Factor code into CXXRecordDecl::getTemplateInstantiationPattern() helper

This moves some code from SemaType.cpp's hasVisibleDefinition() into
DeclCXX.cpp so that it can be used elsewhere. I found one other instance
of code trying to do the same thing, there are probably more. Search for
getInstantiatedFrom() to try to find more.

No functionality change.

Reviewed By: rsmith

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D5783

llvm-svn: 219714

1 files changed, 38 insertions, 0 deletions

diff --git a/clang/lib/AST/DeclCXX.cpp b/clang/lib/AST/DeclCXX.cpp
index 37bd050c697..623cae5bf7a 100644
--- a/clang/lib/AST/DeclCXX.cpp
+++ b/clang/lib/AST/DeclCXX.cpp
@@ -1261,6 +1261,44 @@ CXXRecordDecl::setTemplateSpecializationKind(TemplateSpecializationKind TSK) {
   llvm_unreachable("Not a class template or member class specialization");
 }
 
+const CXXRecordDecl *CXXRecordDecl::getTemplateInstantiationPattern() const {
+  // If it's a class template specialization, find the template or partial
+  // specialization from which it was instantiated.
+  if (auto *TD = dyn_cast<ClassTemplateSpecializationDecl>(this)) {
+    auto From = TD->getInstantiatedFrom();
+    if (auto *CTD = From.dyn_cast<ClassTemplateDecl *>()) {
+      while (auto *NewCTD = CTD->getInstantiatedFromMemberTemplate()) {
+        if (NewCTD->isMemberSpecialization())
+          break;
+        CTD = NewCTD;
+      }
+      return CTD->getTemplatedDecl();
+    }
+    if (auto *CTPSD =
+            From.dyn_cast<ClassTemplatePartialSpecializationDecl *>()) {
+      while (auto *NewCTPSD = CTPSD->getInstantiatedFromMember()) {
+        if (NewCTPSD->isMemberSpecialization())
+          break;
+        CTPSD = NewCTPSD;
+      }
+      return CTPSD;
+    }
+  }
+
+  if (MemberSpecializationInfo *MSInfo = getMemberSpecializationInfo()) {
+    if (isTemplateInstantiation(MSInfo->getTemplateSpecializationKind())) {
+      const CXXRecordDecl *RD = this;
+      while (auto *NewRD = RD->getInstantiatedFromMemberClass())
+        RD = NewRD;
+      return RD;
+    }
+  }
+
+  assert(!isTemplateInstantiation(this->getTemplateSpecializationKind()) &&
+         "couldn't find pattern for class template instantiation");
+  return nullptr;
+}
+
 CXXDestructorDecl *CXXRecordDecl::getDestructor() const {
   ASTContext &Context = getASTContext();
   QualType ClassType = Context.getTypeDeclType(this);