libstdc++: port away from is_trivial in string classes

In preparation for the deprecation of is_trivial (P3247R2), stop using
it from std::string_view. Also, add the same detection to std::string
(described in [strings.general]/2).

libstdc++-v3/ChangeLog:

	* include/bits/basic_string.h: Add a static_assert on the
	char-like type.
	* include/std/string_view: Port away from is_trivial.

Signed-off-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>

diff --git a/libstdc++-v3/include/bits/basic_string.h b/libstdc++-v3/include/bits/basic_string.h
index 17b973c8b45c5c56884649c4070af4380b2f4ca7..8369c24d3ae3eed4bce189fc45e310ecb4e1ff9a 100644 (file)
--- a/libstdc++-v3/include/bits/basic_string.h
+++ b/libstdc++-v3/include/bits/basic_string.h
@@ -88,6 +88,9 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
     class basic_string
     {
 #if __cplusplus >= 202002L
+      static_assert(is_trivially_copyable_v<_CharT>
+         && is_trivially_default_constructible_v<_CharT>
+         && is_standard_layout_v<_CharT>);
       static_assert(is_same_v<_CharT, typename _Traits::char_type>);
       static_assert(is_same_v<_CharT, typename _Alloc::value_type>);
       using _Char_alloc_type = _Alloc;

diff --git a/libstdc++-v3/include/std/string_view b/libstdc++-v3/include/std/string_view
index 96350f96b3c0deb667ac5bc6e38ba6baf861b03c..493edec26dc8180554ffd5dcce5457b30d9facf3 100644 (file)
--- a/libstdc++-v3/include/std/string_view
+++ b/libstdc++-v3/include/std/string_view
@@ -108,7 +108,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     class basic_string_view
     {
       static_assert(!is_array_v<_CharT>);
-      static_assert(is_trivial_v<_CharT> && is_standard_layout_v<_CharT>);
+      static_assert(is_trivially_copyable_v<_CharT>
+         && is_trivially_default_constructible_v<_CharT>
+         && is_standard_layout_v<_CharT>);
       static_assert(is_same_v<_CharT, typename _Traits::char_type>);
 
     public: