`--check` should be the default, option `--fix` should touch files about fix-whitespace

[L-TChen]

I agree that it makes this command safer, but it is not expected for common commands. For example, rm and mv are (very) unsafe, but their default behaviour is to do something that cannot be undone even without any warning. You also need a configuration file to run, otherwise it just does nothing.

[andreasabel]

For example, rm and mv are (very) unsafe, but their default behaviour is to do something that cannot be undone even without any warning.

I'd say these two commands are kind of atomic commands whose effect is very predictable. In contrast, fix-whitespace does an analysis first. Usually, I would like to see the action plan based on the analysis first before committing to it.

I see two main uses of fix-whitespace:

1. In batch mode (like the Agda Makefile): There, one would many --fix directly, but writing an extra --fix in a batch file is zero overhead.
2. Interactively. There, I would usually be careful and --check first, maybe make some adjustments, --check again, and finally --fix.

So the default --check looks more sensible to me.

[andreasabel]

Anyway, there is no consensus, so let's keep the status-quo for now.