Document how to find homebrew-installed Qt5 in macOS

[traversaro]

Qt5 is not symlinked in /usr/local by default in the homebrew formula, so Qt5_DIR needs to be properly set to make sure that CMake-based projects are able to find Qt5.
See https://github.com/robotology/yarp/blob/b30f2a8ec899d2b1ed9475191cbc3db224ffd9c9/doc/installation/install_mac.dox#L137 .
cc @claudiofantacci

[claudiofantacci]

This has always been a majour issue.
I usually symlink QT5 to solve this kind of problem because adding export Qt5_DIR=/usr/local/opt/qt5/lib/cmake do not solve CMake issue 100% of the time.

Actually, by my experience, if you don't symlink QT5 you should add the following:

Qt5Widgets_DIR=/usr/local/opt/qt/lib/cmake/Qt5Widgets
Qt5Test_DIR=/usr/local/opt/qt/lib/cmake/Qt5Test
Qt5Core_DIR=/usr/local/opt/qt/lib/cmake/Qt5Core
Qt5_DIR=/usr/local/opt/qt/lib/cmake
Qt5Concurrent_DIR=/usr/local/opt/qt/lib/cmake/Qt5Concurrent
Qt5Gui_DIR=/usr/local/opt/qt/lib/cmake/Qt5Gui

[traversaro]

I was always able to compile everything by just setting Qt5_DIR, anyone have a different experience @vtikha @DanielePucci @nunoguedelha @claudia-lat ?

[DanielePucci]

I usually disable by setting ICUB_USE_Qt5 = OFF 🛩

[nunoguedelha]

Same for me, I usually only set Qt5_DIR.

[traversaro]

I usually disable by setting ICUB_USE_Qt5 = OFF 🛩

Are you sure? Qt5 is used also in YARP to build yarpmotorgui.

[DanielePucci]

I think so: I usually used the yarpmotorgui using the robot computers

[claudiofantacci]

I was always able to compile everything by just setting Qt5_DIR, anyone have a different experience?

I had some issues with some other packages which I don't recall at this very moment.
It is something related to some Homebrew formulae, not directly to our software, and how they look for QT5.
I guess that setting Qt5_DIR without symlinking it is sufficient.

[lucaTagliapietra]

Readme updated. As soon as the PR will be merged, we can close.

[traversaro]

Fixed by #71 .

[traversaro]

Hi @spotanjo3, what do you mean with "How do I change mine" ? Furthermore, I suggest you to open a new issue, commenting on an old issue is problematic as it tends to be lost.