Introduce a new representation for template template

parameters. Rather than storing them as either declarations (for the
non-dependent case) or expressions (for the dependent case), we now
(always) store them as TemplateNames. 

The primary change here is to add a new kind of TemplateArgument,
which stores a TemplateName. However, making that change ripples to
every switch on a TemplateArgument's kind, also affecting
TemplateArgumentLocInfo/TemplateArgumentLoc, default template
arguments for template template parameters, type-checking of template
template arguments, etc.

This change is light on testing. It should fix several pre-existing
problems with template template parameters, such as:
  - the inability to use dependent template names as template template
  arguments
  - template template parameter default arguments cannot be
  instantiation

However, there are enough pieces missing that more implementation is
required before we can adequately test template template parameters. 



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@86777 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 6 insertions, 6 deletions

diff --git a/lib/Sema/SemaTemplateInstantiate.cpp b/lib/Sema/SemaTemplateInstantiate.cpp
index 9e8dc2ea2c..74f521e3cf 100644
--- a/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/lib/Sema/SemaTemplateInstantiate.cpp
@@ -452,10 +452,11 @@ Decl *TemplateInstantiator::TransformDecl(Decl *D) {
 
   if (TemplateTemplateParmDecl *TTP = dyn_cast<TemplateTemplateParmDecl>(D)) {
     if (TTP->getDepth() < TemplateArgs.getNumLevels()) {
-      assert(TemplateArgs(TTP->getDepth(), TTP->getPosition()).getAsDecl() &&
+      TemplateName Template
+        = TemplateArgs(TTP->getDepth(), TTP->getPosition()).getAsTemplate();
+      assert(!Template.isNull() && Template.getAsTemplateDecl() &&
              "Wrong kind of template template argument");
-      return cast<TemplateDecl>(TemplateArgs(TTP->getDepth(),
-                                             TTP->getPosition()).getAsDecl());
+      return Template.getAsTemplateDecl();
     }
 
     // If the corresponding template argument is NULL or non-existent, it's
@@ -466,9 +467,8 @@ Decl *TemplateInstantiator::TransformDecl(Decl *D) {
                                           TTP->getPosition()))
       return D;
 
-    // FIXME: Implement depth reduction of template template parameters
-    assert(false &&
-      "Reducing depth of template template parameters is not yet implemented");
+    // Fall through to find the instantiated declaration for this template
+    // template parameter.
   }
 
   return SemaRef.FindInstantiatedDecl(cast<NamedDecl>(D), TemplateArgs);