BurntSushi/quickcheck

Trivial cast error when using `#[quickcheck]` inside macro

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#261 opened on Nov 27, 2020

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enhancementhelp wanted

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Description

This is a minimal example:

crate::my_macro!(u32);

#[macro_export]
macro_rules! my_macro {
    ($my_type:ty) => {
        #[quickcheck]
        fn fuzz_my_type(my: $my_type) {
            // ...
        }
    }
}

Results in

error: trivial cast: `fn(u32) {fuzz_my_type::fuzz_my_type}` as `fn(u32)`
   --> ~/fuzz_tests.rs:13:9
    |
  2 |   crate::my_macro!(u32);
    |   ---------------------- in this macro invocation
... 
 13 | /         #[quickcheck]
 14 | |         fn fuzz_my_type(my: $my_type) {
    | |_______________________^

It works if I add #[allow(trivial_casts)], but it should work without flags to the compiler.

Contributor guide

Research direction
Investigate the trivial cast warning generated by the macro expansion and consider adding #[allow(trivial casts)] or fixing the attribute generation.
Tech stack
rust
Domain
testing
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.
Clear
Prerequisites
Rust
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70