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------------------------------------------------------------------------------

--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                              S E M . C H 7                               --

--                                                                          --

--                                 B o d y                                  --

--                                                                          --

--          Copyright (C) 1992-2011, Free Software Foundation, Inc.         --

--                                                                          --

-- GNAT is free software;  you can  redistribute it  and/or modify it under --

-- terms of the  GNU General Public License as published  by the Free Soft- --

-- ware  Foundation;  either version 3,  or (at your option) any later ver- --

-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --

-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --

-- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --

-- for  more details.  You should have  received  a copy of the GNU General --

-- Public License  distributed with GNAT; see file COPYING3.  If not, go to --

-- http://www.gnu.org/licenses for a complete copy of the license.          --

--                                                                          --

-- GNAT was originally developed  by the GNAT team at  New York University. --

-- Extensive contributions were provided by Ada Core Technologies Inc.      --

--                                                                          --

------------------------------------------------------------------------------

--  This package contains the routines to process package specifications and

--  bodies. The most important semantic aspects of package processing are the

--  handling of private and full declarations, and the construction of dispatch

--  tables for tagged types.

with Atree;    use Atree;

with Debug;    use Debug;

with Einfo;    use Einfo;

with Elists;   use Elists;

with Errout;   use Errout;

with Exp_Disp; use Exp_Disp;

with Exp_Dist; use Exp_Dist;

with Exp_Dbug; use Exp_Dbug;

with Lib;      use Lib;

with Lib.Xref; use Lib.Xref;

with Namet;    use Namet;

with Nmake;    use Nmake;

with Nlists;   use Nlists;

with Opt;      use Opt;

with Output;   use Output;

with Restrict; use Restrict;

with Sem;      use Sem;

with Sem_Aux;  use Sem_Aux;

with Sem_Cat;  use Sem_Cat;

with Sem_Ch3;  use Sem_Ch3;

with Sem_Ch6;  use Sem_Ch6;

with Sem_Ch8;  use Sem_Ch8;

with Sem_Ch10; use Sem_Ch10;

with Sem_Ch12; use Sem_Ch12;

with Sem_Ch13; use Sem_Ch13;

with Sem_Disp; use Sem_Disp;

with Sem_Eval; use Sem_Eval;

with Sem_Util; use Sem_Util;

with Sem_Warn; use Sem_Warn;

with Snames;   use Snames;

with Stand;    use Stand;

with Sinfo;    use Sinfo;

with Sinput;   use Sinput;

with Style;

with Uintp;    use Uintp;

package body Sem_Ch7 is

   -----------------------------------

   -- Handling private declarations --

   -----------------------------------

   --  The principle that each entity has a single defining occurrence clashes

   --  with the presence of two separate definitions for private types: the

   --  first is the private type declaration, and the second is the full type

   --  declaration. It is important that all references to the type point to

   --  the same defining occurrence, namely the first one. To enforce the two

   --  separate views of the entity, the corresponding information is swapped

   --  between the two declarations. Outside of the package, the defining

   --  occurrence only contains the private declaration information, while in

   --  the private part and the body of the package the defining occurrence

   --  contains the full declaration. To simplify the swap, the defining

   --  occurrence that currently holds the private declaration points to the

   --  full declaration. During semantic processing the defining occurrence

   --  also points to a list of private dependents, that is to say access types

   --  or composite types whose designated types or component types are

   --  subtypes or derived types of the private type in question. After the

   --  full declaration has been seen, the private dependents are updated to

   --  indicate that they have full definitions.

   -----------------------

   -- Local Subprograms --

   -----------------------

   procedure Analyze_Package_Body_Helper (N : Node_Id);

   --  Does all the real work of Analyze_Package_Body

   procedure Check_Anonymous_Access_Types

     (Spec_Id : Entity_Id;

      P_Body  : Node_Id);

   --  If the spec of a package has a limited_with_clause, it may declare

   --  anonymous access types whose designated type is a limited view, such an

   --  anonymous access return type for a function. This access type cannot be

   --  elaborated in the spec itself, but it may need an itype reference if it

   --  is used within a nested scope. In that case the itype reference is

   --  created at the beginning of the corresponding package body and inserted

   --  before other body declarations.

   procedure Install_Package_Entity (Id : Entity_Id);

   --  Supporting procedure for Install_{Visible,Private}_Declarations. Places

   --  one entity on its visibility chain, and recurses on the visible part if

   --  the entity is an inner package.

   function Is_Private_Base_Type (E : Entity_Id) return Boolean;

   --  True for a private type that is not a subtype

   function Is_Visible_Dependent (Dep : Entity_Id) return Boolean;

   --  If the private dependent is a private type whose full view is derived

   --  from the parent type, its full properties are revealed only if we are in

   --  the immediate scope of the private dependent. Should this predicate be

   --  tightened further???

   procedure Declare_Inherited_Private_Subprograms (Id : Entity_Id);

   --  Called upon entering the private part of a public child package and the

   --  body of a nested package, to potentially declare certain inherited

   --  subprograms that were inherited by types in the visible part, but whose

   --  declaration was deferred because the parent operation was private and

   --  not visible at that point. These subprograms are located by traversing

   --  the visible part declarations looking for non-private type extensions

   --  and then examining each of the primitive operations of such types to

   --  find those that were inherited but declared with a special internal

   --  name. Each such operation is now declared as an operation with a normal

   --  name (using the name of the parent operation) and replaces the previous

   --  implicit operation in the primitive operations list of the type. If the

   --  inherited private operation has been overridden, then it's replaced by

   --  the overriding operation.

   --------------------------

   -- Analyze_Package_Body --

   --------------------------

   procedure Analyze_Package_Body (N : Node_Id) is

      Loc : constant Source_Ptr := Sloc (N);

   begin

      if Debug_Flag_C then

         Write_Str ("==> package body ");

         Write_Name (Chars (Defining_Entity (N)));

         Write_Str (" from ");

         Write_Location (Loc);

         Write_Eol;

         Indent;

      end if;

      --  The real work is split out into the helper, so it can do "return;"

      --  without skipping the debug output.

      Analyze_Package_Body_Helper (N);

      if Debug_Flag_C then

         Outdent;

         Write_Str ("<== package body ");

         Write_Name (Chars (Defining_Entity (N)));

         Write_Str (" from ");

         Write_Location (Loc);

         Write_Eol;

      end if;

   end Analyze_Package_Body;

   ---------------------------------

   -- Analyze_Package_Body_Helper --

   ---------------------------------

   procedure Analyze_Package_Body_Helper (N : Node_Id) is

      HSS              : Node_Id;

      Body_Id          : Entity_Id;

      Spec_Id          : Entity_Id;

      Last_Spec_Entity : Entity_Id;

      New_N            : Node_Id;

      Pack_Decl        : Node_Id;

      procedure Install_Composite_Operations (P : Entity_Id);

      --  Composite types declared in the current scope may depend on types

      --  that were private at the point of declaration, and whose full view

      --  is now in scope. Indicate that the corresponding operations on the

      --  composite type are available.

      ----------------------------------

      -- Install_Composite_Operations --

      ----------------------------------

      procedure Install_Composite_Operations (P : Entity_Id) is

         Id : Entity_Id;

      begin

         Id := First_Entity (P);

         while Present (Id) loop

            if Is_Type (Id)

              and then (Is_Limited_Composite (Id)

                         or else Is_Private_Composite (Id))

              and then No (Private_Component (Id))

            then

               Set_Is_Limited_Composite (Id, False);

               Set_Is_Private_Composite (Id, False);

            end if;

            Next_Entity (Id);

         end loop;

      end Install_Composite_Operations;

   --  Start of processing for Analyze_Package_Body_Helper

   begin

      --  Find corresponding package specification, and establish the current

      --  scope. The visible defining entity for the package is the defining

      --  occurrence in the spec. On exit from the package body, all body

      --  declarations are attached to the defining entity for the body, but

      --  the later is never used for name resolution. In this fashion there

      --  is only one visible entity that denotes the package.

      --  Set Body_Id. Note that this Will be reset to point to the generic

      --  copy later on in the generic case.

      Body_Id := Defining_Entity (N);

      if Present (Corresponding_Spec (N)) then

         --  Body is body of package instantiation. Corresponding spec has

         --  already been set.

         Spec_Id := Corresponding_Spec (N);

         Pack_Decl := Unit_Declaration_Node (Spec_Id);

      else

         Spec_Id := Current_Entity_In_Scope (Defining_Entity (N));

         if Present (Spec_Id)

           and then Is_Package_Or_Generic_Package (Spec_Id)

         then

            Pack_Decl := Unit_Declaration_Node (Spec_Id);

            if Nkind (Pack_Decl) = N_Package_Renaming_Declaration then

               Error_Msg_N ("cannot supply body for package renaming", N);

               return;

            elsif Present (Corresponding_Body (Pack_Decl)) then

               Error_Msg_N ("redefinition of package body", N);

               return;

            end if;

         else

            Error_Msg_N ("missing specification for package body", N);

            return;

         end if;

         if Is_Package_Or_Generic_Package (Spec_Id)

           and then (Scope (Spec_Id) = Standard_Standard

                      or else Is_Child_Unit (Spec_Id))

           and then not Unit_Requires_Body (Spec_Id)

         then

            if Ada_Version = Ada_83 then

               Error_Msg_N

                 ("optional package body (not allowed in Ada 95)?", N);

            else

               Error_Msg_N ("spec of this package does not allow a body", N);

            end if;

         end if;

      end if;

      Set_Is_Compilation_Unit (Body_Id, Is_Compilation_Unit (Spec_Id));

      Style.Check_Identifier (Body_Id, Spec_Id);

      if Is_Child_Unit (Spec_Id) then

         if Nkind (Parent (N)) /= N_Compilation_Unit then

            Error_Msg_NE

              ("body of child unit& cannot be an inner package", N, Spec_Id);

         end if;

         Set_Is_Child_Unit (Body_Id);

      end if;

      --  Generic package case

      if Ekind (Spec_Id) = E_Generic_Package then

         --  Disable expansion and perform semantic analysis on copy. The

         --  unannotated body will be used in all instantiations.

         Body_Id := Defining_Entity (N);

         Set_Ekind (Body_Id, E_Package_Body);

         Set_Scope (Body_Id, Scope (Spec_Id));

         Set_Is_Obsolescent (Body_Id, Is_Obsolescent (Spec_Id));

         Set_Body_Entity (Spec_Id, Body_Id);

         Set_Spec_Entity (Body_Id, Spec_Id);

         New_N := Copy_Generic_Node (N, Empty, Instantiating => False);

         Rewrite (N, New_N);

         --  Update Body_Id to point to the copied node for the remainder of

         --  the processing.

         Body_Id := Defining_Entity (N);

         Start_Generic;

      end if;

      --  The Body_Id is that of the copied node in the generic case, the

      --  current node otherwise. Note that N was rewritten above, so we must

      --  be sure to get the latest Body_Id value.

      Set_Ekind (Body_Id, E_Package_Body);

      Set_Body_Entity (Spec_Id, Body_Id);

      Set_Spec_Entity (Body_Id, Spec_Id);

      --  Defining name for the package body is not a visible entity: Only the

      --  defining name for the declaration is visible.

      Set_Etype (Body_Id, Standard_Void_Type);

      Set_Scope (Body_Id, Scope (Spec_Id));

      Set_Corresponding_Spec (N, Spec_Id);

      Set_Corresponding_Body (Pack_Decl, Body_Id);

      --  The body entity is not used for semantics or code generation, but

      --  it is attached to the entity list of the enclosing scope to simplify

      --  the listing of back-annotations for the types it main contain.

      if Scope (Spec_Id) /= Standard_Standard then

         Append_Entity (Body_Id, Scope (Spec_Id));

      end if;

      --  Indicate that we are currently compiling the body of the package

      Set_In_Package_Body (Spec_Id);

      Set_Has_Completion (Spec_Id);

      Last_Spec_Entity := Last_Entity (Spec_Id);

      Push_Scope (Spec_Id);

      Set_Categorization_From_Pragmas (N);

      Install_Visible_Declarations (Spec_Id);

      Install_Private_Declarations (Spec_Id);

      Install_Private_With_Clauses (Spec_Id);

      Install_Composite_Operations (Spec_Id);

      Check_Anonymous_Access_Types (Spec_Id, N);

      if Ekind (Spec_Id) = E_Generic_Package then

         Set_Use (Generic_Formal_Declarations (Pack_Decl));

      end if;

      Set_Use (Visible_Declarations (Specification (Pack_Decl)));

      Set_Use (Private_Declarations (Specification (Pack_Decl)));

      --  This is a nested package, so it may be necessary to declare certain

      --  inherited subprograms that are not yet visible because the parent

      --  type's subprograms are now visible.

      if Ekind (Scope (Spec_Id)) = E_Package

        and then Scope (Spec_Id) /= Standard_Standard

      then

         Declare_Inherited_Private_Subprograms (Spec_Id);

      end if;

      if Present (Declarations (N)) then

         Analyze_Declarations (Declarations (N));

         Inspect_Deferred_Constant_Completion (Declarations (N));

      end if;

      --  Analyze_Declarations has caused freezing of all types. Now generate

      --  bodies for RACW primitives and stream attributes, if any.

      if Ekind (Spec_Id) = E_Package and then Has_RACW (Spec_Id) then

         --  Attach subprogram bodies to support RACWs declared in spec

         Append_RACW_Bodies (Declarations (N), Spec_Id);

         Analyze_List (Declarations (N));

      end if;

      HSS := Handled_Statement_Sequence (N);

      if Present (HSS) then

         Process_End_Label (HSS, 't', Spec_Id);

         Analyze (HSS);

         --  Check that elaboration code in a preelaborable package body is

         --  empty other than null statements and labels (RM 10.2.1(6)).

         Validate_Null_Statement_Sequence (N);

      end if;

      Validate_Categorization_Dependency (N, Spec_Id);

      Check_Completion (Body_Id);

      --  Generate start of body reference. Note that we do this fairly late,

      --  because the call will use In_Extended_Main_Source_Unit as a check,

      --  and we want to make sure that Corresponding_Stub links are set

      Generate_Reference (Spec_Id, Body_Id, 'b', Set_Ref => False);

      --  For a generic package, collect global references and mark them on

      --  the original body so that they are not resolved again at the point

      --  of instantiation.

      if Ekind (Spec_Id) /= E_Package then

         Save_Global_References (Original_Node (N));

         End_Generic;

      end if;

      --  The entities of the package body have so far been chained onto the

      --  declaration chain for the spec. That's been fine while we were in the

      --  body, since we wanted them to be visible, but now that we are leaving

      --  the package body, they are no longer visible, so we remove them from

      --  the entity chain of the package spec entity, and copy them to the

      --  entity chain of the package body entity, where they will never again

      --  be visible.

      if Present (Last_Spec_Entity) then

         Set_First_Entity (Body_Id, Next_Entity (Last_Spec_Entity));

         Set_Next_Entity (Last_Spec_Entity, Empty);

         Set_Last_Entity (Body_Id, Last_Entity (Spec_Id));

         Set_Last_Entity (Spec_Id, Last_Spec_Entity);

      else

         Set_First_Entity (Body_Id, First_Entity (Spec_Id));

         Set_Last_Entity  (Body_Id, Last_Entity  (Spec_Id));

         Set_First_Entity (Spec_Id, Empty);

         Set_Last_Entity  (Spec_Id, Empty);

      end if;

      End_Package_Scope (Spec_Id);

      --  All entities declared in body are not visible

      declare

         E : Entity_Id;

      begin

         E := First_Entity (Body_Id);

         while Present (E) loop

            Set_Is_Immediately_Visible (E, False);

            Set_Is_Potentially_Use_Visible (E, False);

            Set_Is_Hidden (E);

            --  Child units may appear on the entity list (e.g. if they appear

            --  in the context of a subunit) but they are not body entities.

            if not Is_Child_Unit (E) then

               Set_Is_Package_Body_Entity (E);

            end if;

            Next_Entity (E);

         end loop;

      end;

      Check_References (Body_Id);

      --  For a generic unit, check that the formal parameters are referenced,

      --  and that local variables are used, as for regular packages.

      if Ekind (Spec_Id) = E_Generic_Package then

         Check_References (Spec_Id);

      end if;

      --  The processing so far has made all entities of the package body

      --  public (i.e. externally visible to the linker). This is in general

      --  necessary, since inlined or generic bodies, for which code is

      --  generated in other units, may need to see these entities. The

      --  following loop runs backwards from the end of the entities of the

      --  package body making these entities invisible until we reach a

      --  referencer, i.e. a declaration that could reference a previous

      --  declaration, a generic body or an inlined body, or a stub (which may

      --  contain either of these). This is of course an approximation, but it

      --  is conservative and definitely correct.

      --  We only do this at the outer (library) level non-generic packages.

      --  The reason is simply to cut down on the number of global symbols

      --  generated, which has a double effect: (1) to make the compilation

      --  process more efficient and (2) to give the code generator more

      --  freedom to optimize within each unit, especially subprograms.

      if (Scope (Spec_Id) = Standard_Standard or else Is_Child_Unit (Spec_Id))

        and then not Is_Generic_Unit (Spec_Id)

        and then Present (Declarations (N))

      then

         Make_Non_Public_Where_Possible : declare

            function Has_Referencer

              (L     : List_Id;

               Outer : Boolean) return  Boolean;

            --  Traverse the given list of declarations in reverse order.

            --  Return True if a referencer is present. Return False if none is

            --  found. The Outer parameter is True for the outer level call and

            --  False for inner level calls for nested packages. If Outer is

            --  True, then any entities up to the point of hitting a referencer

            --  get their Is_Public flag cleared, so that the entities will be

            --  treated as static entities in the C sense, and need not have

            --  fully qualified names. Furthermore, if the referencer is an

            --  inlined subprogram that doesn't reference other subprograms,

            --  we keep clearing the Is_Public flag on subprograms. For inner

            --  levels, we need all names to be fully qualified to deal with

            --  the same name appearing in parallel packages (right now this

            --  is tied to their being external).

            --------------------

            -- Has_Referencer --

            --------------------

            function Has_Referencer

              (L     : List_Id;

               Outer : Boolean) return  Boolean

            is

               Has_Referencer_Except_For_Subprograms : Boolean := False;

               D : Node_Id;

               E : Entity_Id;

               K : Node_Kind;

               S : Entity_Id;

               function Check_Subprogram_Ref (N : Node_Id)

                 return Traverse_Result;

               --  Look for references to subprograms

               --------------------------

               -- Check_Subprogram_Ref --

               --------------------------

               function Check_Subprogram_Ref (N : Node_Id)

                 return Traverse_Result

               is

                  V : Node_Id;

               begin

                  --  Check name of procedure or function calls

                  if Nkind_In (N, N_Procedure_Call_Statement, N_Function_Call)

                    and then Is_Entity_Name (Name (N))

                  then

                     return Abandon;

                  end if;

                  --  Check prefix of attribute references

                  if Nkind (N) = N_Attribute_Reference

                    and then Is_Entity_Name (Prefix (N))

                    and then Present (Entity (Prefix (N)))

                    and then Ekind (Entity (Prefix (N))) in Subprogram_Kind

                  then

                     return Abandon;

                  end if;

                  --  Check value of constants

                  if Nkind (N) = N_Identifier

                    and then Present (Entity (N))

                    and then Ekind (Entity (N)) = E_Constant

                  then

                     V := Constant_Value (Entity (N));

                     if Present (V)

                       and then not Compile_Time_Known_Value_Or_Aggr (V)

                     then

                        return Abandon;

                     end if;

                  end if;

                  return OK;

               end Check_Subprogram_Ref;

               function Check_Subprogram_Refs is

                 new Traverse_Func (Check_Subprogram_Ref);

            --  Start of processing for Has_Referencer

            begin

               if No (L) then

                  return False;

               end if;

               D := Last (L);

               while Present (D) loop

                  K := Nkind (D);

                  if K in N_Body_Stub then

                     return True;

                  --  Processing for subprogram bodies

                  elsif K = N_Subprogram_Body then

                     if Acts_As_Spec (D) then

                        E := Defining_Entity (D);

                        --  An inlined body acts as a referencer. Note also

                        --  that we never reset Is_Public for an inlined

                        --  subprogram. Gigi requires Is_Public to be set.

                        --  Note that we test Has_Pragma_Inline here rather

                        --  than Is_Inlined. We are compiling this for a

                        --  client, and it is the client who will decide if

                        --  actual inlining should occur, so we need to assume

                        --  that the procedure could be inlined for the purpose

                        --  of accessing global entities.

                        if Has_Pragma_Inline (E) then

                           if Outer

                             and then Check_Subprogram_Refs (D) = OK

                           then

                              Has_Referencer_Except_For_Subprograms := True;

                           else

                              return True;

                           end if;

                        else

                           Set_Is_Public (E, False);

                        end if;

                     else

                        E := Corresponding_Spec (D);

                        if Present (E) then

                           --  A generic subprogram body acts as a referencer

                           if Is_Generic_Unit (E) then

                              return True;

                           end if;

                           if Has_Pragma_Inline (E) or else Is_Inlined (E) then

                              if Outer

                                and then Check_Subprogram_Refs (D) = OK

                              then

                                 Has_Referencer_Except_For_Subprograms := True;

                              else

                                 return True;

                              end if;

                           end if;

                        end if;

                     end if;

                  --  Processing for package bodies

                  elsif K = N_Package_Body

                    and then Present (Corresponding_Spec (D))

                  then

                     E := Corresponding_Spec (D);

                     --  Generic package body is a referencer. It would seem

                     --  that we only have to consider generics that can be

                     --  exported, i.e. where the corresponding spec is the

                     --  spec of the current package, but because of nested

                     --  instantiations, a fully private generic body may

                     --  export other private body entities. Furthermore,

                     --  regardless of whether there was a previous inlined

                     --  subprogram, (an instantiation of) the generic package

                     --  may reference any entity declared before it.

                     if Is_Generic_Unit (E) then

                        return True;

                     --  For non-generic package body, recurse into body unless

                     --  this is an instance, we ignore instances since they

                     --  cannot have references that affect outer entities.

                     elsif not Is_Generic_Instance (E)

                       and then not Has_Referencer_Except_For_Subprograms

                     then

                        if Has_Referencer

                             (Declarations (D), Outer => False)

                        then

                           return True;

                        end if;

                     end if;

                  --  Processing for package specs, recurse into declarations.

                  --  Again we skip this for the case of generic instances.

                  elsif K = N_Package_Declaration

                    and then not Has_Referencer_Except_For_Subprograms

                  then

                     S := Specification (D);

                     if not Is_Generic_Unit (Defining_Entity (S)) then

                        if Has_Referencer

                             (Private_Declarations (S), Outer => False)

                        then

                           return True;

                        elsif Has_Referencer

                               (Visible_Declarations (S), Outer => False)

                        then

                           return True;

                        end if;

                     end if;

                  --  Objects and exceptions need not be public if we have not

                  --  encountered a referencer so far. We only reset the flag

                  --  for outer level entities that are not imported/exported,

                  --  and which have no interface name.

                  elsif Nkind_In (K, N_Object_Declaration,

                                     N_Exception_Declaration,

                                     N_Subprogram_Declaration)

                  then

                     E := Defining_Entity (D);

                     if Outer

                       and then (not Has_Referencer_Except_For_Subprograms

                                  or else K = N_Subprogram_Declaration)

                       and then not Is_Imported (E)

                       and then not Is_Exported (E)

                       and then No (Interface_Name (E))

                     then

                        Set_Is_Public (E, False);

                     end if;

                  end if;

                  Prev (D);

               end loop;

               return Has_Referencer_Except_For_Subprograms;

            end Has_Referencer;

         --  Start of processing for Make_Non_Public_Where_Possible

         begin

            declare

               Discard : Boolean;

               pragma Warnings (Off, Discard);

            begin

               Discard := Has_Referencer (Declarations (N), Outer => True);

            end;

         end Make_Non_Public_Where_Possible;

      end if;

      --  If expander is not active, then here is where we turn off the

      --  In_Package_Body flag, otherwise it is turned off at the end of the

      --  corresponding expansion routine. If this is an instance body, we need

      --  to qualify names of local entities, because the body may have been

      --  compiled as a preliminary to another instantiation.

      if not Expander_Active then

         Set_In_Package_Body (Spec_Id, False);

         if Is_Generic_Instance (Spec_Id)

           and then Operating_Mode = Generate_Code

         then

            Qualify_Entity_Names (N);

         end if;

      end if;

   end Analyze_Package_Body_Helper;

   ---------------------------------

   -- Analyze_Package_Declaration --

   ---------------------------------

   procedure Analyze_Package_Declaration (N : Node_Id) is

      Id : constant Node_Id := Defining_Entity (N);

      PF : Boolean;

      --  True when in the context of a declared pure library unit

      Body_Required : Boolean;

      --  True when this package declaration requires a corresponding body

      Comp_Unit : Boolean;

      --  True when this package declaration is not a nested declaration

   begin

      --  Analye aspect specifications immediately, since we need to recognize

      --  things like Pure early enough to diagnose violations during analysis.

      if Has_Aspects (N) then

         Analyze_Aspect_Specifications (N, Id);

      end if;

      --  Ada 2005 (AI-217): Check if the package has been erroneously named

      --  in a limited-with clause of its own context. In this case the error