Qt5's qdoc3 seg faults when a qt.index is used

In qtdeclarative, I specify a qt.index. QDoc3 results in a segmentation fault.
I tried to use the qt.index from Qt5 and Qt4.8. I updated all of the Qt5 repositories and compiled them all.

gdb's trace
(gdb) bt
#0 0x000000000040d724 in QListData::isEmpty (this=0x109)
at /home/jpasion/build/qt5/qtbase/include/QtCore/../../../../../gerrit/qt5/qtbase/src/corelib/tools/qlist.h:95
#1 0x0000000000478f24 in QList<RelatedClass>::isEmpty (
this=0x109)
at /home/jpasion/build/qt5/qtbase/include/QtCore/../../../../../gerrit/qt5/qtbase/src/corelib/tools/qlist.h:149
#2 0x00000000004f81a0 in ClassNode::findQmlBaseNode (
this=0x41) at node.cpp:1191
#3 0x00000000004fc63b in QmlClassNode::resolveInheritance (this=0x126e4de0, tree=0x7e2a00) at node.cpp:2008
#4 0x0000000000513543 in Tree::resolveQmlInheritance (
this=0x7e2a00) at tree.cpp:877
#5 0x00000000004f0f67 in processQdocconfFile (
fileName=...) at main.cpp:326
#6 0x00000000004f1a1b in main (argc=2,
argv=0x7fffffffe0d8) at main.cpp:453