libstdc++: Fix tests broken by C++23 P2266R3 "Simpler implicit move"

In C++23 mode these tests started to FAIL because an rvalue reference
parameter can no longer be bound to an lvalue reference return type. As
confirmed by Ville (who added these tests) the problem overloads are not
intended to be called, and only exist to verify that they don't
interfere with the intended behaviour. This changes the function bodies
to just throw, so that the tests will fail if the function is called.

libstdc++-v3/ChangeLog:

	* testsuite/27_io/basic_ostream/inserters_other/char/6.cc:
	Change body of unused operator<< overload to throw if called.
	* testsuite/27_io/basic_ostream/inserters_other/wchar_t/6.cc:
	Likewise.

2 files changed, 2 insertions, 2 deletions

diff --git a/libstdc++-v3/testsuite/27_io/basic_ostream/inserters_other/char/6.cc b/libstdc++-v3/testsuite/27_io/basic_ostream/inserters_other/char/6.cc
index f62023c..e45af3c 100644
--- a/libstdc++-v3/testsuite/27_io/basic_ostream/inserters_other/char/6.cc
+++ b/libstdc++-v3/testsuite/27_io/basic_ostream/inserters_other/char/6.cc
@@ -42,7 +42,7 @@ std::ostream& operator<<(std::ostream&, const X&) = delete;
 
 struct Y {};
 std::ostream& operator<<(std::ostream& os, const Y&) {return os;}
-std::ostream& operator<<(std::ostream&& os, const Y&) {return os;}
+std::ostream& operator<<(std::ostream&& os, const Y&) {throw 1;} // not used
 
 struct Z{};
 
diff --git a/libstdc++-v3/testsuite/27_io/basic_ostream/inserters_other/wchar_t/6.cc b/libstdc++-v3/testsuite/27_io/basic_ostream/inserters_other/wchar_t/6.cc
index 6bbf4a7..7ef6442 100644
--- a/libstdc++-v3/testsuite/27_io/basic_ostream/inserters_other/wchar_t/6.cc
+++ b/libstdc++-v3/testsuite/27_io/basic_ostream/inserters_other/wchar_t/6.cc
@@ -42,7 +42,7 @@ std::wostream& operator<<(std::wostream&, const X&) = delete;
 
 struct Y {};
 std::wostream& operator<<(std::wostream& os, const Y&) {return os;}
-std::wostream& operator<<(std::wostream&& os, const Y&) {return os;}
+std::wostream& operator<<(std::wostream&& os, const Y&) {throw 1;} // not used
 
 struct Z{};