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From: Frode Tenneboe <ft@alne.edh.ericsson.se>
Newsgroups: comp.lang.ada
Subject: GNAT: warning: source alignment....
Date: 17 Jan 2001 16:09:48 GMT
Organization: Ericsson Radar AS
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Date: 2001-01-17T16:09:48+00:00
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In lack of a GNAT specific list, here goes:

I get the following warnings from some legacy code when compilled with GNAT
3.12p:

eh_uif.adb:112:45: warning: source alignment (1) < alignment of "T_WordRec" (2)
eh_uif.adb:113:45: warning: source alignment (1) < alignment of "T_LongRec" (4)
eh_uif.adb:119:47: warning: source alignment (1) < alignment of "T_WordRec" (2)
eh_uif.adb:120:47: warning: source alignment (1) < alignment of "T_LongRec" (4)
eh_uif.adb:163:45: warning: source alignment (1) < alignment of "T_WordRec" (2)
eh_uif.adb:164:45: warning: source alignment (1) < alignment of "T_LongRec" (4)
eh_uif.adb:238:47: warning: source alignment (1) < alignment of "T_WordRec" (2)
eh_uif.adb:239:47: warning: source alignment (1) < alignment of "T_LongRec" (4)

The code (som of it) is as follows:

type T_WordRec is
   record
      w : short_integer;
   end record;
type T_WordPtr is access T_WordRec;
function conv16 is new unchecked_conversion(system.address, T_WordPtr);

WordId : T_WordPtr;
WordId := conv16(UnitId'address);

where UnitId is of:
   type T_UNIT_ITEM is (<>);

I interprete the warning that UnitId is aligned at byte boundaries
whil T_WordRec (nor T_LongRec) is not. Does it make any sense to
use a representation clause on a discrete generic type as above?

Why should the source alignment be an issue here?
I can only find alignment references to target objects - which part of the
RM is this discussed?
What can I do to remove these warnings?

 -Frode
-- 
^ Frode Tenneb�                    | email: ft@edh.ericsson.se      ^
| Ericsson Radar AS. N-1788 Halden |                                |
| Phone: +47 69 21 41 47           | Frode@IRC                      |
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