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| <h3 class="section">5.3 Cross-References to Other Types</h3> |
| |
| <p>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. |
| |
| <p>Another way is with the ‘<samp><span class="samp">x</span></samp>’ type descriptor, which is followed by |
| ‘<samp><span class="samp">s</span></samp>’ for a structure tag, ‘<samp><span class="samp">u</span></samp>’ for a union tag, or ‘<samp><span class="samp">e</span></samp>’ for |
| a enumerator tag, followed by the name of the tag, followed by ‘<samp><span class="samp">:</span></samp>’. |
| If the name contains ‘<samp><span class="samp">::</span></samp>’ between a ‘<samp><span class="samp"><</span></samp>’ and ‘<samp><span class="samp">></span></samp>’ pair (for |
| C<tt>++</tt> templates), such a ‘<samp><span class="samp">::</span></samp>’ does not end the name—only a single |
| ‘<samp><span class="samp">:</span></samp>’ ends the name; see <a href="Nested-Symbols.html#Nested-Symbols">Nested Symbols</a>. |
| |
| <p>For example, the following C declarations: |
| |
| <pre class="example"> struct foo; |
| struct foo *bar; |
| </pre> |
| <p class="noindent">produce: |
| |
| <pre class="example"> .stabs "bar:G16=*17=xsfoo:",32,0,0,0 |
| </pre> |
| <p>Not all debuggers support the ‘<samp><span class="samp">x</span></samp>’ 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. |
| |
| <p>Modula-2 imported types, at least on AIX, use the ‘<samp><span class="samp">i</span></samp>’ type |
| descriptor, which is followed by the name of the module from which the |
| type is imported, followed by ‘<samp><span class="samp">:</span></samp>’, 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 <a href="Typedefs.html#Typedefs">Typedefs</a>) 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 <a href="String-Field.html#String-Field">String Field</a>), or what. The symbol ends with ‘<samp><span class="samp">;</span></samp>’. |
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