ada: Clean up scope depth and related code (tech debt)

[gcc.git] / gcc / ada / sem_ch8.ads

------------------------------------------------------------------------------
--                                                                          --
--                         GNAT COMPILER COMPONENTS                         --
--                                                                          --
--                              S E M _ C H 8                               --
--                                                                          --
--                                 S p e c                                  --
--                                                                          --
--          Copyright (C) 1992-2023, 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 Einfo.Entities; use Einfo.Entities;
with Types;          use Types;
package Sem_Ch8 is

   -----------------------------------
   -- Handling extensions of System --
   -----------------------------------

   --  For targets that define a much larger System package than given in
   --  the RM, we use a child package containing additional declarations,
   --  which is loaded when needed, and whose entities are conceptually
   --  within System itself. The presence of this auxiliary package is
   --  controlled with the pragma Extend_System. The following variable
   --  holds the entity of the auxiliary package, to simplify the special
   --  visibility rules that apply to it.

   System_Aux_Id : Entity_Id := Empty;

   -----------------
   -- Subprograms --
   -----------------

   procedure Analyze_Exception_Renaming         (N : Node_Id);
   procedure Analyze_Expanded_Name              (N : Node_Id);
   procedure Analyze_Generic_Function_Renaming  (N : Node_Id);
   procedure Analyze_Generic_Package_Renaming   (N : Node_Id);
   procedure Analyze_Generic_Procedure_Renaming (N : Node_Id);
   procedure Analyze_Object_Renaming            (N : Node_Id);
   procedure Analyze_Package_Renaming           (N : Node_Id);
   procedure Analyze_Subprogram_Renaming        (N : Node_Id);

   procedure Analyze_Use_Package (N : Node_Id; Chain : Boolean := True);
   --  Analyze a use package clause and control (through the Chain parameter)
   --  whether to add N to the use clause chain for the name denoted within
   --  use clause N in case we are reanalyzing a use clause because of stack
   --  manipulation.

   procedure Analyze_Use_Type (N : Node_Id; Chain : Boolean := True);
   --  Similar to Analyze_Use_Package except the Chain parameter applies to the
   --  type within N's subtype mark Current_Use_Clause.

   procedure End_Scope;
   --  Called at end of scope. On exit from blocks and bodies (subprogram,
   --  package, task, and protected bodies), the name of the current scope
   --  must be removed from the scope stack, and the local entities must be
   --  removed from their homonym chains. On exit from record declarations,
   --  from package specifications, and from tasks and protected type
   --  specifications, more specialized procedures are invoked.

   procedure End_Use_Clauses (Clause : Node_Id);
   --  Invoked on scope exit, to undo the effect of local use clauses. Clause
   --  is the first use-clause of a scope being exited. This can be the current
   --  scope, or some enclosing scopes when building a clean environment to
   --  compile an instance body for inlining.

   procedure End_Use_Package (N : Node_Id);
   procedure End_Use_Type    (N : Node_Id);
   --  Subsidiaries of End_Use_Clauses. Also called directly for use clauses
   --  appearing in context clauses.

   procedure Find_Direct_Name (N : Node_Id);
   --  Given a direct name (Identifier or Operator_Symbol), this routine scans
   --  the homonym chain for the name, searching for corresponding visible
   --  entities to find the referenced entity (or in the case of overloading,
   --  one candidate interpretation). On return, the Entity and Etype fields
   --  are set. In the non-overloaded case, these are the correct entries.
   --  In the overloaded case, the flag Is_Overloaded is set, Etype and Entity
   --  refer to an arbitrary element of the overloads set, and the appropriate
   --  entries have been added to the overloads table entry for the node. The
   --  overloading will be disambiguated during type resolution.
   --
   --  Note, when this is called during semantic analysis in the overloaded
   --  case, the entity set will be the most recently declared homonym. In
   --  particular, the caller may follow the homonym chain checking for all
   --  entries in the current scope, and that will give all homonyms that are
   --  declared before the point of call in the current scope. This is useful
   --  for example in the processing for pragma Inline.
   --
   --  Flag Errors_OK should be set when error diagnostics are desired. Flag
   --  Marker_OK should be set when a N_Variable_Reference_Marker needs to be
   --  generated for a SPARK object in order to detect elaboration issues. Flag
   --  Reference_OK should be set when N must generate a cross reference.

   procedure Find_Selected_Component (N : Node_Id);
   --  Resolve various cases of selected components, recognize expanded names

   procedure Find_Type (N : Node_Id);
   --  Perform name resolution, and verify that the name found is that of a
   --  type. On return the Entity and Etype fields of the node N are set
   --  appropriately. If it is an incomplete type whose full declaration has
   --  been seen, they are set to the entity in the full declaration. If it
   --  is an incomplete type associated with an interface visible through a
   --  limited-with clause, whose full declaration has been seen, they are
   --  set to the entity in the full declaration. Similarly, if the type is
   --  private, it has received a full declaration, and we are in the private
   --  part or body of the package, then the two fields are set to the entity
   --  of the full declaration as well. This procedure also has special
   --  processing for 'Class attribute references.

   function Has_Loop_In_Inner_Open_Scopes (S : Entity_Id) return Boolean;
   --  S is the entity of an open scope. This function determines if there is
   --  an inner scope of S which is a loop (i.e. it appears somewhere in the
   --  scope stack after S).

   function In_Open_Scopes (S : Entity_Id) return Boolean;
   --  S is the entity of a scope. This function determines if this scope is
   --  currently open (i.e. it appears somewhere in the scope stack).

   procedure Initialize;
   --  Initializes data structures used for visibility analysis. Must be
   --  called before analyzing each new main source program.

   procedure Install_Use_Clauses
     (Clause             : Node_Id;
      Force_Installation : Boolean := False);
   --  Applies the use clauses appearing in a given declarative part,
   --  when the corresponding scope has been placed back on the scope
   --  stack after unstacking to compile a different context (subunit or
   --  parent of generic body). Force_Installation is used when called from
   --  Analyze_Subunit.Re_Install_Use_Clauses to insure that, after the
   --  analysis of the subunit, the parent's environment is again identical.

   procedure Mark_Use_Clauses (Id : Node_Or_Entity_Id);
   --  Mark a given entity or node Id's relevant use clauses as effective,
   --  including redundant ones and ones outside of the current scope.

   procedure Push_Scope (S : Scope_Kind_Id);
   --  Make new scope stack entry, pushing S, the entity for a scope onto the
   --  top of the scope table. The current setting of the scope suppress flags
   --  is saved for restoration on exit.

   procedure Pop_Scope;
   --  Remove top entry from scope stack, restoring the saved setting of the
   --  scope suppress flags.

   function Present_System_Aux (N : Node_Id := Empty) return Boolean;
   --  Return True if the auxiliary system file has been successfully loaded.
   --  Otherwise attempt to load it, using the name supplied by a previous
   --  Extend_System pragma, and report on the success of the load. If N is
   --  present, it is a selected component whose prefix is System, or else a
   --  with-clause on system. N is absent when the function is called to find
   --  the visibility of implicit operators.

   function Save_Scope_Stack
     (Handle_Use : Boolean := True) return Elist_Id;
   procedure Restore_Scope_Stack
     (List       : Elist_Id;
      Handle_Use : Boolean := True);
   --  These two subprograms are called from Semantics, when a unit U1 is to
   --  be compiled in the course of the compilation of another unit U2. This
   --  happens whenever Rtsfind is called. U1, the unit retrieved by Rtsfind,
   --  must be compiled in its own context, and the current scope stack
   --  containing U2 and local scopes must be made unreachable. This is
   --  achieved using a call to Save_Scope_Stack. On return, the contents
   --  of the scope stack must be made accessible again with a call to
   --  Restore_Scope_Stack.
   --
   --  The flag Handle_Use indicates whether local use clauses must be removed
   --  or installed. In the case of inlining of instance bodies, the visibility
   --  handling is done fully in Inline_Instance_Body, and use clauses are
   --  handled there. Save_Scope_Stack returns the list of entities which have
   --  been temporarily removed from visibility; that list must be passed to
   --  Restore_Scope_Stack to restore their visibility.

   procedure Set_Use (L : List_Id);
   --  Find use clauses that are declarative items in a package declaration
   --  and set the potentially use-visible flags of imported entities before
   --  analyzing the corresponding package body.

   procedure Update_Use_Clause_Chain;
   --  Called at the end of a declarative region to detect unused use type
   --  clauses and maintain the Current_Use_Clause for type entities.

   procedure ws;
   --  Debugging routine for use in gdb: dump all entities on scope stack

   procedure we (S : Entity_Id);
   --  Debugging routine for use in gdb: dump all entities in given scope

end Sem_Ch8;