CVS difference for ai05s/ai05-0004-1.txt

--- ai05s/ai05-0004-1.txt	2006/03/18 06:09:22	1.1
+++ ai05s/ai05-0004-1.txt	2006/04/20 05:30:39	1.2
@@ -4,7 +4,7 @@
 !priority Low
 !difficulty Easy
 !qualifier Omission
-!subject Not a real issue.
+!subject Presentation issues in the Standard.
 
 !summary
 
@@ -30,10 +30,56 @@
 
 !appendix
 
-From: Randy Brukardt
-Sent: Wednesday, March 15, 2006  9:15 PM
+From: Tucker Taft
+Sent: Wednesday, April 12, 2006  12:48 PM
 
-No comments yet.
+We have a relative newcomer to Ada doing some of
+our Ada 2005 work, and it is useful because it forces
+me to actually *read* what we have written in the
+reference manual.  I came upon this wording in 4.6(24.*):
+
+     If there is no type that is the ancestor of both
+     the target type and the operand type, and they are
+     not both class-wide types, one of the following
+     rules shall apply:
+
+       * If the target type is a numeric type, ...
+       * If the target type is an array type, ...
+       * If the target type is universal access, ...
+       * If the target type is a general access...
+       * If the target type is a pool-specific access...
+       * If the target type is an access-to-subprogram...
+
+In explaining this to our engineer, I found the introductory
+paragraph to be a confusing way of putting things.  In our
+next revision, I would suggest we reword the introductory
+paragraph roughly as follows:
+
+     If there is no type that is the ancestor of both
+     the target type and the operand type, and they are
+     not both class-wide types, then the target type
+     shall be a numeric type, an array type, or
+     an access type; further: ... [same bullets as before]
+
+As introduced now, you have to read all of the following bullets
+to figure out what kind of types *might* be covered by these
+set of rules, and we are relying on the phrase
+"one of the following shall apply" to effectively say that
+record types do not allow conversions other than those
+allowed for in 4.6(21-23.1).  And there are a lot of rules to
+read (not just the six abstracted above), since most of the rules
+have several sub-bullets.  For example, are all access types
+(including anonymous ones) covered by at least one of the rules?
+It takes some time to decide.  In general, as written the
+introductory paragraph seems to put an undue and unnecessary
+burden on the reader to decide whether exactly one of the rules
+applies to any given situation.
+
+For what it is worth, the specific case we wanted to know
+about was conversion between an interface and a non-interface
+type.  You can easily get lost in the long-winded rules
+relating to access types and think that your case might
+be covered.
 
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