[OpenCL] Update comments/diagnostics to refer to C++ for OpenCL

Clang doesn't implement OpenCL C++, change the comments to
reflect that.

Differential Revision: https://reviews.llvm.org/D64867

llvm-svn: 366421
diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 97fd92b..73b4f50 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -3559,7 +3559,8 @@
       isInvalid = DS.setFunctionSpecInline(Loc, PrevSpec, DiagID);
       break;
     case tok::kw_virtual:
-      // OpenCL C++ v1.0 s2.9: the virtual function qualifier is not supported.
+      // C++ for OpenCL does not allow virtual function qualifier, to avoid
+      // function pointers restricted in OpenCL v2.0 s6.9.a.
       if (getLangOpts().OpenCLCPlusPlus) {
         DiagID = diag::err_openclcxx_virtual_function;
         PrevSpec = Tok.getIdentifierInfo()->getNameStart();