Lint permissions.set_readonly(false)

[Alexendoo]

What it does

The lint would catch any usage of Permissions::set_readonly called with false

.set_readonly(false) on unix platforms sets the file to be world writable - rust-lang/rust#101644

Lint Name

permissions_set_readonly_false

Category

suspicious

Advantage

The behaviour is surprising, so a lint to inform people that it's probably not doing what they expect would be useful

Drawbacks

If someone knows about that behaviour and is using it intentionally it would be a false positive, however in that case the #[allow] would be a good indicator to others that it is intentional

It's possible that the behaviour will be changed or deprecated upstream before the lint is written

Example

let f = File::create("foo.txt")?;
let metadata = f.metadata()?;
let mut permissions = metadata.permissions();

permissions.set_readonly(false);

[Alexendoo]

Hi, welcome to Clippy!

The most direct way would be to take a look at the expression's kind to see if it's an ExprKind::Lit, there you can check that the literal is a LitKind::Bool(false)

[Alexendoo]

It could be, there is https://doc.rust-lang.org/nightly/nightly-rustc/clippy_utils/consts/fn.constant_simple.html

It's not a full const evaluator so it wouldn't be catching [Method]Calls, the main thing it'd get here would be consts but that doesn't seem super likely to occur

[Alexendoo]

Added by #10063