SUMMARY
Compilation/Syntax error: template specialization in different namespace

STEPS TO REPRODUCE
1. git clone heaptrack
2. mkdir heaptrack/build
3. cd heaptrack/build
4. cmake ..
5. make

OBSERVED RESULT

[ 33%] Building CXX object src/analyze/gui/CMakeFiles/heaptrack_gui_private.dir/parser.cpp.o
/tmp/heaptrack/src/analyze/gui/parser.cpp:37:13: error: specialization of ‘template<class _Tp> struct std::hash’ in different namespace [-fpermissive]
 struct std::hash<QString> {
             ^
In file included from /usr/include/c++/5/bits/basic_string.h:5574:0,
                 from /usr/include/c++/5/string:52,
                 from /usr/include/c++/5/random:40,
                 from /usr/include/c++/5/bits/stl_algo.h:66,
                 from /usr/include/c++/5/algorithm:62,
                 from /usr/include/x86_64-linux-gnu/qt5/QtCore/qglobal.h:85,
                 from /usr/include/x86_64-linux-gnu/qt5/QtCore/qnamespace.h:37,
                 from /usr/include/x86_64-linux-gnu/qt5/QtCore/qobjectdefs.h:41,
                 from /usr/include/x86_64-linux-gnu/qt5/QtCore/qobject.h:40,
                 from /usr/include/x86_64-linux-gnu/qt5/QtCore/QObject:1,
                 from /tmp/heaptrack/src/analyze/gui/parser.h:22,
                 from /tmp/heaptrack/src/analyze/gui/parser.cpp:19:
/usr/include/c++/5/bits/functional_hash.h:58:12: error:   from definition of ‘template<class _Tp> struct std::hash’ [-fpermissive]
     struct hash;

EXPECTED RESULT

compilation should complete.

SOFTWARE/OS VERSIONS
gcc version 5.5.0 20171010 (Ubuntu 5.5.0-12ubuntu1~16.04) 

ADDITIONAL INFORMATION
CMAKE OUTPUT:
-- The following OPTIONAL packages have been found:

 * Qt5Gui (required version >= 5.5.1)
 * Qt5Widgets
 * ECM (required version >= 1.0.0)
 * KF5CoreAddons
 * KF5I18n
 * KF5ItemModels
 * KF5ThreadWeaver
 * KF5ConfigWidgets
 * KF5KIO
 * KF5
 * Qt5Core (required version >= 5.5.1)
 * Qt5Test
 * Qt5 (required version >= 5.2.0)

-- The following REQUIRED packages have been found:

 * Threads
 * ZLIB
 * Libunwind
 * Boost (required version >= 1.41.0)
 * Gettext
 * PythonInterp

-- The following RECOMMENDED packages have not been found:

 * Zstd
   Zstandard offers better (de)compression performance compared with gzip/zlib, making heaptrack faster and datafiles smaller.
 * KChart (required version >= 2.6.0)
   Required for the heaptrack_gui executable. Get it from the kdiagram module.

-- Configuring done
-- Generating done
-- Build files have been written to: /tmp/heaptrack/build