From: Jonathan Wakely <jwakely@redhat.com>
Date: Tue, 19 Oct 2021 10:53:27 +0000 (+0100)
Subject: libstdc++: Change std::variant union member to empty struct
X-Git-Tag: basepoints/gcc-13~3805
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5a8832b1659e311437d25b7ec8b078be27ae54b8;p=thirdparty%2Fgcc.git

libstdc++: Change std::variant union member to empty struct

This more clearly expresses the intent (a completely unused, trivial
type) than using char. It's also consistent with the unions in
std::optional.

libstdc++-v3/ChangeLog:

	* include/std/variant (_Uninitialized): Use an empty struct
	for the unused union member, instead of char.
---

diff --git a/libstdc++-v3/include/std/variant b/libstdc++-v3/include/std/variant
index d18365fde22d..3da7dad1e829 100644
--- a/libstdc++-v3/include/std/variant
+++ b/libstdc++-v3/include/std/variant
@@ -293,8 +293,10 @@ namespace __variant
       constexpr _Type&& _M_get() && noexcept
       { return std::move(_M_storage); }
 
+      struct _Empty_byte { };
+
       union {
-	char _M_nope;
+	_Empty_byte _M_empty;
 	_Type _M_storage;
       };
 #else