Struct mozjs::jsapi::mozilla::DebugOnly

#[repr(C)]
pub struct DebugOnly {
    pub _address: u8,
}

DebugOnly contains a value of type T, but only in debug builds. In release builds, it does not contain a value. This helper is intended to be used with MOZ_ASSERT()-style macros, allowing one to write:

DebugOnly check = func(); MOZ_ASSERT(check);

more concisely than declaring |check| conditional on #ifdef DEBUG.

DebugOnly instances can only be coerced to T in debug builds. In release builds they don’t have a value, so type coercion is not well defined.

NOTE: DebugOnly instances still take up one byte of space, plus padding, even in optimized, non-DEBUG builds (see bug 1253094 comment 37 for more info). For this reason the class is MOZ_STACK_CLASS to prevent consumers using DebugOnly for struct/class members and unwittingly inflating the size of their objects in release builds.

Fields

_address: u8

Trait Implementations

impl Debug for DebugOnly

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl PartialEq for DebugOnly

fn eq(&self, other: &DebugOnly) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for DebugOnly