[PATCH] Skip some unnecessary type checks.

[Samuel Benzaquen]

================
Comment at: include/clang/AST/ASTTypeTraits.h:264
@@ -253,4 +263,3 @@
   bool operator==(const DynTypedNode &Other) const {
-    if (!NodeKind.isBaseOf(Other.NodeKind) &&
-        !Other.NodeKind.isBaseOf(NodeKind))
+    if (!NodeKind.isSame(Other.NodeKind))
       return false;
----------------
klimek wrote:
> Why doesn't this change behavior? -> can we not get the same node with a different more or less specific type?
It used to be that DynTypedNode::create() stored the static type of the node in NodeKind.
Recently we added ASTNodeKind::getFromNode() to get the dynamic type of the node and we store that on the DTN.
This was necessary for the RestrictKind optimizations.
Now that we store the exact node kind, we can compare them directly. This is also why we can drop the dyn_cast<> in favor of just cast<> in DynCastPtrConverter::get() below. The node kind check is enough.
Do you want a comment here?

http://reviews.llvm.org/D6468