/**
 * @name Modification of dictionary returned by locals()
 * @description Modifications of the dictionary returned by locals() are not propagated to the local variables of a function.
 * @kind problem
 * @tags quality
 * reliability
 * correctness
 * @problem.severity warning
 * @sub-severity low
 * @precision very-high
 * @id py/modification-of-locals
 */

import python
private import LegacyPointsTo

predicate originIsLocals(ControlFlowNodeWithPointsTo n) {
 n.pointsTo(_, _, Value::named("locals").getACall())
}

predicate modification_of_locals(ControlFlowNode f) {
 originIsLocals(f.(SubscriptNode).getObject()) and
 (f.isStore() or f.isDelete())
 or
 exists(string mname, AttrNode attr |
 attr = f.(CallNode).getFunction() and
 originIsLocals(attr.getObject(mname))
 |
 mname in ["pop", "popitem", "update", "clear"]
 )
}

from AstNode a, ControlFlowNode f
where
 modification_of_locals(f) and
 a = f.getNode() and
 // in module level scope `locals() == globals()`
 // see https://docs.python.org/3/library/functions.html#locals
 // FP report in https://github.com/github/codeql/issues/6674
 not a.getScope() instanceof ModuleScope
select a, "Modification of the locals() dictionary will have no effect on the local variables."