Move the template instantiation logic for template arguments into the

general tree transformation. Also, implement template instantiation
for parameter packs.

In addition, introduce logic to enter the appropriate context for
subexpressions that are not potentially evaluated.

llvm-svn: 78114

2 files changed, 89 insertions, 50 deletions

diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp
index a995181d019..c281b96a9ea 100644
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -331,9 +331,6 @@ namespace {
     /// \brief Transform the given template name by instantiating it.
     TemplateName TransformTemplateName(TemplateName Template);
     
-    /// \brief Transform the given template argument by instantiating it.
-    TemplateArgument TransformTemplateArgument(const TemplateArgument &Arg);
-    
     /// \brief Transforms a template type parameter type by performing 
     /// substitution of the corresponding template type argument.
     QualType TransformTemplateTypeParmType(const TemplateTypeParmType *T);
@@ -360,11 +357,6 @@ TemplateInstantiator::TransformTemplateName(TemplateName Template) {
                                            TemplateArgs);
 }
 
-TemplateArgument 
-TemplateInstantiator::TransformTemplateArgument(const TemplateArgument &Arg) {
-  return getSema().Instantiate(Arg, TemplateArgs);
-}
-
 QualType 
 TemplateInstantiator::TransformTemplateTypeParmType(
                                               const TemplateTypeParmType *T) {
@@ -852,42 +844,7 @@ Sema::InstantiateTemplateName(TemplateName Name, SourceLocation Loc,
 
 TemplateArgument Sema::Instantiate(TemplateArgument Arg, 
                                    const TemplateArgumentList &TemplateArgs) {
-  switch (Arg.getKind()) {
-  case TemplateArgument::Null:
-    assert(false && "Should never have a NULL template argument");
-    break;
-    
-  case TemplateArgument::Type: {
-    QualType T = InstantiateType(Arg.getAsType(), TemplateArgs, 
-                                 Arg.getLocation(), DeclarationName());
-    if (T.isNull())
-      return TemplateArgument();
-    
-    return TemplateArgument(Arg.getLocation(), T);
-  }
-
-  case TemplateArgument::Declaration:
-    // FIXME: Template instantiation for template template parameters.
-    return Arg;
-
-  case TemplateArgument::Integral:
-    return Arg;
-
-  case TemplateArgument::Expression: {
-    // Template argument expressions are not potentially evaluated.
-    EnterExpressionEvaluationContext Unevaluated(*this, Action::Unevaluated);
-
-    Sema::OwningExprResult E = InstantiateExpr(Arg.getAsExpr(), TemplateArgs);
-    if (E.isInvalid())
-      return TemplateArgument();
-    return TemplateArgument(E.takeAs<Expr>());
-  }
-  
-  case TemplateArgument::Pack:
-    assert(0 && "FIXME: Implement!");
-    break;
-  }
-
-  assert(false && "Unhandled template argument kind");
-  return TemplateArgument();
+  TemplateInstantiator Instantiator(*this, TemplateArgs, SourceLocation(),
+                                    DeclarationName());
+  return Instantiator.TransformTemplateArgument(Arg);
 }
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 622f7b44cd9..0aefda7f118 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -47,7 +47,7 @@ namespace clang {
 /// a new AST node.
 ///
 /// Subclasses can customize the transformation at various levels. The 
-/// most course-grained transformations involve replacing TransformType(),
+/// most coarse-grained transformations involve replacing TransformType(),
 /// TransformExpr(), TransformDecl(), TransformNestedNameSpecifier(),
 /// TransformTemplateName(), or TransformTemplateArgument() with entirely
 /// new implementations.
@@ -172,7 +172,10 @@ public:
   
   /// \brief Transform the given template argument.
   ///
-  /// FIXME: At the moment, subclasses must override this.
+  /// By default, this operation transforms the type, expression, or 
+  /// declaration stored within the template argument and constructs a 
+  /// new template argument from the transformed result. Subclasses may
+  /// override this function to provide alternate behavior.
   TemplateArgument TransformTemplateArgument(const TemplateArgument &Arg);
   
 #define ABSTRACT_TYPE(CLASS, PARENT)
@@ -397,6 +400,62 @@ public:
   }    
 };
   
+template<typename Derived>
+TemplateArgument 
+TreeTransform<Derived>::TransformTemplateArgument(const TemplateArgument &Arg) {
+  switch (Arg.getKind()) {
+  case TemplateArgument::Null:
+  case TemplateArgument::Integral:
+    return Arg;
+      
+  case TemplateArgument::Type: {
+    QualType T = getDerived().TransformType(Arg.getAsType());
+    if (T.isNull())
+      return TemplateArgument();
+    return TemplateArgument(Arg.getLocation(), T);
+  }
+      
+  case TemplateArgument::Declaration: {
+    Decl *D = getDerived().TransformDecl(Arg.getAsDecl());
+    if (!D)
+      return TemplateArgument();
+    return TemplateArgument(Arg.getLocation(), D);
+  }
+      
+  case TemplateArgument::Expression: {
+    // Template argument expressions are not potentially evaluated.
+    EnterExpressionEvaluationContext Unevaluated(getSema(), 
+                                                 Action::Unevaluated);
+    
+    Sema::OwningExprResult E = getDerived().TransformExpr(Arg.getAsExpr());
+    if (E.isInvalid())
+      return TemplateArgument();
+    return TemplateArgument(E.takeAs<Expr>());
+  }
+      
+  case TemplateArgument::Pack: {
+    llvm::SmallVector<TemplateArgument, 4> TransformedArgs;
+    TransformedArgs.reserve(Arg.pack_size());
+    for (TemplateArgument::pack_iterator A = Arg.pack_begin(), 
+                                      AEnd = Arg.pack_end();
+         A != AEnd; ++A) {
+      TemplateArgument TA = getDerived().TransformTemplateArgument(*A);
+      if (TA.isNull())
+        return TA;
+      
+      TransformedArgs.push_back(TA);
+    }
+    TemplateArgument Result;
+    Result.setArgumentPack(TransformedArgs.data(), TransformedArgs.size(), 
+                           true);
+    return Result;
+  }
+  }
+  
+  // Work around bogus GCC warning
+  return TemplateArgument();
+}
+
 //===----------------------------------------------------------------------===//
 // Type transformation
 //===----------------------------------------------------------------------===//
@@ -558,14 +617,22 @@ TreeTransform<Derived>::TransformConstantArrayWithExprType(
   if (ElementType.isNull())
     return QualType();
   
+  // Array bounds are not potentially evaluated contexts
+  EnterExpressionEvaluationContext Unevaluated(SemaRef, Action::Unevaluated);
+  
+  Sema::OwningExprResult Size = getDerived().TransformExpr(T->getSizeExpr());
+  if (Size.isInvalid())
+    return QualType();
+  
   if (!getDerived().AlwaysRebuild() &&
-      ElementType == T->getElementType())
+      ElementType == T->getElementType() &&
+      Size.get() == T->getSizeExpr())
     return QualType(T, 0);
   
   return getDerived().RebuildConstantArrayWithExprType(ElementType, 
                                                        T->getSizeModifier(),
                                                        T->getSize(),
-                                        /*FIXME: Transform?*/T->getSizeExpr(),
+                                                       Size.takeAs<Expr>(),
                                                    T->getIndexTypeQualifier(),
                                                        T->getBracketsRange());
 }
@@ -611,6 +678,9 @@ QualType TreeTransform<Derived>::TransformVariableArrayType(
   if (ElementType.isNull())
     return QualType();
   
+  // Array bounds are not potentially evaluated contexts
+  EnterExpressionEvaluationContext Unevaluated(SemaRef, Action::Unevaluated);
+
   Sema::OwningExprResult Size = getDerived().TransformExpr(T->getSizeExpr());
   if (Size.isInvalid())
     return QualType();
@@ -636,6 +706,9 @@ QualType TreeTransform<Derived>::TransformDependentSizedArrayType(
   if (ElementType.isNull())
     return QualType();
   
+  // Array bounds are not potentially evaluated contexts
+  EnterExpressionEvaluationContext Unevaluated(SemaRef, Action::Unevaluated);
+  
   Sema::OwningExprResult Size = getDerived().TransformExpr(T->getSizeExpr());
   if (Size.isInvalid())
     return QualType();
@@ -661,6 +734,9 @@ QualType TreeTransform<Derived>::TransformDependentSizedExtVectorType(
   if (ElementType.isNull())
     return QualType();
   
+  // Vector sizes are not potentially evaluated contexts
+  EnterExpressionEvaluationContext Unevaluated(SemaRef, Action::Unevaluated);
+
   Sema::OwningExprResult Size = getDerived().TransformExpr(T->getSizeExpr());
   if (Size.isInvalid())
     return QualType();
@@ -757,6 +833,9 @@ QualType TreeTransform<Derived>::TransformTypedefType(const TypedefType *T) {
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformTypeOfExprType(
                                                     const TypeOfExprType *T) { 
+  // typeof expressions are not potentially evaluated contexts
+  EnterExpressionEvaluationContext Unevaluated(SemaRef, Action::Unevaluated);
+  
   Sema::OwningExprResult E = getDerived().TransformExpr(T->getUnderlyingExpr());
   if (E.isInvalid())
     return QualType();
@@ -785,6 +864,9 @@ QualType TreeTransform<Derived>::TransformTypeOfType(const TypeOfType *T) {
   
 template<typename Derived> 
 QualType TreeTransform<Derived>::TransformDecltypeType(const DecltypeType *T) { 
+  // decltype expressions are not potentially evaluated contexts
+  EnterExpressionEvaluationContext Unevaluated(SemaRef, Action::Unevaluated);
+  
   Sema::OwningExprResult E = getDerived().TransformExpr(T->getUnderlyingExpr());
   if (E.isInvalid())
     return QualType();