$ cargo uninstall rustfmt && rustup component add rustfmt-preview
      Removing /home/alex/.cargo/bin/cargo-fmt
      Removing /home/alex/.cargo/bin/rustfmt
  info: downloading component 'rustfmt-preview'
  info: installing component 'rustfmt-preview'
  $ bindgen bindings.h -- -I/usr/local/include/libr > /dev/null
  Custom { kind: Other, error: StringError("Cannot find binary path") }
  $ rustc --version
  rustc 1.28.0-nightly (29f48ccf3 2018-06-03)
  $ cat bindings.h 
  #include <r_lib.h>
  #include <r_asm.h>
  #include <r_reg.h>
  #include <r_anal.h>
  #include <r_bin.h>