@@ -87,7 +87,37 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
{
typedef typename __gnu_cxx::__alloc_traits<_Alloc>::template
rebind<_CharT>::other _Char_alloc_type;
+
+#if __cpp_lib_constexpr_string < 201907L
typedef __gnu_cxx::__alloc_traits<_Char_alloc_type> _Alloc_traits;
+#else
+ template<typename _Traits2, typename _Dummy_for_PR85282>
+ struct _Alloc_traits_impl : __gnu_cxx::__alloc_traits<_Char_alloc_type>
+ {
+ typedef __gnu_cxx::__alloc_traits<_Char_alloc_type> _Base;
+
+ [[__gnu__::__always_inline__]]
+ static constexpr typename _Base::pointer
+ allocate(_Char_alloc_type& __a, typename _Base::size_type __n)
+ {
+ pointer __p = _Base::allocate(__a, __n);
+ if (__builtin_is_constant_evaluated())
+ // Begin the lifetime of characters in allocated storage.
+ for (size_type __i = 0; __i < __n; ++__i)
+ std::construct_at(__builtin_addressof(__p[__i]));
+ return __p;
+ }
+ };
+
+ template<typename _Dummy_for_PR85282>
+ struct _Alloc_traits_impl<char_traits<_CharT>, _Dummy_for_PR85282>
+ : __gnu_cxx::__alloc_traits<_Char_alloc_type>
+ {
+ // std::char_traits begins the lifetime of characters.
+ };
+
+ using _Alloc_traits = _Alloc_traits_impl<_Traits, void>;
+#endif
// Types:
public:
@@ -485,7 +515,10 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
basic_string()
_GLIBCXX_NOEXCEPT_IF(is_nothrow_default_constructible<_Alloc>::value)
: _M_dataplus(_M_local_data())
- { _M_set_length(0); }
+ {
+ _M_use_local_data();
+ _M_set_length(0);
+ }
/**
* @brief Construct an empty string using allocator @a a.
@@ -494,7 +527,10 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
explicit
basic_string(const _Alloc& __a) _GLIBCXX_NOEXCEPT
: _M_dataplus(_M_local_data(), __a)
- { _M_set_length(0); }
+ {
+ _M_use_local_data();
+ _M_set_length(0);
+ }
/**
* @brief Construct string with copy of value of @a __str.
@@ -490,7 +490,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
#if __cpp_lib_is_constant_evaluated
if (__builtin_is_constant_evaluated())
{
- auto __newp = this->_M_get_allocator().allocate(__new_size);
+ auto __newp = _Alloc_traits::allocate(_M_get_allocator(),
+ __new_size);
_S_copy(__newp, this->_M_data(), __pos);
_S_copy(__newp + __pos, __s, __len2);
_S_copy(__newp + __pos + __len2, __p + __len1, __how_much);
@@ -569,6 +570,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
__p = _M_create(__n, __capacity);
this->_S_copy(__p, _M_data(), length()); // exclude trailing null
+#if __cpp_lib_is_constant_evaluated
+ if (__builtin_is_constant_evaluated())
+ traits_type::assign(__p + length(), __n - length(), _CharT());
+#endif
_M_dispose();
_M_data(__p);
_M_capacity(__n);
@@ -36,11 +36,11 @@
#pragma GCC system_header
-#include <bits/stl_algobase.h> // std::copy, std::fill_n
#include <bits/postypes.h> // For streampos
#include <cwchar> // For WEOF, wmemmove, wmemset, etc.
-#if __cplusplus > 201703L
+#if __cplusplus >= 202002L
# include <compare>
+# include <bits/stl_construct.h>
#endif
#ifndef _GLIBCXX_ALWAYS_INLINE
@@ -100,7 +100,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static _GLIBCXX14_CONSTEXPR void
assign(char_type& __c1, const char_type& __c2)
- { __c1 = __c2; }
+ {
+#if __cpp_constexpr_dynamic_alloc && __cpp_lib_is_constant_evaluated
+ if (std::is_constant_evaluated())
+ std::construct_at(__builtin_addressof(__c1), __c2);
+ else
+#endif
+ __c1 = __c2;
+ }
static _GLIBCXX_CONSTEXPR bool
eq(const char_type& __c1, const char_type& __c2)
@@ -240,8 +247,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
char_traits<_CharT>::
copy(char_type* __s1, const char_type* __s2, std::size_t __n)
{
- // NB: Inline std::copy so no recursive dependencies.
- std::copy(__s2, __s2 + __n, __s1);
+#if __cpp_lib_is_constant_evaluated
+ if (std::is_constant_evaluated())
+ {
+ for (std::size_t __i = 0; __i < __n; ++__i)
+ std::construct_at(__s1 + __i, __s2[__i]);
+ return __s1;
+ }
+#endif
+
+ __builtin_memcpy(__s1, __s2, __n * sizeof(char_type));
return __s1;
}
@@ -251,8 +266,26 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
char_traits<_CharT>::
assign(char_type* __s, std::size_t __n, char_type __a)
{
- // NB: Inline std::fill_n so no recursive dependencies.
- std::fill_n(__s, __n, __a);
+#if __cpp_lib_is_constant_evaluated
+ if (std::is_constant_evaluated())
+ {
+ for (std::size_t __i = 0; __i < __n; ++__i)
+ std::construct_at(__s + __i, __a);
+ return __s;
+ }
+#endif
+
+ if _GLIBCXX17_CONSTEXPR (sizeof(_CharT) == 1 && __is_trivial(_CharT))
+ {
+ unsigned char __c;
+ __builtin_memcpy(&__c, __builtin_addressof(__a), 1);
+ __builtin_memset(__s, __c, __n);
+ }
+ else
+ {
+ for (std::size_t __i = 0; __i < __n; ++__i)
+ __s[__i] = __a;
+ }
return __s;
}
@@ -304,7 +337,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static _GLIBCXX17_CONSTEXPR void
assign(char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
- { __c1 = __c2; }
+ {
+#if __cpp_constexpr_dynamic_alloc && __cpp_lib_is_constant_evaluated
+ if (std::is_constant_evaluated())
+ std::construct_at(__builtin_addressof(__c1), __c2);
+ else
+#endif
+ __c1 = __c2;
+ }
static _GLIBCXX_CONSTEXPR bool
eq(const char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
@@ -435,7 +475,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static _GLIBCXX17_CONSTEXPR void
assign(char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
- { __c1 = __c2; }
+ {
+#if __cpp_constexpr_dynamic_alloc && __cpp_lib_is_constant_evaluated
+ if (std::is_constant_evaluated())
+ std::construct_at(__builtin_addressof(__c1), __c2);
+ else
+#endif
+ __c1 = __c2;
+ }
static _GLIBCXX_CONSTEXPR bool
eq(const char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
@@ -556,7 +603,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static _GLIBCXX17_CONSTEXPR void
assign(char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
- { __c1 = __c2; }
+ {
+#if __cpp_constexpr_dynamic_alloc && __cpp_lib_is_constant_evaluated
+ if (std::is_constant_evaluated())
+ std::construct_at(__builtin_addressof(__c1), __c2);
+ else
+#endif
+ __c1 = __c2;
+ }
static _GLIBCXX_CONSTEXPR bool
eq(const char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
@@ -692,7 +746,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static _GLIBCXX17_CONSTEXPR void
assign(char_type& __c1, const char_type& __c2) noexcept
- { __c1 = __c2; }
+ {
+#if __cpp_constexpr_dynamic_alloc && __cpp_lib_is_constant_evaluated
+ if (std::is_constant_evaluated())
+ std::construct_at(__builtin_addressof(__c1), __c2);
+ else
+#endif
+ __c1 = __c2;
+ }
static constexpr bool
eq(const char_type& __c1, const char_type& __c2) noexcept
@@ -806,7 +867,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static _GLIBCXX17_CONSTEXPR void
assign(char_type& __c1, const char_type& __c2) noexcept
- { __c1 = __c2; }
+ {
+#if __cpp_constexpr_dynamic_alloc && __cpp_lib_is_constant_evaluated
+ if (std::is_constant_evaluated())
+ std::construct_at(__builtin_addressof(__c1), __c2);
+ else
+#endif
+ __c1 = __c2;
+ }
static constexpr bool
eq(const char_type& __c1, const char_type& __c2) noexcept
@@ -38,6 +38,7 @@
#include <ext/vstring_util.h>
#include <ext/rc_string_base.h>
#include <ext/sso_string_base.h>
+#include <bits/stl_algobase.h> // std::min
namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
{
@@ -39,9 +39,11 @@
#include <iosfwd>
#include <bits/char_traits.h>
+#include <bits/functexcept.h>
#include <bits/functional_hash.h>
#include <bits/range_access.h>
#include <bits/ostream_insert.h>
+#include <bits/stl_algobase.h>
#include <ext/numeric_traits.h>
#if __cplusplus >= 202002L
@@ -105,10 +105,24 @@ test04()
}
}
+constexpr bool
+test05()
+{
+ std::string s;
+ s.resize_and_overwrite(20, [](char* p, auto n) {
+ *p = '!'; // direct assignment should be OK
+ std::char_traits<char>::copy(p, "constexpr", 9);
+ return 9;
+ });
+ VERIFY( s == "constexpr" );
+ return true;
+}
+
int main()
{
test01();
test02();
test03();
test04();
+ static_assert( test05() );
}