Re: [PATCH v1 2/3] kconfig: Ask user if string needs to be changed when dependency changed

Mickaël Salaün [off-list ref] writes:

Content of string configuration may depend on related kernel
configurations.  Modify oldconfig and syncconfig to inform users about
possible required configuration update and give them the opportunity to
update it:
* if dependencies of this string has changed (e.g. enabled or disabled),
* and if the current value of this string is different than the (new)
  default one.

I have a number of questions:

1. Why is a change in dependencies necessarily means that the dependent's
   value must be revised? Here is a specific example (to make sure we are
   talking about the same things):

   config FOO
     string "Foo value"
     depends on BAR || BAZ

   Why, in the general case, when I disable BAR and enable BAZ I must
   also revise the value of FOO?

2. How do you know that what's in the user's .config is the old default
   and in Kconfig -- the new default value? What if in the user's .config
   is a custom value (with which the user is perfectly happy) and what's
   in Kconfig is the old default (which the user has already seen)?

3. Why limit this to strings only?

This is particularly relevant for CONFIG_LSM which contains a list of
LSMs enabled at boot, but users will not have a chance to update this
list with a make oldconfig.

If my understanding above is correct, this feels like it's been purpose-
made to address whatever issue you are having with CONFIG_LSM. If so,
what about potential numerous other options that don't have this issue
but will now be presented to the user for modification?