[Development] Qt warnings and -Weverything/-Werror

[achartier at fastmail.fm]

Hi all,

I would like to enable the -Weverything and -Werror Clang compiler flags
for my application code to treat all warnings as errors. Unfortunately,
Qt itself generates a large number of warnings. I would like to suppress
the warnings generated for Qt code but have Clang report all the
warnings (errors) in my application code.

I have searched a lot on this subject and have not found a solution that
really works. The proper way to do this is to use the -isystem flag and
specify the Qt include directories so they may be treated as system
headers, however qmake seems to always pass the Qt include directories
with the -I argument no matter what I do (I even tried INCLUDEPATH -=
<Qt_include_dirs> to no avail).

The only approach that has worked so far is to use the -Wno flag to
disable certain warnings. This is far from desirable, as then the
warning checking in my application code is tied to the quality of the Qt
codebase.

This bug report (https://bugreports.qt-project.org/browse/QTBUG-7220)
seems to indicate that this is currently not possible with qmake. I hope
this isn't the case and that someone has a solution for this problem.

Any help is greatly appreciated.

Thanks,

Alfonso