Fix C++ PCH issue.

The canonical FunctionTemplateDecl contains the specializations but we cannot use getCanonicalDecl on Template because it may still be initializing.
Write and read it from PCH.
Fixes http://llvm.org/PR8134

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@113744 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Serialization/ASTReaderDecl.cpp b/lib/Serialization/ASTReaderDecl.cpp
index 77cd426..e5a87b0 100644
--- a/lib/Serialization/ASTReaderDecl.cpp
+++ b/lib/Serialization/ASTReaderDecl.cpp
@@ -294,6 +294,10 @@
     FD->TemplateOrSpecialization = FTInfo;
 
     if (FD->isCanonicalDecl()) { // if canonical add to template's set.
+      // The template that contains the specializations set. It's not safe to
+      // use getCanonicalDecl on Template since it may still be initializing.
+      FunctionTemplateDecl *CanonTemplate
+        = cast<FunctionTemplateDecl>(Reader.GetDecl(Record[Idx++]));
       // Get the InsertPos by FindNodeOrInsertPos() instead of calling
       // InsertNode(FTInfo) directly to avoid the getASTContext() call in
       // FunctionTemplateSpecializationInfo's Profile().
@@ -303,9 +307,9 @@
       FunctionTemplateSpecializationInfo::Profile(ID, TemplArgs.data(),
                                                   TemplArgs.size(), C);
       void *InsertPos = 0;
-      Template->getSpecializations().FindNodeOrInsertPos(ID, InsertPos);
+      CanonTemplate->getSpecializations().FindNodeOrInsertPos(ID, InsertPos);
       assert(InsertPos && "Another specialization already inserted!");
-      Template->getSpecializations().InsertNode(FTInfo, InsertPos);
+      CanonTemplate->getSpecializations().InsertNode(FTInfo, InsertPos);
     }
     break;
   }
@@ -1041,7 +1045,7 @@
 
     // Read the function specialization declarations.
     // FunctionTemplateDecl's FunctionTemplateSpecializationInfos are filled
-    // through the specialized FunctionDecl's setFunctionTemplateSpecialization.
+    // when reading the specialized FunctionDecl.
     unsigned NumSpecs = Record[Idx++];
     while (NumSpecs--)
       Reader.GetDecl(Record[Idx++]);
diff --git a/lib/Serialization/ASTWriterDecl.cpp b/lib/Serialization/ASTWriterDecl.cpp
index 3f990e7..7697466 100644
--- a/lib/Serialization/ASTWriterDecl.cpp
+++ b/lib/Serialization/ASTWriterDecl.cpp
@@ -257,6 +257,12 @@
     }
     
     Writer.AddSourceLocation(FTSInfo->getPointOfInstantiation(), Record);
+
+    if (D->isCanonicalDecl()) {
+      // Write the template that contains the specializations set. We will
+      // add a FunctionTemplateSpecializationInfo to it when reading.
+      Writer.AddDeclRef(FTSInfo->getTemplate()->getCanonicalDecl(), Record);
+    }
     break;
   }
   case FunctionDecl::TK_DependentFunctionTemplateSpecialization: {