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>.

llvm-svn: 76098
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index b43aadb..f30927c 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -1092,7 +1092,7 @@
     return T;
   
   if (T->isPointerType()) {
-    QualType Pointee = T->getAsPointerType()->getPointeeType();
+    QualType Pointee = T->getAs<PointerType>()->getPointeeType();
     if (Pointee->isAnyPointerType()) {
       QualType ResultType = getObjCGCQualType(Pointee, GCAttr);
       return getPointerType(ResultType);
@@ -2779,7 +2779,7 @@
     return;
   }
   
-  if (const PointerType *PT = T->getAsPointerType()) {
+  if (const PointerType *PT = T->getAs<PointerType>()) {
     QualType PointeeTy = PT->getPointeeType();
     bool isReadOnly = false;
     // For historical/compatibility reasons, the read-only qualifier of the
@@ -2794,8 +2794,8 @@
     }
     else if (OutermostType) {
       QualType P = PointeeTy;
-      while (P->getAsPointerType())
-        P = P->getAsPointerType()->getPointeeType();
+      while (P->getAs<PointerType>())
+        P = P->getAs<PointerType>()->getPointeeType();
       if (P.isConstQualified()) {
         isReadOnly = true;
         S += 'r';
@@ -3035,7 +3035,7 @@
   TypedefDecl *TD = TT->getDecl();
 
   // typedef struct objc_selector *SEL;
-  const PointerType *ptr = TD->getUnderlyingType()->getAsPointerType();
+  const PointerType *ptr = TD->getUnderlyingType()->getAs<PointerType>();
   if (!ptr)
     return;
   const RecordType *rec = ptr->getPointeeType()->getAsStructureType();
@@ -3159,7 +3159,7 @@
       if (Ty->isObjCObjectPointerType())
         GCAttrs = QualType::Strong;
       else if (Ty->isPointerType())
-        return getObjCGCAttrKind(Ty->getAsPointerType()->getPointeeType());
+        return getObjCGCAttrKind(Ty->getAs<PointerType>()->getPointeeType());
     }
     // Non-pointers have none gc'able attribute regardless of the attribute
     // set on them.
@@ -3519,8 +3519,8 @@
   case Type::Pointer:
   {
     // Merge two pointer types, while trying to preserve typedef info
-    QualType LHSPointee = LHS->getAsPointerType()->getPointeeType();
-    QualType RHSPointee = RHS->getAsPointerType()->getPointeeType();
+    QualType LHSPointee = LHS->getAs<PointerType>()->getPointeeType();
+    QualType RHSPointee = RHS->getAs<PointerType>()->getPointeeType();
     QualType ResultType = mergeTypes(LHSPointee, RHSPointee);
     if (ResultType.isNull()) return QualType();
     if (getCanonicalType(LHSPointee) == getCanonicalType(ResultType))
@@ -3532,8 +3532,8 @@
   case Type::BlockPointer:
   {
     // Merge two block pointer types, while trying to preserve typedef info
-    QualType LHSPointee = LHS->getAsBlockPointerType()->getPointeeType();
-    QualType RHSPointee = RHS->getAsBlockPointerType()->getPointeeType();
+    QualType LHSPointee = LHS->getAs<BlockPointerType>()->getPointeeType();
+    QualType RHSPointee = RHS->getAs<BlockPointerType>()->getPointeeType();
     QualType ResultType = mergeTypes(LHSPointee, RHSPointee);
     if (ResultType.isNull()) return QualType();
     if (getCanonicalType(LHSPointee) == getCanonicalType(ResultType))
diff --git a/clang/lib/AST/DeclPrinter.cpp b/clang/lib/AST/DeclPrinter.cpp
index 84ae729..55d39e5 100644
--- a/clang/lib/AST/DeclPrinter.cpp
+++ b/clang/lib/AST/DeclPrinter.cpp
@@ -90,7 +90,7 @@
   while (!BaseType->isSpecifierType()) {
     if (isa<TypedefType>(BaseType))
       break;
-    else if (const PointerType* PTy = BaseType->getAsPointerType())
+    else if (const PointerType* PTy = BaseType->getAs<PointerType>())
       BaseType = PTy->getPointeeType();
     else if (const ArrayType* ATy = dyn_cast<ArrayType>(BaseType))
       BaseType = ATy->getElementType();
diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index 5d22f38..74928bc 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -279,9 +279,9 @@
 
 QualType CallExpr::getCallReturnType() const {
   QualType CalleeType = getCallee()->getType();
-  if (const PointerType *FnTypePtr = CalleeType->getAsPointerType())
+  if (const PointerType *FnTypePtr = CalleeType->getAs<PointerType>())
     CalleeType = FnTypePtr->getPointeeType();
-  else if (const BlockPointerType *BPT = CalleeType->getAsBlockPointerType())
+  else if (const BlockPointerType *BPT = CalleeType->getAs<BlockPointerType>())
     CalleeType = BPT->getPointeeType();
   
   const FunctionType *FnType = CalleeType->getAsFunctionType();
@@ -430,7 +430,7 @@
 /// getFunctionType - Return the underlying function type for this block.
 ///
 const FunctionType *BlockExpr::getFunctionType() const {
-  return getType()->getAsBlockPointerType()->
+  return getType()->getAs<BlockPointerType>()->
                     getPointeeType()->getAsFunctionType();
 }
 
@@ -991,7 +991,7 @@
       QualType T = VD->getType();
       // dereferencing to an object pointer is always a gc'able candidate
       if (T->isPointerType() && 
-          T->getAsPointerType()->getPointeeType()->isObjCObjectPointerType())
+          T->getAs<PointerType>()->getPointeeType()->isObjCObjectPointerType())
         return true;
         
     }
@@ -1419,7 +1419,7 @@
   if (const ExplicitCastExpr *CE = dyn_cast<ExplicitCastExpr>(this)) {
     if (!Ctx.getLangOptions().CPlusPlus) {
       // Check that it is a cast to void*.
-      if (const PointerType *PT = CE->getType()->getAsPointerType()) {
+      if (const PointerType *PT = CE->getType()->getAs<PointerType>()) {
         QualType Pointee = PT->getPointeeType();
         if (Pointee.getCVRQualifiers() == 0 && 
             Pointee->isVoidType() &&                              // to void*
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 2c29347..9473e4f 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/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())
diff --git a/clang/lib/AST/Type.cpp b/clang/lib/AST/Type.cpp
index 18fa76b..13d0cb0 100644
--- a/clang/lib/AST/Type.cpp
+++ b/clang/lib/AST/Type.cpp
@@ -202,7 +202,7 @@
   return false;
 }
 bool Type::isVoidPointerType() const {
-  if (const PointerType *PT = getAsPointerType())
+  if (const PointerType *PT = getAs<PointerType>())
     return PT->getPointeeType()->isVoidType();
   return false;
 }
@@ -296,51 +296,15 @@
 }
 
 QualType Type::getPointeeType() const {
-  if (const PointerType *PT = getAsPointerType())
+  if (const PointerType *PT = getAs<PointerType>())
     return PT->getPointeeType();
   if (const ObjCObjectPointerType *OPT = getAsObjCObjectPointerType())
     return OPT->getPointeeType();
-  if (const BlockPointerType *BPT = getAsBlockPointerType())
+  if (const BlockPointerType *BPT = getAs<BlockPointerType>())
     return BPT->getPointeeType();
   return QualType();
 }
 
-const PointerType *Type::getAsPointerType() const {
-  // If this is directly a pointer type, return it.
-  if (const PointerType *PTy = dyn_cast<PointerType>(this))
-    return PTy;
-  
-  // If the canonical form of this type isn't the right kind, reject it.
-  if (!isa<PointerType>(CanonicalType)) {
-    // Look through type qualifiers
-    if (isa<PointerType>(CanonicalType.getUnqualifiedType()))
-      return CanonicalType.getUnqualifiedType()->getAsPointerType();
-    return 0;
-  }
-
-  // If this is a typedef for a pointer type, strip the typedef off without
-  // losing all typedef information.
-  return cast<PointerType>(getDesugaredType());
-}
-
-const BlockPointerType *Type::getAsBlockPointerType() const {
-  // If this is directly a block pointer type, return it.
-  if (const BlockPointerType *PTy = dyn_cast<BlockPointerType>(this))
-    return PTy;
-  
-  // If the canonical form of this type isn't the right kind, reject it.
-  if (!isa<BlockPointerType>(CanonicalType)) {
-    // Look through type qualifiers
-    if (isa<BlockPointerType>(CanonicalType.getUnqualifiedType()))
-      return CanonicalType.getUnqualifiedType()->getAsBlockPointerType();
-    return 0;
-  }
-  
-  // If this is a typedef for a block pointer type, strip the typedef off 
-  // without losing all typedef information.
-  return cast<BlockPointerType>(getDesugaredType());
-}
-
 const ReferenceType *Type::getAsReferenceType() const {
   // If this is directly a reference type, return it.
   if (const ReferenceType *RTy = dyn_cast<ReferenceType>(this))
@@ -429,7 +393,7 @@
   // Also, C++ references and member pointers can point to a variably modified
   // type, where VLAs appear as an extension to C++, and should be treated
   // correctly.
-  if (const PointerType *PT = getAsPointerType())
+  if (const PointerType *PT = getAs<PointerType>())
     return PT->getPointeeType()->isVariablyModifiedType();
   if (const ReferenceType *RT = getAsReferenceType())
     return RT->getPointeeType()->isVariablyModifiedType();