[strict] Add set.pop() to strict analyzer

Summary: This method was missing from the strict analyzer, causing STRICTSTATIC linker errors in D35905142.

Test Plan: `arc lint util/enum.py --take STRICTSTATIC`

Reviewers: sinancepel, #strictmodules, #staticpython

Reviewed By: sinancepel

Subscribers: jbiesnecker, orvid, #cinder

Differential Revision: https://phabricator.intern.facebook.com/D35942257

StrictModules/Objects/iterable_objects.cpp

@@ -1002,6 +1002,19 @@ std::shared_ptr<BaseStrictObject> StrictSet::set__init__(
   return NoneObject();
 }
 
+std::shared_ptr<BaseStrictObject> StrictSet::setPop(
+    std::shared_ptr<StrictSet> self,
+    const CallerContext& caller) {
+  checkExternalModification(self, caller);
+  if(self->data_.empty()) {
+    caller.raiseExceptionStr(KeyErrorType(), "pop from an empty set");
+  }
+  auto iter = self->data_.begin();
+  auto result = std::move(*iter);
+  self->data_.erase(iter);
+  return result;
+}
+
 std::shared_ptr<BaseStrictObject> StrictSet::setUpdate(
     std::shared_ptr<StrictSet> self,
     const CallerContext& caller,
@@ -1047,6 +1060,7 @@ void StrictSetType::addMethods() {
   StrictSetLikeType::addMethods();
   addMethod("add", StrictSet::setAdd);
   addMethodDefault("__init__", StrictSet::set__init__, nullptr);
+  addMethod("pop", StrictSet::setPop);
   addMethod("update", StrictSet::setUpdate);
   addPyWrappedMethodObj<>(
       kDunderRepr,

StrictModules/Objects/iterable_objects.h

@@ -422,6 +422,10 @@ class StrictSet final : public StrictSetLike {
       const CallerContext& caller,
       std::shared_ptr<BaseStrictObject> arg = nullptr);
 
+  static std::shared_ptr<BaseStrictObject> setPop(
+      std::shared_ptr<StrictSet> self,
+      const CallerContext& caller);
+
   static std::shared_ptr<BaseStrictObject> setUpdate(
       std::shared_ptr<StrictSet> self,
       const CallerContext& caller,

StrictModules/Tests/comparison_tests/interpreter_test.txt

@@ -3680,11 +3680,13 @@ s.update([5, 6])
 l4 = len(s)
 s.update([5, 6])
 l5 = len(s)
+s.pop()  # cannot guarantee the same element popped
+l6 = len(s)
 b1 = set().issubset(s)
 b2 = set() <= s
 b3 = s <= set()
 ---
-l1 l2 l3 l4 l5 b1 b2 b3
+l1 l2 l3 l4 l5 l6 b1 b2 b3
 ---
 ---
 test_frozenset_init