Without myapp.c already existing, it won't catch the pc -> c rule.
NMAKE : fatal error U1073: don't know how to make 'myapp.obj'
If I have an existing myapp.c file, update the myapp.pc file (thus making it newer) and then do an nmake, it all works fine - it will build all the way through to myapp.exe. If I don't have the myapp.c file but I, instead, make the app: dependency myapp.c then it will run the proper rule and make myapp.pc. Build all - the /A option - doesn't make any difference.
If I can't get this working then I'm going to have to specify a rule for each pc -> c and I have a lot of those.