This patch removes a spurious error on a call to a function that applies to a predicated tagged type, when the actual in the call is class-wide. The argument must be converted to be type-specific, given that the predicate function is not dispatching and cannot accept a class-wide actual.
Executing: gnatmake -q -gnata main main must yield: Predicate checked Predicate checked Predicate checked Predicate checked Predicate checked Predicate checked --- with Predicate_Ints; use Predicate_Ints; procedure Main is Thing1 : Int := (0, 100, 50); Thing2 : Approx_Int := (0, 100, 50, 13); begin Call_Bump (Thing1); Call_Bump (Thing2); end; --- package Predicate_Ints is type Int is tagged record Min, Max, Value : Integer; end record with Predicate => Value in Min .. Max and then Checked; procedure Bump (Arg : in out Int); procedure Call_Bump (Arg : in out Int'Class); function Checked return Boolean; type Approx_Int is new Int with record Precision : Natural; end record; end Predicate_Ints; --- with Text_IO; use Text_IO; package body Predicate_Ints is function Checked return Boolean is begin Put_Line ("Predicate checked"); return True; end; procedure Bump (Arg : in out Int) is begin Arg.Value := Arg.Value + 1; end Bump; procedure Call_Bump (Arg : in out Int'Class) is begin Arg.Bump; end Call_Bump; end Predicate_Ints; Tested on x86_64-pc-linux-gnu, committed on trunk 2017-10-09 Ed Schonberg <schonb...@adacore.com> * exp_util.adb (Make_Predicate_Call): If the type of the expression to which the predicate check applies is tagged, convert the expression to that type. This is in most cases a no-op, but is relevant if the expression is clas-swide, because the predicate function being invoked is not a primitive of the type and cannot take a class-wide actual.
Index: exp_util.adb =================================================================== --- exp_util.adb (revision 253559) +++ exp_util.adb (working copy) @@ -9305,11 +9305,23 @@ -- Case of calling normal predicate function - Call := - Make_Function_Call (Loc, - Name => New_Occurrence_Of (Func_Id, Loc), - Parameter_Associations => New_List (Relocate_Node (Expr))); + -- If the type is tagged, the expression may be class-wide, in which + -- case it has to be converted to its root type, given that the + -- generated predicate function is not dispatching. + if Is_Tagged_Type (Typ) then + Call := + Make_Function_Call (Loc, + Name => New_Occurrence_Of (Func_Id, Loc), + Parameter_Associations => + New_List (Convert_To (Typ, Relocate_Node (Expr)))); + else + Call := + Make_Function_Call (Loc, + Name => New_Occurrence_Of (Func_Id, Loc), + Parameter_Associations => New_List (Relocate_Node (Expr))); + end if; + Restore_Ghost_Mode (Saved_GM); return Call;