Unchecked Code Syntax

This section describes the syntax for unchecked code constructs.

Unchecked Functions

A function MAY be marked with the unchecked modifier to indicate that calling it requires a checked block.

The unchecked modifier requires the unchecked_code preview feature. Using unchecked without enabling this feature is a compile-time error.

function = [ "pub" ] [ "unchecked" ] "fn" IDENT "(" [ params ] ")" [ "->" type ] "{" block "}" ;

unchecked fn dangerous_operation() -> i32 {
    42
}

pub unchecked fn public_dangerous() -> i32 {
    0
}

Checked Blocks

A checked block is an expression that enables unchecked operations within its body.

checked_expr = "checked" "{" block "}" ;

A checked block evaluates its body and returns the value of the final expression. The type of a checked block is the type of its body expression.

fn main() -> i32 {
    let x = checked {
        let a = 10;
        let b = 32;
        a + b
    };
    x
}

Raw Pointer Types

Rue provides two raw pointer types for low-level memory access:

• ptr const T - a pointer to immutable data of type T
• ptr mut T - a pointer to mutable data of type T

ptr_type = "ptr" ( "const" | "mut" ) type ;

Raw pointer types are parsed in Phase 1 but semantic analysis (type checking, pointer operations) is implemented in later phases. Until Phase 2 is implemented, using pointer types results in an "unknown type" error.

// These parse correctly but fail type checking until Phase 2
fn takes_ptr(p: ptr const i32) -> i32 { 0 }
fn takes_mut_ptr(p: ptr mut i32) -> i32 { 0 }
unchecked fn get_ptr() -> ptr const i32 { @panic() }