libstdc++: Remove non-void static assertions in variant's std::get [PR111172]

A void template argument would cause a substitution failure when trying
to form a reference for the return type, so the function body would
never be instantiated.

libstdc++-v3/ChangeLog:

	PR libstdc++/111172
	* include/std/variant (get<T>): Remove !is_void static
	assertions.

diff --git a/libstdc++-v3/include/std/variant b/libstdc++-v3/include/std/variant
index 7cb7c3b1d4d99997fff71c76f57e247324402fab..36eec8d829bb3cccdeb0379c84848a27b5dd0d77 100644 (file)
--- a/libstdc++-v3/include/std/variant
+++ b/libstdc++-v3/include/std/variant
@@ -1123,7 +1123,6 @@ namespace __variant
     {
       static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
                    "T must occur exactly once in alternatives");
-      static_assert(!is_void_v<_Tp>, "_Tp must not be void");
       constexpr size_t __n = std::__find_uniq_type_in_pack<_Tp, _Types...>();
       return std::get<__n>(__v);
     }
@@ -1134,7 +1133,6 @@ namespace __variant
     {
       static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
                    "T must occur exactly once in alternatives");
-      static_assert(!is_void_v<_Tp>, "_Tp must not be void");
       constexpr size_t __n = std::__find_uniq_type_in_pack<_Tp, _Types...>();
       return std::get<__n>(std::move(__v));
     }
@@ -1145,7 +1143,6 @@ namespace __variant
     {
       static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
                    "T must occur exactly once in alternatives");
-      static_assert(!is_void_v<_Tp>, "_Tp must not be void");
       constexpr size_t __n = std::__find_uniq_type_in_pack<_Tp, _Types...>();
       return std::get<__n>(__v);
     }
@@ -1156,7 +1153,6 @@ namespace __variant
     {
       static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
                    "T must occur exactly once in alternatives");
-      static_assert(!is_void_v<_Tp>, "_Tp must not be void");
       constexpr size_t __n = std::__find_uniq_type_in_pack<_Tp, _Types...>();
       return std::get<__n>(std::move(__v));
     }