which are unordered by happens before
(that is, neither <i>r</i> happens before <i>w</i>
nor <i>w</i> happens before <i>r</i>).
</p>

<p>
A <i>write-write data race</i> on memory location <i>x</i>
consists of two write-like memory operations <i>w</i> and <i>w'</i> on <i>x</i>,
at least one of which is non-synchronizing,
which are unordered by happens before.
</p>

<p>

the result parameters before they are returned.
If the deferred function has any return values, they are discarded when
the function completes.
(See also the section on <a href="#Handling_panics">handling panics</a>.)
</p>

<pre>
lock(l)
defer unlock(l)  // unlocking happens before surrounding function returns

// prints 3 2 1 0 before surrounding function returns

the result parameters before they are returned.
If the deferred function has any return values, they are discarded when
the function completes.
(See also the section on <a href="#Handling_panics">handling panics</a>.)
</p>

<pre>
lock(l)
defer unlock(l)  // unlocking happens before surrounding function returns

// prints 3 2 1 0 before surrounding function returns