GCC warns for -Wnull-dereference on multiple locations

[orbitcowboy]

Compiling tinyxml2 on Linux with GCC and -Wnull-dereference set

$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/7/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 7.3.0-27ubuntu1~18.04' --with-bugurl=file:///usr/share/doc/gcc-7/README.Bugs --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++ --prefix=/usr --with-gcc-major-version-only --program-suffix=-7 --program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --enable-default-pie --with-system-zlib --with-target-system-zlib --enable-objc-gc=auto --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 7.3.0 (Ubuntu 7.3.0-27ubuntu1~18.04)

gives a bunch of interesting warnings

../srcext/tinyxml2/tinyxml2.h: In member function ‘virtual tinyxml2::XMLNode* tinyxml2::XMLUnknown::ShallowClone(tinyxml2::XMLDocument*) const’:
../srcext/tinyxml2/tinyxml2.h:1929:5: warning: potential null pointer dereference [-Wnull-dereference]
     returnNode->_memPool = &pool;
     ^~~~~~~~~~
../srcext/tinyxml2/tinyxml2.h: In member function ‘virtual tinyxml2::XMLNode* tinyxml2::XMLComment::ShallowClone(tinyxml2::XMLDocument*) const’:
../srcext/tinyxml2/tinyxml2.h:1929:5: warning: potential null pointer dereference [-Wnull-dereference]
     returnNode->_memPool = &pool;
     ^~~~~~~~~~
../srcext/tinyxml2/tinyxml2.cpp: In member function ‘tinyxml2::XMLNode* tinyxml2::XMLNode::DeepClone(tinyxml2::XMLDocument*) const’:
../srcext/tinyxml2/tinyxml2.cpp:844:19: warning: potential null pointer dereference [-Wnull-dereference]
     if ( addThis->_document != _document ) {
          ~~~~~~~~~^~~~~~~~~
../srcext/tinyxml2/tinyxml2.cpp:844:19: warning: potential null pointer dereference [-Wnull-dereference]
     if ( addThis->_document != _document ) {
          ~~~~~~~~~^~~~~~~~~
../srcext/tinyxml2/tinyxml2.cpp:844:19: warning: potential null pointer dereference [-Wnull-dereference]
     if ( addThis->_document != _document ) {
          ~~~~~~~~~^~~~~~~~~
../srcext/tinyxml2/tinyxml2.cpp:844:19: warning: potential null pointer dereference [-Wnull-dereference]
     if ( addThis->_document != _document ) {
          ~~~~~~~~~^~~~~~~~~
../srcext/tinyxml2/tinyxml2.cpp:844:19: warning: potential null pointer dereference [-Wnull-dereference]
     if ( addThis->_document != _document ) {
          ~~~~~~~~~^~~~~~~~~
../srcext/tinyxml2/tinyxml2.cpp:844:19: warning: potential null pointer dereference [-Wnull-dereference]
     if ( addThis->_document != _document ) {
          ~~~~~~~~~^~~~~~~~~
../srcext/tinyxml2/tinyxml2.cpp:844:19: warning: potential null pointer dereference [-Wnull-dereference]
     if ( addThis->_document != _document ) {
          ~~~~~~~~~^~~~~~~~~
../srcext/tinyxml2/tinyxml2.cpp:844:19: warning: potential null pointer dereference [-Wnull-dereference]
     if ( addThis->_document != _document ) {
          ~~~~~~~~~^~~~~~~~~
In file included from ../srcext/tinyxml2/tinyxml2.cpp:24:0:
../srcext/tinyxml2/tinyxml2.h: In member function ‘virtual tinyxml2::XMLNode* tinyxml2::XMLElement::ShallowClone(tinyxml2::XMLDocument*) const’:
../srcext/tinyxml2/tinyxml2.h:1929:5: warning: potential null pointer dereference [-Wnull-dereference]
     returnNode->_memPool = &pool;
     ^~~~~~~~~~
../srcext/tinyxml2/tinyxml2.cpp: In member function ‘void tinyxml2::XMLDocument::DeepCopy(tinyxml2::XMLDocument*) const’:
../srcext/tinyxml2/tinyxml2.cpp:844:19: warning: potential null pointer dereference [-Wnull-dereference]
     if ( addThis->_document != _document ) {
          ~~~~~~~~~^~~~~~~~~
In file included from ../srcext/tinyxml2/tinyxml2.cpp:24:0:
../srcext/tinyxml2/tinyxml2.h: In member function ‘NodeType* tinyxml2::XMLDocument::CreateUnlinkedNode(tinyxml2::MemPoolT<PoolElementSize>&) [with NodeType = tinyxml2::XMLComment; int PoolElementSize = 104]’:
../srcext/tinyxml2/tinyxml2.h:1929:5: warning: potential null pointer dereference [-Wnull-dereference]
     returnNode->_memPool = &pool;
     ^~~~~~~~~~
../srcext/tinyxml2/tinyxml2.h: In member function ‘NodeType* tinyxml2::XMLDocument::CreateUnlinkedNode(tinyxml2::MemPoolT<PoolElementSize>&) [with NodeType = tinyxml2::XMLText; int PoolElementSize = 112]’:
../srcext/tinyxml2/tinyxml2.h:1929:5: warning: potential null pointer dereference [-Wnull-dereference]
     returnNode->_memPool = &pool;
     ^~~~~~~~~~
../srcext/tinyxml2/tinyxml2.h: In member function ‘NodeType* tinyxml2::XMLDocument::CreateUnlinkedNode(tinyxml2::MemPoolT<PoolElementSize>&) [with NodeType = tinyxml2::XMLUnknown; int PoolElementSize = 104]’:
../srcext/tinyxml2/tinyxml2.h:1929:5: warning: potential null pointer dereference [-Wnull-dereference]
     returnNode->_memPool = &pool;
     ^~~~~~~~~~
../srcext/tinyxml2/tinyxml2.h: In member function ‘NodeType* tinyxml2::XMLDocument::CreateUnlinkedNode(tinyxml2::MemPoolT<PoolElementSize>&) [with NodeType = tinyxml2::XMLElement; int PoolElementSize = 120]’:
../srcext/tinyxml2/tinyxml2.h:1929:5: warning: potential null pointer dereference [-Wnull-dereference]
     returnNode->_memPool = &pool;
     ^~~~~~~~~~