$ uname -a Linux rogue 2.6.16-gentoo-r13 #1 PREEMPT Tue Aug 1 13:59:12 GMT 2006 i686 AMD Athlon(TM) XP 2000+ GNU/Linux $ gcc -v Using built-in specs. Target: i686-pc-linux-gnu Configured with: ../gcc-4.1.1/configure --prefix=/home/laguest/opt/gcc-4.1.1 --enable-libada --enable-languages=c,c++,java,objc,ada Thread model: posix gcc version 4.1.1 $ gnatmake -gnat05 -gnatwj test_observers.adb gcc -c -gnat05 -gnatwj test_observers.adb +===========================GNAT BUG DETECTED==============================+ | 4.1.1 (i686-pc-linux-gnu) Assert_Failure atree.adb:812 | | Error detected at subjects.ads:17:3 | | Please submit a bug report; see http://gcc.gnu.org/bugs.html. | | Use a subject line meaningful to you and us to track the bug. | | Include the entire contents of this bug box in the report. | | Include the exact gcc or gnatmake command that you entered. | | Also include sources listed below in gnatchop format | | (concatenated together with no headers between files). | +==========================================================================+ Please include these source files with error report Note that list may not be accurate in some cases, so please double check that the problem can still be reproduced with the set of files listed. test_observers.adb my_observer.ads observers.ads subjects.ads compilation abandoned gnatmake: "test_observers.adb" compilation error with My_Observer; with Subjects; procedure Test_Observers is Obs : Observers.Observer_Access := new My_Observer.My_Observer_Type; Subject : Subjects.Subject; begin -- Subjects.Attach(Subject, Obs); Subject.Attach(Obs); Subject.Notify; end Test_Observers; package body My_Observer is procedure Update(Self : in My_Observer_Type) is begin Ada.TexT_IO.Put_Line("[My_Observer.Update]"); end Update; end My_Observer; with Observers; package My_Observer is type My_Observer_Type is new Observers.Observer with private; procedure Update(Self : in My_Observer_Type); private type My_Observer_Type is new Observers.Observer with null record; end My_Observer; limited with Observers; with Ada.Containers.Doubly_Linked_Lists; with Ada.Finalization; package Subjects is type Subject is new Ada.Finalization.Limited_Controlled with private; procedure Attach(Self : in out Subject'Class; Observer : access Observers.Observer); procedure Detach(Self : in out Subject'Class; Observer : access Observers.Observer); procedure Notify(Self : in Subject); private function Equals(Left, Right : access Observers.Observer) return Boolean; package Observer_Lists is new Ada.Containers.Doubly_Linked_Lists(Observers.Observer_Access, Equals); type Subject is new Ada.Finalization.Limited_Controlled with record Observer_List : Observer_Lists.List; end record; end Subjects; with Observers; package body Subjects is use type Observer_Lists.Cursor; -- Add an observer to this subject's internal list. procedure Attach(Self : in out Subject'Class; Observer : access Observers.Observer) is begin Self.Observer_List.Append(New_Item => Observer); end Attach; -- Remove an observer from this subject's internal list. procedure Detach(Self : in out Subject'Class; Observer : access Observers.Observer) is Position : Observer_Lists.Cursor := Self.Observer_List.Find(Observer); begin if Position /= Observer_Lists.No_Element then Self.Observer_List.Delete(Position); end if; end Detach; -- Notify all observers who are monitoring this subject that something has happened. procedure Notify(Self : in Subject) is Current : Observer_Lists.Cursor := Self.Observer_List.First; begin while Current /= Observer_Lists.No_Element loop Observer_Lists.Element(Current).Update; Current := Observer_Lists.Next(Current); end loop; end Notify; function Equals(Left, Right : access Observers.Observer) return Boolean is begin if Left = Right then return True; end if; return False; end Equals; end Subjects; package Observers is type Observer is abstract tagged private; type Observer_Access is access all Observers.Observer'Class; procedure Update(Self : in Observer) is abstract; private type Observer is abstract tagged null record; end Observers;
Using the current SVN source (17/09/06) I get a slightly different error (with the same source): gcc -c -gnat05 test_observers.adb +===========================GNAT BUG DETECTED==============================+ | 4.2.0 20060917 (experimental) (i686-pc-linux-gnu) Assert_Failure atree.adb:812| | Error detected at subjects.ads:17:3 | | Please submit a bug report; see http://gcc.gnu.org/bugs.html. | | Use a subject line meaningful to you and us to track the bug. | | Include the entire contents of this bug box in the report. | | Include the exact gcc or gnatmake command that you entered. | | Also include sources listed below in gnatchop format | | (concatenated together with no headers between files). | +==========================================================================+ Please include these source files with error report Note that list may not be accurate in some cases, so please double check that the problem can still be reproduced with the set of files listed. test_observers.adb my_observer.ads observers.ads subjects.ads compilation abandoned gnatmake: "test_observers.adb" compilation error
Seems this was an error based on the use of a limited view of a type. I don't know whether this is actually allowed in the Ada 2005 standard, i.e passing a reference to a limited view to a container? Should this bug be left open? Luke.
Confirmed. $ gcc -c -gnat05 test_observers.adb +===========================GNAT BUG DETECTED==============================+ | 4.2.0 20060915 (experimental) (x86_64-unknown-linux-gnu) Assert_Failure atree.adb:812| | Error detected at subjects.ads:19:3 | I'm not sure this is valid too, so I'm tagging this as ICE on invalid code (in all cases this is a bug since the compiler should never ICE).
Confirmed on SVN trunk +===========================GNAT BUG DETECTED==============================+ | 4.3.0 20071207 (experimental) (i686-pc-linux-gnu) Assert_Failure atree.adb:962| | Error detected at subjects.ads:19:3 |
This is still a problem on 4.4.0 trunk. Luke.
Reduced test case: package Observers is type Observer is tagged null record; type Observer_Access is access all Observers.Observer'Class; end Observers; limited with Observers; with Ada.Containers.Doubly_Linked_Lists; package Subjects is function Equals(Left, Right : access Observers.Observer) return Boolean; package Observer_Lists is new Ada.Containers.Doubly_Linked_Lists(Observers.Observer_Access, Equals); end Subjects; with Observers; -- this line triggers the bug package body Subjects is function Equals(Left, Right : access Observers.Observer) return Boolean is begin return False; end Equals; end Subjects; With the line that triggers the bug: gcc-4.1 -c -gnat05 subjects.adb +===========================GNAT BUG DETECTED==============================+ | 4.1.3 20070518 (prerelease) (Debian 4.1.2-8) (x86_64-pc-linux-gnu) | | Assert_Failure atree.adb:812 | | Error detected at subjects.ads:8:3 | gcc-4.3 -c -gnat05 subjects.adb +===========================GNAT BUG DETECTED==============================+ | 4.3.1 20080401 (prerelease) (x86_64-pc-linux-gnu) Assert_Failure atree.adb:886| | Error detected at subjects.ads:8:3 | Without the line that triggers the bug: gcc-4.1 -c -gnat05 subjects.adb subjects.ads:9:49: premature use of incomplete type subjects.ads:9:49: instantiation abandoned gcc-4.3 -c -gnat05 subjects.adb subjects.ads:9:49: premature use of incomplete type subjects.ads:9:49: instantiation abandoned
Further reduced test case: replace observers.ads with: package Observers is type Observer is new Integer; type Observer_Access is access Observer; end Observers; and the bug is still there.
Yes, the bug manifests when the view on the type is limited at this point *but* we know the underlying type (because of a non-limited with for example). This triggers it if you compile p2.adb: package P1 is type T is null record; end P1; limited with P1; package P2 is pragma Elaborate_Body; generic type T is private; package G is end G; package I1 is new G (P1.T); end P2; with P1; package body P2 is end P2; I'm testing a fix.
Subject: Bug 29015 Author: sam Date: Wed Apr 16 12:37:38 2008 New Revision: 134345 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=134345 Log: gcc/ada/ PR ada/29015 * sem_ch12.adb (Instantiate_Type): Check whether the full view of the type is known instead of the underlying type. gcc/testsuite/ PR ada/29015 * gnat.dg/incomplete1.ads, gnat.dg/incomplete2.ads, gnat.dg/incomplete2.adb: New. Added: trunk/gcc/testsuite/gnat.dg/incomplete1.ads trunk/gcc/testsuite/gnat.dg/incomplete2.adb trunk/gcc/testsuite/gnat.dg/incomplete2.ads Modified: trunk/gcc/ada/ChangeLog trunk/gcc/ada/sem_ch12.adb trunk/gcc/testsuite/ChangeLog
This is fixed in the current GCC SVN.