Rust popular?

Tiobe language rankings for May 2019:

Rust is ranked 34th at 0.335%, below Lisp and Prolog. Go is ranked 19th at 1.114%. C is ranked 2nd at 14.233%

Rust does not have a stable, standard BNF grammar specification. The language reference document for Rust has 33 or 34 unspecified missing language definitions [see "FIXME" sections].