Table of Contents

Jumps and labels

Jumps leave or continue a loop before it would normally finish. Labels can name an outer loop, and goto is available for the uncommon cases where a direct jump makes the control flow clearer.

break exits the innermost enclosing loop statement immediately. Execution resumes at the statement following that loop. break label exits the enclosing loop statement marked with label.

var i = 0
while true {
    if i == 10 {
        break
    }

    i += 1
}

A break statement must appear within a loop, while, or for statement. Placing break in any expression context, including the bodies of if, while, or for expressions, produces diagnostic RAV1902. Using break outside a loop reports diagnostic RAV2600. A labeled break must name an enclosing labeled loop. Labels on ordinary statements remain goto targets and produce diagnostic RAV2606 when used as a break target.

continue statements

continue skips the remainder of the current loop iteration and jumps to the loop's re-check point. continue label skips to the next iteration of the enclosing loop statement marked with label.

for value in values {
    if value.isOdd {
        continue
    }

    print(value)
}

continue follows the same placement rules as break: it may only appear inside loop, while, or for statements. Using it from an expression context results in diagnostic RAV1903, and placing it outside a loop reports diagnostic RAV2601. A labeled continue must name an enclosing labeled loop. Labels on ordinary statements remain goto targets and produce diagnostic RAV2606 when used as a continue target.

outer: loop {
    inner: loop {
        if shouldStop {
            break outer
        }

        continue inner
    }
}

Labeled statements

A labeled statement prefixes another statement with an identifier followed by a colon:

start:
print("running")

Labels introduce symbolic targets that goto statements can reference. A label applies to the next statement in the source. When a newline immediately follows the colon, the compiler synthesizes an empty statement so the label remains a valid target even without an explicit body. Multiple labels may precede the same statement.

Label names are scoped to the containing function body. Declaring the same label more than once in the same body is an error (RAV2500). Labels participate in semantic lookup just like other declarations, so tools can navigate to them.

Like all statements, a label may only appear where the grammar permits statements. Attempting to nest a labeled statement inside an expression body (for example, inside the branches of an if expression) reports diagnostic RAV1905.

goto statements

The goto statement jumps to a labeled statement within the same function-like body:

start:
print("loop")
goto start

Evaluation of a goto statement ends the current statement immediately and transfers control to the target label. Targets may appear before or after the goto; backward jumps form loops while forward jumps skip ahead in the block. Jumping to a nonexistent label produces diagnostic RAV2501.

Gotos cannot escape the body they are declared in. A goto inside a function, lambda, or accessor may only refer to labels declared in that same body. The compiler ensures any scopes exited by the jump are correctly unwound before branching.

goto statements follow the same placement rules as other control-flow statements: they are only legal in statement contexts. Embedding a goto inside an expression context (such as the body of an if expression) produces diagnostic RAV1904.

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