[commit] Describe "incomplete type" (was: <incomplete type>)

[Eli Zaretskii <eliz at gnu dot org>]

Jim's reply on gdb@ caused me to look for "incomplete type" in the
manual.  Since I didn't find it, I added it.  Thanks for the clear
explanation, Jim.

Committed.

2005-08-27  Eli Zaretskii  <eliz@gnu.org>

	(Variables, Symbols): Document the "<incomplete type>" message and
	its reasons.

Index: gdb/doc/gdb.texinfo
===================================================================
RCS file: /cvs/src/src/gdb/doc/gdb.texinfo,v
retrieving revision 1.277
diff -u -r1.277 gdb.texinfo
--- gdb/doc/gdb.texinfo	27 Aug 2005 12:04:58 -0000	1.277
+++ gdb/doc/gdb.texinfo	27 Aug 2005 12:47:41 -0000
@@ -5179,6 +5179,11 @@
 @xref{C, , Debugging C++}, for more info about debug info formats
 that are best suited to C@t{++} programs.
 
+If you ask to print an object whose contents are unknown to
+@value{GDBN}, e.g., because its data type is not completely specified
+by the debug information, @value{GDBN} will say @samp{<incomplete
+type>}.  @xref{Symbols, incomplete type}, for more about this.
+
 @node Arrays
 @section Artificial arrays
 
@@ -10008,6 +10013,30 @@
 As with @code{whatis}, using @code{ptype} without an argument refers to
 the type of @code{$}, the last value in the value history.
 
+@cindex incomplete type
+Sometimes, programs use opaque data types or incomplete specifications
+of complex data structure.  If the debug information included in the
+program does not allow @value{GDBN} to display a full declaration of
+the data type, it will say @samp{<incomplete type>}.  For example,
+given these declarations:
+
+@smallexample
+    struct foo;
+    struct foo *fooptr;
+@end smallexample
+
+@noindent
+but no definition for @code{struct foo} itself, @value{GDBN} will say:
+
+@smallexample
+  (gdb) ptype foo
+  $1 = <incomplete type>
+@end smallexample
+
+@noindent
+``Incomplete type'' is C terminology for data types that are not
+completely specified.
+
 @kindex info types
 @item info types @var{regexp}
 @itemx info types