Steps to reproduce on xenial (or probably bionic as well):
apt update && apt install curl wget htop git vim ccache build-essential libtool autotools-dev automake pkg-config bsdmainutils libssl-dev libevent-dev libboost-all-dev clang libqt5gui5 libqt5core5a libqt5dbus5 qttools5-dev qttools5-dev-tools libprotobuf-dev protobuf-compiler libdb5.3++-dev -y
git clone https://github.com/bitcoin/bitcoin.git && cd bitcoin && git checkout master
./autogen.sh && ./configure --with-incompatible-bdb CC=clang CXX=clang++ && make -j 9
Making all in src
make[1]: Entering directory '/bitcoin/bitcoin/bitcoin/bitcoin/src'
make[2]: Entering directory '/bitcoin/bitcoin/bitcoin/bitcoin/src'
make[3]: Entering directory '/bitcoin/bitcoin/bitcoin/bitcoin'
make[3]: Leaving directory '/bitcoin/bitcoin/bitcoin/bitcoin'
CXX qt/qt_libbitcoinqt_a-walletframe.o
CXX libbitcoin_util_a-clientversion.o
In file included from qt/walletframe.cpp:5:
In file included from ./qt/walletframe.h:9:
In file included from /usr/include/x86_64-linux-gnu/qt5/QtCore/QMap:1:
/usr/include/x86_64-linux-gnu/qt5/QtCore/qmap.h:617:27: warning: returning address of local temporary object [-Wreturn-stack-address]
return n ? n->value : adefaultValue;
^~~~~~~~~~~~~
qt/walletframe.cpp:85:45: note: in instantiation of member function 'QMap<QString, WalletView *>::value' requested here
WalletView *walletView = mapWalletViews.value(name);
^
/usr/include/x86_64-linux-gnu/qt5/QtCore/qmap.h:386:44: note: binding reference variable 'adefaultValue' here
const T value(const Key &key, const T &defaultValue = T()) const;
^ ~~~