Remove the explicit SDNodeIterator::operator= in favor of the implicit default

There doesn't seem to be any need to assert that iterator assignment is
between iterators over the same node - if you want to reuse an iterator
variable to iterate another node, that's perfectly acceptable. Just
don't mix comparisons between iterators into disjoint sequences, as
usual.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231135 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Analysis/CFLAliasAnalysis.cpp

@@ -151,15 +151,13 @@ struct FunctionInfo {
 
 struct CFLAliasAnalysis;
 
-struct FunctionHandle : public CallbackVH {
+struct FunctionHandle final : public CallbackVH {
   FunctionHandle(Function *Fn, CFLAliasAnalysis *CFLAA)
       : CallbackVH(Fn), CFLAA(CFLAA) {
     assert(Fn != nullptr);
     assert(CFLAA != nullptr);
   }
 
-  virtual ~FunctionHandle() {}
-
   void deleted() override { removeSelfFromCache(); }
   void allUsesReplacedWith(Value *) override { removeSelfFromCache(); }