macOS 10.14.6
JUCE 5.4.5
XCode 11.1
My first encounter with JUCE was successful. Following the tutorial, I managed to create a test Audio application and was able to build and test in XCode. So far, so good!
Buoyed with this success, I then tried to follow the instructions for creating an audio plugin. I set the filename and then checked that the VST3 and AU checkboxes were selected as well as the MIDI inputs and outputs settings.
When I hit the build button within XCode, the build failed with the following error…
However, when I repeated the process with only the VST3 checkbox enabled, my XCode build succeeded.
For my own personal needs, this isn’t a problem because my main DAW is Bitwig which doesn’t support AUs, but I may find that am not too bad at this plugin malarkey in the future and will obviously want to support AUs.
My question is, therefore: Is my build failure to be expected? Am I being prematurely ambitious, only to find out in the next tutorial exactly what I am doing wrong? Forgive me if this is the case, only I am very keen to make progress with JUCE having been inspired this evening by watching a video of the great Steve Duda, who wishes that he could have used JUCE when developing Serum, apparently!
It’s ironic that, after 30 years of avoiding C++ as a programming language as a professional developer, I should now be willing to dip my toes into C++, albeit with a great deal of hand-holding by JUCE. It’s a shame that my current favourite Golang isn’t supported, but on the plus side, if all goes well, I will be finally able to call myself a “proper” developer 
UPDATE: I tried again selecting AU by itself as the plugin type, but that failed as well. I’ve just discovered that others have had this issue as well: AU on XCode 10: ResMerger Error. I’m not in a position to fix this myself, so I’ll just have to wait till someone else or JUCE fix it!