Pasting Formed an Invalid Preprocessing Token Error

I wish I could tell you more. It's not my code. Rather a sample for scanning a matrix keyboard. Removing the line to get rid of the error, is not going to happen but put a smile on my face. I'm glad you're not my doctor :>) Terminating with a ; didn't help.

Here it is in FIFO.h . I don't know what to look for sorry but in my research have understood the use of ## can cause problems . 

The entire 3rd party project seems to me to be so complex that I can't make much out of it , so I think I will write my own code. After some build attempts, i have 17 files to contend with, without opening any of the 3 additional directories. I'm just trying to scan a matrix keyboard , a 4 X 5. I'm pining now for the simpler time when I used Microchip and MPLab.

I'd like to continue to use the TIVA Launchpad, but Keil apparently did not think to include that board on it's list of those supported, despite there being at least tens of thousands of techies who trained on this development board. I tried the patch, they hastily put out, for version 5.xxx, to calm the protesters and have now reverted back to version 4. xxxx, searching for bug free experiences and simpler error messages. I'd love to stick with ARM cause I know it's the uC of the present and future, but they certainly aren't making it easier.  

Yes but not originally for some reason, as I alluded to in my last update. I did install that patch, but continued to have problems, perhaps because I did not use the default installation locations. Things just got so messy that I started all over again and reinstalled my Keil, both 4.xx and 5.xx, using the defaults. Since so much of the code I was using had been written on earlier editions, I have decided to revert back to using 4.xx. i am now looking at these preprocessor tokens to try and better understand what these errors mean and what I need to do to get rid of them. I'm not even sure this code will build in 4.xx on account of the ##. Thanks.

Someone smarter than I could probably get rid of the ##. The task probably requires a FIFO Queue for the scanning output and a wise person could probably show you a way to make one with that macro sans ##.

Yes I agree,,, a FIFO does make sense here to buffer the key presses until done, but I haven't seen one before with those token thingys either. These error codes too,,,, If I drop a semicolon from the end of a line, I fully expect to see "Discombobulation error eleventy-two on hyper fradistat, bashed bindelwarfer" Instead of, you know... "Line not terminated with a semicolon". I seem to be mumbling the question "Why ?" instead of what, how or where when using software, most of the time , as in "Why did they do that ?".