Add a flag to make a full build instead bypassing build cache

[itsUndefined]

Hi.

After many bugs from updating packages that update the build_runner and corrupt build cache I was wondering if it would be possible to add a flag --clear or similar on build/watch that runs the command dart run build_runner clean before building or before starting to watch.

[davidmorgan]

What do you mean by "corrupt the build cache"?

It should not be possible to cause incorrect builds during normal use, so if you know a way to do so, please let me know and I will fix it :)

build_runner already checks and does the equivalent of clean on startup if it thinks a clean is necessary.

[itsUndefined]

I tried to replicate the steps that I took today to replicate the buggy build

1. upgraded to beta flutter 3.37, build_runner 2.8.0
2. downgrade back to stable 3.35, build_runner 2.7.1

and the issue did not happen again. I probably did something stupid like switching git branches while a build was in progress.

[davidmorgan]

In theory changes during the build should be okay, but it's not well tested.

I'm actually just getting to the end of a refactor of this part of build_runner, so I'll be happy to also look at any problems around reliability.