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--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                              S E M _ R E S                               --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--          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.      --

--                                                                          --

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--  Resolution processing for all subexpression nodes. Note that the separate

--  package Sem_Aggr contains the actual resolution routines for aggregates,

--  which are separated off since aggregate processing is complex.

with Types; use Types;

package Sem_Res is

   --  As described in Sem_Ch4, the type resolution proceeds in two phases.

   --  The first phase is a bottom up pass that is achieved during the

   --  recursive traversal performed by the Analyze procedures. This phase

   --  determines unambiguous types, and collects sets of possible types

   --  where the interpretation is potentially ambiguous.

   --  On completing this bottom up pass, which corresponds to a call to

   --  Analyze on a complete context, the Resolve routine is called which

   --  performs a top down resolution with recursive calls to itself to

   --  resolve operands.

   --  Since in practice a lot of semantic analysis has to be postponed until

   --  types are known (e.g. static folding, setting of suppress flags), the

   --  Resolve routines also complete the semantic analysis, and call the

   --  expander for possibly expansion of the completely type resolved node.

   procedure Resolve (N : Node_Id; Typ : Entity_Id);

   procedure Resolve (N : Node_Id; Typ : Entity_Id; Suppress : Check_Id);

   --  Top level type-checking procedure, called in a complete context. The

   --  construct N, which is a subexpression, has already been analyzed, and

   --  is required to be of type Typ given the analysis of the context (which

   --  uses the information gathered on the bottom up phase in Analyze). The

   --  resolve routines do various other processing, e.g. static evaluation.

   --  If a Suppress argument is present, then the resolution is done with the

   --  specified check suppressed (can be All_Checks to suppress all checks).

   procedure Resolve (N : Node_Id);

   --  A version of Resolve where the type to be used for resolution is

   --  taken from the Etype (N). This is commonly used in cases where the

   --  context does not add anything and the first pass of analysis found

   --  the correct expected type.

   procedure Resolve_Discrete_Subtype_Indication

     (N   : Node_Id;

      Typ : Entity_Id);

   --  Resolve subtype indications in choices (case statements and

   --  aggregates) and in index constraints. Note that the resulting Etype

   --  of the subtype indication node is set to the Etype of the contained

   --  range (i.e. an Itype is not constructed for the actual subtype).

   procedure Resolve_Entry (Entry_Name : Node_Id);

   --  Find name of entry being called, and resolve prefix of name with its

   --  own type. For now we assume that the prefix cannot be overloaded and

   --  the name of the entry plays no role in the resolution.

   procedure Analyze_And_Resolve (N : Node_Id);

   procedure Analyze_And_Resolve (N : Node_Id; Typ : Entity_Id);

   procedure Analyze_And_Resolve

     (N        : Node_Id;

      Typ      : Entity_Id;

      Suppress : Check_Id);

   procedure Analyze_And_Resolve

     (N        : Node_Id;

      Suppress : Check_Id);

   --  These routines combine the effect of Analyze and Resolve. If a Suppress

   --  argument is present, then the analysis is done with the specified check

   --  suppressed (can be All_Checks to suppress all checks). These checks are

   --  suppressed for both the analysis and resolution. If the type argument

   --  is not present, then the Etype of the expression after the Analyze

   --  call is used for the Resolve.

   procedure Ambiguous_Character (C : Node_Id);

   --  Give list of candidate interpretations when a character literal cannot

   --  be resolved, for example in a (useless) comparison such as 'A' = 'B'.

   --  In Ada 95 the literals in question can be of type Character or Wide_

   --  Character. In Ada 2005 Wide_Wide_Character is also a candidate. The

   --  node may also be overloaded with user-defined character types.

   procedure Check_Parameterless_Call (N : Node_Id);

   --  Several forms of names can denote calls to entities without para-

   --  meters. The context determines whether the name denotes the entity

   --  or a call to it. When it is a call, the node must be rebuilt

   --  accordingly and reanalyzed to obtain possible interpretations.

   --

   --  The name may be that of an overloadable construct, or it can be an

   --  explicit dereference of a prefix that denotes an access to subprogram.

   --  In that case, we want to convert the name into a call only if the

   --  context requires the return type of the subprogram.  Finally, a

   --  parameterless protected subprogram appears as a selected component.

   --

   --  The parameter T is the Typ for the corresponding resolve call.

   procedure Preanalyze_And_Resolve (N : Node_Id; T : Entity_Id);

   --  Performs a pre-analysis of expression node N. During pre-analysis,

   --  N is analyzed and then resolved against type T, but no expansion

   --  is carried out for N or its children. For more info on pre-analysis

   --  read the spec of Sem.

   procedure Preanalyze_And_Resolve (N : Node_Id);

   --  Same, but use type of node because context does not impose a single type

   function Valid_Conversion

     (N           : Node_Id;

      Target      : Entity_Id;

      Operand     : Node_Id;

      Report_Errs : Boolean := True) return Boolean;

   --  Verify legality rules given in 4.6 (8-23). Target is the target type

   --  of the conversion, which may be an implicit conversion of an actual

   --  parameter to an anonymous access type (in which case N denotes the

   --  actual parameter and N = Operand). Returns a Boolean result indicating

   --  whether the conversion is legal. Reports errors in the case of illegal

   --  conversions, unless Report_Errs is False.

private

   procedure Resolve_Implicit_Type (N : Node_Id) renames Resolve;

   pragma Inline (Resolve_Implicit_Type);

   --  We use this renaming to make the application of Inline very explicit

   --  to this version, since other versions of Resolve are not inlined.

end Sem_Res;