For Fedora Rawhide run the following as root:
dnf config-manager addrepo --from-repofile=https://download.opensuse.org/repositories/home:ignatenkobrain:rust/Fedora_Rawhide/home:ignatenkobrain:rust.repo
dnf install rust-bindgen
For Fedora 32 run the following as root:
dnf config-manager --add-repo https://download.opensuse.org/repositories/home:ignatenkobrain:rust/Fedora_32/home:ignatenkobrain:rust.repo
dnf install rust-bindgen
For Fedora 31 run the following as root:
dnf config-manager --add-repo https://download.opensuse.org/repositories/home:ignatenkobrain:rust/Fedora_31/home:ignatenkobrain:rust.repo
dnf install rust-bindgen