How to deal with #[warn(clippy::too_many_arguments)]

[igalic]

We've recently started a PR to clippy-fy our code Plume-org/Plume#462 and we're hitting some limits in Ructe, with regard to how templates are generated as functions

in our case, as functions with lots of parameters, despite having extracted a BaseContext

Here's an example of such a function: https://github.com/Plume-org/Plume/blob/master/templates/posts/details.rs.html#L12

[kaj]

Wow, that's a lot of parameters! But even with fewer parameters, I have seen the same problem.

So, what should we do? Just add #[allow(clippy::too_many_arguments)] to all generated templates? Or can we say that the the template module has a limit of e.g. 14 arguments instead of the default 7 ?

[kaj]

https://rust-lang.github.io/rust-clippy/master/index.html#too_many_arguments says that there is a configuration too-many-arguments-threshold: u64, but I don't know if it can be configured in a module. On the other hand, e.g. nrc/derive-new#13 (comment) may apply to us, maybe for templats with lots of arguments, some arguments should be grouped so there is fewer arguments total?

Another approach may be to simply set too-many-arguments-threshold to a larger value in the lint configuration of a project that uses templates with many argumens?

[igalic]

i think the problem in our case is that the module in question is src/main.rs: https://github.com/Plume-org/Plume/blob/42dca3daaee3e647337ceb7e18ab97b8a133a95e/src/main.rs#L62-L66

A submodule thereof is routes, where i've done some of our finest work thanks to the too_many_arguments lint! Plume-org/Plume@965e97c

[kaj]

I just verified that this workaround works for me:

mod foo {
    #![allow(clippy::too_many_arguments)]
    include!(concat!(env!("OUT_DIR"), "/templates.rs"));
}
use foo::templates;

A bit ugly, but might be worthwile while we try to figure out a better way to handle things.

[kaj]

Seems ok to close this. I'll just throw in a note that the dummy module in the above-mentioned workaround don't seem to be needed any more (I don't know why it was needed beore). So the "workaround" can be reduced to:

#[allow(clippy::too_many_arguments)]
include!(concat!(env!("OUT_DIR"), "/templates.rs"));

... which doesn't even feel like a workaround, but rather proper clippy configuration.

[vbrandl]

I have a kinda similar problem in vbrandl/hoc so I don't know if this requires a new issue, but I think it fits here:

warning: this expression borrows a reference (`&mut W`) that is immediately dereferenced by the compiler
  --> /home/me/code/hoc/target/debug/build/hoc-7df636231525c575/out/templates/template_p500_html.rs:10:6
   |
10 | base(&mut _ructe_out_, "Internal Server Error - Hits-of-Code Badges", "500 - Internal Server Error", |mut _ructe_out_| {
   |      ^^^^^^^^^^^^^^^^ help: change this to: `_ructe_out_`
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_borrow

I tried working around that lint:

mod workaround {
    #[allow(clippy::needless_borrow)]
    include!(concat!(env!("OUT_DIR"), "/templates.rs"));
}
use workaround::templates;

But this doesn't seem to work anymore:

warning: unused attribute `allow`
  --> src/lib.rs:52:5
   |
52 |     #[allow(clippy::needless_borrow)]
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: `#[warn(unused_attributes)]` on by default
note: the built-in attribute `allow` will be ignored, since it's applied to the macro invocation `include`
  --> src/lib.rs:53:5
   |
53 |     include!(concat!(env!("OUT_DIR"), "/templates.rs"));
   |     ^^^^^^^

Is there another way to suppress clippy lints for ructe templates?

[kaj]

That is separate, and a lint that started to appear on all ructe templates witch rustc / clippy version 1.57. I'm thinking of changing the generated signature to fix it, perhaps as tried in #107 , perhaps in some slightly different way.