A type can be used before it is defined; one common way to deal with that situation is just to use a type reference to a type which has not yet been defined.
Another way is with the x
type descriptor, which is followed by
s
for a structure tag, u
for a union tag, or e
for
a enumerator tag, followed by the name of the tag, followed by :
.
If the name contains ::
between a <
and >
pair (for
C++ templates), such a ::
does not end the name--only a single
:
ends the name; see Nested Symbols.
For example, the following C declarations:
struct foo; struct foo *bar;
produce:
.stabs "bar:G16=*17=xsfoo:",32,0,0,0
Not all debuggers support the x
type descriptor, so on some
machines GCC does not use it. I believe that for the above example it
would just emit a reference to type 17 and never define it, but I
haven't verified that.
Modula-2 imported types, at least on AIX, use the i
type
descriptor, which is followed by the name of the module from which the
type is imported, followed by :
, followed by the name of the
type. There is then optionally a comma followed by type information for
the type. This differs from merely naming the type (see Typedefs) in
that it identifies the module; I don't understand whether the name of
the type given here is always just the same as the name we are giving
it, or whether this type descriptor is used with a nameless stab
(see String Field), or what. The symbol ends with ;
.