From: Jonathan Wakely <jwakely@redhat.com>
Date: Tue, 5 Oct 2021 15:38:42 +0000 (+0100)
Subject: libstdc++: Ensure std::span and std::string_view are trivially copyable (P2251R1)
X-Git-Tag: basepoints/gcc-13~4119
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1f51e9af7b615838424214e6aaea0de793cb10fe;p=thirdparty%2Fgcc.git

libstdc++: Ensure std::span and std::string_view are trivially copyable (P2251R1)

The recently approved P2251R1 paper requires these types to be trivially
copyable. They always have been in libstdc++, but add tests to check it.

libstdc++-v3/ChangeLog:

	* testsuite/21_strings/basic_string_view/requirements/trivially_copyable.cc:
	New test.
	* testsuite/23_containers/span/trivially_copyable.cc: New test.
---

diff --git a/libstdc++-v3/testsuite/21_strings/basic_string_view/requirements/trivially_copyable.cc b/libstdc++-v3/testsuite/21_strings/basic_string_view/requirements/trivially_copyable.cc
new file mode 100644
index 000000000000..3f2589c61d8b
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string_view/requirements/trivially_copyable.cc
@@ -0,0 +1,11 @@
+// { dg-do compile { target c++17 } }
+
+// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2251r1.pdf
+
+#include <string_view>
+
+static_assert( std::is_trivially_copyable_v<std::string_view> );
+static_assert( std::is_trivially_copyable_v<std::wstring_view> );
+
+struct traits : std::char_traits<char> { };
+static_assert( std::is_trivially_copyable_v<std::basic_string_view<char, traits>> );
diff --git a/libstdc++-v3/testsuite/23_containers/span/trivially_copyable.cc b/libstdc++-v3/testsuite/23_containers/span/trivially_copyable.cc
new file mode 100644
index 000000000000..e37482935550
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/span/trivially_copyable.cc
@@ -0,0 +1,13 @@
+// { dg-options "-std=gnu++20" }
+// { dg-do compile { target c++20 } }
+
+// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2251r1.pdf
+
+#include <span>
+
+static_assert( std::is_trivially_copyable_v<std::span<int>> );
+static_assert( std::is_trivially_copyable_v<std::span<int, 42>> );
+
+struct NonTrivial { NonTrivial(); NonTrivial(const NonTrivial&); };
+static_assert( std::is_trivially_copyable_v<std::span<NonTrivial>> );
+static_assert( std::is_trivially_copyable_v<std::span<NonTrivial, 99>> );