In /usr/bin/rust-gdb line 10:
  RUSTC="rustc"
  ^---^ SC2034: RUSTC appears unused. Verify use (or export if used externally).


In /usr/bin/rust-gdb line 23:
PYTHONPATH="$PYTHONPATH:$GDB_PYTHON_MODULE_DIRECTORY" exec ${RUST_GDB} \
                                                           ^---------^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
PYTHONPATH="$PYTHONPATH:$GDB_PYTHON_MODULE_DIRECTORY" exec "${RUST_GDB}" \

For more information:
  https://www.shellcheck.net/wiki/SC2034 -- RUSTC appears unused. Verify use ...
  https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ...