Add --no-runtime-exs

[mhanberg]

This adds a new CLI option to mix run that will skip loading the runtime.exs file.

This is useful when you want to load a VM with all of the project's code and dependencies, but don't want to actually start it in any way.

runtime.exs can use your project's dependencies, which might not be compiled yet if also using the --no-compile option.

Normally you can simply gate your entire runtime.exs file in a condition that checks for an environment variable, but in the case of developer tooling like a language server, you can't alter the code.

---

I'm not entirely sure if this is the best way to solve my problem, so I am interested in your thoughts here. I thought about
re-using the --no-start option to control whether the runtime.exs is executed, but I figured that is a backwards incompatible change, so I opted for a new option.

(If you think this is reasonable to include, I will add tests/docs)

For more context, I have run into a situation in Next LS where a user's runtime.exs fails due to the code not yet being compiled (because I are using the --no-compile flag).

I am intentionally not wanting any code to 'run', which is why I also pass the --no-start flag, which I think made me surprised that runtime.exs still ran.

LMKWYT

[josevalim]

@mhanberg what task are you invoking as the entry point? If you don't want it to not start nor compile, then maybe you should be calling only the loadpaths task and not any task that may start or compile code? For example, here is what we do for mix help:

    args = ["--no-elixir-version-check", "--no-deps-check", "--no-archives-check"]
    Mix.Task.run("loadpaths", args)
    Mix.Task.reenable("loadpaths")
    Mix.Task.reenable("deps.loadpaths")

[mhanberg]

The entry point (started as a port) is

args: [
        System.find_executable("elixir"),
            "--sname",
            sname,
            "-S",
            "mix",
            "run",
            "--no-halt",
            "--no-compile",
            "--no-start"
          ]

I'll try out loadpaths after work today, thanks!

[mhanberg]

@josevalim i'll hopefully get some time to look into your suggestion tonight, I had a crazy weekend (wife broke her leg 🥵, she's doing well now).

thanks again!

[josevalim]

No rush and a speedy recovery to her! By the way, we talked a bit about language servers yesterday during the stream: https://www.twitch.tv/videos/1868498801

[mhanberg]

No rush and a speedy recovery to her!

Thanks!

By the way, we talked a bit about language servers yesterday during the stream: https://www.twitch.tv/videos/1868498801

Nice!

[mhanberg]

Your approach of using loadpaths seems to work as expected, thanks!