| Message ID | 20170907095834.GA15662@adacore.com |
|---|---|
| State | New |
| Headers | show |
| Series | [Ada] Spurious error in precondition and classwide parameter | expand |
Index: exp_disp.adb =================================================================== --- exp_disp.adb (revision 251838) +++ exp_disp.adb (working copy) @@ -701,6 +701,16 @@ while Present (F) loop if F = Entity (N) then Rewrite (N, New_Copy_Tree (A)); + + -- If the formal is class-wide, and thus not a + -- controlling argument, preserve its type because + -- it may appear in a nested call with a class-wide + -- parameter. + + if Is_Class_Wide_Type (Etype (F)) then + Set_Etype (N, Etype (F)); + end if; + exit; end if;
This patch fixes a spurious error on a classwide precondition for a subprogram S that is a primitive of some type T, when the precondition includes a dispatching call on a classwide formal of S whose type is urelated to T. The following must compile quietly: gnatmake -q main --- with Derived_Objects; with Using_Interfaces; with Using_Objects; procedure Main is D : aliased Derived_Objects.Derived_Object; U : aliased Using_Objects.Using_Object; UI : not null access Using_Interfaces.Using_Interface'Class := U'Access; begin U.Use_An_Object (D); UI.Use_An_Object (D); U.Use_A_Valid_Object (D); UI.Use_A_Valid_Object (D); end Main; --- package Base_Objects is type Base_Object is tagged null record; function Is_Valid (This : in Base_Object) return Boolean is (True); end Base_Objects; --- with Base_Objects; package Derived_Objects is type Derived_Object is new Base_Objects.Base_Object with null record; end Derived_Objects; --- with Base_Objects; package Using_Interfaces is type Using_Interface is limited interface; procedure Use_An_Object (This : aliased in out Using_Interface; Obj : in Base_Objects.Base_Object'Class) is abstract; procedure Use_A_Valid_Object (This : aliased in out Using_Interface; Obj : in Base_Objects.Base_Object'Class) is abstract with Pre'Class => Obj.Is_Valid; end Using_Interfaces; --- with Base_Objects; with Using_Interfaces; package Using_Objects is type Using_Object is limited new Using_Interfaces.Using_Interface with null record; procedure Use_An_Object (This : aliased in out Using_Object; Base : in Base_Objects.Base_Object'Class) is null; procedure Use_A_Valid_Object (This : aliased in out Using_Object; Base : in Base_Objects.Base_Object'Class) is null; end Using_Objects; Tested on x86_64-pc-linux-gnu, committed on trunk 2017-09-07 Ed Schonberg <schonberg@adacore.com> * exp_disp.adb (Replace_Formals): If thr formal is classwide, and thus not a controlling argument, preserve its type after rewriting because it may appear in an nested call with a classwide parameter.