Unsolved WARNING: QMAKESPEC does not support multiple BUILDS

[DRoscoe]

Note: I originally asked this on the Embedded forum, but I realize its more of a generic question and I wasn't getting any traction on the problem (see below)

I have a SUBDIRS project which I am using to create a multi-library. I use the following qmake command on the top-level project:

qmake -spec macx-xcode -recursive

The generates a working XCode project file, but not without generating many of the following warnings:

WARNING: QMAKESPEC does not support multiple BUILDS

I don't like seeing these warnings. Am I doing something wrong? I have to use -recursive since I am bringing in multiple library projects files, to get the all to build as part of the whole project. I appreciate any insight.

[DRoscoe]

Here is the top-level SUBDIRS project. Each subdirectory listed has its own .pro file.

CONFIG += c++11 ordered
TEMPLATE = subdirs

SUBDIRS +=
aop_logger
aop_xml
aop_serial
aop_util
aop_measure
MoreMath
MathUtilities
DataCollection
DebugLogger
BufferedSharedMemory
AvionicsBus
AircraftDataModel
WindModel
TableLookups
configuration
AtosUtils
dna
aop_data
aop_comm
tap_data
tap_messaging
RouteContainer
arinc_io_adapter
aop_interface
tap_display_app