YES! The software needs the capability to ALLOW THIS FILE THIS TIME, and also an IGNORE THIS RULE UNTIL NEXT (DEFINITIONS OR PROGRAM) UPDATE feature.
Maybe not available as the default, but power users need to be able to configure it as an option to the "Ask" option.
I started out asking for exactly this a month or so ago when I was fighting a false positive as well. I was told, as some are telling in this thread, that there are other ways to do it. Those other ways are not sufficient!
Here's a scenario that the current "exclude after the fact" measures do not work with.
1. You're building software sources into executables.
2. Avast triggers a false positive and kills an intermediate file that has a temporary name assigned by the build software.
3. You can't tell it to IGNORE THIS FILE, THIS TIME, so the build fails, interrupting your productivity. Neither can you tell it to exclude the particular (flawed) rule that made the false positive happen in the first place. This forces you to deal with the Avast! problem immediately.
4. You go to the Chest and try to exclude that file from there, but next time you build the file is given a different temporary name, so the build fails and you spin your wheels some more. This forces you to have to move from "set it and forget it" to "expert" level in Avast configuration.
5. You finally, in disgust, exclude your entire development folder structure so you can get back to work after having been distracted for a good long time figuring out the convoluted Avast! UI. Hopefully you haven't been fired yet, and you have to work late to catch back up.
6. You submit the file as a false-positive, wasting more of your time that you could be working.
7. Some weeks / months later, MAYBE some other Avast issue makes you remember that you've excluded an entire block of your disk from all protection and you remove the exclusion (and maybe the false-positive detection has been corrected). Hopefully some malware hasn't found a way to use that exclusion to its advantage.
How do I know this is such detail?
-Noel