Re: GNAT: no visible subprogram matches the specification for "Put"

[Stephen Leake <stephen_leake@stephe-leake.org>]

On Friday, October 4, 2019 at 11:53:34 AM UTC-7, Vincent Marciante wrote:
> Hi all,
> 
> I think that I might be hitting a GNAT defect but am not sure.
> I already have a work-around but wanted some feedback before 
> I go through channels to submit this to Adacore (if actually 
> a defect.)  Maybe I am missing some overloading rule but I 
> think that the following should compile and run: one part that 
> appears in the middle does compile and does produce the expected
> output but the second to last unit does not compile useing a 
> GNATPRO 19 series compiler.  That place is marked with --Builder
> results.
> 
> So, should all of the following be compilable?
> 
> with Ada.Text_IO;
> 
> package Ada_Text_IO_Adaptor is
> 
>   procedure Put
>            (X    : in Integer;
>             Base : in Ada.Text_IO.Number_Base);
> 
>   procedure New_Line;
> 
> end Ada_Text_IO_Adaptor;
> 
> -------
> 
> with Ada.Integer_Text_IO;
> 
> package body Ada_Text_IO_Adaptor is
> 
>   procedure Put
>            (X    : in Integer;
>             Base : in Ada.Text_IO.Number_Base) is
>   begin
>     Ada.Integer_Text_IO.Put(Item=>X,Base=>Base);
>   end Put;
> 
>   procedure New_Line is
>   begin
>     Ada.Text_IO.New_Line;
>   end New_Line;
> 
> end Ada_Text_IO_Adaptor;
> 
> -------
> 
> generic
> 
>   type Number_Base is range <>;
>   Default_Base : Number_Base;
> 
>   with procedure Put      (X    : in Integer;
>                            Base : in Number_Base 
>                                   := Default_Base) is <>;
>   with procedure Put      (X    : in String) is <>;
>   with procedure Put_Line (X    : in String) is <>;
>   with procedure New_Line is <>;
> 
> package Signature_Package_Generic is end;
> 
> -------
> 
> with Ada.Text_IO, Ada.Integer_Text_IO, Ada_Text_IO_Adaptor;
>  use Ada.Text_IO, Ada.Integer_Text_IO, Ada_Text_IO_Adaptor;
> 
> with Signature_Package_Generic;
> 
> package Signature_Package_Instance is
>     new Signature_Package_Generic
>                          (Number_Base  => Ada.Text_IO.Number_Base,
>                           Default_Base => 10);
> 
> -------
> 
> with Signature_Package_Generic;
> generic
>   with package Instance is new Signature_Package_Generic(<>);
> procedure Signature_Package_Instance_Test_Generic;
> 
> -------
> 
> procedure Signature_Package_Instance_Test_Generic is
> begin 
>   Instance.New_Line;
>   Instance.Put_Line("Direct Instance Put_Line(""string"")");
>   Instance.Put     ("Direct Instance Put     (""string"")");
> end;
> 
> -------
> 
> with      Signature_Package_Instance;
> with      Signature_Package_Instance_Test_Generic;
> procedure Signature_Package_Instance_Test is 
>       new Signature_Package_Instance_Test_Generic
>          (Signature_Package_Instance); --compiles and runs as expected
> 
> -------
> 
> with Signature_Package_Generic;
> generic
>   with package Instance is new Signature_Package_Generic(<>);
> package Signature_Package_Reexport_Generic is
> 
>   subtype Number_Base is Instance.Number_Base;
>   Default_Base : Number_Base := Instance.Default_Base;
> 
>   procedure Put      (X    : in Integer;
>                       Base : in Number_Base
>                              := Default_Base) renames Instance. Put;
>   procedure Put      (X    : in String)       renames Instance. Put; -- instantiation error
>   procedure Put_Line (X    : in String)       renames Instance. Put_Line;
>   procedure New_Line                          renames Instance. New_Line;
> 
> end Signature_Package_Reexport_Generic;
> 
> -------
> 
> with    Signature_Package_Instance;
> with    Signature_Package_Reexport_Generic;
> package Signature_Package_Reexport_Instance is
>     new Signature_Package_Reexport_Generic
>        (Signature_Package_Instance);
> --Builder results
> --    Signature_Package_Reexport_Instance.ads
> --        108:1 instantiation error at  signature_package_reexport_generic.ads:98
> --        108:1 no visible subprogram matches the specification for "Put"
> 
> -------
> 
> with      Signature_Package_Reexport_Instance;
> procedure Signature_Package_Reexport_Test is
> begin 
>   Signature_Package_Reexport_Instance.New_Line;
>   Signature_Package_Reexport_Instance.Put_Line("Reexport Put_Line(""string"")");
>   Signature_Package_Reexport_Instance.Put     ("Reexport Put     (""string"")");
> end;

What "Put" do you think is visible at the declaration of Signature_Package_Reexport_Instance? There is no "use" clause in effect.

--  Stephe