The following example:
package Test is
type X is limited interface;
function Return_X return X is abstract;
task type Y is new X with
end Y;
overriding function Return_X return Y;
end Test;
does not compile with the following message:
test.ads:9:20: subprogram "Return_X" is not overriding.
As far as I can judge, it because of the following check in
gcc/ada/sem_util.adb (function Find_Overridden_Synchronized_Primitive,
line 3070):
...
and then Etype (Result_Definition (Parent (Def_Id))) =
Etype (Result_Definition (Parent (Subp)))
...
(the code can be traced back to at least gcc 4.1.2)
I am not sure that this is indeed a bug in the compiler and not some obscure
feature of the standard, though I failed to find in the ARM any explicit
prohibition for controlling-result functions of synchronized types.
--
Summary: functions with controlling result do not work with
synchronized interfaces
Product: gcc
Version: 4.3.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: ada
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: Artem dot Andreev at oktetlabs dot ru
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38974
