Rename ActiveTemplateInstantiation to CodeSynthesisContext in preparation for
using it for other kinds of context (where we currently produce context notes
in a highly ad-hoc manner).

llvm-svn: 295919
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 945fa89..cc50e6c 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -13465,10 +13465,10 @@
   //   for a class.*
   //
   //   * The class-key of the elaborated-type-specifier is required.
-  if (!ActiveTemplateInstantiations.empty()) {
-    // Do not complain about the form of friend template types during
-    // template instantiation; we will already have complained when the
-    // template was declared.
+  if (!CodeSynthesisContexts.empty()) {
+    // Do not complain about the form of friend template types during any kind
+    // of code synthesis. For template instantiation, we will have complained
+    // when the template was defined.
   } else {
     if (!T->isElaboratedTypeSpecifier()) {
       // If we evaluated the type to a record type, suggest putting