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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;