Symfony based autocomplete breaks SCP autocomplete

This has probably nothing to do with your robo compspec. Nor with the _scp completion function associated with scp.

It is probably due to your COMP_WORDBREAKS=${COMP_WORDBREAKS//:}.

You removed : from the list of separators. Apparently _scp is robust enough to behave the same with or without : as a word separator. It returns the same list of candidate completions. But the token that gets substituted when _scp returns only one candidate for the completion of, e.g. scp host:public_ht, is host:public_ht, instead of just public_ht. Proof:

$ _foobar () { COMPREPLY=bazcux; return 0; }$ complete -o default -F _foobar foobar$ echo $COMP_WORDBREAKS"'><=;|&(:

If you try to complete foobar host:public_ht, you get foobar host:bazcux because the substituted token is just public_ht. While with:

$ COMP_WORDBREAKS=${COMP_WORDBREAKS//:}$ echo $COMP_WORDBREAKS"'><=;|&(

if you try to complete foobar host:public_ht, you get foobar bazcux because it is the complete host:public_ht that is replaced by bazcux.

The solution to your problem is probably to adapt your _robo completion function such that it does not require that : is not a word separator. Something like:

_stem () {    local lcur lprev    lcur="$cur"    stem="$lcur"    for (( i = cword - 1; i >= 0; i -= 1 )); do        lprev="${words[i]}"        [[ $lcur == ":" ]] && [[ $lprev == ":" ]] && break        [[ $lcur != ":" ]] && [[ $lprev != ":" ]] && break        stem="$lprev$stem"        lcur="$lprev"    done}_robo () {    local cur prev words cword    _init_completion || return    local stem options    options=($(__robo_list_opts) $(__robo_list_cmds))    COMPREPLY=()    _stem    COMPREPLY=($(compgen -W '${options[@]}' -- "$stem"))    [[ $stem =~ : ]] && stem=${stem%:*}: && COMPREPLY=(${COMPREPLY[@]#"$stem"})    return 0}complete -o default -F _robo robo

A much (apparently) simpler solution consists in replacing the _stem function above by the existing __reassemble_comp_words_by_ref function of the bash_completion library:

_robo () {    local cur prev words cword    _init_completion || return    __reassemble_comp_words_by_ref ":" words cword    options=($(__robo_list_opts) $(__robo_list_cmds))    COMPREPLY=($(compgen -W '${options[@]}' -- "$cur"))    return 0}complete -o default -F _robo robo

All this is probably not exactly what you want. I do not know robo.il and there are probably many improvements that would take more context into account to propose specific completions. But it may be a starting point.