Add member template 'Type::getAs<T>', which converts a Type* to a respective T*.
This method is intended to eventually replace the individual
Type::getAsXXXType<> methods.

The motivation behind this change is twofold:

1) Reduce redundant implementations of Type::getAsXXXType() methods. Most of
them are basically copy-and-paste.

2) By centralizing the implementation of the getAs<Type> logic we can more
smoothly move over to Doug Gregor's proposed canonical type smart pointer
scheme.

Along with this patch:

a) Removed 'Type::getAsPointerType()'; now clients use getAs<PointerType>.
b) Removed 'Type::getAsBlockPointerTypE()'; now clients use getAs<BlockPointerType>.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@76098 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index 2c29347..9473e4f 100644
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -222,7 +222,7 @@
   if (E->isArrow()) {
     if (!EvaluatePointer(E->getBase(), result, Info))
       return APValue();
-    Ty = E->getBase()->getType()->getAsPointerType()->getPointeeType();
+    Ty = E->getBase()->getType()->getAs<PointerType>()->getPointeeType();
   } else {
     result = Visit(E->getBase());
     if (result.isUninit())
@@ -351,7 +351,7 @@
   if (!EvaluateInteger(IExp, AdditionalOffset, Info))
     return APValue();
 
-  QualType PointeeType = PExp->getType()->getAsPointerType()->getPointeeType();
+  QualType PointeeType = PExp->getType()->getAs<PointerType>()->getPointeeType();
   uint64_t SizeOfPointee;
   
   // Explicitly handle GNU void* and function pointer arithmetic extensions.
@@ -1029,7 +1029,7 @@
 
       if (E->getOpcode() == BinaryOperator::Sub) {
         const QualType Type = E->getLHS()->getType();
-        const QualType ElementType = Type->getAsPointerType()->getPointeeType();
+        const QualType ElementType = Type->getAs<PointerType>()->getPointeeType();
 
         uint64_t D = LHSValue.getLValueOffset() - RHSValue.getLValueOffset();
         if (!ElementType->isVoidType() && !ElementType->isFunctionType())