Our Qt 4.5 project has a root .pro file that has a SUBDIRS qmake variable. When qmake is called on this root .pro file, it generates a Makefile that calls “qmake && make” for each sub directory.
Now the problem is that for 100+ sub folders, this takes a long time for a one liner change of an other wise up to date project to be detected. (It takes about 13 seconds, waaay to long.) Running make at the root of the project first changes directory to all the sub dirs and runs a do nothing make, until it finds the one directory it actually needs to do work in. (A work around at the moment is to manually cd into the folder that you know you made a code change in, and just run make. For our eclipse environment, this is to clumsy.)
Ideally only the root .pro file should be tweaked, but I will accept answers that hacks the root Makefile as well.
Any suggestions to reduce the trivial make time would be appreciated.
This is a classic argument for the recursive make considered harmful theory: Your problem is that you have dozens of single Makefiles instead of one large one. The only way around the predicament is to refactor the .pro files so that only a single Makefile is generated. I don’t know enough about qmake to tell you how to do that, though, sorry.