Tsche

The given example is invalid, attribute-namespaces must be identifiers ([dcl.attr.grammar](https://standards.pydong.org/c++/dcl.attr.grammar#nt:attribute-namespace)), therefore scope resolution operators may not appear in an attribute-namespace. Anyway, https://github.com/tree-sitter/tree-sitter-cpp/pull/278 implements this.

This defect was one of the reasons I wrote my own library :P Related: https://github.com/boostorg/pfr/issues/16 https://github.com/boostorg/pfr/issues/20 https://github.com/boostorg/pfr/issues/162 https://github.com/boostorg/pfr/issues/169 https://github.com/boostorg/pfr/issues/170

`std::integer_sequence` is an empty type, so the destructuring expansion statement ```cpp template for (constexpr auto index : std::integer_sequence{}) { /* ... */ } ``` would result in zero expansions rather...