Give the RecursiveASTVisitor a configuration function

shouldWalkTypesOfTypeLocs() that determines whether it should walk the
Types within TypeLocs. This walk is redundant, but perhaps required
for some clients. Disabling this redundant walk in the unexpanded
parameter pack finder produces better results, because we get
parameter packs with source location info *unless* such source
location information isn't available.

llvm-svn: 122287

2 files changed, 11 insertions, 4 deletions

diff --git a/clang/include/clang/AST/RecursiveASTVisitor.h b/clang/include/clang/AST/RecursiveASTVisitor.h
index 263b0065815..97ff44d4795 100644
--- a/clang/include/clang/AST/RecursiveASTVisitor.h
+++ b/clang/include/clang/AST/RecursiveASTVisitor.h
@@ -144,6 +144,10 @@ public:
   /// template instantiations.
   bool shouldVisitTemplateInstantiations() const { return false; }
 
+  /// \brief Return whether this visitor should recurse into the types of
+  /// TypeLocs.
+  bool shouldWalkTypesOfTypeLocs() const { return true; }
+  
   /// \brief Recursively visit a statement or expression, by
   /// dispatching to Traverse*() based on the argument's dynamic type.
   ///
@@ -760,14 +764,15 @@ DEF_TRAVERSE_TYPE(ObjCObjectPointerType, {
 // ----------------- TypeLoc traversal -----------------
 
 // This macro makes available a variable TL, the passed-in TypeLoc.
-// It calls WalkUpFrom* for the Type in the given TypeLoc, in addition
-// to WalkUpFrom* for the TypeLoc itself, such that existing clients
-// that override the WalkUpFrom*Type() and/or Visit*Type() methods
+// If requested, it calls WalkUpFrom* for the Type in the given TypeLoc, 
+// in addition to WalkUpFrom* for the TypeLoc itself, such that existing 
+// clients that override the WalkUpFrom*Type() and/or Visit*Type() methods
 // continue to work.
 #define DEF_TRAVERSE_TYPELOC(TYPE, CODE)                                \
   template<typename Derived>                                            \
   bool RecursiveASTVisitor<Derived>::Traverse##TYPE##Loc(TYPE##Loc TL) { \
-    TRY_TO(WalkUpFrom##TYPE(TL.getTypePtr()));                          \
+    if (getDerived().shouldWalkTypesOfTypeLocs())                       \
+      TRY_TO(WalkUpFrom##TYPE(TL.getTypePtr()));                        \
     TRY_TO(WalkUpFrom##TYPE##Loc(TL));                                  \
     { CODE; }                                                           \
     return true;                                                        \
diff --git a/clang/lib/Sema/SemaTemplateVariadic.cpp b/clang/lib/Sema/SemaTemplateVariadic.cpp
index e71c2334ca5..681bc8d0726 100644
--- a/clang/lib/Sema/SemaTemplateVariadic.cpp
+++ b/clang/lib/Sema/SemaTemplateVariadic.cpp
@@ -38,6 +38,8 @@ namespace {
                   llvm::SmallVectorImpl<UnexpandedParameterPack> &Unexpanded)
       : Unexpanded(Unexpanded) { }
 
+    bool shouldWalkTypesOfTypeLocs() const { return false; }
+    
     //------------------------------------------------------------------------
     // Recording occurrences of (unexpanded) parameter packs.
     //------------------------------------------------------------------------