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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- L I B . L O A D --
-- --
-- S p e c --
-- --
-- Copyright (C) 1992-2007, 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 child package contains the function used to load a separately
-- compiled unit, as well as the routine used to initialize the unit
-- table and load the main source file.
package Lib.Load is
-------------------------------
-- Handling of Renamed Units --
-------------------------------
-- A compilation unit can be a renaming of another compilation unit.
-- Such renamed units are not allowed as parent units, that is you
-- cannot declare a unit:
-- with x;
-- package x.y is end;
-- where x is a renaming of some other package. However you can refer
-- to a renamed unit in a with clause:
-- package p is end;
-- package p.q is end;
-- with p;
-- package pr renames p;
-- with pr.q ....
-- This means that in the context of a with clause, the normal fixed
-- correspondence between unit and file names is broken. In the above
-- example, there is no file named pr-q.ads, since the actual child
-- unit is p.q, and it will be found in file p-q.ads.
-- In order to deal with this case, we have to first load pr.ads, and
-- then discover that it is a renaming of p, so that we know that pr.q
-- really refers to p.q. Furthermore this can happen at any level:
-- with p.q;
-- package p.r renames p.q;
-- with p.q;
-- package p.q.s is end;
-- with p.r.s ...
-- Now we have a case where the parent p.r is a child unit and is
-- a renaming. This shows that renaming can occur at any level.
-- Finally, consider:
-- with pr.q.s ...
-- Here the parent pr.q is not itself a renaming, but it really refers
-- to the unit p.q, and again we cannot know this without loading the
-- parent. The bottom line here is that while the file name of a unit
-- always corresponds to the unit name, the unit name as given to the
-- Load_Unit function may not be the real unit.
-----------------
-- Subprograms --
-----------------
procedure Initialize;
-- Initialize internal tables
procedure Initialize_Version (U : Unit_Number_Type);
-- This is called once the source file corresponding to unit U has been
-- fully scanned. At that point the checksum is computed, and can be used
-- to initialize the version number.
procedure Load_Main_Source;
-- Called at the start of compiling a new main source unit to initialize
-- the library processing for the new main source. Establishes and
-- initializes the units table entry for the new main unit (leaving
-- the Unit_File_Name entry of Main_Unit set to No_File if there are no
-- more files. Otherwise the main source file has been opened and read
-- and then closed on return.
function Load_Unit
(Load_Name : Unit_Name_Type;
Required : Boolean;
Error_Node : Node_Id;
Subunit : Boolean;
Corr_Body : Unit_Number_Type := No_Unit;
Renamings : Boolean := False;
With_Node : Node_Id := Empty) return Unit_Number_Type;
-- This function loads and parses the unit specified by Load_Name (or
-- returns the unit number for the previously constructed units table
-- entry if this is not the first call for this unit). Required indicates
-- the behavior on a file not found condition, as further described below,
-- and Error_Node is the node in the calling program to which error
-- messages are to be attached.
--
-- If the corresponding file is found, the value returned by Load is the
-- unit number that indexes the corresponding entry in the units table. If
-- a serious enough parser error occurs to prevent subsequent semantic
-- analysis, then the Fatal_Error flag of the returned entry is set and
-- in addition, the fatal error flag of the calling unit is also set.
--
-- If the corresponding file is not found, then the behavior depends on
-- the setting of Required. If Required is False, then No_Unit is returned
-- and no error messages are issued. If Required is True, then an error
-- message is posted, and No_Unit is returned.
--
-- A special case arises in the call from Rtsfind, where Error_Node is set
-- to Empty. In this case Required is False, and the caller in any case
-- treats any error as fatal.
--
-- The Subunit parameter is True to load a subunit, and False to load
-- any other kind of unit (including all specs, package bodies, and
-- subprogram bodies).
--
-- The Corr_Body argument is normally defaulted. It is set only in the
-- case of loading the corresponding spec when the main unit is a body.
-- In this case, Corr_Body is the unit number of this corresponding
-- body. This is used to set the Serial_Ref_Unit field of the unit
-- table entry. It is also used to deal with the special processing
-- required by RM 10.1.4(4). See description in lib.ads.
--
-- Renamings activates the handling of renamed units as separately
-- described in the documentation of this unit. If this parameter is
-- set to True, then Load_Name may not be the real unit name and it
-- is necessary to load parents to find the real name.
--
-- From_Limited_With is True if we are loading a unit X found in a
-- limited-with clause, or some unit in the context of X. It is used to
-- avoid the check on circular dependency (Ada 2005, AI-50217)
procedure Change_Main_Unit_To_Spec;
-- This procedure is called if the main unit file contains a No_Body pragma
-- and no other tokens. The effect is, if possible, to change the main unit
-- from the body it references now, to the corresponding spec. This has the
-- effect of ignoring the body, which is what we want. If it is impossible
-- to successfully make the change, then the call has no effect, and the
-- file is unchanged (this will lead to an error complaining about the
-- inappropriate No_Body spec).
function Create_Dummy_Package_Unit
(With_Node : Node_Id;
Spec_Name : Unit_Name_Type) return Unit_Number_Type;
-- With_Node is the Node_Id of a with statement for which the file could
-- not be found, and Spec_Name is the corresponding unit name. This call
-- creates a dummy package unit so that compilation can continue without
-- blowing up when the missing unit is referenced.
procedure Make_Instance_Unit (N : Node_Id);
-- When a compilation unit is an instantiation, it contains both the
-- declaration and the body of the instance, each of which can have its
-- own elaboration routine. The file itself corresponds to the declaration.
-- We create an additional entry for the body, so that the binder can
-- generate the proper elaboration calls to both. The argument N is the
-- compilation unit node created for the body.
procedure Version_Update (U : Node_Id; From : Node_Id);
-- This routine is called when unit U is found to be semantically
-- dependent on unit From. It updates the version of U to register
-- dependence on the version of From. The arguments are compilation
-- unit nodes for the relevant library nodes.
end Lib.Load;
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