introduce a new ASTContext::getCanonicalType method. This is the first

step towards fixing PR2189.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@49291 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 13 insertions, 0 deletions

diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index a68fea469d..0b513ecbd1 100644
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -931,6 +931,19 @@ QualType ASTContext::getPointerDiffType() const {
 //                              Type Operators
 //===----------------------------------------------------------------------===//
 
+/// getCanonicalType - Return the canonical (structural) type corresponding to
+/// the specified potentially non-canonical type.  The non-canonical version
+/// of a type may have many "decorated" versions of types.  Decorators can
+/// include typedefs, 'typeof' operators, etc. The returned type is guaranteed
+/// to be free of any of these, allowing two canonical types to be compared
+/// for exact equality with a simple pointer comparison.
+QualType ASTContext::getCanonicalType(QualType T) {
+  QualType CanType = T.getTypePtr()->getCanonicalTypeInternal();
+  return QualType(CanType.getTypePtr(),
+                  T.getCVRQualifiers() | CanType.getCVRQualifiers());
+}
+
+
 /// getArrayDecayedType - Return the properly qualified result of decaying the
 /// specified array type to a pointer.  This operation is non-trivial when
 /// handling typedefs etc.  The canonical type of "T" must be an array type,