Also I did not install rust by myself:

# guix package --list-installed | grep rust

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Mar 28, 2019, 4:43 AM by znavko@tutanota.com:

Hello! I ran `guix system reconfigure /etc/config.scm` and now rust is compiling. Rust is compiling too long.

I've produced `guix graph --type=reverse-package rust | dot -Tsvg > r.svg` to see why does guix do this, but there is no answer.

My config and rust reverse dependecies tree are in attach.

A tree has only one node - rust.