Ignore interpolation for comments

[gl-yziquel]

Hi.

I've just been shuffling around some build instructions encapsulated in my justfiles. And commented out one such build instruction (since the build system of jax has been in flux).

#cd jax-{{TAG}} && bazelisk run --verbose-failure=true //jaxlib/tools:build_wheel -- --output_path=dist --cpu=x86_64

just then told me the following:

error: Variable `TAG` not defined

So, basically, it tried to interpolate the TAG value in the comment. I believe this is a situation where you should opt out of interpolation.

Of course, this depends whether or not the comment is a comment for the shell, or a comment for just. It seems to be a comment for the shell, in which case, well, I would understand just not being aware of what is a comment for the shell.

Nonetheless, the ergonomics of it seems suboptimal: I'd like to wildly refactor my build instructions without having just complaining about failing to interpolate my comments...

EDIT: It can be fixed by putting the # as the first element of the line and not putting it after the tab. But, still, it feels wrong.

[laniakea64]

By default it's still an arbitrary line for the shell, so interpolation would be expected. But shouldn't it become a just comment if the justfile does set ignore-comments? Surprisingly, set ignore-comments doesn't eliminate this error? 👀

[gl-yziquel]

I'll give it a shot with set ignore-comments. I learn about just every day...

P.S.: feel free to close.

[laniakea64]

I'll give it a shot with set ignore-comments. ...

P.S.: feel free to close.

😕 To be clear, I expected set ignore-comments to be the solution to the error, but it doesn't work for me with latest just master:

set ignore-comments

foo:
	echo recipe
	#echo {{not_an_interpolation}}
	echo recipe

error: Variable `not_an_interpolation` not defined
 ——▶ justfile:5:10
  │
5 │     #echo {{not_an_interpolation}}
  │             ^^^^^^^^^^^^^^^^^^^^

So I would wonder if this is a bug?

[casey]

It's not quite a bug, I think originally the point of ignore-comments was just to not print and execute comment lines, but they would still be parsed and analyzed.

I thought it would be hard also skip analysis (when unknown variable errors are raised) but it turned out to be pretty straightforward. As of #2180, comments are now parsed but not analyzed when ignore-comments is set. Since they're parsed, they need to be valid syntax, but you won't get unknown variable errors anymore.