* core-customization: improved SAFE variable handling
- SAFE can either be a function or t.
- When it's t, use a default validation function
`(lambda (val) (validate-value val TYPE t))`
- When it's a function, use the supplied function.
* Fixed bugs in go and groovy layer
In almost any cases, it's better to supply `t` instead of a function, to
`SAFE` argument of `spacemacs|defc`.
For example,
```elisp
(spacemacs|defc go-use-gocheck-for-testing nil
"If using gocheck for testing when running the tests -check.f will be used instead of -run to specify the test that will be ran. Gocheck is mandatory for testing suites."
'boolean nil #'booleanp)
```
If its value is nil, it evaluate to `nil`, which means that `nil` is not
a safe value for `go-use-gocheck-for-testing` local variable.
But clearly it is.
* core-customization: improved SAFE variable handling
- Added a function `spacemacs-customization//get-variable-validator`.
This function is designed to be used with `safe-local-variable`
property of spacemacs custom variables.
See details in the docstring.
```elisp
(put 'FOO 'safe-local-variable
(apply-partially 'spacemacs-customization//get-variable-validator
'FOO))
```
- This is better than a lambda since `apply-partially` returns a compiled
function. (Though the performace gain may be tiny.)
- This is better than simply calling `validate-value`, because it returns
nil when value is nil. But sometimes nil is a valid value.
Co-authored-by: Lucius Hu <lebensterben@users.noreply.github.com>
