/etc/bash_completion.d/boinc is in boinc-client 7.4.23+dfsg-1+deb8u1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94  | _boinc()
{
    local cur prev opts
    COMPREPLY=()
    cur="${COMP_WORDS[COMP_CWORD]}"
    prev="${COMP_WORDS[COMP_CWORD-1]}"
    opts="$(boinc --help | \
        sed -n -r 's/^[[:space:]]*(--[a-z_]*).*/\1/p')"
    # Handle options that require one or more arguments.
    case "$prev" in
        --attach_project|--detach_project|--reset_project|--update_prefs|\
        --gui_rpc_port)
            return 0
        ;;
    esac
    # Handle options that require two arguments.
    if [[ COMP_CWORD -gt 1 ]]; then
        pprev="${COMP_WORDS[COMP_CWORD-2]}"
        case "$pprev" in
            --attach_project)
                return 0
            ;;
        esac
    fi
    if [[ "$cur" == -* ]]; then
        COMPREPLY=( $(compgen -W "$opts" -- "$cur") )
        return 0
    fi
}
complete -F _boinc -o default boinc
_boinccmd()
{
    local cur prev opts cmds
    COMPREPLY=()
    cur="${COMP_WORDS[COMP_CWORD]}"
    prev="${COMP_WORDS[COMP_CWORD-1]}"
    opts="--host --passwd -h --help -V --version"
    cmds="$(boinccmd --help 2>&1 | \
        sed -n -r 's/^[[:space:]]*(--[a-z_]*).*/\1/p')"
    # The following construct assures that:
    # - no command follows if one of $opts or $cmds was given
    # - after --host follows only one command or --passwd and one command
    # - after --passwd follows only one command
    if [[ $COMP_CWORD -eq 1 ]]; then
        COMPREPLY=( $(compgen -W "$opts $cmds" -- "$cur") )
        return 0
    else
        if [[ "${COMP_WORDS[@]}" =~ ".* --host .* --passwd .*" ]]; then
            if [[ $COMP_CWORD -eq 5 ]]; then
                COMPREPLY=( $(compgen -W "$cmds" -- "$cur") )
            fi
        elif [[ "${COMP_WORDS[@]}" =~ ".* --passwd .*" ]]; then
            if [[ $COMP_CWORD -eq 3 ]]; then
                COMPREPLY=( $(compgen -W "$cmds" -- "$cur") )
            fi
        elif [[ "${COMP_WORDS[@]}" =~ ".* --host .*" ]]; then
            if [[ $COMP_CWORD -eq 3 ]]; then
                COMPREPLY=( $(compgen -W "--passwd $cmds" -- "$cur") )
            fi
       fi
    fi
    # Handle options/commands that require one or more arguments.
    case "$prev" in
        --get_messages|--passwd)
            return 0
        ;;
        --host)
            _known_hosts
            return 0
        ;;
        --set_run_mode|--set_network_mode)
            COMPREPLY=( $(compgen -W "always auto never" -- "$cur") )
            return 0
        ;;
        --set_screensaver_mode)
            COMPREPLY=( $(compgen -W "on off" -- "$cur") )
            return 0
        ;;
    esac
}
complete -F _boinccmd boinccmd
# vim: syntax=sh
 |