[llvm-dev] Shell auto-completion for ld.lld linker

[shivam gupta via llvm-dev]

Hi Rui,

On Mon, Jul 8, 2019, 12:02 PM Rui Ueyama <ruiu at google.com> wrote:

> Hi Shivam,
>
> As to the process of how to add a new feature to lld, it is recommended to
> start a new discussion thread at the llvm-dev mailing list, so thank you
> for starting this new thread. It is fine to create a proof-of-concept
> implementation, but I don't think you'd want to spend too much time on it
> before you get an agreement that a proposed new feature looks like a good
> one.
>
> Speaking of the proposed feature, I have a couple of comments and
> questions as follows:
>
>  - Compilers have an extremely large number of command line options, and
> the number is growing. Many features accessible via the command line can be
> enabled/disabled at ./configure-time. Because of these facts, a static
> command-line completion setting doesn't work well for compilers. But I
> don't think that neither conditions are true to linkers; linkers don't have
> large number of options, and new options are not added very frequently.
> Most commands, like tar or ls, doesn't have a feature to support
> command-line auto-comletion. What makes linkers special from other commands?
>
Now these commands got auto-completion for both zsh
<https://github.com/zsh-users/zsh/tree/master/Completion/Unix/Command> and
bash <https://github.com/scop/bash-completion/tree/master/completions>
shell.So I think we can also write auto-completion for lld as it has more
options than them.


>  - Can't the auto-completion script for GNU ld work for lld? As you said,
> that may lack a few command options, but it should work in most cases, and
> I'm not personally worried too much if an auto-completion is not very
> precise.
>
Yeah! we can do something like gcc
<https://github.com/zsh-users/zsh/blob/master/Completion/Unix/Command/_gcc>
is doing for clang in zsh-completion package but we are also working to
have separate auto-completion for clang using --autocomplete api. Also in
bash shell when I parse --help option for completion, gnu ld gives 185 and
ld.lld gives 204 possibilities in which these options
<https://docs.google.com/document/d/1kEiK0TlXyZ58OU8O_8ikQYnCUIR3xC1n5I1UCAPNOTI/edit?usp=sharing>
are different from each other so there is a big gap between them and
getting wrong auto-completion is not good to have.

 - Somewhat related to the previous point, but on some systems, lld is
> installed as /usr/bin/ld. How do you distinguish it from GNU ld, or do we
> really need to distinguish them?
>
 I think you're talking about FreeBSD or symlink to ld. For them it doesn't
need to be distinguished though, it can be distinguished if we read binary.


>  - Users are not expected to use a linker directly. Instead, they are
> expected to invoke a linker using a compiler driver (i.e. clang or
> clang++). Does your auto-completion work to autocomplete -Wl,-foo options
> given to a compiler driver?
>
No,Current implementation of --autocomplete api is not completing linker
options but we are also going to make some improvements in clang
--autocomplete interface in next few weeks once lld completion is landed.

Regards,
Shivam

>
> On Mon, Jul 8, 2019 at 2:44 PM shivam gupta <shivam98.tkg at gmail.com>
> wrote:
>
>> Hi lld developers,
>> As a GSoC student I wrote static ld.lld auto-completion scripts for zsh
>> and bash shell because it doesn't have much options and flags for dynamic
>> completion. Whether I send pr to zsh-completion/bash-completion package or
>> open phabricator review for them? Also gnu ld has already autocompletion
>> for bash shell but l am not merging ld and lld completion scripts to one
>> file because lld lacks some options compare to ld and bash completion
>> scripts only parse --help argument. Scripts are attached to the mail!
>> Regards
>> Shivam
>>
>
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