[PATCH] PR libstdc++/85843 fix "should be explicitly initialized" warnings

[Jonathan Wakely]

        PR libstdc++/85843
        * src/c++11/cow-stdexcept.cc (logic_error, runtime_error): Explicitly
        initialize base class to avoid warnings.

Tested powerpc64le-linux, committed to trunk.



commit e64c045676caee3153d62bdaaf207bb331f10d3d
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Mon May 21 00:24:05 2018 +0100

    PR libstdc++/85843 fix "should be explicitly initialized" warnings
    
            PR libstdc++/85843
            * src/c++11/cow-stdexcept.cc (logic_error, runtime_error): 
Explicitly
            initialize base class to avoid warnings.

diff --git a/libstdc++-v3/src/c++11/cow-stdexcept.cc 
b/libstdc++-v3/src/c++11/cow-stdexcept.cc
index 7b42da1e133..5ad3d94ae31 100644
--- a/libstdc++-v3/src/c++11/cow-stdexcept.cc
+++ b/libstdc++-v3/src/c++11/cow-stdexcept.cc
@@ -56,13 +56,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   // Copy constructors and assignment operators defined using COW std::string
 
   logic_error::logic_error(const logic_error& e) noexcept
-  : _M_msg(e._M_msg) { }
+  : exception(e), _M_msg(e._M_msg) { }
 
   logic_error& logic_error::operator=(const logic_error& e) noexcept
   { _M_msg = e._M_msg; return *this; }
 
   runtime_error::runtime_error(const runtime_error& e) noexcept
-  : _M_msg(e._M_msg) { }
+  : exception(e), _M_msg(e._M_msg) { }
 
   runtime_error&
   runtime_error::operator=(const runtime_error& e) noexcept