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[libc++] Simplify the implementation of __is_referenceable (#130043)
The `__is_referenceable` builtin has been removed from Clang, since all its uses have been replaced by builtins themselves. This trait only exists for GCC compatibility and to word around some issues in the other traits. The non-builtin implementation has been refactored to use variable templates instead, making the implementation much simpler.
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+211
-223
lines changed

8 files changed

+211
-223
lines changed

‎libcxx/include/__type_traits/add_lvalue_reference.h

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -25,7 +25,7 @@ using __add_lvalue_reference_t _LIBCPP_NODEBUG = __add_lvalue_reference(_Tp);
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#else
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28-
template <class _Tp, bool = __libcpp_is_referenceable<_Tp>::value>
28+
template <class _Tp, bool = __is_referenceable_v<_Tp>>
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struct __add_lvalue_reference_impl {
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using type _LIBCPP_NODEBUG = _Tp;
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};

‎libcxx/include/__type_traits/add_pointer.h

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -26,7 +26,7 @@ template <class _Tp>
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using __add_pointer_t _LIBCPP_NODEBUG = __add_pointer(_Tp);
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#else
29-
template <class _Tp, bool = __libcpp_is_referenceable<_Tp>::value || is_void<_Tp>::value>
29+
template <class _Tp, bool = __is_referenceable_v<_Tp> || is_void<_Tp>::value>
3030
struct __add_pointer_impl {
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using type _LIBCPP_NODEBUG = __libcpp_remove_reference_t<_Tp>*;
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};

‎libcxx/include/__type_traits/add_rvalue_reference.h

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -25,7 +25,7 @@ using __add_rvalue_reference_t _LIBCPP_NODEBUG = __add_rvalue_reference(_Tp);
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#else
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28-
template <class _Tp, bool = __libcpp_is_referenceable<_Tp>::value>
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template <class _Tp, bool = __is_referenceable_v<_Tp> >
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struct __add_rvalue_reference_impl {
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using type _LIBCPP_NODEBUG = _Tp;
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};

‎libcxx/include/__type_traits/decay.h

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -55,7 +55,7 @@ struct _LIBCPP_TEMPLATE_VIS decay {
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using _Up _LIBCPP_NODEBUG = __libcpp_remove_reference_t<_Tp>;
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public:
58-
using type _LIBCPP_NODEBUG = typename __decay<_Up, __libcpp_is_referenceable<_Up>::value>::type;
58+
using type _LIBCPP_NODEBUG = typename __decay<_Up, __is_referenceable_v<_Up> >::type;
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};
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template <class _Tp>

‎libcxx/include/__type_traits/is_referenceable.h

Lines changed: 4 additions & 16 deletions
Original file line numberDiff line numberDiff line change
@@ -10,31 +10,19 @@
1010
#define _LIBCPP___TYPE_TRAITS_IS_REFERENCEABLE_H
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#include <__config>
13-
#include <__type_traits/integral_constant.h>
14-
#include <__type_traits/is_same.h>
13+
#include <__type_traits/void_t.h>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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2019
_LIBCPP_BEGIN_NAMESPACE_STD
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22-
#if __has_builtin(__is_referenceable)
23-
template <class _Tp>
24-
struct __libcpp_is_referenceable : integral_constant<bool, __is_referenceable(_Tp)> {};
25-
#else
26-
struct __libcpp_is_referenceable_impl {
27-
template <class _Tp>
28-
static _Tp& __test(int);
29-
template <class _Tp>
30-
static false_type __test(...);
31-
};
21+
template <class _Tp, class = void>
22+
inline const bool __is_referenceable_v = false;
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template <class _Tp>
34-
struct __libcpp_is_referenceable
35-
: integral_constant<bool, _IsNotSame<decltype(__libcpp_is_referenceable_impl::__test<_Tp>(0)), false_type>::value> {
36-
};
37-
#endif // __has_builtin(__is_referenceable)
25+
inline const bool __is_referenceable_v<_Tp, __void_t<_Tp&> > = true;
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_LIBCPP_END_NAMESPACE_STD
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‎libcxx/test/libcxx/utilities/meta/is_referenceable.compile.pass.cpp

Lines changed: 192 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,192 @@
1+
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
5+
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
9+
10+
// __is_referenceable_v<Tp>
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//
12+
// [defns.referenceable] defines "a referenceable type" as:
13+
// An object type, a function type that does not have cv-qualifiers
14+
// or a ref-qualifier, or a reference type.
15+
//
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17+
// XFAIL: FROZEN-CXX03-HEADERS-FIXME
18+
19+
#include <type_traits>
20+
#include <cassert>
21+
22+
#include "test_macros.h"
23+
24+
struct Foo {};
25+
26+
static_assert((!std::__is_referenceable_v<void>), "");
27+
static_assert((std::__is_referenceable_v<int>), "");
28+
static_assert((std::__is_referenceable_v<int[3]>), "");
29+
static_assert((std::__is_referenceable_v<int[]>), "");
30+
static_assert((std::__is_referenceable_v<int&>), "");
31+
static_assert((std::__is_referenceable_v<const int&>), "");
32+
static_assert((std::__is_referenceable_v<int*>), "");
33+
static_assert((std::__is_referenceable_v<const int*>), "");
34+
static_assert((std::__is_referenceable_v<Foo>), "");
35+
static_assert((std::__is_referenceable_v<const Foo>), "");
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static_assert((std::__is_referenceable_v<Foo&>), "");
37+
static_assert((std::__is_referenceable_v<const Foo&>), "");
38+
#if TEST_STD_VER >= 11
39+
static_assert((std::__is_referenceable_v<Foo&&>), "");
40+
static_assert((std::__is_referenceable_v<const Foo&&>), "");
41+
#endif
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43+
static_assert((std::__is_referenceable_v<int __attribute__((__vector_size__(8)))>), "");
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static_assert((std::__is_referenceable_v<const int __attribute__((__vector_size__(8)))>), "");
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static_assert((std::__is_referenceable_v<float __attribute__((__vector_size__(16)))>), "");
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static_assert((std::__is_referenceable_v<const float __attribute__((__vector_size__(16)))>), "");
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48+
// Functions without cv-qualifiers are referenceable
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static_assert((std::__is_referenceable_v<void()>), "");
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#if TEST_STD_VER >= 11
51+
static_assert((!std::__is_referenceable_v<void() const>), "");
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static_assert((!std::__is_referenceable_v<void() &>), "");
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static_assert((!std::__is_referenceable_v<void() const&>), "");
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static_assert((!std::__is_referenceable_v<void() &&>), "");
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static_assert((!std::__is_referenceable_v<void() const&&>), "");
56+
#endif
57+
58+
static_assert((std::__is_referenceable_v<void(int)>), "");
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#if TEST_STD_VER >= 11
60+
static_assert((!std::__is_referenceable_v<void(int) const>), "");
61+
static_assert((!std::__is_referenceable_v<void(int) &>), "");
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static_assert((!std::__is_referenceable_v<void(int) const&>), "");
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static_assert((!std::__is_referenceable_v<void(int) &&>), "");
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static_assert((!std::__is_referenceable_v<void(int) const&&>), "");
65+
#endif
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67+
static_assert((std::__is_referenceable_v<void(int, float)>), "");
68+
#if TEST_STD_VER >= 11
69+
static_assert((!std::__is_referenceable_v<void(int, float) const>), "");
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static_assert((!std::__is_referenceable_v<void(int, float) &>), "");
71+
static_assert((!std::__is_referenceable_v<void(int, float) const&>), "");
72+
static_assert((!std::__is_referenceable_v<void(int, float) &&>), "");
73+
static_assert((!std::__is_referenceable_v<void(int, float) const&&>), "");
74+
#endif
75+
76+
static_assert((std::__is_referenceable_v<void(int, float, Foo&)>), "");
77+
#if TEST_STD_VER >= 11
78+
static_assert((!std::__is_referenceable_v<void(int, float, Foo&) const>), "");
79+
static_assert((!std::__is_referenceable_v<void(int, float, Foo&) &>), "");
80+
static_assert((!std::__is_referenceable_v<void(int, float, Foo&) const&>), "");
81+
static_assert((!std::__is_referenceable_v<void(int, float, Foo&) &&>), "");
82+
static_assert((!std::__is_referenceable_v<void(int, float, Foo&) const&&>), "");
83+
#endif
84+
85+
static_assert((std::__is_referenceable_v<void(...)>), "");
86+
#if TEST_STD_VER >= 11
87+
static_assert((!std::__is_referenceable_v<void(...) const>), "");
88+
static_assert((!std::__is_referenceable_v<void(...) &>), "");
89+
static_assert((!std::__is_referenceable_v<void(...) const&>), "");
90+
static_assert((!std::__is_referenceable_v<void(...) &&>), "");
91+
static_assert((!std::__is_referenceable_v<void(...) const&&>), "");
92+
#endif
93+
94+
static_assert((std::__is_referenceable_v<void(int, ...)>), "");
95+
#if TEST_STD_VER >= 11
96+
static_assert((!std::__is_referenceable_v<void(int, ...) const>), "");
97+
static_assert((!std::__is_referenceable_v<void(int, ...) &>), "");
98+
static_assert((!std::__is_referenceable_v<void(int, ...) const&>), "");
99+
static_assert((!std::__is_referenceable_v<void(int, ...) &&>), "");
100+
static_assert((!std::__is_referenceable_v<void(int, ...) const&&>), "");
101+
#endif
102+
103+
static_assert((std::__is_referenceable_v<void(int, float, ...)>), "");
104+
#if TEST_STD_VER >= 11
105+
static_assert((!std::__is_referenceable_v<void(int, float, ...) const>), "");
106+
static_assert((!std::__is_referenceable_v<void(int, float, ...) &>), "");
107+
static_assert((!std::__is_referenceable_v<void(int, float, ...) const&>), "");
108+
static_assert((!std::__is_referenceable_v<void(int, float, ...) &&>), "");
109+
static_assert((!std::__is_referenceable_v<void(int, float, ...) const&&>), "");
110+
#endif
111+
112+
static_assert((std::__is_referenceable_v<void(int, float, Foo&, ...)>), "");
113+
#if TEST_STD_VER >= 11
114+
static_assert((!std::__is_referenceable_v<void(int, float, Foo&, ...) const>), "");
115+
static_assert((!std::__is_referenceable_v<void(int, float, Foo&, ...) &>), "");
116+
static_assert((!std::__is_referenceable_v<void(int, float, Foo&, ...) const&>), "");
117+
static_assert((!std::__is_referenceable_v<void(int, float, Foo&, ...) &&>), "");
118+
static_assert((!std::__is_referenceable_v<void(int, float, Foo&, ...) const&&>), "");
119+
#endif
120+
121+
// member functions with or without cv-qualifiers are referenceable
122+
static_assert((std::__is_referenceable_v<void (Foo::*)()>), "");
123+
static_assert((std::__is_referenceable_v<void (Foo::*)() const>), "");
124+
#if TEST_STD_VER >= 11
125+
static_assert((std::__is_referenceable_v<void (Foo::*)() &>), "");
126+
static_assert((std::__is_referenceable_v<void (Foo::*)() const&>), "");
127+
static_assert((std::__is_referenceable_v<void (Foo::*)() &&>), "");
128+
static_assert((std::__is_referenceable_v<void (Foo::*)() const&&>), "");
129+
#endif
130+
131+
static_assert((std::__is_referenceable_v<void (Foo::*)(int)>), "");
132+
static_assert((std::__is_referenceable_v<void (Foo::*)(int) const>), "");
133+
#if TEST_STD_VER >= 11
134+
static_assert((std::__is_referenceable_v<void (Foo::*)(int) &>), "");
135+
static_assert((std::__is_referenceable_v<void (Foo::*)(int) const&>), "");
136+
static_assert((std::__is_referenceable_v<void (Foo::*)(int) &&>), "");
137+
static_assert((std::__is_referenceable_v<void (Foo::*)(int) const&&>), "");
138+
#endif
139+
140+
static_assert((std::__is_referenceable_v<void (Foo::*)(int, float)>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, float) const>), "");
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#if TEST_STD_VER >= 11
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, float) &>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, float) const&>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, float) &&>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, float) const&&>), "");
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#endif
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149+
static_assert((std::__is_referenceable_v<void (Foo::*)(int, float, Foo&)>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, float, Foo&) const>), "");
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#if TEST_STD_VER >= 11
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, float, Foo&) &>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, float, Foo&) const&>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, float, Foo&) &&>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, float, Foo&) const&&>), "");
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#endif
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static_assert((std::__is_referenceable_v<void (Foo::*)(...)>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(...) const>), "");
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#if TEST_STD_VER >= 11
161+
static_assert((std::__is_referenceable_v<void (Foo::*)(...) &>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(...) const&>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(...) &&>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(...) const&&>), "");
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#endif
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, ...)>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, ...) const>), "");
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#if TEST_STD_VER >= 11
170+
static_assert((std::__is_referenceable_v<void (Foo::*)(int, ...) &>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, ...) const&>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, ...) &&>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, ...) const&&>), "");
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#endif
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, float, ...)>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, float, ...) const>), "");
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#if TEST_STD_VER >= 11
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, float, ...) &>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, float, ...) const&>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, float, ...) &&>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, float, ...) const&&>), "");
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#endif
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, float, Foo&, ...)>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, float, Foo&, ...) const>), "");
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#if TEST_STD_VER >= 11
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, float, Foo&, ...) &>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, float, Foo&, ...) const&>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, float, Foo&, ...) &&>), "");
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static_assert((std::__is_referenceable_v<void (Foo::*)(int, float, Foo&, ...) const&&>), "");
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#endif

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