AI12-0036 is a binding interpretation which adds the following legality
rule:
The actual type for a formal derived type shall be tagged if and only
if the formal derived type is a private extension.
Implement this new compile-time check. The check is implemented without
checking the value of Ada_Version because the AI is a binding
intepretation, and because the possible consequences of failing to
detect a violation may be severe.
Tested on x86_64-pc-linux-gnu, committed on trunk
2019-12-12 Steve Baird <ba...@adacore.com>
gcc/ada/
* sem_ch12.adb
(Instantiate_Type.Validate_Derived_Type_Instance): Implement the
legality check of AI12-0036--- gcc/ada/sem_ch12.adb
+++ gcc/ada/sem_ch12.adb
@@ -13166,6 +13166,35 @@ package body Sem_Ch12 is
Abandon_Instantiation (Actual);
end if;
end if;
+
+ -- Don't check Ada_Version here (for now) because AI12-0036 is
+ -- a binding interpretation; this decision may be reversed if
+ -- the situation turns out to be similar to that of the preceding
+ -- Is_Limited_Type test (see preceding comment).
+
+ declare
+ Formal_Is_Private_Extension : constant Boolean :=
+ Nkind (Parent (A_Gen_T)) = N_Private_Extension_Declaration;
+
+ Actual_Is_Tagged : constant Boolean := Is_Tagged_Type (Act_T);
+ begin
+ if Actual_Is_Tagged /= Formal_Is_Private_Extension then
+ if In_Instance then
+ null;
+ else
+ if Actual_Is_Tagged then
+ Error_Msg_NE
+ ("actual for & cannot be a tagged type",
+ Actual, Gen_T);
+ else
+ Error_Msg_NE
+ ("actual for & must be a tagged type",
+ Actual, Gen_T);
+ end if;
+ Abandon_Instantiation (Actual);
+ end if;
+ end if;
+ end;
end Validate_Derived_Type_Instance;
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