Can "immutable" functions be removed? about diamond HOT 2 CLOSED

Someone could not remove a function that is defined directly in a diamond proxy. But such functions still need to be returned by the loupe functions which means they need to be added to storage with the address address(this). So the require statement checks if there is an attempt to remove an immutable function and throws an error if so.

The EIP2535 standard says this:

All immutable functions must be emitted in the DiamondCut event as new functions added. And the loupe functions must return information about immutable functions if they exist. The facet address for an immutable function is the diamond’s address. Any attempt to delete or replace an immutable function must revert.

from diamond.

@mudgen That makes total sense. Thank you for clearing that out!

I was trying to understand why that check wasn't added on the LibDiamond.addFunctions() which makes it possible to add address(this) as a facetAddress. Then noone will be able to remove or replace that function.
But it is intended behaviour according to the EIP.

from diamond.