From: Nathaniel Shead <nathanieloshead@gmail.com>
Date: Fri, 11 Nov 2022 11:23:31 +0000 (+1100)
Subject: libstdc++: Set active union member in constexpr std::string [PR103295]
X-Git-Tag: basepoints/gcc-14~3297
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=52672be7d328df50f9a05ce3ab44ebcae50fee1b;p=thirdparty%2Fgcc.git

libstdc++: Set active union member in constexpr std::string [PR103295]

Clang still complains about using std::string in constexpr contexts due
to the changes made in commit 98a0d72a. This patch ensures that we set
the active member of the union as according to [class.union.general] p6.

libstdc++-v3/ChangeLog:

	PR libstdc++/103295
	* include/bits/basic_string.h (_M_use_local_data): Set active
	member to _M_local_buf.

Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com>
---

diff --git a/libstdc++-v3/include/bits/basic_string.h b/libstdc++-v3/include/bits/basic_string.h
index 9c2b57f5a1d7..109915653af0 100644
--- a/libstdc++-v3/include/bits/basic_string.h
+++ b/libstdc++-v3/include/bits/basic_string.h
@@ -352,8 +352,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
       {
 #if __cpp_lib_is_constant_evaluated
 	if (std::is_constant_evaluated())
-	  for (_CharT& __c : _M_local_buf)
-	    __c = _CharT();
+	  for (size_type __i = 0; __i <= _S_local_capacity; ++__i)
+	    _M_local_buf[__i] = _CharT();
 #endif
 	return _M_local_data();
       }