AI05-288 specifies that subtype conformance is required for actual types for
generic formal access-to-subprogram types, rather than just mode conformance.
This is a binding interpretation.
Compiling pack2.adb must yield:
pack2.adb:4:37: not subtype conformant with declaration at pack1.ads:2
pack2.adb:4:37: type of "N" does not match
generic
type ACC is access procedure (N : Natural);
package Pack1 is
procedure Test1 (A : out ACC);
end Pack1;
---
package body Pack1 is
procedure Test1 (A : out ACC) is
begin
null;
end Test1;
end Pack1;
---
package Pack2 is
procedure Cause_A_Problem;
end Pack2;
---
with Pack1;
package body Pack2 is
type Actual_Acc is access procedure (N : Integer);
package New_Pack1 is new Pack1 (Actual_Acc);
procedure Cause_A_Problem is
X : Actual_Acc;
begin
New_Pack1.Test1 (X);
X (-1); -- PROBLEM
end Cause_A_Problem;
end Pack2;
---
Tested on x86_64-pc-linux-gnu, committed on trunk
2012-03-15 Ed Schonberg <schonb...@adacore.com>
* sem_ch6.ads, sem_ch6.adb (Check_Subtype_Conformant): add
Get_Inst formal, so that conformance within an instantiation
follows renamings of formals. This is similar to what is already
done in Check_Mode_conformant.
* sem_ch12.adb (Vailidate_Access_Subprogram_Instance): check that
formal and actual are subtype conformant. Previously only mode
conformance was required.
Index: sem_ch12.adb
===================================================================
--- sem_ch12.adb (revision 185390)
+++ sem_ch12.adb (working copy)
@@ -10433,7 +10433,11 @@
Abandon_Instantiation (Actual);
end if;
- Check_Mode_Conformant
+ -- In Ada 2012, actuals for access_to_subprograms must be subtype
+ -- conformant with the generic formal. Previous to AI05-288 only mode
+ -- conformance was required.
+
+ Check_Subtype_Conformant
(Designated_Type (Act_T),
Designated_Type (A_Gen_T),
Actual,
Index: sem_ch6.adb
===================================================================
--- sem_ch6.adb (revision 185390)
+++ sem_ch6.adb (working copy)
@@ -7251,14 +7251,16 @@
(New_Id : Entity_Id;
Old_Id : Entity_Id;
Err_Loc : Node_Id := Empty;
- Skip_Controlling_Formals : Boolean := False)
+ Skip_Controlling_Formals : Boolean := False;
+ Get_Inst : Boolean := False)
is
Result : Boolean;
pragma Warnings (Off, Result);
begin
Check_Conformance
(New_Id, Old_Id, Subtype_Conformant, True, Result, Err_Loc,
- Skip_Controlling_Formals => Skip_Controlling_Formals);
+ Skip_Controlling_Formals => Skip_Controlling_Formals,
+ Get_Inst => Get_Inst);
end Check_Subtype_Conformant;
---------------------------
Index: sem_ch6.ads
===================================================================
--- sem_ch6.ads (revision 185390)
+++ sem_ch6.ads (working copy)
@@ -28,7 +28,7 @@
type Conformance_Type is
(Type_Conformant, Mode_Conformant, Subtype_Conformant, Fully_Conformant);
- pragma Ordered (Conformance_Type);
+ -- pragma Ordered (Conformance_Type);
-- Conformance type used in conformance checks between specs and bodies,
-- and for overriding. The literals match the RM definitions of the
-- corresponding terms. This is an ordered type, since each conformance
@@ -141,7 +141,8 @@
(New_Id : Entity_Id;
Old_Id : Entity_Id;
Err_Loc : Node_Id := Empty;
- Skip_Controlling_Formals : Boolean := False);
+ Skip_Controlling_Formals : Boolean := False;
+ Get_Inst : Boolean := False);
-- Check that two callable entities (subprograms, entries, literals)
-- are subtype conformant, post error message if not (RM 6.3.1(16)),
-- the flag being placed on the Err_Loc node if it is specified, and
