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

--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                             E X P _ A L F A                              --

--                                                                          --

--                                 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.      --

--                                                                          --

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

with Atree;    use Atree;

with Einfo;    use Einfo;

with Exp_Attr; use Exp_Attr;

with Exp_Ch4;  use Exp_Ch4;

with Exp_Ch6;  use Exp_Ch6;

with Exp_Dbug; use Exp_Dbug;

with Exp_Util; use Exp_Util;

with Nlists;   use Nlists;

with Rtsfind;  use Rtsfind;

with Sem_Aux;  use Sem_Aux;

with Sem_Res;  use Sem_Res;

with Sem_Util; use Sem_Util;

with Sinfo;    use Sinfo;

with Snames;   use Snames;

with Stand;    use Stand;

with Tbuild;   use Tbuild;

package body Exp_Alfa is

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

   -- Local Subprograms --

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

   procedure Expand_Alfa_Call (N : Node_Id);

   --  This procedure contains common processing for function and procedure

   --  calls:

   --    * expansion of actuals to introduce necessary temporaries

   --    * replacement of renaming by subprogram renamed

   procedure Expand_Alfa_N_Attribute_Reference (N : Node_Id);

   --  Expand attributes 'Old and 'Result only

   procedure Expand_Alfa_N_In (N : Node_Id);

   --  Expand set membership into individual ones

   procedure Expand_Alfa_N_Object_Renaming_Declaration (N : Node_Id);

   --  Perform name evaluation for a renamed object

   procedure Expand_Alfa_N_Simple_Return_Statement (N : Node_Id);

   --  Insert conversion on function return if necessary

   procedure Expand_Alfa_Simple_Function_Return (N : Node_Id);

   --  Expand simple return from function

   procedure Expand_Potential_Renaming (N : Node_Id);

   --  N denotes a N_Identifier or N_Expanded_Name. If N references a renaming,

   --  replace N with the renamed object.

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

   -- Expand_Alfa --

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

   procedure Expand_Alfa (N : Node_Id) is

   begin

      case Nkind (N) is

         when N_Attribute_Reference =>

            Expand_Alfa_N_Attribute_Reference (N);

         when N_Block_Statement     |

              N_Package_Body        |

              N_Package_Declaration |

              N_Subprogram_Body     =>

            Qualify_Entity_Names (N);

         when N_Function_Call            |

              N_Procedure_Call_Statement =>

            Expand_Alfa_Call (N);

         when N_Expanded_Name |

              N_Identifier    =>

            Expand_Potential_Renaming (N);

         when N_In =>

            Expand_Alfa_N_In (N);

         when N_Not_In =>

            Expand_N_Not_In (N);

         when N_Object_Renaming_Declaration =>

            Expand_Alfa_N_Object_Renaming_Declaration (N);

         when N_Simple_Return_Statement =>

            Expand_Alfa_N_Simple_Return_Statement (N);

         when others =>

            null;

      end case;

   end Expand_Alfa;

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

   -- Expand_Alfa_Call --

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

   procedure Expand_Alfa_Call (N : Node_Id) is

      Call_Node   : constant Node_Id := N;

      Parent_Subp : Entity_Id;

      Subp        : Entity_Id;

   begin

      --  Ignore if previous error

      if Nkind (Call_Node) in N_Has_Etype

        and then Etype (Call_Node) = Any_Type

      then

         return;

      end if;

      --  Call using access to subprogram with explicit dereference

      if Nkind (Name (Call_Node)) = N_Explicit_Dereference then

         Subp        := Etype (Name (Call_Node));

         Parent_Subp := Empty;

      --  Case of call to simple entry, where the Name is a selected component

      --  whose prefix is the task, and whose selector name is the entry name

      elsif Nkind (Name (Call_Node)) = N_Selected_Component then

         Subp        := Entity (Selector_Name (Name (Call_Node)));

         Parent_Subp := Empty;

      --  Case of call to member of entry family, where Name is an indexed

      --  component, with the prefix being a selected component giving the

      --  task and entry family name, and the index being the entry index.

      elsif Nkind (Name (Call_Node)) = N_Indexed_Component then

         Subp        := Entity (Selector_Name (Prefix (Name (Call_Node))));

         Parent_Subp := Empty;

      --  Normal case

      else

         Subp        := Entity (Name (Call_Node));

         Parent_Subp := Alias (Subp);

      end if;

      --  Various expansion activities for actuals are carried out

      Expand_Actuals (N, Subp);

      --  If the subprogram is a renaming, replace it in the call with the name

      --  of the actual subprogram being called.

      if Present (Parent_Subp) then

         Parent_Subp := Ultimate_Alias (Parent_Subp);

         --  The below setting of Entity is suspect, see F109-018 discussion???

         Set_Entity (Name (Call_Node), Parent_Subp);

      end if;

   end Expand_Alfa_Call;

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

   -- Expand_Alfa_N_Attribute_Reference --

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

   procedure Expand_Alfa_N_Attribute_Reference (N : Node_Id) is

      Id : constant Attribute_Id := Get_Attribute_Id (Attribute_Name (N));

   begin

      case Id is

         when Attribute_Old    |

              Attribute_Result =>

            Expand_N_Attribute_Reference (N);

         when others =>

            null;

      end case;

   end Expand_Alfa_N_Attribute_Reference;

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

   -- Expand_Alfa_N_In --

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

   procedure Expand_Alfa_N_In (N : Node_Id) is

   begin

      if Present (Alternatives (N)) then

         Expand_Set_Membership (N);

      end if;

   end Expand_Alfa_N_In;

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

   -- Expand_Alfa_N_Object_Renaming_Declaration --

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

   procedure Expand_Alfa_N_Object_Renaming_Declaration (N : Node_Id) is

   begin

      --  Unconditionally remove all side effects from the name

      Evaluate_Name (Name (N));

   end Expand_Alfa_N_Object_Renaming_Declaration;

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

   -- Expand_Alfa_N_Simple_Return_Statement --

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

   procedure Expand_Alfa_N_Simple_Return_Statement (N : Node_Id) is

   begin

      --  Defend against previous errors (i.e. the return statement calls a

      --  function that is not available in configurable runtime).

      if Present (Expression (N))

        and then Nkind (Expression (N)) = N_Empty

      then

         return;

      end if;

      --  Distinguish the function and non-function cases:

      case Ekind (Return_Applies_To (Return_Statement_Entity (N))) is

         when E_Function          |

              E_Generic_Function  =>

            Expand_Alfa_Simple_Function_Return (N);

         when E_Procedure         |

              E_Generic_Procedure |

              E_Entry             |

              E_Entry_Family      |

              E_Return_Statement =>

            null;

         when others =>

            raise Program_Error;

      end case;

   exception

      when RE_Not_Available =>

         return;

   end Expand_Alfa_N_Simple_Return_Statement;

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

   -- Expand_Alfa_Simple_Function_Return --

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

   procedure Expand_Alfa_Simple_Function_Return (N : Node_Id) is

      Scope_Id : constant Entity_Id :=

                   Return_Applies_To (Return_Statement_Entity (N));

      --  The function we are returning from

      R_Type : constant Entity_Id := Etype (Scope_Id);

      --  The result type of the function

      Exp : constant Node_Id := Expression (N);

      pragma Assert (Present (Exp));

      Exptyp : constant Entity_Id := Etype (Exp);

      --  The type of the expression (not necessarily the same as R_Type)

   begin

      --  Check the result expression of a scalar function against the subtype

      --  of the function by inserting a conversion. This conversion must

      --  eventually be performed for other classes of types, but for now it's

      --  only done for scalars.

      --  ???

      if Is_Scalar_Type (Exptyp) then

         Rewrite (Exp, Convert_To (R_Type, Exp));

         --  The expression is resolved to ensure that the conversion gets

         --  expanded to generate a possible constraint check.

         Analyze_And_Resolve (Exp, R_Type);

      end if;

   end Expand_Alfa_Simple_Function_Return;

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

   -- Expand_Potential_Renaming --

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

   procedure Expand_Potential_Renaming (N : Node_Id) is

      E : constant Entity_Id := Entity (N);

      T : constant Entity_Id := Etype (N);

   begin

      --  Replace a reference to a renaming with the actual renamed object

      if Ekind (E) in Object_Kind and then Present (Renamed_Object (E)) then

         Rewrite (N, New_Copy_Tree (Renamed_Object (E)));

         Reset_Analyzed_Flags (N);

         Analyze_And_Resolve (N, T);

      end if;

   end Expand_Potential_Renaming;

end Exp_Alfa;