Cast error when building OpenGL extension on MIPS64

cast from 'QAbstractOpenGLExtensionPrivate*' to 'const QOpenGLExtension_SUN_triangle_listPrivate*' increases required alignment of target type [-Werror=cast-align]

/home/sun/qt/qt5/qtbase/src/openglextensions/qopenglextensions.h:17577:5: note: in expansion of macro ‘Q_DECLARE_PRIVATE’
     Q_DECLARE_PRIVATE(QOpenGLExtension_SUN_triangle_list)
     ^~~~~~~~~~~~~~~~~
/home/sun/qt/qt5/qtbase/src/openglextensions/qopenglextensions.h: In member function ‘const QOpenGLExtension_SUN_triangle_listPrivate* QOpenGLExtension_SUN_triangle_list::d_func() const’:
../../include/QtCore/../../../../qt5/qtbase/src/corelib/global/qglobal.h:1042:119: error: cast from ‘QAbstractOpenGLExtensionPrivate*’ to ‘const QOpenGLExtension_SUN_triangle_listPrivate*’ increases required alignment of target type [-Werror=cast-align]
     inline const Class##Private* d_func() const { return reinterpret_cast<const Class##Private *>(qGetPtrHelper(d_ptr)); } \
                                                                                                                       ^
/home/sun/qt/qt5/qtbase/src/openglextensions/qopenglextensions.h:17577:5: note: in expansion of macro ‘Q_DECLARE_PRIVATE’
     Q_DECLARE_PRIVATE(QOpenGLExtension_SUN_triangle_list)
     ^~~~~~~~~~~~~~~~~
/home/sun/qt/qt5/qtbase/src/openglextensions/qopenglextensions.h: In member function ‘QOpenGLExtension_SUN_vertexPrivate* QOpenGLExtension_SUN_vertex::d_func()’:
../../include/QtCore/../../../../qt5/qtbase/src/corelib/global/qglobal.h:1041:101: error: cast from ‘QAbstractOpenGLExtensionPrivate*’ to ‘QOpenGLExtension_SUN_vertexPrivate*’ increases required alignment of target type [-Werror=cast-align]
     inline Class##Private* d_func() { return reinterpret_cast<Class##Private *>(qGetPtrHelper(d_ptr)); } \
                                                                                                     ^
/home/sun/qt/qt5/qtbase/src/openglextensions/qopenglextensions.h:17716:5: note: in expansion of macro ‘Q_DECLARE_PRIVATE’
     Q_DECLARE_PRIVATE(QOpenGLExtension_SUN_vertex)
     ^~~~~~~~~~~~~~~~~
/home/sun/qt/qt5/qtbase/src/openglextensions/qopenglextensions.h: In member function ‘const QOpenGLExtension_SUN_vertexPrivate* QOpenGLExtension_SUN_vertex::d_func() const’:
../../include/QtCore/../../../../qt5/qtbase/src/corelib/global/qglobal.h:1042:119: error: cast from ‘QAbstractOpenGLExtensionPrivate*’ to ‘const QOpenGLExtension_SUN_vertexPrivate*’ increases required alignment of target type [-Werror=cast-align]
     inline const Class##Private* d_func() const { return reinterpret_cast<const Class##Private *>(qGetPtrHelper(d_ptr)); } \
                                                                                                                       ^
/home/sun/qt/qt5/qtbase/src/openglextensions/qopenglextensions.h:17716:5: note: in expansion of macro ‘Q_DECLARE_PRIVATE’
     Q_DECLARE_PRIVATE(QOpenGLExtension_SUN_vertex)
     ^~~~~~~~~~~~~~~~~
cc1plus: all warnings being treated as errors
make: *** [Makefile:411: .obj/header_qopenglextensions.o] Error 1

[sun@localhost openglextensions]$ g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/mips64el-redhat-linux/8/lto-wrapper
Target: mips64el-redhat-linux
Configured with: ../configure --enable-bootstrap --enable-languages=c,c++,objc,obj-c++,fortran,go,lto --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared --enable-threads=posix --enable-checking=release --enable-multilib --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --with-gcc-major-version-only --with-linker-hash-style=both --enable-plugin --enable-initfini-array --with-isl --disable-libmpx --enable-gnu-indirect-function --with-long-double-128 --with-arch=mips64r2 --with-abi=64 --build=mips64el-redhat-linux
Thread model: posix
gcc version 8.1.0 20180502 (Red Hat 8.1.0-0.21) (GCC)