[PyQt] PyQt5 5.7.1 Bug: debug build on Windows broken

Mathias Born mathias.born at gmx.de
Mon Jan 16 21:44:23 GMT 2017

> From: Phil Thompson [mailto:phil at riverbankcomputing.com]
> Sent: Montag, 16. Januar 2017 10:14
> To: Mathias Born <mathias.born at gmx.de>
> Cc: pyqt at riverbankcomputing.com
> Subject: Re: [PyQt] PyQt5 5.7.1 Bug: debug build on Windows broken
> On 15 Jan 2017, at 9:44 pm, Mathias Born <mathias.born at gmx.de> wrote:
> >
> > Still doesn't work for me.
> >
> > I installed the new SIP snapshot and tried to install the new PyQt
> > There are two problems. The PyQt configure.py does not call sip with the
> new
> > "-D" command line option for debug builds. I get the same error message.
> Are you sure you are running configure.py with a debug version? Does
> sys.gettotalrefcount exist?

No, I did not.

> > But even if I hack configure.py to add "-D", I still get the same error
> > message:
> Did you hack it in both places?

No, only in one. It was just a hack :-)

Anyway, this is how I finally made it to work:

I've run configure.py with the debug version "python_d.exe", with
option " --debug".
This compiled and installed successfully.
However, all PyQt modules were still linking to the wrong python DLL.
(There are separate DLLs for the limited and the full API on Windows.)
I had to change line 741 of PyQt's configure.py:

             # See if we are using the limited API.
             if not self.py_debug and (py_major == 3 and py_minor >= 4):

This is important because my application which embeds Python and PyQt
also makes use of boost::python, which is incompatible with the limited API.
That's why I always have to link to the full API DLL, and it looks like you
can't have
PyQt link to the limited API at the same time in a debug build.
Surprisingly, this works in a release build.

That fact that you have to run configure.py using "python_d.exe" should be
explained in the docs. And then, is there still need for the "--debug"?

It would be nice if there were an option to disable the use of the limited
API for
release builds.

Best Regards,

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