Remove unnecessary explicit return statements

Docs > Datadog Security > Code Security > Static Code Analysis (SAST) > SAST Rules > Remove unnecessary explicit return statements

Metadata

ID: rust-code-quality/needless-return

Language: Rust

Severity: Warning

Category: Code Style

Description

In Rust, a function returns the value of its last expression implicitly — no return keyword is needed. An explicit return at the end of a function body is therefore redundant and adds visual noise without any benefit.

How to remediate?

Remove the return keyword and the trailing semicolon from the last expression:

// Before
fn add(a: i32, b: i32) -> i32 {
    return a + b;
}

// After
fn add(a: i32, b: i32) -> i32 {
    a + b
}

Non-Compliant Code Examples

fn explicit_return() -> i32 {
    return 42;
}

fn explicit_return_expr(x: i32) -> i32 {
    let y = x * 2;
    return y;
}

Compliant Code Examples

fn implicit_return() -> i32 {
    42
}

fn early_return(x: i32) -> i32 {
    if x < 0 {
        return 0; // early exit — not the last statement of the outer block
    }
    x * 2
}

fn cfg_return() -> &'static str {
    #[cfg(unix)]
    return "unix";

    "other"
}

fn with_inner_fn() -> String {
    return helper("foo");

    fn helper(s: &str) -> String {
        s.to_string()
    }
}

fn foo() -> String {
    return s("foo");
    
    fn s(input: &str) -> String {
        input.to_string()
    }    
}

impl Default for LineEnding {
    fn default() -> Self {
        #[cfg(unix)]
        return Self::Unix;

        tracing!("foo")
        Self::Windows
    }
}

fn cfg_return() -> &'static str {
    #[cfg(unix)]
    //
    return "unix";

    "other"
}