From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-267966-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 10886 invoked by alias); 29 Nov 2008 09:09:14 -0000
Received: (qmail 10735 invoked by uid 48); 29 Nov 2008 09:07:53 -0000
Date: Sat, 29 Nov 2008 09:09:00 -0000
Subject: [Bug ada/38315]  New: Unclear type error message when inheriting from interface and tagged type
X-Bugzilla-Reason: CC
Message-ID: <bug-38315-17015@http.gcc.gnu.org/bugzilla/>
Reply-To: gcc-bugzilla@gcc.gnu.org
To: gcc-bugs@gcc.gnu.org
From: "fraser at thewhitelion dot org" <gcc-bugzilla@gcc.gnu.org>
Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-bugs.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-help@gcc.gnu.org>
Sender: gcc-bugs-owner@gcc.gnu.org
X-SW-Source: 2008-11/txt/msg02540.txt.bz2

Example code at the end.  When I compile it, I get this error:

[fraser@kimba]$ gcc -c unclear_override.ads 
unclear_override.ads:13:20: not subtype conformant with operation inherited at
line 11
unclear_override.ads:13:20: type of "Item" does not match

The problem is that in real life, Interface_1, Abstract_1 and Abstract_2 were
all in different packages, and I'd just added Interface_1 but was not aware
that Proc was also declared in Abstract_1.  Since the error message made no
mention of Abstract_1, nor that Proc was inherited from two places, it was
difficult to diagnose this problem -- clearly the type of Item *does* match (so
I thought).  Would it be possible to add a reference in the error to the
specific declaration that causes the type error?  I.e. the declaration of Proc
for Abstract_1.

package Unclear_Override is

   type Interface_1 is interface;
   procedure Proc (Item : access Interface_1) is abstract;

   type Abstract_1 is abstract tagged null record;
   procedure Proc (Item : not null access Abstract_1) is abstract;

   type Abstract_2 is abstract tagged null record;

   type Definite_1 is new Abstract_1 and Interface_1 with null record;

   procedure Proc (Item : access Definite_1);

end Unclear_Override;


-- 
           Summary: Unclear type error message when inheriting from
                    interface and tagged type
           Product: gcc
           Version: 4.3.2
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: ada
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: fraser at thewhitelion dot org
GCC target triplet: x86_64-redhat-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38315