An upcoming change in mainline LLVM is a little stricter about template syntax, causing OpenUSD to fail to compile.

`Sdf_Children<ChildPolicy>::_UpdateChildNames()` includes a template call that was in violation of ISO C standards to compile properly.

ISO C++03 14.2/4:

> When the name of a member template specialization appears after . or -> in a postfix-expression, or after nested-name-specifier in a qualified-id, and the postfix-expression or qualified-id explicitly depends on a template-parameter (14.6.2), the member template name must be prefixed by the keyword template. Otherwise the name is assumed to name a non-template.

Explicitly adding the template keyword resolves this. Unfortunately this also gets tagged as unnecessary by older LLVM versions or other compilers, but c'est la vie.

Author: dgovil

pxr/usd/sdf/children.cpp

@@ -190,7 +190,7 @@ Sdf_Children<ChildPolicy>::_UpdateChildNames() const
     _childNamesValid = true;
 
     if (_layer) {
-        _childNames = _layer->GetFieldAs<std::vector<FieldType> >(
+        _childNames = _layer->template GetFieldAs<std::vector<FieldType>>(
             _parentPath, _childrenKey);
     } else {
         _childNames.clear();