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From: yoehoduv@protonmail.com
Newsgroups: comp.lang.ada
Subject: use type does not seem to work for types in generic package
 instantiations
Date: Tue, 18 Feb 2020 01:37:57 +0000
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It looks like use type has no effect when the type is from a package
declared in the same region as the use type statement.

I can make the primitive subprograms of a type directly visible with
`use all type` like this:

     package Type_Package is
        type T is null record;
        procedure Action(X: T) is null;
     end Type_Package;

     with Type_Package;
     procedure Use_Type is
        use all type Type_Package.T;
        X: Type_Package.T;
     begin
        Action(X);
     end Use_Type;

However, it does not seem to work when I move `Type_Package` inside
`Use_Type`.

     procedure Use_Type is
        package Type_Package is
           type T is null record;
           procedure Action(X: T) is null;
        end Type_Package;
        use all type Type_Package.T;
        X: Type_Package.T;
     begin
        Action(X);
     end Use_Type;

I get

     gcc -c use_type.adb
     use_type.adb:9:04: "Action" is not visible
     use_type.adb:9:04: non-visible declaration at line 4
     gnatmake: "use_type.adb" compilation error

The same thing occurs when I instantiate a generic package.  For
example, when I want to use the data types in `Ada.Containers`.

     package Element_Set is
        new Ada.Containers.Hashed_Sets(Element_Type, Hash, "=");
     use all type Element_Set.Set;

The `use type` clause here seems to have no effect.

Does anyone know why?

I originally posted this at
<https://stackoverflow.com/questions/60246613/how-to-use-a-type-from-a-child-package-generic-package-instantiation>