rust-lang/rust-clippy

transmute_ptr_to_ref suggestion doesn't with some outer expression types

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#1,754 opened on May 12, 2017

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C-bugT-middlegood first issue

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Description

clippy suggests the following replacement

-                mem::transmute::<*mut c_void, &mut Box<FnMut(&Button)>>(data)(&button)
+                &mut *(data as *mut Box<FnMut(&Button)>)(&button)

but we should suggest parens around the &mut *...

bonus points if the parens only appear if necessary

Contributor guide

Research direction
Understand the transmute ptr to ref lint and modify the suggestion generation to wrap the expression in parentheses when it's used as part of a larger expression (e.g., function call). Investigate the lint's code in clippy lints/src/transmute.rs and the suggestion helper to ensure correct syntax.
Tech stack
rust
Domain
developer experiencetooling
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Mostly clear
Prerequisites
Rustclippy internal architecture
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75