and it used their own proprietary toolchain, as a layer on top of visual studio iirc, that kind of worked in debug but actually no, I remember we had to purchase a specific nokia to run in dev mode, as not every nokia supported it or was actually supported by the toolchain at the time.
and I remember another pain point was feature detection, but can't recall the specifics.
I think VS was used before my time (2005), but then it used CodeWarrior and then after that Nokia's own IDE called Carbide.
It had MMP files which described the project and the files in it, a then a tool called 'abld' which was a perl script that did the compiling, which actually had two commands to clean... 'abld clean' and 'abld reallyclean' :)
and I remember another pain point was feature detection, but can't recall the specifics.