Cannot compile individual .cpp files in Qt Creator with imported CMake build

[Robert Hairgrove]

When I build a project using qmake, compiling a single source file I had just edited always worked by simply right-clicking on the file in the Projects list and selecting "Build" from the context menu.

I built another project (not my own) using the cmake build system which I had cloned from their GitLab hosting site. I built it first successfully from the command line using just cmake, then imported the top-level CMakeFiles.txt into Qt. It parses and builds everything successfully when I build the whole project.

However, after editing a single file, for eample named xyz.cpp, and trying to just compile it as described above, I get the error:

:-1: error: No rule to make target 'xyz.cpp.o'.  Stop.

Is there another way to do this? Otherwise, I have to wait several minutes for CMake to go through the whole build process just for one file.

I am using Qt Creator 4.12.2 on Linux Ubuntu 18.04.4 with GCC version 7.5.0. It is a KDE5 project which provides its own Qt libraries which are version 5 (not sure about the minor version number, though). My local Qt installation is 5.12.9, but this isn't used by that project.