Support passing values into dbg with the pipe operator

[mulias]

This PR (hopefully) wraps up the work started in #7038 and continued in #7054, fully implementing #5894, dbg as an expression.

In the feedback I got for #7038 there was general agreement that the functions in desugar.rs could use some refactoring to consolidate params into a shared struct. My initial intuition was that this should be a new struct, independent of the existing can::Env struct. Once I started implementing the desugaring for |> dbg I realized I would have to pass desugar specific args through the rest of canonicalization, which means the two parts essentially need the same set of args and it makes more sense to share one struct.

Use a shared env for desugaring and the rest of canonicalization

This refactor simplifies the desugar pass by reducing the number of arguments threaded through each recursive function call.

• Add the module src string to Env.
• Add line_info to Env as a lazy-evaled getter function.
• Refactor desugar functions to take the can::Env struct in place of a number of params. This is mostly a find-and-replace, but in a few places Vec::from_iter_in was changed to Vec::with_capacity_in followed by a for loop in order to avoid lifetime issues.
• Remove unnecessary linter annotations for clippy::too_many_arguments

Support passing values into dbg with the pipe operator

In order to desugar dbg in a pipeline we need to allow a bare dbg node in desugaring and only report it as an error if the bare node survives to the next step of canonicalization. This means we move the error code out of desugar_expr and into canonicalize_expr. This is much simpler to do now that these functions use the same env struct, since previously we would have had to pass down extra args to canonicalize_expr. Sharing the env struct means that we also don't have to worry about calculating line_info more than once.

[mulias]

This file was accidentally committed early as part of a previous PR. I've updated the source code for the test, so the contents of the snapshot have updated, even though it looks like it should be a new test case.

[smores56]

I tested this out with basic-cli v0.15, all of my dbg usages were working! My past self would have really appreciated this last year, you've really improved the quality of life of Roc debugging here.

[smores56]

nitpick: just a callout to remember to remove this, I presume that's why it's underscored here

[mulias]

good catch

[smores56]

This is ready to merge, just waiting for whether @mulias agrees with my PR comments or not. Once that's resolved, we're good to go

[mulias]

@smores56 I added two commits to address your feedback. I think the doc comment is more helpful where it is now, but let me know what you think.

[smores56]

Uh oh, it looks like you didn't propagate the function arg change...

error[E0061]: this function takes 3 arguments but 4 arguments were supplied
    --> crates/compiler/can/src/desugar.rs:1310:17
     |
1310 |         value: *desugar_dbg_stmt(env, scope, tmp_var, tmp_var),
     |                 ^^^^^^^^^^^^^^^^    -------
     |                                     | |
     |                                     | unexpected argument of type `&mut scope::Scope`
     |                                     help: remove the extra argument
     |
note: function defined here
    --> crates/compiler/can/src/desugar.rs:1333:4
     |
1333 | fn desugar_dbg_stmt<'a>(
     |    ^^^^^^^^^^^^^^^^
1334 |     env: &mut Env<'a>,
     |     -----------------
1335 |     condition: &'a Loc<Expr<'a>>,
     |     ----------------------------
1336 |     continuation: &'a Loc<Expr<'a>>,
     |     -------------------------------

[mulias]

Never pays to rush a change!