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<h3 class="section">Unnamed struct/union fields within structs/unions.</h3>
<p>For compatibility with other compilers, GCC allows you to define
a structure or union that contains, as fields, structures and unions
without names. For example:
<pre class="example"> struct {
int a;
union {
int b;
float c;
};
int d;
} foo;
</pre>
<p>In this example, the user would be able to access members of the unnamed
union with code like <code>foo.b</code>. Note that only unnamed structs and
unions are allowed, you may not have, for example, an unnamed
<code>int</code>.
<p>You must never create such structures that cause ambiguous field definitions.
For example, this structure:
<pre class="example"> struct {
int a;
struct {
int a;
};
} foo;
</pre>
<p>It is ambiguous which <code>a</code> is being referred to with <code>foo.a</code>.
Such constructs are not supported and must be avoided. In the future,
such constructs may be detected and treated as compilation errors.
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