This patch adds aa warning when a formal fixed point type is instantiated with
a type that has a user-defined arithmetic operations, but the generic has no
corresponding formal functions. This is worth a warning because of the special
semantics of fixed-point operators, in particular multiplying operators.
Compiling procfix.adb must yield:
procfix.adb:23:28: warning:
instance does not use primitive operation "*" at line 5
The warning disappears if a formal subprogram declaration is added to the
generic:
with function "*" (X, Y :Fix) return Fix is <>;
---
with Text_IO; use Text_IO;
procedure Procfix is
package P is
type T is delta 0.1 range -10.0 .. 10.0;
function "*" (X, Y: T) return T;
end P;
use P;
package body P is
function "*" (X, Y: T) return T is
begin
return (X + Y) / 2.0;
end;
end P;
generic
type Fix is delta <>;
package Try is
X : Fix := 3.0;
Y : Fix := X * X;
end;
package Inst is new Try (T);
use Inst;
begin
Put_Line (T'Image (Inst.Y));
end;
Tested on x86_64-pc-linux-gnu, committed on trunk
2016-07-06 Ed Schonberg <schonb...@adacore.com>
* sem_ch12.adb (Check_Fixed_Point_Actual): Add a warning when
a formal fixed point type is instantiated with a type that has
a user-defined arithmetic operations, but the generic has no
corresponding formal functions. This is worth a warning because
of the special semantics of fixed-point operators.
Index: sem_ch12.adb
===================================================================
--- sem_ch12.adb (revision 238040)
+++ sem_ch12.adb (working copy)
@@ -1105,6 +1105,12 @@
-- In Ada 2005, indicates partial parameterization of a formal
-- package. As usual an other association must be last in the list.
+ procedure Check_Fixed_Point_Actual (Actual : Node_Id);
+ -- Warn if an actual fixed-point type has user-defined arithmetic
+ -- operations, but there is no corresponding formal in the generic,
+ -- in which case the predefined operations will be used. This merits
+ -- a warning because of the special semantics of fixed point ops.
+
procedure Check_Overloaded_Formal_Subprogram (Formal : Entity_Id);
-- Apply RM 12.3(9): if a formal subprogram is overloaded, the instance
-- cannot have a named association for it. AI05-0025 extends this rule
@@ -1187,6 +1193,52 @@
end Check_Overloaded_Formal_Subprogram;
-------------------------------
+ -- Check_Fixed_Point_Actual --
+ -------------------------------
+
+ procedure Check_Fixed_Point_Actual (Actual : Node_Id) is
+ Typ : constant Entity_Id := Entity (Actual);
+ Prims : constant Elist_Id := Collect_Primitive_Operations (Typ);
+ Elem : Elmt_Id;
+ Formal : Node_Id;
+
+ begin
+ -- Locate primitive operations of the type that are arithmetic
+ -- operations.
+
+ Elem := First_Elmt (Prims);
+ while Present (Elem) loop
+ if Nkind (Node (Elem)) = N_Defining_Operator_Symbol then
+
+ -- Check whether the generic unit has a formal subprogram of
+ -- the same name. This does not check types but is good enough
+ -- to justify a warning.
+
+ Formal := First_Non_Pragma (Formals);
+ while Present (Formal) loop
+ if Nkind (Formal) = N_Formal_Concrete_Subprogram_Declaration
+ and then Chars (Defining_Entity (Formal)) =
+ Chars (Node (Elem))
+ then
+ exit;
+ end if;
+
+ Next (Formal);
+ end loop;
+
+ if No (Formal) then
+ Error_Msg_Sloc := Sloc (Node (Elem));
+ Error_Msg_NE
+ ("?instance does not use primitive operation&#",
+ Actual, Node (Elem));
+ end if;
+ end if;
+
+ Next_Elmt (Elem);
+ end loop;
+ end Check_Fixed_Point_Actual;
+
+ -------------------------------
-- Has_Fully_Defined_Profile --
-------------------------------
@@ -1613,6 +1665,10 @@
(Formal, Match, Analyzed_Formal, Assoc),
Assoc);
+ if Is_Fixed_Point_Type (Entity (Match)) then
+ Check_Fixed_Point_Actual (Match);
+ end if;
+
-- An instantiation is a freeze point for the actuals,
-- unless this is a rewritten formal package, or the
-- formal is an Ada 2012 formal incomplete type.
