[Ada] Crash on illegal use of limited view of classwide type

[Arnaud Charlet <charlet at adacore dot com>]

This patch fixes a compiler crash on an attempt to assign to a record component
whose type is the limited view of a classwide type.

Compiling

   gcc -c c3a1004e.adb

must yield:

   c3a1004e.adb:9:07: invalid use of limited view of "Department'CLASS"

---
limited with C3A1004E;
package C3A1004D is -- Departments
   type Emp_Ptr is access all C3A1004E.Employee'Class;
   type Department is tagged private;

private
   subtype Dept_Name is String (1 .. 13);
   type T_List is array (Positive range <>) of Emp_Ptr;

   type Department is tagged record
      Id   : Dept_Name := "<<Dept_Name>>";
      List : T_List (1 .. 5);
      Tot  : Natural := 0;
      During_Mod : Boolean := False;
   end record;
end C3A1004D;
---
package C3A1004E.Stub_Data is
   type C3A1004D_Department_Class_Access is
       access all C3A1004D.Department'Class;

   type Stub_Data_Type_Assign_Employee_dacb0f_a2752f is record
      D : C3A1004D_Department_Class_Access;
   end record;
   Stub_Data_Assign_Employee_dacb0f_a2752f :
       Stub_Data_Type_Assign_Employee_dacb0f_a2752f;

end C3A1004E.Stub_Data;
---
with C3A1004E.Stub_Data; use C3A1004E.Stub_Data;
--  with C3A1004D;    --  missing
package body C3A1004E
is
   procedure Assign_Employee
     (E : in out Employee;
      D : in out C3A1004D.Department'Class) is
   begin
      D := Stub_Data.Stub_Data_Assign_Employee_dacb0f_a2752f.D.all;
   end Assign_Employee;

end C3A1004E;
---
limited with C3A1004D;
package C3A1004E is -- Employees
   type Dept_Ptr is access all C3A1004D.Department'Class;
   type Employee is tagged private;

   type Emp_Ptr is access all Employee'Class; -- used by function 'hire'

   procedure Assign_Employee
     (E : in out Employee;
      D : in out C3A1004D.Department'Class);

private
   type Employee is tagged record
      Dept : Dept_Ptr;
      Id   : access String;
      During_Mod : Boolean := False;
   end record;
end C3A1004E;

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

2015-11-18  Ed Schonberg  <schonberg@adacore.com>

	* sem_ch5.adb (Analyze_Assignment): Diagnose assignment where
	left-hand side has a limited view of a class-wide type.
	* sem_ch6.adb (Detected_And_Exchange): Do not install a non-limited
	view if the scope of the type of the formal is visible through
	a limited_with_clause, even if the non-limited view is available.

Attachment: difs
Description: Text document