rust-lang / rust-lang/rust-clippy

Lint to warn about str::as_ptr() usage in ffi call

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@fpdotmonkey is already working on this.

Since Jul 10, 2026.

A-lint good first issue L-correctness T-middle
Dominant language
Rust
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Description

Hello.
It would be nice to have a warning when using str::as_ptr() in a ffi call instead of using CStr.

For instance, in the following code:

unsafe { printf("Hello".as_ptr() as *const _) };

should give a warning and propose something like:

let cstring = CString::new("Hello".as_bytes()).unwrap();
unsafe { printf(cstring.as_ptr()) };

Thanks to add this lint.

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