The current instance of a type in an aspect specification is an object of
the type. If the type is scalar, it cannot be the prefix of an attribute
reference such as 'First, whose prefix must an array object (even though it
can be a scalar type in other contexts).
Compiling foo.adb must yield:
foo.adb:3:29:
prefix of "First" attribute cannot be the current instance of a scalar type
foo.adb:6:29:
prefix of "First" attribute cannot be the current instance of a scalar type
---
procedure Foo is
type T_Data_Sending_Frequency is new Natural
with Default_Value => T_Data_Sending_Frequency'First;
type Infrequent is new Natural
with Default_Value => Infrequent'First + 3;
begin
null;
end;
Tested on x86_64-pc-linux-gnu, committed on trunk
2016-04-20 Ed Schonberg <schonb...@adacore.com>
* sem_attr.adb (Check_Type): Reject an attribute reference in
an aspect expression, when the prefix of the reference is the
current instance of the type to which the aspect applies.
Index: sem_attr.adb
===================================================================
--- sem_attr.adb (revision 235243)
+++ sem_attr.adb (working copy)
@@ -1408,10 +1408,41 @@
--------------------------------
procedure Check_Array_Or_Scalar_Type is
+ function In_Aspect_Specification return Boolean;
+ -- A current instance of a type in an aspect specification is an
+ -- object and not a type, and therefore cannot be of a scalar type
+ -- in the prefix of one of the array attributes if the attribute
+ -- reference is part of an aspect expression.
+
+ -----------------------------
+ -- In_Aspect_Specification --
+ -----------------------------
+
+ function In_Aspect_Specification return Boolean is
+ P : Node_Id;
+
+ begin
+ P := Parent (N);
+ while Present (P) loop
+ if Nkind (P) = N_Aspect_Specification then
+ return P_Type = Entity (P);
+
+ elsif Nkind (P) in N_Declaration then
+ return False;
+ end if;
+
+ P := Parent (P);
+ end loop;
+
+ return False;
+ end In_Aspect_Specification;
+
+ -- Local variables
+
+ Dims : Int;
Index : Entity_Id;
- D : Int;
- -- Dimension number for array attributes
+ -- Start of processing for Check_Array_Or_Scalar_Type
begin
-- Case of string literal or string literal subtype. These cases
@@ -1431,6 +1462,12 @@
if Present (E1) then
Error_Attr ("invalid argument in % attribute", E1);
+
+ elsif In_Aspect_Specification then
+ Error_Attr
+ ("prefix of % attribute cannot be the current instance of a "
+ & "scalar type", P);
+
else
Set_Etype (N, P_Base_Type);
return;
@@ -1466,9 +1503,9 @@
Set_Etype (N, Base_Type (Etype (Index)));
else
- D := UI_To_Int (Intval (E1));
+ Dims := UI_To_Int (Intval (E1));
- for J in 1 .. D - 1 loop
+ for J in 1 .. Dims - 1 loop
Next_Index (Index);
end loop;
