create a variable API that filters out constants and immutables

[0xalpharush]

There's discussion about changing code data location keywords and it would be convenient/ more robust to have one API rather than filtering state_variables.

For example, this code could use the new API #1451

Ref ethereum/solidity#13723

[dokzai]

I would like to help out with this issue. Can you share more information?

[0xalpharush]

There's several places where code like contract.state_variables_ordered if not (variable.is_constant or variable.is_immutable) exists. We could an API that only returns variables that have a storage location instead of filtering everywhere and having to update if a new non-storage keyword is add e.g. codedata in place of constant and immutable https://crytic.github.io/slither/slither/core/declarations/contract.html#Contract.state_variables_ordered

[0xalpharush]

For instance

slither/slither/detectors/variables/unchanged_state_variables.py

Lines 95 to 100 in e3dcf1e

	variables.append(c.state_variables)
	functions.append(c.all_functions_called)
	valid_candidates: Set[StateVariable] = {
	item for sublist in variables for item in sublist if _valid_candidate(item)
	}

slither/slither/printers/summary/variable_order.py

Line 32 in e3dcf1e

if not variable.is_constant and not variable.is_immutable:

slither/slither/tools/upgradeability/checks/variable_initialization.py

Lines 46 to 47 in e3dcf1e

	for s in self.contract.state_variables_ordered:
	if s.initialized and not (s.is_constant or s.is_immutable):

slither/slither/tools/read_storage/read_storage.py

Line 401 in e3dcf1e

if not var.is_constant and not var.is_immutable:

slither/slither/core/compilation_unit.py

Lines 299 to 300 in e3dcf1e

	for var in contract.state_variables_ordered:
	if var.is_constant or var.is_immutable:

[dokzai]

Hi @0xalpharush

https://github.com/dokzai/slither/blob/4f4acae1af3e4c68555972ea09afe686427d20db/slither/core/declarations/contract.py#L440-L464

Please let me know if the following changes are what you had in mind for the new API.

Thanks!

[0xalpharush]

Looks good! Go ahead and open a PR please