg_t::__u128:
+# ifndef _LIBCPP_HAS_NO_INT128
+ return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__u128_);
+# else
+ __libcpp_unreachable();
+# endif
+ case __format::__arg_t::__float:
+ return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__float_);
+ case __format::__arg_t::__double:
+ return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__double_);
+ case __format::__arg_t::__long_double:
+ return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__long_double_);
+ case __format::__arg_t::__const_char_type_ptr:
+ return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__const_char_type_ptr_);
+ case __format::__arg_t::__string_view:
+ return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__string_view_);
+ case __format::__arg_t::__ptr:
+ return std::invoke_r<_Rp>(std::forward<_Visitor>(__vis), __arg.__value_.__ptr_);
+ case __format::__arg_t::__handle:
+ return std::invoke_r<_Rp>(
+ std::forward<_Visitor>(__vis), typename basic_format_arg<_Context>::handle{__arg.__value_.__handle_});
+ }
+
+ __libcpp_unreachable();
+}
+# endif
+
/// Contains the values used in basic_format_arg.
///
/// This is a separate type so it's possible to store the values and types in
@@ -227,6 +278,18 @@ class _LIBCPP_TEMPLATE_VIS basic_format_arg {
_LIBCPP_HIDE_FROM_ABI explicit operator bool() const noexcept { return __type_ != __format::__arg_t::__none; }
+# if _LIBCPP_STD_VER >= 26
+ template <class _Visitor>
+ _LIBCPP_HIDE_FROM_ABI decltype(auto) visit(this basic_format_arg __arg, _Visitor&& __vis) {
+ return std::__visit_format_arg(std::forward<_Visitor>(__vis), __arg);
+ }
+
+ template <class _Rp, class _Visitor>
+ _LIBCPP_HIDE_FROM_ABI _Rp visit(this basic_format_arg __arg, _Visitor&& __vis) {
+ return std::__visit_format_arg<_Rp>(std::forward<_Visitor>(__vis), __arg);
+ }
+# endif
+
private:
using char_type = typename _Context::char_type;
@@ -267,7 +330,8 @@ class _LIBCPP_TEMPLATE_VIS basic_format_arg<_Context>::handle {
// This function is user facing, so it must wrap the non-standard types of
// the "variant" in a handle to stay conforming. See __arg_t for more details.
template <class _Visitor, class _Context>
-_LIBCPP_HIDE_FROM_ABI decltype(auto) visit_format_arg(_Visitor&& __vis, basic_format_arg<_Context> __arg) {
+_LIBCPP_DEPRECATED_IN_CXX26 _LIBCPP_HIDE_FROM_ABI decltype(auto)
+visit_format_arg(_Visitor&& __vis, basic_format_arg<_Context> __arg) {
switch (__arg.__type_) {
# ifndef _LIBCPP_HAS_NO_INT128
case __format::__arg_t::__i128: {
diff --git a/libcxx/include/format b/libcxx/include/format
index ab9b336d0cdabe..e1566fb4636a7b 100644
--- a/libcxx/include/format
+++ b/libcxx/include/format
@@ -170,7 +170,7 @@ namespace std {
template<class Context> class basic_format_arg;
template<class Visitor, class Context>
- see below visit_format_arg(Visitor&& vis, basic_format_arg<Context> arg);
+ see below visit_format_arg(Visitor&& vis, basic_format_arg<Context> arg); // deprecated in C++26
// [format.arg.store], class template format-arg-store
template<class Context, class... Args> struct format-arg-store; // exposition only
diff --git a/libcxx/test/std/utilities/format/format.arguments/format.arg/visit_format_arg.pass.cpp b/libcxx/test/std/utilities/format/format.arguments/format.arg/visit.pass.cpp
similarity index 77%
rename from libcxx/test/std/utilities/format/format.arguments/format.arg/visit_format_arg.pass.cpp
rename to libcxx/test/std/utilities/format/format.arguments/format.arg/visit.pass.cpp
index 3ddf2d0ff732a7..c3b1609c159c8d 100644
--- a/libcxx/test/std/utilities/format/format.arguments/format.arg/visit_format_arg.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.arguments/format.arg/visit.pass.cpp
@@ -10,18 +10,26 @@
// <format>
+// class basic_format_arg;
+
+// template<class Visitor>
+// decltype(auto) visit(this basic_format_arg arg, Visitor&& vis); // since C++26
+
// template<class Visitor, class Context>
-// see below visit_format_arg(Visitor&& vis, basic_format_arg<Context> arg);
+// see below visit_format_arg(Visitor&& vis, basic_format_arg<Context> arg); // deprecated in C++26
#include <algorithm>
-#include <format>
#include <cassert>
+#include <format>
#include <type_traits>
#include "constexpr_char_traits.h"
-#include "test_macros.h"
#include "make_string.h"
#include "min_allocator.h"
+#include "test_macros.h"
+
+// Deprecated `std::visit_format_arg` should be tested in C++26 or newer.
+TEST_CLANG_DIAGNOSTIC_IGNORED("-Wdeprecated-declarations")
template <class Context, class To, class From>
void test(From value) {
@@ -31,20 +39,41 @@ void test(From value) {
LIBCPP_ASSERT(format_args.__size() == 1);
assert(format_args.get(0));
- auto result = std::visit_format_arg(
- [v = To(value)](auto a) -> To {
- if constexpr (std::is_same_v<To, decltype(a)>) {
- assert(v == a);
- return a;
- } else {
- assert(false);
- return {};
- }
- },
- format_args.get(0));
+#if _LIBCPP_STD_VER >= 26
+ // member
+ {
+ auto result = format_args.get(0).visit([v = To(value)](auto a) -> To {
+ if constexpr (std::is_same_v<To, decltype(a)>) {
+ assert(v == a);
+ return a;
+ } else {
+ assert(false);
+ return {};
+ }
+ });
+
+ using ct = std::common_type_t<From, To>;
+ assert(static_cast<ct>(result) == static_cast<ct>(value));
+ }
+#endif
- using ct = std::common_type_t<From, To>;
- assert(static_cast<ct>(result) == static_cast<ct>(value));
+ // non-member
+ {
+ auto result = std::visit_format_arg(
+ [v = To(value)](auto a) -> To {
+ if constexpr (std::is_same_v<To, decltype(a)>) {
+ assert(v == a);
+ return a;
+ } else {
+ assert(false);
+ return {};
+ }
+ },
+ format_args.get(0));
+
+ using ct = std::common_type_t<From, To>;
+ assert(static_cast<ct>(result) == static_cast<ct>(value));
+ }
}
// Some types, as an extension, are stored in the variant. The Standard
@@ -75,8 +104,8 @@ void test_string_view(From value) {
assert(format_args.get(0));
using CharT = typename Context::char_type;
- using To = std::basic_string_view<CharT>;
- using V = std::basic_string<CharT>;
+ using To = std::basic_string_view<CharT>;
+ using V = std::basic_string<CharT>;
auto result = std::visit_format_arg(
[v = V(value.begin(), value.end())](auto a) -> To {
if constexpr (std::is_same_v<To, decltype(a)>) {
@@ -170,8 +199,7 @@ void test() {
test<Context, int, int>(std::numeric_limits<short>::max());
test<Context, int, int>(std::numeric_limits<int>::max());
- using LongToType =
- std::conditional_t<sizeof(long) == sizeof(int), int, long long>;
+ using LongToType = std::conditional_t<sizeof(long) == sizeof(int), int, long long>;
test<Context, LongToType, long>(std::numeric_limits<long>::min());
test<Context, LongToType, long>(std::numeric_limits<int>::min());
@@ -202,14 +230,11 @@ void test() {
// Test unsigned integer types.
test<Context, unsigned, unsigned char>(0);
- test<Context, unsigned, unsigned char>(
- std::numeric_limits<unsigned char>::max());
+ test<Context, unsigned, unsigned char>(std::numeric_limits<unsigned char>::max());
test<Context, unsigned, unsigned short>(0);
- test<Context, unsigned, unsigned short>(
- std::numeric_limits<unsigned char>::max());
- test<Context, unsigned, unsigned short>(
- std::numeric_limits<unsigned short>::max());
+ test<Context, unsigned, unsigned short>(std::numeric_limits<unsigned char>::max());
+ test<Context, unsigned, unsigned short>(std::numeric_limits<unsigned short>::max());
test<Context, unsigned, unsigned>(0);
test<Context, unsigned, unsigned>(std::numeric_limits<unsigned char>::max());
@@ -217,30 +242,20 @@ void test() {
test<Context, unsigned, unsigned>(std::numeric_limits<unsigned>::max());
using UnsignedLongToType =
- std::conditional_t<sizeof(unsigned long) == sizeof(unsigned), unsigned,
- unsigned long long>;
+ std::conditional_t<sizeof(unsigned long) == sizeof(unsigned), unsigned, unsigned long long>;
test<Context, UnsignedLongToType, unsigned long>(0);
- test<Context, UnsignedLongToType, unsigned long>(
- std::numeric_limits<unsigned char>::max());
- test<Context, UnsignedLongToType, unsigned long>(
- std::numeric_limits<unsigned short>::max());
- test<Context, UnsignedLongToType, unsigned long>(
- std::numeric_limits<unsigned>::max());
- test<Context, UnsignedLongToType, unsigned long>(
- std::numeric_limits<unsigned long>::max());
+ test<Context, UnsignedLongToType, unsigned long>(std::numeric_limits<unsigned char>::max());
+ test<Context, UnsignedLongToType, unsigned long>(std::numeric_limits<unsigned short>::max());
+ test<Context, UnsignedLongToType, unsigned long>(std::numeric_limits<unsigned>::max());
+ test<Context, UnsignedLongToType, unsigned long>(std::numeric_limits<unsigned long>::max());
test<Context, unsigned long long, unsigned long long>(0);
- test<Context, unsigned long long, unsigned long long>(
- std::numeric_limits<unsigned char>::max());
- test<Context, unsigned long long, unsigned long long>(
- std::numeric_limits<unsigned short>::max());
- test<Context, unsigned long long, unsigned long long>(
- std::numeric_limits<unsigned>::max());
- test<Context, unsigned long long, unsigned long long>(
- std::numeric_limits<unsigned long>::max());
- test<Context, unsigned long long, unsigned long long>(
- std::numeric_limits<unsigned long long>::max());
+ test<Context, unsigned long long, unsigned long long>(std::numeric_limits<unsigned char>::max());
+ test<Context, unsigned long long, unsigned long long>(std::numeric_limits<unsigned short>::max());
+ test<Context, unsigned long long, unsigned long long>(std::numeric_limits<unsigned>::max());
+ test<Context, unsigned long long, unsigned long long>(std::numeric_limits<unsigned long>::max());
+ test<Context, unsigned long long, unsigned long long>(std::numeric_limits<unsigned long long>::max());
#ifndef TEST_HAS_NO_INT128
test_handle<Context, __uint128_t>(0);
@@ -262,16 +277,12 @@ void test() {
test<Context, double, double>(std::numeric_limits<double>::min());
test<Context, double, double>(std::numeric_limits<double>::max());
- test<Context, long double, long double>(
- -std::numeric_limits<long double>::max());
- test<Context, long double, long double>(
- -std::numeric_limits<long double>::min());
+ test<Context, long double, long double>(-std::numeric_limits<long double>::max());
+ test<Context, long double, long double>(-std::numeric_limits<long double>::min());
test<Context, long double, long double>(-0.0);
test<Context, long double, long double>(0.0);
- test<Context, long double, long double>(
- std::numeric_limits<long double>::min());
- test<Context, long double, long double>(
- std::numeric_limits<long double>::max());
+ test<Context, long double, long double>(std::numeric_limits<long double>::min());
+ test<Context, long double, long double>(std::numeric_limits<long double>::max());
// Test const CharT pointer types.
@@ -307,8 +318,7 @@ void test() {
}
{
- using From = std::basic_string<CharT, constexpr_char_traits<CharT>,
- std::allocator<CharT>>;
+ using From = std::basic_string<CharT, constexpr_char_traits<CharT>, std::allocator<CharT>>;
test_string_view<Context>(From());
test_string_view<Context>(From(empty.c_str()));
@@ -316,8 +326,7 @@ void test() {
}
{
- using From =
- std::basic_string<CharT, std::char_traits<CharT>, min_allocator<CharT>>;
+ using From = std::basic_string<CharT, std::char_traits<CharT>, min_allocator<CharT>>;
test_string_view<Context>(From());
test_string_view<Context>(From(empty.c_str()));
@@ -325,8 +334,7 @@ void test() {
}
{
- using From = std::basic_string<CharT, constexpr_char_traits<CharT>,
- min_allocator<CharT>>;
+ using From = std::basic_string<CharT, constexpr_char_traits<CharT>, min_allocator<CharT>>;
test_string_view<Context>(From());
test_string_view<Context>(From(empty.c_str()));
diff --git a/libcxx/test/std/utilities/format/format.arguments/format.arg/visit.return_type.pass.cpp b/libcxx/test/std/utilities/format/format.arguments/format.arg/visit.return_type.pass.cpp
new file mode 100644
index 00000000000000..470df35ef97196
--- /dev/null
+++ b/libcxx/test/std/utilities/format/format.arguments/format.arg/visit.return_type.pass.cpp
@@ -0,0 +1,326 @@
+//===----------------------------------------------------------------------===//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20, c++23
+// UNSUPPORTED: GCC-ALWAYS_INLINE-FIXME
+
+// <format>
+
+// class basic_format_arg;
+
+// template<class R, class Visitor>
+// R visit(this basic_format_arg arg, Visitor&& vis);
+
+#include <algorithm>
+#include <cassert>
+#include <format>
+#include <type_traits>
+
+#include "constexpr_char_traits.h"
+#include "make_string.h"
+#include "min_allocator.h"
+#include "test_macros.h"
+
+// The expected result type shouldn't matter,therefore use a hardcoded value for simplicity.
+using ExpectedResultType = bool;
+constexpr ExpectedResultType visited{true};
+
+template <class ExpectedR>
+ExpectedR make_expected_result() {
+ if constexpr (std::is_same_v<ExpectedR, bool>) {
+ return true;
+ } else if constexpr (std::is_same_v<ExpectedR, long>) {
+ return 192812079084L;
+ } else {
+ return "visited";
+ }
+}
+
+template <class Context, class To, class ExpectedR, class From>
+void test(From value, const ExpectedR& expectedValue) {
+ auto store = std::make_format_args<Context>(value);
+ std::basic_format_args<Context> format_args{store};
+
+ LIBCPP_ASSERT(format_args.__size() == 1);
+ assert(format_args.get(0));
+
+ // member
+ {
+ std::same_as<ExpectedR> decltype(auto) result =
+ format_args.get(0).template visit<ExpectedR>([v = To(value)](auto a) -> ExpectedR {
+ if constexpr (std::is_same_v<To, decltype(a)>) {
+ assert(v == a);
+ return make_expected_result<ExpectedR>();
+ } else {
+ assert(false);
+ return {};
+ }
+ });
+
+ assert(result == expectedValue);
+ }
+}
+
+// Some types, as an extension, are stored in the variant. The Standard
+// requires them to be observed as a handle.
+template <class Context, class T, class ExpectedR>
+void test_handle(T value, ExpectedR expectedValue) {
+ auto store = std::make_format_args<Context>(value);
+ std::basic_format_args<Context> format_args{store};
+
+ LIBCPP_ASSERT(format_args.__size() == 1);
+ assert(format_args.get(0));
+
+ std::same_as<ExpectedR> decltype(auto) result = format_args.get(0).template visit<ExpectedR>([](auto a) -> ExpectedR {
+ // TODO: This check fails
+ (void)a;
+ // assert((std::is_same_v<decltype(a), typename std::basic_format_arg<Context>::handle>));
+
+ return make_expected_result<ExpectedR>();
+ });
+
+ assert(result == expectedValue);
+}
+
+// Test specific for string and string_view.
+//
+// Since both result in a string_view there's no need to pass this as a
+// template argument.
+template <class Context, class ExpectedR, class From>
+void test_string_view(From value, ExpectedR expectedValue) {
+ auto store = std::make_format_args<Context>(value);
+ std::basic_format_args<Context> format_args{store};
+
+ LIBCPP_ASSERT(format_args.__size() == 1);
+ assert(format_args.get(0));
+
+ using CharT = typename Context::char_type;
+ using To = std::basic_string_view<CharT>;
+ using V = std::basic_string<CharT>;
+
+ std::same_as<ExpectedR> decltype(auto) result =
+ format_args.get(0).template visit<ExpectedR>([v = V(value.begin(), value.end())](auto a) -> ExpectedR {
+ if constexpr (std::is_same_v<To, decltype(a)>) {...
[truncated]
``````````
</details>
https://github.com/llvm/llvm-project/pull/76449
More information about the libcxx-commits
mailing list