WIP implementation of explicit function template specialization. This

first implementation recognizes when a function declaration is an
explicit function template specialization (based on the presence of a
template<> header), performs template argument deduction + ambiguity
resolution to determine which template is being specialized, and hooks

There are many caveats here:
  - We completely and totally drop any explicitly-specified template
  arguments on the floor
  - We don't diagnose any of the extra semantic things that we should
  diagnose. 
  - I haven't looked to see that we're getting the right linkage for
  explicit specializations

On a happy note, this silences a bunch of errors that show up in
libstdc++'s <iostream>, although Clang still can't get through the
entire header.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@82728 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 18 insertions, 4 deletions

diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
index 1a7aaac6f7..25d3d44cc8 100644
--- a/lib/AST/Decl.cpp
+++ b/lib/AST/Decl.cpp
@@ -689,7 +689,10 @@ void
 FunctionDecl::setFunctionTemplateSpecialization(ASTContext &Context,
                                                 FunctionTemplateDecl *Template,
                                      const TemplateArgumentList *TemplateArgs,
-                                                void *InsertPos) {
+                                                void *InsertPos,
+                                              TemplateSpecializationKind TSK) {
+  assert(TSK != TSK_Undeclared && 
+         "Must specify the type of function template specialization");
   FunctionTemplateSpecializationInfo *Info
     = TemplateOrSpecialization.dyn_cast<FunctionTemplateSpecializationInfo*>();
   if (!Info)
@@ -697,13 +700,24 @@ FunctionDecl::setFunctionTemplateSpecialization(ASTContext &Context,
 
   Info->Function = this;
   Info->Template.setPointer(Template);
-  Info->Template.setInt(TSK_ImplicitInstantiation - 1);
+  Info->Template.setInt(TSK - 1);
   Info->TemplateArguments = TemplateArgs;
   TemplateOrSpecialization = Info;
 
   // Insert this function template specialization into the set of known
-  // function template specialiations.
-  Template->getSpecializations().InsertNode(Info, InsertPos);
+  // function template specializations.
+  if (InsertPos)
+    Template->getSpecializations().InsertNode(Info, InsertPos);
+  else {
+    // Try to insert the new node. If there is an existing node, remove it 
+    // first.
+    FunctionTemplateSpecializationInfo *Existing
+      = Template->getSpecializations().GetOrInsertNode(Info);
+    if (Existing) {
+      Template->getSpecializations().RemoveNode(Existing);
+      Template->getSpecializations().GetOrInsertNode(Info);
+    }
+  }
 }
 
 TemplateSpecializationKind FunctionDecl::getTemplateSpecializationKind() const {