From: Jonathan Wakely <jwakely@redhat.com>
Date: Wed, 9 Aug 2023 10:11:31 +0000 (+0100)
Subject: libstdc++: Fix constexpr functions to conform to older standards
X-Git-Tag: releases/gcc-11.5.0~562
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=27bad57576ca73988038d2c56e0dcbc22606900c;p=thirdparty%2Fgcc.git

libstdc++: Fix constexpr functions to conform to older standards

Some constexpr functions were inadvertently relying on relaxed constexpr
rules from later standards.

libstdc++-v3/ChangeLog:

	* include/experimental/bits/fs_path.h (path::string): Use
	_GLIBCXX17_CONSTEXPR not _GLIBCXX_CONSTEXPR for 'if constexpr'.
	* include/std/charconv (__to_chars_8): Initialize variable for
	C++17 constexpr rules.

(cherry picked from commit b3a2b307b9deea719fb725a86df43b82176fe459)
---

diff --git a/libstdc++-v3/include/experimental/bits/fs_path.h b/libstdc++-v3/include/experimental/bits/fs_path.h
index 65d63e433e08..50e470827142 100644
--- a/libstdc++-v3/include/experimental/bits/fs_path.h
+++ b/libstdc++-v3/include/experimental/bits/fs_path.h
@@ -1020,7 +1020,7 @@ namespace __detail
     inline std::basic_string<_CharT, _Traits, _Allocator>
     path::string(const _Allocator& __a) const
     {
-      if _GLIBCXX_CONSTEXPR (is_same<_CharT, value_type>::value)
+      if _GLIBCXX17_CONSTEXPR (is_same<_CharT, value_type>::value)
 	return { _M_pathname.begin(), _M_pathname.end(), __a };
 
       using _WString = basic_string<_CharT, _Traits, _Allocator>;
diff --git a/libstdc++-v3/include/std/charconv b/libstdc++-v3/include/std/charconv
index 65f923993fa3..dc93c4c07bbc 100644
--- a/libstdc++-v3/include/std/charconv
+++ b/libstdc++-v3/include/std/charconv
@@ -235,7 +235,7 @@ namespace __detail
       static_assert(is_unsigned<_Tp>::value, "implementation bug");
 
       to_chars_result __res;
-      unsigned __len;
+      unsigned __len = 0;
 
       if _GLIBCXX17_CONSTEXPR (__gnu_cxx::__int_traits<_Tp>::__digits <= 16)
 	{