[Feature request] Tab completion of options for a user defined alias

[cassepipe]

Bugzilla Link	50184
Version	10.0
OS	Linux
CC	@JDevlieghere

Extended Description

Hi !

I was advised to file a bug report after I had posted my issue on StackOverflow :

https://stackoverflow.com/questions/67231162/lldb-tab-completion-after-user-defined-aliases/67305975#67305975

I defined the following alias in lldb :

command alias bfn breakpoint set -n %1

Sadly, this alias does not allow Tab completion as the regular command does.

All the time gained in typing the command is lost typing whole identifiers that are sometimes quite complex.

Nevertheless, buit-in aliases allow for completion so I assume there's a way to achieve the same behaviour for user defined aliases.

Thanks for your time and the work you put in making great software.

[DavidSpickett]

At some point this started working, or it already was but the behaviour is a bit strange.

(lldb) command alias bfn breakpoint set -n %1
(lldb) b<tab>
No breakpoints currently set.
(lldb) bf<tab>
(lldb) bfn
error: Not enough arguments provided; you need at least 1 arguments to use this alias.
error: 'bfn' is not a valid command.
(lldb) command unalias b
(lldb) b<tab>
(lldb) breakpoint
(lldb) bfn
error: Not enough arguments provided; you need at least 1 arguments to use this alias.
error: 'bfn' is not a valid command.

I think what's happening is that built in commands (and built in aliases) are checked first. If there's an unambiguous match within just those, it uses that.

If there isn't, like for bf, only then does it check the user aliases. I'll see if this is intentional.

[DavidSpickett]

Some patches along the way:

• [lldb] Add test to document alias tab completion behaviour #65760
• [lldb] Correctly invalidate unloaded image tokens #65945
• 825adbe

Once those are all in I'll change the overall behaviour.

[DavidSpickett]

#65974

[DavidSpickett]

Now that the above has landed, the command compeltion works in a way that makes sense, with commands and aliases as equally important.

lldb is always going to choose an exact match if it can, unlike say, ls:

$ ls foo<TAB>
foo   food

lldb would instead give you foo and move on to completing the rest of the command.

This makes breakpoints quite a bad example of this feature because b will always complete to the built in alias to the breakpoint commands. But if you alias it to brkpt, br will now suggest breakpoint and brkpt which is what you'd expect.

[DavidSpickett]

However, this bug is not about the completion of the command itself but of the options. Arguments in this context is positional arguments, those we can complete, options are -foo options.

(lldb) b
Available completions:
        __do_global_dtors_aux
        __libc_csu_fini
        __libc_csu_init
        _fini
        _init
        _start
        call_weak_fn
        deregister_tm_clones
        frame_dummy
        main
        register_tm_clones

b is an alias but we can complete the argument to that alias.

(lldb) command alias bfn breakpoint set -n %1
(lldb) bfn m<tab>
<nothing>

If your alias includes an option, we cannot complete that option.

(lldb) breakpoint set -n
Available completions:
        __do_global_dtors_aux
        __libc_csu_fini
        __libc_csu_init
        _fini
        _init
        _start
        call_weak_fn
        deregister_tm_clones
        frame_dummy
        main
        register_tm_clones

If you use the full command you can complete it.