Make error of mixed implicit and normal rules

In my case, the error was due to idiotically putting an extraneous : at the end of the dependency line:

%.o: %.cpp:
     g++ -c -o %@ $<

I am here to remind the successor, check your path, is there any space in it? We wasted all afternoon on this!

That error message is printed by GNU make when you have something that looks like a pattern rule output (containing a %) as well as something that looks like a normal output (no %) on the left-hand side of a : in a rule declaration. For example:

%.pat normal:
        @echo $@

So on line 235 of your Makefile, you have managed to put together something that "looks like" that construct. To avoid the error, fix that declaration, most likely by splitting it into two:

%.pat:
        @echo $@

normal:
        @echo $@

Without seeing the complete makefile that produced this error there's not much more advice we can give you.