[Ada] Interface conversions and limited_with clauses.

[Arnaud Charlet <charlet at adacore dot com>]

In conversions of prefixed calls involving interfaces, the expression in the
conversion may have a limited view of a type obtained transitively through
several contexts. Use the non-limited view if available, to enable subsequent
interface membership tests.

The following must compile quietly:

   gcc -c rich_graph.adb

---
with Edge;
with Vertex;
with Graph;
package Rich_Graph is
   type Object is new Graph.Object with private;
   type Class_Ref is access all Object'Class;

   overriding function Other_End
     (G : in Object;
      E : in Edge.Class_Ref;
      V : in Vertex.Class_Ref) return Vertex.Class_Ref;

private
   type Object is new Graph.Object with null record;
end Rich_Graph;
---
with Rich_Edge;
with Rich_Vertex;
package body Rich_Graph is
   overriding function Other_End
     (G : in Object;
      E : in Edge.Class_Ref;
      V : in Vertex.Class_Ref) return Vertex.Class_Ref
   is
      Rich_E : Rich_Edge.Class_Ref;
      Rich_V : Rich_Vertex.Class_Ref;

   begin
      Rich_E := Rich_Edge.Class_Ref (E);
      Rich_V := Rich_Vertex.Class_Ref (V);

      return Vertex.Class_Ref (Rich_E.Other_End (Rich_V));
   end Other_End;
end Rich_Graph;
---
package Edge is
   type Object is limited interface;
   type Class_Ref is access all Object'Class;
end Edge;
---
package Vertex is
   type Object is limited interface;
   type Class_Ref is access all Object'Class;
end Vertex;
---
with Vertex;
with Edge;
package Graph is
   type Object is limited interface;
   type Class_Ref is access all Object'Class;

   function Other_End
     (Graph : in Object;
      E     : in Edge.Class_Ref;
      V     : in Vertex.Class_Ref) return Vertex.Class_Ref is abstract;
end Graph;
---
with Edge;
limited with Rich_Vertex;
package Rich_Edge is
   type Object is limited interface and Edge.Object;
   type Class_Ref is access all Object'Class;

   function Other_End
     (E     : in Object;
      V     : access Rich_Vertex.Object'Class)
      return Rich_Vertex.Class_Ref is abstract;
end Rich_Edge;
---
with Vertex;
package Rich_Vertex is
   type Object is limited interface and Vertex.Object;
   type Class_Ref is access all Object'Class;
end Rich_Vertex;

Tested on x86_64-pc-linux-gnu, committed on trunk

2014-07-29  Ed Schonberg  <schonberg@adacore.com>

	* sem_res.adb (Resolve_Type_Conversion): If the type of the
	expression is a limited view, use the non-limited view when
	available.

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