TITLE: Anonymous structs and unions


RESPONSE: clamage@taumet.Eng.Sun.COM (Steve Clamage), 7 Jun 94


By "anonymous struct" (which DEC C allows, BTW) we usually mean a
struct with no tag and no object or type declared:

	struct { ... } ;

This violates the C rule that a declaration must declare a tag, object,
or type, but we don't have that rule in C++. On the other hand, there
is no way under C++ rules to access the members of the struct.

Anonymous unions are allowed in C++, and we have explicit language**
which explains how the member names are exported into the enclosing
scope. There is no such language for structs.

The original example looked something like

	struct outer {
		struct {	// anonymous
			int i, j;
		};
	} x;

after which an expression like "x.i" apparently referred to the "i" member
of the anonymous struct. This would be the case with an anonymous union,
but the analagous situation with structs is not part of the ARM or the
Working Paper. So the expression "x.i" should generate an error, as there
is no "i" in the scope of "x", but only in an inaccessable inner scope.

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** which is nothing compared to the explicit language heard when
people argue about C++ language rules ...