Move missing/multiple calls to init/del queries to folder

Author: joefarebrother

python/ql/src/Classes/CallsToInitDel/MethodCallOrder.qll

@@ -0,0 +1,77 @@
+deprecated module;
+
+import python
+
+// Helper predicates for multiple call to __init__/__del__ queries.
+pragma[noinline]
+private predicate multiple_invocation_paths_helper(
+  FunctionInvocation top, FunctionInvocation i1, FunctionInvocation i2, FunctionObject multi
+) {
+  i1 != i2 and
+  i1 = top.getACallee+() and
+  i2 = top.getACallee+() and
+  i1.getFunction() = multi
+}
+
+pragma[noinline]
+private predicate multiple_invocation_paths(
+  FunctionInvocation top, FunctionInvocation i1, FunctionInvocation i2, FunctionObject multi
+) {
+  multiple_invocation_paths_helper(top, i1, i2, multi) and
+  i2.getFunction() = multi
+}
+
+/** Holds if `self.name` calls `multi` by multiple paths, and thus calls it more than once. */
+predicate multiple_calls_to_superclass_method(ClassObject self, FunctionObject multi, string name) {
+  exists(FunctionInvocation top, FunctionInvocation i1, FunctionInvocation i2 |
+    multiple_invocation_paths(top, i1, i2, multi) and
+    top.runtime(self.declaredAttribute(name)) and
+    self.getASuperType().declaredAttribute(name) = multi
+  |
+    // Only called twice if called from different functions,
+    // or if one call-site can reach the other.
+    i1.getCall().getScope() != i2.getCall().getScope()
+    or
+    i1.getCall().strictlyReaches(i2.getCall())
+  )
+}
+
+/** Holds if all attributes called `name` can be inferred to be methods. */
+private predicate named_attributes_not_method(ClassObject cls, string name) {
+  cls.declaresAttribute(name) and not cls.declaredAttribute(name) instanceof FunctionObject
+}
+
+/** Holds if `f` actually does something. */
+private predicate does_something(FunctionObject f) {
+  f.isBuiltin() and not f = theObjectType().lookupAttribute("__init__")
+  or
+  exists(Stmt s | s = f.getFunction().getAStmt() and not s instanceof Pass)
+}
+
+/** Holds if `meth` looks like it should have a call to `name`, but does not */
+private predicate missing_call(FunctionObject meth, string name) {
+  exists(CallNode call, AttrNode attr |
+    call.getScope() = meth.getFunction() and
+    call.getFunction() = attr and
+    attr.getName() = name and
+    not exists(FunctionObject f | f.getACall() = call)
+  )
+}
+
+/** Holds if `self.name` does not call `missing`, even though it is expected to. */
+predicate missing_call_to_superclass_method(
+  ClassObject self, FunctionObject top, FunctionObject missing, string name
+) {
+  missing = self.getASuperType().declaredAttribute(name) and
+  top = self.lookupAttribute(name) and
+  /* There is no call to missing originating from top */
+  not top.getACallee*() = missing and
+  /* Make sure that all named 'methods' are objects that we can understand. */
+  not exists(ClassObject sup |
+    sup = self.getAnImproperSuperType() and
+    named_attributes_not_method(sup, name)
+  ) and
+  not self.isAbstract() and
+  does_something(missing) and
+  not missing_call(top, name)
+}