path: root/gcc/ada/sem_ch3.ads

------------------------------------------------------------------------------
--                                                                          --
--                         GNAT COMPILER COMPONENTS                         --
--                                                                          --
--                              S E M _ C H 3                               --
--                                                                          --
--                                 S p e c                                  --
--                                                                          --
--          Copyright (C) 1992-2010, 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 Nlists; use Nlists;
with Types;  use Types;

package Sem_Ch3 is
   procedure Analyze_Component_Declaration         (N : Node_Id);
   procedure Analyze_Full_Type_Declaration         (N : Node_Id);
   procedure Analyze_Incomplete_Type_Decl          (N : Node_Id);
   procedure Analyze_Itype_Reference               (N : Node_Id);
   procedure Analyze_Number_Declaration            (N : Node_Id);
   procedure Analyze_Object_Declaration            (N : Node_Id);
   procedure Analyze_Others_Choice                 (N : Node_Id);
   procedure Analyze_Private_Extension_Declaration (N : Node_Id);
   procedure Analyze_Subtype_Indication            (N : Node_Id);
   procedure Analyze_Variant_Part                  (N : Node_Id);

   procedure Analyze_Subtype_Declaration
     (N    : Node_Id;
      Skip : Boolean := False);
   --  Called to analyze a subtype declaration. The parameter Skip is used for
   --  Ada 2005 (AI-412). We set to True in order to avoid reentering the
   --  defining identifier of N when analyzing a rewritten incomplete subtype
   --  declaration.

   function Access_Definition
     (Related_Nod : Node_Id;
      N           : Node_Id) return Entity_Id;
   --  An access definition defines a general access type for a formal
   --  parameter. The procedure is called when processing formals, when
   --  the current scope is the subprogram. The Implicit type is attached
   --  to the Related_Nod put into the enclosing scope, so that the only
   --  entities defined in the spec are the formals themselves.

   procedure Access_Subprogram_Declaration
     (T_Name : Entity_Id;
      T_Def  : Node_Id);
   --  The subprogram specification yields the signature of an implicit
   --  type, whose Ekind is Access_Subprogram_Type. This implicit type is
   --  the designated type of the declared access type. In subprogram calls,
   --  the signature of the implicit type works like the profile of a regular
   --  subprogram.

   procedure Add_Internal_Interface_Entities (Tagged_Type : Entity_Id);
   --  Add to the list of primitives of Tagged_Type the internal entities
   --  associated with covered interface primitives. These entities link the
   --  interface primitives with the tagged type primitives that cover them.

   procedure Analyze_Declarations (L : List_Id);
   --  Called to analyze a list of declarations (in what context ???). Also
   --  performs necessary freezing actions (more description needed ???)

   procedure Analyze_Interface_Declaration (T : Entity_Id; Def : Node_Id);
   --  Analyze an interface declaration or a formal interface declaration

   procedure Array_Type_Declaration (T : in out Entity_Id; Def : Node_Id);
   --  Process an array type declaration. If the array is constrained, we
   --  create an implicit parent array type, with the same index types and
   --  component type.

   procedure Access_Type_Declaration (T : Entity_Id; Def : Node_Id);
   --  Process an access type declaration

   procedure Build_Itype_Reference (Ityp : Entity_Id; Nod : Node_Id);
   --  Create a reference to an internal type, for use by Gigi. The back-end
   --  elaborates itypes on demand, i.e. when their first use is seen. This can
   --  lead to scope anomalies if the first use is within a scope that is
   --  nested within the scope that contains the point of definition of the
   --  itype. The Itype_Reference node forces the elaboration of the itype
   --  in the proper scope. The node is inserted after Nod, which is the
   --  enclosing declaration that generated Ityp.
   --
   --  A related mechanism is used during expansion, for itypes created in
   --  branches of conditionals. See Ensure_Defined in exp_util.
   --  Could both mechanisms be merged ???

   procedure Check_Abstract_Overriding (T : Entity_Id);
   --  Check that all abstract subprograms inherited from T's parent type have
   --  been overridden as required, and that nonabstract subprograms have not
   --  been incorrectly overridden with an abstract subprogram.

   procedure Check_Aliased_Component_Types (T : Entity_Id);
   --  Given an array type or record type T, check that if the type is
   --  nonlimited, then the nominal subtype of any components of T that
   --  have discriminants must be constrained.

   procedure Check_Completion (Body_Id : Node_Id := Empty);
   --  At the end of a declarative part, verify that all entities that require
   --  completion have received one. If Body_Id is absent, the error indicating
   --  a missing completion is placed on the declaration that needs completion.
   --  If Body_Id is present, it is the defining identifier of a package body,
   --  and errors are posted on that node, rather than on the declarations that
   --  require completion in the package declaration.

   procedure Derive_Subprogram
     (New_Subp     : in out Entity_Id;
      Parent_Subp  : Entity_Id;
      Derived_Type : Entity_Id;
      Parent_Type  : Entity_Id;
      Actual_Subp  : Entity_Id := Empty);
   --  Derive the subprogram Parent_Subp from Parent_Type, and replace the
   --  subsidiary subtypes with the derived type to build the specification
   --  of the inherited subprogram (returned in New_Subp). For tagged types,
   --  the derived subprogram is aliased to that of the actual (in the
   --  case where Actual_Subp is nonempty) rather than to the corresponding
   --  subprogram of the parent type.

   procedure Derive_Subprograms
     (Parent_Type    : Entity_Id;
      Derived_Type   : Entity_Id;
      Generic_Actual : Entity_Id := Empty);
   --  To complete type derivation, collect/retrieve the primitive operations
   --  of the parent type, and replace the subsidiary subtypes with the derived
   --  type, to build the specs of the inherited ops. For generic actuals, the
   --  mapping of the primitive operations to those of the parent type is also
   --  done by rederiving the operations within the instance. For tagged types,
   --  the derived subprograms are aliased to those of the actual, not those of
   --  the ancestor.
   --
   --  Note: one might expect this to be private to the package body, but there
   --  is one rather unusual usage in package Exp_Dist.

   function Find_Hidden_Interface
     (Src  : Elist_Id;
      Dest : Elist_Id) return Entity_Id;
   --  Ada 2005: Determine whether the interfaces in list Src are all present
   --  in the list Dest. Return the first differing interface, or Empty
   --  otherwise.

   function Find_Type_Of_Subtype_Indic (S : Node_Id) return Entity_Id;
   --  Given a subtype indication S (which is really an N_Subtype_Indication
   --  node or a plain N_Identifier), find the type of the subtype mark.

   function Find_Type_Name (N : Node_Id) return Entity_Id;
   --  Enter the identifier in a type definition, or find the entity already
   --  declared, in the case of the full declaration of an incomplete or
   --  private type. If the previous declaration is tagged then the class-wide
   --  entity is propagated to the identifier to prevent multiple incompatible
   --  class-wide types that may be created for self-referential anonymous
   --  access components.

   function Get_Discriminant_Value
     (Discriminant       : Entity_Id;
      Typ_For_Constraint : Entity_Id;
      Constraint         : Elist_Id) return Node_Id;
   --  ??? MORE DOCUMENTATION
   --  Given a discriminant somewhere in the Typ_For_Constraint tree and a
   --  Constraint, return the value of that discriminant.

   function Is_Null_Extension (T : Entity_Id) return Boolean;
   --  Returns True if the tagged type T has an N_Full_Type_Declaration that
   --  is a null extension, meaning that it has an extension part without any
   --  components and does not have a known discriminant part.

   function Is_Visible_Component (C : Entity_Id) return Boolean;
   --  Determines if a record component C is visible in the present context.
   --  Note that even though component C could appear in the entity chain
   --  of a record type, C may not be visible in the current context. For
   --  instance, C may be a component inherited in the full view of a private
   --  extension which is not visible in the current context.

   procedure Make_Index
     (I            : Node_Id;
      Related_Nod  : Node_Id;
      Related_Id   : Entity_Id := Empty;
      Suffix_Index : Nat := 1);
   --  Process an index that is given in an array declaration, an entry
   --  family declaration or a loop iteration. The index is given by an
   --  index declaration (a 'box'), or by a discrete range. The later can
   --  be the name of a discrete type, or a subtype indication.
   --
   --  Related_Nod is the node where the potential generated implicit types
   --  will be inserted. The 2 last parameters are used for creating the name.

   procedure Make_Class_Wide_Type (T : Entity_Id);
   --  A Class_Wide_Type is created for each tagged type definition. The
   --  attributes of a class-wide type are inherited from those of the type T.
   --  If T is introduced by a private declaration, the corresponding class
   --  wide type is created at the same time, and therefore there is a private
   --  and a full declaration for the class-wide type as well.

   function OK_For_Limited_Init_In_05
     (Typ : Entity_Id;
      Exp : Node_Id) return Boolean;
   --  Presuming Exp is an expression of an inherently limited type Typ,
   --  returns True if the expression is allowed in an initialization context
   --  by the rules of Ada 2005. We use the rule in RM-7.5(2.1/2), "...it is an
   --  aggregate, a function_call, or a parenthesized expression or qualified
   --  expression whose operand is permitted...". Note that in Ada 95 mode,
   --  we sometimes wish to give warnings based on whether the program _would_
   --  be legal in Ada 2005. Note that Exp must already have been resolved,
   --  so we can know whether it's a function call (as opposed to an indexed
   --  component, for example). In the case where Typ is a limited interface's
   --  class-wide type, then the expression is allowed to be of any kind if its
   --  type is a nonlimited descendant of the interface.

   function OK_For_Limited_Init
     (Typ : Entity_Id;
      Exp : Node_Id) return Boolean;
   --  Always False in Ada 95 mode. Equivalent to OK_For_Limited_Init_In_05 in
   --  Ada 2005 mode.

   procedure Preanalyze_Spec_Expression (N : Node_Id; T : Entity_Id);
   --  Default and per object expressions do not freeze their components, and
   --  must be analyzed and resolved accordingly. The analysis is done by
   --  calling the Preanalyze_And_Resolve routine and setting the global
   --  In_Default_Expression flag. See the documentation section entitled
   --  "Handling of Default and Per-Object Expressions" in sem.ads for full
   --  details. N is the expression to be analyzed, T is the expected type.
   --  This mechanism is also used for aspect specifications that have an
   --  expression parameter that needs similar preanalysis.

   procedure Process_Full_View (N : Node_Id; Full_T, Priv_T : Entity_Id);
   --  Process some semantic actions when the full view of a private type is
   --  encountered and analyzed. The first action is to create the full views
   --  of the dependant private subtypes. The second action is to recopy the
   --  primitive operations of the private view (in the tagged case).
   --  N is the N_Full_Type_Declaration node.
   --
   --    Full_T is the full view of the type whose full declaration is in N.
   --
   --    Priv_T is the private view of the type whose full declaration is in N.

   procedure Process_Range_Expr_In_Decl
     (R           : Node_Id;
      T           : Entity_Id;
      Check_List  : List_Id := Empty_List;
      R_Check_Off : Boolean := False);
   --  Process a range expression that appears in a declaration context. The
   --  range is analyzed and resolved with the base type of the given type, and
   --  an appropriate check for expressions in non-static contexts made on the
   --  bounds. R is analyzed and resolved using T, so the caller should if
   --  necessary link R into the tree before the call, and in particular in the
   --  case of a subtype declaration, it is appropriate to set the parent
   --  pointer of R so that the types get properly frozen. Check_List is used
   --  when the subprogram is called from Build_Record_Init_Proc and is used to
   --  return a set of constraint checking statements generated by the Checks
   --  package. R_Check_Off is set to True when the call to Range_Check is to
   --  be skipped.

   function Process_Subtype
     (S           : Node_Id;
      Related_Nod : Node_Id;
      Related_Id  : Entity_Id := Empty;
      Suffix      : Character := ' ') return Entity_Id;
   --  Process a subtype indication S and return corresponding entity.
   --  Related_Nod is the node where the potential generated implicit types
   --  will be inserted. The Related_Id and Suffix parameters are used to
   --  build the associated Implicit type name.

   procedure Process_Discriminants
     (N    : Node_Id;
      Prev : Entity_Id := Empty);
   --  Process the discriminants contained in an N_Full_Type_Declaration or
   --  N_Incomplete_Type_Decl node N. If the declaration is a completion,
   --  Prev is entity on the partial view, on which references are posted.
   --  However, note that Process_Discriminants is called for a completion only
   --  if partial view had no discriminants (else we just check conformance
   --  between the two views and do not call Process_Discriminants again for
   --  the completion).

   function Replace_Anonymous_Access_To_Protected_Subprogram
     (N : Node_Id) return Entity_Id;
   --  Ada 2005 (AI-254): Create and decorate an internal full type declaration
   --  for an anonymous access to protected subprogram. For a record component
   --  declaration, the type is created in the enclosing scope, for an array
   --  type declaration or an object declaration it is simply placed ahead of
   --  this declaration.

   procedure Set_Completion_Referenced (E : Entity_Id);
   --  If E is the completion of a private or incomplete  type declaration,
   --  or the completion of a deferred constant declaration, mark the entity
   --  as referenced. Warnings on unused entities, if needed, go on the
   --  partial view.

end Sem_Ch3;