Simplify if let statements that immediately return unwrapped value

[tvolk131]

What it does

Reduce simple if let statements that immediately return the unwrapped value by replacing the if let with a ?.

Lint Name

collapsible_if_let_return

Category

style

Advantage

Encourages concise code and proper use of the ? operator.

Drawbacks

None that I can think of.

Example

fn example_fn() -> Result<(), CustomError> {
    if let Err(err) = run_some_process() {
        return Err(err);
    }
    // Other function logic...
    Ok(())
}

Could be written as:

fn example_fn() -> Result<(), CustomError> {
    run_some_process()?;
    // Other function logic...
    Ok(())
}

And, if there were no other function logic, could further be reduced to:

fn example_fn() -> Result<(), CustomError> {
    run_some_process()
}

[camsteffen]

This can be an enhancement of the question_mark lint.

[J-ZhengLi]

Is it true that the clippy_utils::higher::IfLet::hir function does not pickup if let Err(err) = function_call() {} as a recognized pattern?

It detects

if let Err(err) = function_call() {
    return Err(err);
} else {}

but not without else, what am I missing?

[dswij]

Is it true that the clippy_utils::higher::IfLet::hir function does not pickup if let Err(err) = function_call() {} as a recognized pattern?

It detects

if let Err(err) = function_call() {
    return Err(err);
} else {}

but not without else, what am I missing?

If you're referring to

rust-clippy/clippy_lints/src/question_mark.rs

Lines 98 to 99 in 0b143e3

	if let Some(higher::IfLet { let_pat, let_expr, if_then, if_else: Some(if_else) })
	= higher::IfLet::hir(cx, expr);

not firing without else, it's because of the pattern match in L98 to only match on if_else: Some(..).

clippy_utils::higher::IfLet::hir does pick up if let without else. In fact, question_mark lint only checks for returns in the else arm right now.

[J-ZhengLi]

... it's because of the pattern match in L98 to only match on if_else: Some(..).
clippy_utils::higher::IfLet::hir does pick up if let without else. In fact, question_mark lint only checks for returns in the else arm right now.

Thank you for pointing that out~

[dswij]

@J-ZhengLi are you working on this? If so, you can comment @rustbot claim to assign yourself to this issue :)

[J-ZhengLi]

@J-ZhengLi are you working on this? If so, you can comment @rustbot claim to assign yourself to this issue :)

Well... fine, I guess I'll give it a try.

@rustbot claim