Fix bool_comparison lint usage with macros

[nbaksalyar]

Fixes #3973.

Clippy gives wrong suggestions on bool comparisons with results of macros, such as e.g. bool == cfg!(feature = abc). This PR fixes the problem by checking if any side of a binary expresion is expanded from a macro.

There's a similar problem present with rustfix, so the bool_comparison.fixed file has been changed manually for now.

[oli-obk]

There's a similar problem present with rustfix, so the bool_comparison.fixed file has been changed manually for now.

rustfix should only apply clippy's suggestions, if there's a problem I presume it's due to clippy. What was the issue you encountered?

[nbaksalyar]

What was the issue you encountered?

The same one: cfg!(feature = "debugging") got replaced with just false and the expression transformed to if !abc {}.

[flip1995]

This is a little bit to restrictive: Playground

This won't suggest anything for macro! == true. But this could be simplified to macro!.

---

While testing this, I found another "bug". Clippy suggests for this:

warning: equality checks against true are unnecessary
 --> src/main.rs:8:8
  |
8 |     if m!(func) == true {
  |        ^^^^^^^^^^^^^^^^ help: try simplifying it as shown: `$func()`
  |
  = note: #[warn(clippy::bool_comparison)] on by default
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#bool_comparison

This suggestion is not applicable, obviously. This can be fixed by changing this line

rust-clippy/clippy_lints/src/needless_bool.rs

Line 271 in 1cdac4a

let hint = Sugg::hir_with_applicability(cx, expr, "..", &mut applicability);

with

rust-clippy/clippy_lints/src/utils/sugg.rs

Line 84 in 3e760cc

pub fn hir_with_macro_callsite(cx: &LateContext<'_, '_>, expr: &hir::Expr, default: &'a str) -> Self {

But that won't be that easy, since we need a function, which adapts the applicability. So either

1. you can try to fix this in this PR
2. you can open an issue and leave this for later

[nbaksalyar]

Thanks for the review!

I'd love to fix this in this PR. :)

[flip1995]

Ping from triage @nbaksalyar. Any updates on this? The bottom part of #3983 (comment) is just additional work, which you can leave out in this PR and we can open an issue for this.

[flip1995]

Ping from triage @nbaksalyar. This PR didn't get an update for quite some time now, therefore I'll close this to keep the PR queue clean. Thanks for your contribution and feel free to reopen it whenever you got time to work on this!

[nbaksalyar]

Hi @flip1995, sorry for lack of progress on this one.
I'm still interested to complete this, so I'll address your comments and reopen it soon. Thank you!

[flip1995]

Thanks! If you have any questions just ask here.

[HKalbasi]

finished in #6211
@rustbot label -S-inactive-closed