void type

void is the absence of a type. It is used as the return type of functions that produce no value.

Not a value

void has no size, no alignment, and no values. It cannot be stored, passed, or returned. It only marks that a function returns nothing.

Usage

Function return type

A function with return type void produces no value:

func void f[]
    // ...
end

Calling it leaves nothing on the stack:

call f

Untyped pointers

var ptr *void; // mark ptr as pointing to *anything*

Rules

• void cannot be used as a variable type:

var x void   // error

• void cannot be used as a struct or union field type:

struct S
    x void   // error
end

• void cannot be a parameter type:

func f[void]   // error

• A void function cannot return a value:

func void f[]
    32 return   // error: function returns `void`
end

• A non-void function must return a value:

func int f[]
    // error: missing return
end