We need to apply remove_cvref_t on decltype(_Xv) for default template argument
due PR115314. The constant_wrapper::value is declared as decltype((__Xv)) due
PR125188.
libstdc++-v3/ChangeLog:
* include/bits/funcref_impl.h (function_ref::function_ref): Rename
template parameter from __cwfn to __fn and use it direclty.
* include/bits/funcwrap.h (function_ref): Rename template parameter
to __fn.
(std::constant_wrapper): Use auto as non-type template parameter,
and refeference it as value.
* include/bits/utility.h (__CwFixedValue): Remove.
* testsuite/20_util/constant_wrapper/generic.cc: Remove arrays
and string literal tests. Add test for address of value.
* testsuite/20_util/constant_wrapper/other_wrappers.cc:
Remove test_array.
Reviewed-by: Patrick Palka <[email protected]>
---
v2 clearly marks is as RFC and applies suggestion from Patrick:
- name second template parameter in forward declaration
- reffer to PR115314 instead of PR117004
libstdc++-v3/include/bits/funcref_impl.h | 15 ++--
libstdc++-v3/include/bits/funcwrap.h | 8 +-
libstdc++-v3/include/bits/utility.h | 50 +++----------
.../20_util/constant_wrapper/generic.cc | 74 ++++++-------------
.../constant_wrapper/other_wrappers.cc | 14 ----
.../constant_wrapper/type_param_neg.cc | 9 +++
6 files changed, 52 insertions(+), 118 deletions(-)
create mode 100644
libstdc++-v3/testsuite/20_util/constant_wrapper/type_param_neg.cc
diff --git a/libstdc++-v3/include/bits/funcref_impl.h
b/libstdc++-v3/include/bits/funcref_impl.h
index 9fc8432b42b..c51e1a54ff2 100644
--- a/libstdc++-v3/include/bits/funcref_impl.h
+++ b/libstdc++-v3/include/bits/funcref_impl.h
@@ -132,12 +132,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 4256. Incorrect constrains for function_ref constructors from nontype
/// Target object is __fn. There is no bound object.
- template<auto __cwfn, typename _Fn>
+ template<auto __fn, typename _Fn>
requires __is_invocable_using<const _Fn&>
constexpr
- function_ref(constant_wrapper<__cwfn, _Fn>) noexcept
+ function_ref(constant_wrapper<__fn, _Fn>) noexcept
{
- constexpr const _Fn& __fn = constant_wrapper<__cwfn, _Fn>::value;
if constexpr (sizeof...(_ArgTypes) > 0)
if constexpr ((... && _ConstExprParam<remove_cvref_t<_ArgTypes>>))
static_assert(!requires {
@@ -153,14 +152,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
/// Target object is equivalent to std::bind_front<_fn>(std::ref(__ref)).
/// Bound object is object referenced by second parameter.
- template<auto __cwfn, typename _Fn, typename _Up,
+ template<auto __fn, typename _Fn, typename _Up,
typename _Td = remove_reference_t<_Up>>
requires (!is_rvalue_reference_v<_Up&&>)
&& __is_invocable_using<const _Fn&, _Td _GLIBCXX_MOF_CV&>
constexpr
- function_ref(constant_wrapper<__cwfn, _Fn>, _Up&& __ref) noexcept
+ function_ref(constant_wrapper<__fn, _Fn>, _Up&& __ref) noexcept
{
- constexpr const _Fn& __fn = constant_wrapper<__cwfn, _Fn>::value;
if constexpr (is_pointer_v<_Fn> || is_member_pointer_v<_Fn>)
static_assert(__fn != nullptr);
@@ -176,12 +174,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
/// Target object is equivalent to std::bind_front<_fn>(__ptr).
/// Bound object is object pointed by second parameter (if any).
- template< auto __cwfn, typename _Fn, typename _Td>
+ template<auto __fn, typename _Fn, typename _Td>
requires __is_invocable_using<const _Fn&, _Td _GLIBCXX_MOF_CV*>
constexpr
- function_ref(constant_wrapper<__cwfn, _Fn>, _Td _GLIBCXX_MOF_CV* __ptr)
noexcept
+ function_ref(constant_wrapper<__fn, _Fn>, _Td _GLIBCXX_MOF_CV* __ptr)
noexcept
{
- constexpr const _Fn& __fn = constant_wrapper<__cwfn, _Fn>::value;
if constexpr (is_pointer_v<_Fn> || is_member_pointer_v<_Fn>)
static_assert(__fn != nullptr);
if constexpr (is_member_pointer_v<_Fn>)
diff --git a/libstdc++-v3/include/bits/funcwrap.h
b/libstdc++-v3/include/bits/funcwrap.h
index 07163f3a5a3..670efa63b4a 100644
--- a/libstdc++-v3/include/bits/funcwrap.h
+++ b/libstdc++-v3/include/bits/funcwrap.h
@@ -592,16 +592,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
requires is_function_v<_Fn>
function_ref(_Fn*) -> function_ref<_Fn>;
- template<auto __cwfn, typename _Fn>
+ template<auto __fn, typename _Fn>
requires is_function_v<remove_pointer_t<_Fn>>
- function_ref(constant_wrapper<__cwfn, _Fn>)
+ function_ref(constant_wrapper<__fn, _Fn>)
-> function_ref<remove_pointer_t<_Fn>>;
- template<auto __cwfn, typename _Fn, typename _Tp,
+ template<auto __fn, typename _Fn, typename _Tp,
typename _SignaturePtr =
decltype(__polyfunc::__deduce_funcref<_Fn, _Tp&>())>
requires (!is_void_v<_SignaturePtr>)
- function_ref(constant_wrapper<__cwfn, _Fn>, _Tp&&)
+ function_ref(constant_wrapper<__fn, _Fn>, _Tp&&)
-> function_ref<remove_pointer_t<_SignaturePtr>>;
/// @cond undocumented
diff --git a/libstdc++-v3/include/bits/utility.h
b/libstdc++-v3/include/bits/utility.h
index dac02e4a479..9bfc0c3d17f 100644
--- a/libstdc++-v3/include/bits/utility.h
+++ b/libstdc++-v3/include/bits/utility.h
@@ -141,42 +141,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
#endif
#ifdef __glibcxx_constant_wrapper // C++ >= 26
- template<typename _Tp>
- struct _CwFixedValue
- {
- using __type = _Tp;
-
- constexpr
- _CwFixedValue(__type __v) noexcept
- : _M_data(__v) { }
-
- __type _M_data;
- };
-
- template<typename _Tp, size_t _Extent>
- struct _CwFixedValue<_Tp[_Extent]>
- {
- using __type = _Tp[_Extent];
-
- constexpr
- _CwFixedValue(_Tp (&__arr)[_Extent]) noexcept
- : _CwFixedValue(__arr, typename _Build_index_tuple<_Extent>::__type())
- { }
-
- template<size_t... _Indices>
- constexpr
- _CwFixedValue(_Tp (&__arr)[_Extent], _Index_tuple<_Indices...>) noexcept
- : _M_data{__arr[_Indices]...}
- { }
-
- _Tp _M_data[_Extent];
- };
-
- template<typename _Tp, size_t _Extent>
- _CwFixedValue(_Tp (&)[_Extent]) -> _CwFixedValue<_Tp[_Extent]>;
-
- template<_CwFixedValue _Xv,
- typename = typename decltype(_CwFixedValue(_Xv))::__type>
+ // remove_cvref_t needed due PR117004
+ template<auto _Xv, typename = remove_cvref_t<decltype(_Xv)>>
struct constant_wrapper;
template<typename _Tp>
@@ -430,12 +396,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{ return {}; }
};
- template<_CwFixedValue _Xv, typename>
+ template<auto _Xv, typename _Vt>
struct constant_wrapper : _CwOperators
{
- static constexpr const auto& value = _Xv._M_data;
+ // Use decltype((_Xv)) instead of decltype(auto) due PR125188
+ static constexpr decltype((_Xv)) value = (_Xv);
using type = constant_wrapper;
- using value_type = typename decltype(_Xv)::__type;
+ using value_type = decltype(_Xv);
+ static_assert(is_same_v<value_type, _Vt>);
template<_ConstExprParam _Right>
constexpr auto
@@ -490,8 +458,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<auto __cw, typename _Fn>
constexpr bool __is_constant_wrapper_v<constant_wrapper<__cw, _Fn>> = true;
- template<_CwFixedValue _Tp>
- constexpr auto cw = constant_wrapper<_Tp>{};
+ template<auto _Xv>
+ constexpr auto cw = constant_wrapper<_Xv>{};
#endif
#ifdef __glibcxx_integer_sequence // C++ >= 14
diff --git a/libstdc++-v3/testsuite/20_util/constant_wrapper/generic.cc
b/libstdc++-v3/testsuite/20_util/constant_wrapper/generic.cc
index bd41fc4ca3a..f256e08fe0b 100644
--- a/libstdc++-v3/testsuite/20_util/constant_wrapper/generic.cc
+++ b/libstdc++-v3/testsuite/20_util/constant_wrapper/generic.cc
@@ -12,54 +12,6 @@ check_same(auto actual, auto expected)
static_assert(std::same_as<decltype(actual), decltype(expected)>);
};
-
-constexpr void
-test_c_arrays()
-{
- constexpr double x[] = {1.1, 2.2, 3.3};
- auto cx = std::cw<x>;
- auto access = [](auto x, size_t i)
- { return x[i]; };
-
- check_same(std::cw<x>[0], x[0]);
- check_same(std::cw<x>[1], x[1]);
- check_same(std::cw<x>[2], x[2]);
-
- check_same(cx[std::cw<0>], std::cw<x[0]>);
- check_same(cx[std::cw<1>], std::cw<x[1]>);
- check_same(cx[std::cw<2>], std::cw<x[2]>);
-}
-
-constexpr size_t
-deduce_cstr_size(auto str)
-{
- size_t sz = 0;
- while(str[sz++] != '\0') { }
- return sz;
-}
-
-constexpr void
-test_string_literals()
-{
- auto foo = std::cw<"foo">;
- constexpr const typename decltype(foo)::value_type & cstr = foo;
- constexpr size_t N = std::size(cstr);
- constexpr auto foo_view = std::string_view(cstr, N-1);
-
- constexpr const char (&cstr1)[deduce_cstr_size(foo)] = foo;
- constexpr size_t N1 = std::size(cstr);
-
- static_assert(static_cast<char const*>(cstr) ==
- static_cast<char const*>(cstr1));
- static_assert(N1 == N);
-
- static_assert(foo[0] == 'f');
- static_assert(foo[1] == 'o');
- static_assert(foo[2] == 'o');
- static_assert(foo[3] == '\0');
- static_assert(static_cast<char const *>(foo) == foo_view);
-}
-
constexpr bool
convert_constexpr(auto c)
{
@@ -93,6 +45,29 @@ test_ints()
VERIFY(two + 3 == std::cw<5>);
}
+constexpr void
+test_objects()
+{
+ if consteval {
+ return;
+ }
+
+ auto check = []<auto V>
+ {
+ auto* ptr1 = &V, *ptr2= &std::constant_wrapper<V>::value;
+ VERIFY(ptr1 == ptr2);
+ VERIFY(&V == &std::constant_wrapper<V>::value);
+ std::constant_wrapper<V> cw;
+ VERIFY(&V == &cw.value);
+ };
+
+ struct Obj
+ { int x; };
+
+ check.operator()<Obj{10}>();
+ check.operator()<Obj{20}>();
+}
+
constexpr int
add(int i, int j)
{ return i + j; }
@@ -586,12 +561,11 @@ test_assignment()
std::cw<ConstAssignable{2}>);
}
-
constexpr bool
test_all()
{
- test_c_arrays();
test_ints();
+ test_objects();
test_function_object();
test_function_pointer();
test_indexable1();
diff --git a/libstdc++-v3/testsuite/20_util/constant_wrapper/other_wrappers.cc
b/libstdc++-v3/testsuite/20_util/constant_wrapper/other_wrappers.cc
index fe45c5a8516..a5e2189ef80 100644
--- a/libstdc++-v3/testsuite/20_util/constant_wrapper/other_wrappers.cc
+++ b/libstdc++-v3/testsuite/20_util/constant_wrapper/other_wrappers.cc
@@ -30,19 +30,6 @@ test_mix_integer_constant()
check_same(w2 + c3, std::cw<5>);
}
-constexpr void
-test_array()
-{
- constexpr double x[] = {1.1, 2.2, 3.3};
- auto cx = std::cw<x>;
- auto i2 = std::integral_constant<int, 2>{};
- auto w2 = ConstWrapper<int, 2>{};
-
- check_same(x[i2], x[2]);
- check_same(cx[i2], std::cw<x[2]>);
- check_same(cx[w2], std::cw<x[2]>);
-}
-
constexpr void
test_function_object()
{
@@ -61,7 +48,6 @@ constexpr bool
test_all()
{
test_mix_integer_constant();
- test_array();
test_function_object();
return true;
}
diff --git a/libstdc++-v3/testsuite/20_util/constant_wrapper/type_param_neg.cc
b/libstdc++-v3/testsuite/20_util/constant_wrapper/type_param_neg.cc
new file mode 100644
index 00000000000..48895091611
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/constant_wrapper/type_param_neg.cc
@@ -0,0 +1,9 @@
+// { dg-do compile { target c++26 } }
+#include <utility>
+
+std::constant_wrapper<1, float> c1; // { dg-error "from here" }
+std::constant_wrapper<1.0, int> c2; // { dg-error "from here" }
+std::constant_wrapper<1, int const> c3; // { dg-error "from here" }
+std::constant_wrapper<1, int const&> c4; // { dg-error "from here" }
+
+// { dg-prune-output "static assertion failed" }
--
2.54.0
