qdoc fails for many modules due to qtimer.h

I tried to build Qt's documentation from scratch in WebXML for Qt 5.13.0 (downloaded from the Web installer). However, many modules fail due to an error in qtimer.h:

src/corelib/kernel/qtimer.h:104:29: error: class member cannot be redeclared

This refers to implementations of callOnTimeout (the three ones hidden by Q_CLANG_QDOC). The same issue is also present in https://bugreports.qt.io/browse/QTBUG-74603 (actually, it's the only other mention I got for this specific error from Google).

I tried with both the precompiled qdoc (the MinGW 64 package) and with a qdoc I compiled myself (with Clang 8.0.0), both gave the same error. However, it should be possible to make it work, as the official documentation has all three implementation of callOnTimeout (https://doc.qt.io/qt-5/qtimer.html#callOnTimeout).

If I delete the third declaration of callOnTimeout, qdoc works properly; if this declaration is present, nothing gets generated for many modules (like Qt 3D).