Clean up our handling of local instantiation scopes, which keep track

of the mapping from local declarations to their instantiated
counterparts during template instantiation. Previously, we tried to do
some unholy merging of local instantiation scopes that involved
storing a single hash table along with an "undo" list on the
side... which was ugly, and never handled function parameters
properly.

Now, we just keep separate hash tables for each local instantiation
scope, and "combining" two scopes means that we'll look in each of the
combined hash tables. The combined scope stack is rarely deep, and
this makes it easy to avoid the "undo" issues we were hitting. Also,
I've simplified the logic for function parameters: if we're declaring
a function and we need the function parameters to live longer, we just
push them back into the local instantiation scope where we need them. 

Fixes PR6990.

llvm-svn: 102732

1 files changed, 9 insertions, 7 deletions

diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 5143b77f592..445cf17aadf 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -2907,17 +2907,19 @@ QualType
 TreeTransform<Derived>::TransformFunctionProtoType(TypeLocBuilder &TLB,
                                                    FunctionProtoTypeLoc TL,
                                                    QualType ObjectType) {
-  FunctionProtoType *T = TL.getTypePtr();
-  QualType ResultType = getDerived().TransformType(TLB, TL.getResultLoc());
-  if (ResultType.isNull())
-    return QualType();
-
-  // Transform the parameters.
+  // Transform the parameters. We do this first for the benefit of template
+  // instantiations, so that the ParmVarDecls get/ placed into the template
+  // instantiation scope before we transform the function type.
   llvm::SmallVector<QualType, 4> ParamTypes;
   llvm::SmallVector<ParmVarDecl*, 4> ParamDecls;
   if (getDerived().TransformFunctionTypeParams(TL, ParamTypes, ParamDecls))
     return QualType();
-
+  
+  FunctionProtoType *T = TL.getTypePtr();
+  QualType ResultType = getDerived().TransformType(TLB, TL.getResultLoc());
+  if (ResultType.isNull())
+    return QualType();
+  
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() ||
       ResultType != T->getResultType() ||