Function data_mask 

unsafe fn data_mask(data: SEXP, enclos: SEXP) -> SEXP

A new environment enclosed by enclos that binds each named element of the list data, as eval() builds one for a list envir. Bound in reverse so the first of two same-named elements wins, as in eval().

Safety

R’s main thread, inside a miniextendr boundary; data a rooted list, enclos an environment. The result is unprotected.