First of all, the redo of the iterator portion in response to
https://gcc.gnu.org/ml/gcc-patches/2019-11/msg01467.html passed testing.
This patch contains constexpr char_traits. I also found an old extension
that had been left out of the constexpr bandwagon that I caught up.
This patch also includes constexpr string_view::copy which depends on
teh type_traits.
This gets all of p1032 except string::copy (although constexpr
char_traits should almost enable this too once constexpr string is in).
I'm done.
This passes on x86_64-linux.
OK?
2019-11-16 Edward Smith-Rowland <3dw...@verizon.net>
Implement the char_traits and string_view part of C++20 p1032 Misc.
constexpr bits.
* include/bits/char_traits.h (move, copy, assign): Constexpr.
* include/bits/stl_algobase.h (__memcpy, __memset): New.
* include/ext/pod_char_traits.h (from, to, operator==, operator<)
(assign, eq, lt, compare, length, find, move, copy, assign)
(to_char_type, to_int_type, eq_int_type, eof, not_eof):
Make these constespr for appropriate standards.
* testsuite/21_strings/char_traits/requirements/char/constexpr.cc: New test.
* testsuite/21_strings/char_traits/requirements/wchar_t/constexpr.cc: New test.
* include/std/string_view (copy): Constexpr.
* testsuite/21_strings/basic_string_view/operations/copy/char/constexpr.cc: New test.
* testsuite/21_strings/basic_string_view/operations/copy/wchar_t/constexpr.cc: New test.
Index: include/bits/char_traits.h
===================================================================
--- include/bits/char_traits.h (revision 278318)
+++ include/bits/char_traits.h (working copy)
@@ -113,13 +113,13 @@
static _GLIBCXX14_CONSTEXPR const char_type*
find(const char_type* __s, std::size_t __n, const char_type& __a);
- static char_type*
+ static _GLIBCXX20_CONSTEXPR char_type*
move(char_type* __s1, const char_type* __s2, std::size_t __n);
- static char_type*
+ static _GLIBCXX20_CONSTEXPR char_type*
copy(char_type* __s1, const char_type* __s2, std::size_t __n);
- static char_type*
+ static _GLIBCXX20_CONSTEXPR char_type*
assign(char_type* __s, std::size_t __n, char_type __a);
static _GLIBCXX_CONSTEXPR char_type
@@ -179,18 +179,17 @@
}
template<typename _CharT>
- typename char_traits<_CharT>::char_type*
+ _GLIBCXX20_CONSTEXPR typename char_traits<_CharT>::char_type*
char_traits<_CharT>::
move(char_type* __s1, const char_type* __s2, std::size_t __n)
{
if (__n == 0)
return __s1;
- return static_cast<_CharT*>(__builtin_memmove(__s1, __s2,
- __n * sizeof(char_type)));
+ return static_cast<_CharT*>(std::__memmove<true>(__s1, __s2, __n));
}
template<typename _CharT>
- typename char_traits<_CharT>::char_type*
+ _GLIBCXX20_CONSTEXPR typename char_traits<_CharT>::char_type*
char_traits<_CharT>::
copy(char_type* __s1, const char_type* __s2, std::size_t __n)
{
@@ -200,7 +199,7 @@
}
template<typename _CharT>
- typename char_traits<_CharT>::char_type*
+ _GLIBCXX20_CONSTEXPR typename char_traits<_CharT>::char_type*
char_traits<_CharT>::
assign(char_type* __s, std::size_t __n, char_type __a)
{
@@ -349,28 +348,28 @@
return static_cast<const char_type*>(__builtin_memchr(__s, __a, __n));
}
- static char_type*
+ static _GLIBCXX20_CONSTEXPR char_type*
move(char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
return __s1;
- return static_cast<char_type*>(__builtin_memmove(__s1, __s2, __n));
+ return static_cast<char_type*>(std::__memmove<true>(__s1, __s2, __n));
}
- static char_type*
+ static _GLIBCXX20_CONSTEXPR char_type*
copy(char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
return __s1;
- return static_cast<char_type*>(__builtin_memcpy(__s1, __s2, __n));
+ return static_cast<char_type*>(std::__memcpy(__s1, __s2, __n));
}
- static char_type*
+ static _GLIBCXX20_CONSTEXPR char_type*
assign(char_type* __s, size_t __n, char_type __a)
{
if (__n == 0)
return __s;
- return static_cast<char_type*>(__builtin_memset(__s, __a, __n));
+ return static_cast<char_type*>(std::__memset(__s, __a, __n));
}
static _GLIBCXX_CONSTEXPR char_type
@@ -458,27 +457,42 @@
return wmemchr(__s, __a, __n);
}
- static char_type*
+ static _GLIBCXX20_CONSTEXPR char_type*
move(char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
return __s1;
+#ifdef __cpp_lib_is_constant_evaluated
+ if (std::is_constant_evaluated())
+ return static_cast<char_type*>(std::__memmove<true>(__s1, __s2, __n));
+ else
+#endif
return wmemmove(__s1, __s2, __n);
}
- static char_type*
+ static _GLIBCXX20_CONSTEXPR char_type*
copy(char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
return __s1;
+#ifdef __cpp_lib_is_constant_evaluated
+ if (std::is_constant_evaluated())
+ return static_cast<char_type*>(std::__memcpy(__s1, __s2, __n));
+ else
+#endif
return wmemcpy(__s1, __s2, __n);
}
- static char_type*
+ static _GLIBCXX20_CONSTEXPR char_type*
assign(char_type* __s, size_t __n, char_type __a)
{
if (__n == 0)
return __s;
+#ifdef __cpp_lib_is_constant_evaluated
+ if (std::is_constant_evaluated())
+ return static_cast<char_type*>(std::__memset(__s, __a, __n));
+ else
+#endif
return wmemset(__s, __a, __n);
}
@@ -567,28 +581,28 @@
return static_cast<const char_type*>(__builtin_memchr(__s, __a, __n));
}
- static char_type*
+ static _GLIBCXX20_CONSTEXPR char_type*
move(char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
return __s1;
- return static_cast<char_type*>(__builtin_memmove(__s1, __s2, __n));
+ return static_cast<char_type*>(std::__memmove<true>(__s1, __s2, __n));
}
- static char_type*
+ static _GLIBCXX20_CONSTEXPR char_type*
copy(char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
return __s1;
- return static_cast<char_type*>(__builtin_memcpy(__s1, __s2, __n));
+ return static_cast<char_type*>(std::__memcpy(__s1, __s2, __n));
}
- static char_type*
+ static _GLIBCXX20_CONSTEXPR char_type*
assign(char_type* __s, size_t __n, char_type __a)
{
if (__n == 0)
return __s;
- return static_cast<char_type*>(__builtin_memset(__s, __a, __n));
+ return static_cast<char_type*>(std::__memset(__s, __a, __n));
}
static _GLIBCXX_CONSTEXPR char_type
@@ -680,25 +694,23 @@
return 0;
}
- static char_type*
+ static _GLIBCXX20_CONSTEXPR char_type*
move(char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
return __s1;
- return (static_cast<char_type*>
- (__builtin_memmove(__s1, __s2, __n * sizeof(char_type))));
+ return static_cast<char_type*>(std::__memmove<true>(__s1, __s2, __n));
}
- static char_type*
+ static _GLIBCXX20_CONSTEXPR char_type*
copy(char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
return __s1;
- return (static_cast<char_type*>
- (__builtin_memcpy(__s1, __s2, __n * sizeof(char_type))));
+ return static_cast<char_type*>(std::__memcpy(__s1, __s2, __n));
}
- static char_type*
+ static _GLIBCXX20_CONSTEXPR char_type*
assign(char_type* __s, size_t __n, char_type __a)
{
for (size_t __i = 0; __i < __n; ++__i)
@@ -783,25 +795,23 @@
return 0;
}
- static char_type*
+ static _GLIBCXX20_CONSTEXPR char_type*
move(char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
return __s1;
- return (static_cast<char_type*>
- (__builtin_memmove(__s1, __s2, __n * sizeof(char_type))));
+ return (static_cast<char_type*>(std::__memmove<true>(__s1, __s2, __n)));
}
- static char_type*
+ static _GLIBCXX20_CONSTEXPR char_type*
copy(char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
return __s1;
- return (static_cast<char_type*>
- (__builtin_memcpy(__s1, __s2, __n * sizeof(char_type))));
+ return (static_cast<char_type*>(std::__memcpy(__s1, __s2, __n)));
}
- static char_type*
+ static _GLIBCXX20_CONSTEXPR char_type*
assign(char_type* __s, size_t __n, char_type __a)
{
for (size_t __i = 0; __i < __n; ++__i)
Index: include/bits/stl_algobase.h
===================================================================
--- include/bits/stl_algobase.h (revision 278318)
+++ include/bits/stl_algobase.h (working copy)
@@ -107,6 +107,50 @@
}
/*
+ * A constexpr wrapper for __builtin_memmove.
+ * @param __num The number of elements of type _Tp (not bytes).
+ */
+ template<typename _Tp>
+ _GLIBCXX14_CONSTEXPR
+ inline void*
+ __memcpy(_Tp* __dst, const _Tp* __src, size_t __num)
+ {
+#ifdef __cpp_lib_is_constant_evaluated
+ if (std::is_constant_evaluated())
+ {
+ for(; __num > 0; --__num)
+ *__dst++ = *__src++;
+ return __dst;
+ }
+ else
+#endif
+ return __builtin_memcpy(__dst, __src, sizeof(_Tp) * __num);
+ return __dst;
+ }
+
+ /*
+ * A constexpr wrapper for __builtin_memmove.
+ * @param __num The number of elements of type _Tp (not bytes).
+ */
+ template<typename _Tp>
+ _GLIBCXX14_CONSTEXPR
+ inline void*
+ __memset(_Tp* __dst, _Tp __a, size_t __num)
+ {
+#ifdef __cpp_lib_is_constant_evaluated
+ if (std::is_constant_evaluated())
+ {
+ for(; __num > 0; --__num)
+ *__dst = __a;
+ return __dst;
+ }
+ else
+#endif
+ return __builtin_memset(__dst, __a, sizeof(_Tp) * __num);
+ return __dst;
+ }
+
+ /*
* A constexpr wrapper for __builtin_memcmp.
* @param __num The number of elements of type _Tp (not bytes).
*/
Index: include/ext/pod_char_traits.h
===================================================================
--- include/ext/pod_char_traits.h (revision 278318)
+++ include/ext/pod_char_traits.h (working copy)
@@ -56,7 +56,7 @@
value_type value;
template<typename V2>
- static char_type
+ static _GLIBCXX_CONSTEXPR char_type
from(const V2& v)
{
char_type ret = { static_cast<value_type>(v) };
@@ -64,7 +64,7 @@
}
template<typename V2>
- static V2
+ static _GLIBCXX_CONSTEXPR V2
to(const char_type& c)
{
V2 ret = { static_cast<V2>(c.value) };
@@ -74,13 +74,13 @@
};
template<typename _Value, typename _Int, typename _St>
- inline bool
+ inline _GLIBCXX_CONSTEXPR bool
operator==(const character<_Value, _Int, _St>& lhs,
const character<_Value, _Int, _St>& rhs)
{ return lhs.value == rhs.value; }
template<typename _Value, typename _Int, typename _St>
- inline bool
+ inline _GLIBCXX_CONSTEXPR bool
operator<(const character<_Value, _Int, _St>& lhs,
const character<_Value, _Int, _St>& rhs)
{ return lhs.value < rhs.value; }
@@ -102,19 +102,19 @@
typedef fpos<state_type> pos_type;
typedef streamoff off_type;
- static void
+ static _GLIBCXX14_CONSTEXPR void
assign(char_type& __c1, const char_type& __c2)
{ __c1 = __c2; }
- static bool
+ static _GLIBCXX_CONSTEXPR bool
eq(const char_type& __c1, const char_type& __c2)
{ return __c1 == __c2; }
- static bool
+ static _GLIBCXX_CONSTEXPR bool
lt(const char_type& __c1, const char_type& __c2)
{ return __c1 < __c2; }
- static int
+ static _GLIBCXX14_CONSTEXPR int
compare(const char_type* __s1, const char_type* __s2, size_t __n)
{
for (size_t __i = 0; __i < __n; ++__i)
@@ -123,7 +123,7 @@
return 0;
}
- static size_t
+ static _GLIBCXX14_CONSTEXPR size_t
length(const char_type* __s)
{
const char_type* __p = __s;
@@ -132,7 +132,7 @@
return (__p - __s);
}
- static const char_type*
+ static _GLIBCXX14_CONSTEXPR const char_type*
find(const char_type* __s, size_t __n, const char_type& __a)
{
for (const char_type* __p = __s; size_t(__p - __s) < __n; ++__p)
@@ -141,7 +141,7 @@
return 0;
}
- static char_type*
+ static _GLIBCXX20_CONSTEXPR char_type*
move(char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
@@ -150,7 +150,7 @@
(__builtin_memmove(__s1, __s2, __n * sizeof(char_type)));
}
- static char_type*
+ static _GLIBCXX20_CONSTEXPR char_type*
copy(char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
@@ -159,7 +159,7 @@
return __s1;
}
- static char_type*
+ static _GLIBCXX20_CONSTEXPR char_type*
assign(char_type* __s, size_t __n, char_type __a)
{
std::fill_n(__s, __n, __a);
@@ -166,19 +166,19 @@
return __s;
}
- static char_type
+ static _GLIBCXX_CONSTEXPR char_type
to_char_type(const int_type& __i)
{ return char_type::template from(__i); }
- static int_type
+ static _GLIBCXX_CONSTEXPR int_type
to_int_type(const char_type& __c)
{ return char_type::template to<int_type>(__c); }
- static bool
+ static _GLIBCXX_CONSTEXPR bool
eq_int_type(const int_type& __c1, const int_type& __c2)
{ return __c1 == __c2; }
- static int_type
+ static _GLIBCXX_CONSTEXPR int_type
eof()
{
int_type __r = { static_cast<typename __gnu_cxx::__conditional_type
@@ -187,7 +187,7 @@
return __r;
}
- static int_type
+ static _GLIBCXX_CONSTEXPR int_type
not_eof(const int_type& __c)
{ return eq_int_type(__c, eof()) ? int_type() : __c; }
};
Index: testsuite/21_strings/char_traits/requirements/char/constexpr.cc
===================================================================
--- testsuite/21_strings/char_traits/requirements/char/constexpr.cc (nonexistent)
+++ testsuite/21_strings/char_traits/requirements/char/constexpr.cc (working copy)
@@ -0,0 +1,42 @@
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+//
+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+#include <string>
+
+constexpr bool
+test()
+{
+ auto ok = true;
+
+ char casv[8]{"ello, W"};
+
+ char das[8]{};
+ std::char_traits<char>::move(das, casv, 7);
+ std::char_traits<char>::copy(das, casv, 7);
+ std::char_traits<char>::assign(das, 7, 'x');
+
+ return ok;
+}
+
+int
+main()
+{
+ static_assert(test());
+}
Index: testsuite/21_strings/char_traits/requirements/wchar_t/constexpr.cc
===================================================================
--- testsuite/21_strings/char_traits/requirements/wchar_t/constexpr.cc (nonexistent)
+++ testsuite/21_strings/char_traits/requirements/wchar_t/constexpr.cc (working copy)
@@ -0,0 +1,42 @@
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+//
+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+#include <string>
+
+constexpr bool
+test()
+{
+ auto ok = true;
+
+ wchar_t cawsv[8]{L"ello, W"};
+
+ wchar_t wdas[8]{};
+ std::char_traits<wchar_t>::move(wdas, cawsv, 7);
+ std::char_traits<wchar_t>::copy(wdas, cawsv, 7);
+ std::char_traits<wchar_t>::assign(wdas, 7, L'x');
+
+ return ok;
+}
+
+int
+main()
+{
+ static_assert(test());
+}
Index: include/std/string_view
===================================================================
--- include/std/string_view (revision 278318)
+++ include/std/string_view (working copy)
@@ -252,6 +252,7 @@
// [string.view.ops], string operations:
+ _GLIBCXX20_CONSTEXPR
size_type
copy(_CharT* __str, size_type __n, size_type __pos = 0) const
{
Index: testsuite/21_strings/basic_string_view/operations/copy/char/constexpr.cc
===================================================================
--- testsuite/21_strings/basic_string_view/operations/copy/char/constexpr.cc (nonexistent)
+++ testsuite/21_strings/basic_string_view/operations/copy/char/constexpr.cc (working copy)
@@ -0,0 +1,37 @@
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+//
+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+#include <string_view>
+
+constexpr bool
+test_string_view()
+{
+ auto ok = true;
+
+ constexpr std::string_view sv = "Hello, World!!!";
+ char casv[8]{};
+ sv.copy(casv, 7, 1);
+
+ ok = ok && (casv[0] == 'e');
+
+ return ok;
+}
+
+static_assert(test_string_view());
Index: testsuite/21_strings/basic_string_view/operations/copy/wchar_t/constexpr.cc
===================================================================
--- testsuite/21_strings/basic_string_view/operations/copy/wchar_t/constexpr.cc (nonexistent)
+++ testsuite/21_strings/basic_string_view/operations/copy/wchar_t/constexpr.cc (working copy)
@@ -0,0 +1,37 @@
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+//
+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+#include <string_view>
+
+constexpr bool
+test_string_view()
+{
+ auto ok = true;
+
+ constexpr std::wstring_view wsv = L"Hello, World!!!";
+ wchar_t cawsv[8]{};
+ wsv.copy(cawsv, 7, 1);
+
+ ok = ok && (cawsv[0] == L'e');
+
+ return ok;
+}
+
+static_assert(test_string_view());
