In Ada 2012 formal parameters can be declared explicitly aliased. Mode
conformance now requires that both or neither formal be aliased.
Compiling alias.adb must yield:
alias.adb:7:13: not fully conformant with declaration at line 6
alias.adb:7:13: aliased parameter mismatch
alias.ads:7:24: not subtype conformant with operation inherited at line 5
alias.ads:7:24: aliased parameter mismatch
---
package Alias is
type R is tagged null record;
procedure Change (Obj : R);
type R2 is new R with null record;
overriding
procedure Change (Obj : aliased R2); -- ERROR
end Alias;
---
package body Alias is
procedure Change (Obj : R) is begin null; end;
procedure Change (Obj : aliased R2) is begin null; end;
function check (Obj : R) return Integer;
function check (Obj : aliased R) return Integer is -- ERROR
begin
return R'Size;
end;
end Alias;
Tested on x86_64-pc-linux-gnu, committed on trunk
2012-06-14 Ed Schonberg <schonb...@adacore.com>
* sem_ch6.adb (Check_Conformance): Add Ada 2012 check on mode
conformance: "aliased" must apply to both or neither formal
parameters.
Index: sem_ch6.adb
===================================================================
--- sem_ch6.adb (revision 188605)
+++ sem_ch6.adb (working copy)
@@ -5503,6 +5503,18 @@
end if;
end if;
+ -- Ada 2012: mode conformance also requires that formal parameters
+ -- be both aliased, or neither.
+
+ if Ctype >= Mode_Conformant
+ and then Ada_Version >= Ada_2012
+ then
+ if Is_Aliased (Old_Formal) /= Is_Aliased (New_Formal) then
+ Conformance_Error
+ ("\aliased parameter mismatch!", New_Formal);
+ end if;
+ end if;
+
if Ctype = Fully_Conformant then
-- Names must match. Error message is more accurate if we do
