Can we add a larger variety of tests? Given how simple the BindingDecl case seems to be I don't expect any surprises but it would be good to verify that cases like mixed types, references and bit-fields work as expected.
This change in itself is not enough to support BindingDecl. The tests pass but the resulting AST is not correct because DecompositionDecl is not imported yet. Still no visible problem happens, the DecompositionDecl is just visited and imported as a VarDecl. The import of DecompositionDecl can be added later (but I am not sure if without it the new import of BindingDecl will not cause hidden problems).
Improved the test variety a bit. (std::tuple is more difficult to handle because need for namespace std.)