[committed] libstdc++: Fix -Wmaybe-uninitialized false positive [PR103984]

[Jonathan Wakely via Gcc-patches]

Tested powerpc64le-linux, pushed to trunk.

-- >8 --

This fixes a false positive warning seen with LTO:

12/bits/regex_compiler.tcc:443:32: error: '__last_char._M_char' may be used 
uninitialized [-Werror=maybe-uninitialized]

Given that the std::regex code is not very efficient anyway, the
overhead of initializing this byte should be minimal.

libstdc++-v3/ChangeLog:

        PR middle-end/103984
        * include/bits/regex_compiler.h (_BracketMatcher::_M_char): Use
        default member initializer.
---
 libstdc++-v3/include/bits/regex_compiler.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libstdc++-v3/include/bits/regex_compiler.h 
b/libstdc++-v3/include/bits/regex_compiler.h
index 174aefe75f7..348c170c81a 100644
--- a/libstdc++-v3/include/bits/regex_compiler.h
+++ b/libstdc++-v3/include/bits/regex_compiler.h
@@ -125,7 +125,7 @@ namespace __detail
       struct _BracketState
       {
        enum class _Type : char { _None, _Char, _Class } _M_type = _Type::_None;
-       _CharT _M_char;
+       _CharT _M_char = _CharT();
 
        void
        set(_CharT __c) noexcept { _M_type = _Type::_Char; _M_char = __c; }
-- 
2.34.1