fix incorrect suggestions related to parentheses in needless_return

[lapla-cogito]

close #12157

needless_return sometimes makes incorrect suggestions by omitting necessary enclosing parentheses. This PR resolves the issue by using clippy_utils::sugg::Sugg.

changelog: [needless_return]: now makes correct suggestions which require enclosing parentheses

[rustbot]

r? @Alexendoo

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[lapla-cogito]

Rebased.

[lapla-cogito]

Rebased.

[lapla-cogito]

@Alexendoo Should I do a reassign? (I pinged you because it's been over 2 weeks)

[lapla-cogito]

r? clippy

[lapla-cogito]

r? @Manishearth

[Manishearth]

r? @samueltardieu since he started reviewing

[lapla-cogito]

Ah, I thought Samuel could approve but not have the privilege to merge.

[Manishearth]

He's clippy-contributors, I can merge once he's done.

[samueltardieu]

I am not sure this is the right fix, as I don't think that the problem lies in returns.rs. Moreover, fixing it this way removes an explanatory message "and wrap the sequence with parentheses".

I think that you would obtain a better result by fixing clippy_utils::binary_expr_needs_parentheses(). I have the impression that you can add a condition to the match of the inner contains_block() function to cover the problematic cases:

            ExprKind::Cast(lhs, _) => contains_block(lhs, true),

Doing so while letting return.rs untouched seems to pass your new tests just fine, while keeping the explanatory wrapping message when appropriate.

WDYT?

[lapla-cogito]

@samueltardieu Sorry for the late reply. Certainly removing NeedsPar would provide a bad description to users, so fixed it, thanks.

[samueltardieu]

I can merge once he's done.

@Manishearth This now looks good to me, feel free to merge as you please.

[lapla-cogito]

@Manishearth Could you take a look at this when you have some time?

[Alexendoo]

👍