Initial infrastructure for class template partial specialization. Here

we have the basics of declaring and storing class template partial
specializations, matching class template partial specializations at
instantiation time via (limited) template argument deduction, and
using the class template partial specialization's pattern for
instantiation. 

This patch is enough to make a simple is_pointer type trait work, but
not much else.




git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@72662 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 27 insertions, 8 deletions

diff --git a/lib/Sema/SemaTemplateInstantiate.cpp b/lib/Sema/SemaTemplateInstantiate.cpp
index 3cac739818..d3d771b0eb 100644
--- a/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/lib/Sema/SemaTemplateInstantiate.cpp
@@ -822,14 +822,34 @@ Sema::InstantiateClassTemplateSpecialization(
   if (ClassTemplateSpec->getSpecializationKind() != TSK_Undeclared)
     return true;
 
-  // FIXME: Push this class template instantiation onto the instantiation stack,
-  // checking for recursion that exceeds a certain depth.
-
-  // FIXME: Perform class template partial specialization to select the best
-  // template.
   ClassTemplateDecl *Template = ClassTemplateSpec->getSpecializedTemplate();
-
   CXXRecordDecl *Pattern = Template->getTemplatedDecl();
+  const TemplateArgumentList *TemplateArgs 
+    = &ClassTemplateSpec->getTemplateArgs();
+
+  // Determine whether any class template partial specializations
+  // match the given template arguments.
+  llvm::SmallVector<ClassTemplatePartialSpecializationDecl *, 4> Matched;
+  for (llvm::FoldingSet<ClassTemplatePartialSpecializationDecl>::iterator 
+         Partial = Template->getPartialSpecializations().begin(),
+         PartialEnd = Template->getPartialSpecializations().end();
+       Partial != PartialEnd;
+       ++Partial) {
+    if (DeduceTemplateArguments(&*Partial, ClassTemplateSpec->getTemplateArgs()))
+      Matched.push_back(&*Partial);
+  }
+
+  if (Matched.size() == 1) {
+    Pattern = Matched[0];
+    // FIXME: set TemplateArgs to the template arguments of the
+    // partial specialization, instantiated with the deduced template
+    // arguments.
+  } else if (Matched.size() > 1) {
+    // FIXME: Implement partial ordering of class template partial
+    // specializations.
+    Diag(ClassTemplateSpec->getLocation(), 
+         diag::unsup_template_partial_spec_ordering);
+  }
 
   // Note that this is an instantiation.  
   ClassTemplateSpec->setSpecializationKind(
@@ -837,8 +857,7 @@ Sema::InstantiateClassTemplateSpecialization(
                                              : TSK_ImplicitInstantiation);
 
   return InstantiateClass(ClassTemplateSpec->getLocation(),
-                          ClassTemplateSpec, Pattern,
-                          ClassTemplateSpec->getTemplateArgs(),
+                          ClassTemplateSpec, Pattern, *TemplateArgs,
                           ExplicitInstantiation);
 }