gcc/ada/sem_res.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                              S E M _ R E S                               --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2018, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNAT; see file COPYING3.  If not, go to --
  19 -- http://www.gnu.org/licenses for a complete copy of the license.          --
  20 --                                                                          --
  21 -- GNAT was originally developed  by the GNAT team at  New York University. --
  22 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  23 --                                                                          --
  24 ------------------------------------------------------------------------------
  25
  26 --  Resolution processing for all subexpression nodes. Note that the separate
  27 --  package Sem_Aggr contains the actual resolution routines for aggregates,
  28 --  which are separated off since aggregate processing is complex.
  29
  30 with Types; use Types;
  31
  32 package Sem_Res is
  33
  34    --  As described in Sem_Ch4, the type resolution proceeds in two phases.
  35    --  The first phase is a bottom up pass that is achieved during the
  36    --  recursive traversal performed by the Analyze procedures. This phase
  37    --  determines unambiguous types, and collects sets of possible types
  38    --  where the interpretation is potentially ambiguous.
  39
  40    --  On completing this bottom up pass, which corresponds to a call to
  41    --  Analyze on a complete context, the Resolve routine is called which
  42    --  performs a top down resolution with recursive calls to itself to
  43    --  resolve operands.
  44
  45    --  Since in practice a lot of semantic analysis has to be postponed until
  46    --  types are known (e.g. static folding, setting of suppress flags), the
  47    --  Resolve routines also complete the semantic analysis, and call the
  48    --  expander for possible expansion of the completely type resolved node.
  49
  50    procedure Ambiguous_Character (C : Node_Id);
  51    --  Give list of candidate interpretations when a character literal cannot
  52    --  be resolved, for example in a (useless) comparison such as 'A' = 'B'.
  53    --  In Ada 95 the literals in question can be of type Character or Wide_
  54    --  Character. In Ada 2005 Wide_Wide_Character is also a candidate. The
  55    --  node may also be overloaded with user-defined character types.
  56
  57    procedure Analyze_And_Resolve (N : Node_Id);
  58    procedure Analyze_And_Resolve (N : Node_Id; Typ : Entity_Id);
  59    procedure Analyze_And_Resolve
  60      (N        : Node_Id;
  61       Typ      : Entity_Id;
  62       Suppress : Check_Id);
  63    procedure Analyze_And_Resolve
  64      (N        : Node_Id;
  65       Suppress : Check_Id);
  66    --  These routines combine the effect of Analyze and Resolve. If a Suppress
  67    --  argument is present, then the analysis is done with the specified check
  68    --  suppressed (can be All_Checks to suppress all checks). These checks are
  69    --  suppressed for both the analysis and resolution. If the type argument
  70    --  is not present, then the Etype of the expression after the Analyze
  71    --  call is used for the Resolve.
  72
  73    procedure Check_Parameterless_Call (N : Node_Id);
  74    --  Several forms of names can denote calls to entities without parameters.
  75    --  The context determines whether the name denotes the entity or a call to
  76    --  it. When it is a call, the node must be rebuilt accordingly and
  77    --  reanalyzed to obtain possible interpretations.
  78    --
  79    --  The name may be that of an overloadable construct, or it can be an
  80    --  explicit dereference of a prefix that denotes an access to subprogram.
  81    --  In that case, we want to convert the name into a call only if the
  82    --  context requires the return type of the subprogram. Finally, a
  83    --  parameterless protected subprogram appears as a selected component.
  84    --
  85    --  The parameter T is the Typ for the corresponding resolve call.
  86
  87    procedure Preanalyze_And_Resolve (N : Node_Id; T : Entity_Id);
  88    --  Performs a preanalysis of expression node N. During preanalysis, N is
  89    --  analyzed and then resolved against type T, but no expansion is carried
  90    --  out for N or its children. For more info on preanalysis read the spec
  91    --  of Sem.
  92
  93    procedure Preanalyze_And_Resolve (N : Node_Id);
  94    --  Same, but use type of node because context does not impose a single type
  95
  96    procedure Preanalyze_With_Freezing_And_Resolve (N : Node_Id; T : Entity_Id);
  97    --  Same, but perform freezing of static expressions of N or its children.
  98
  99    procedure Resolve (N : Node_Id; Typ : Entity_Id);
 100    procedure Resolve (N : Node_Id; Typ : Entity_Id; Suppress : Check_Id);
 101    --  Top-level type-checking procedure, called in a complete context. The
 102    --  construct N, which is a subexpression, has already been analyzed, and
 103    --  is required to be of type Typ given the analysis of the context (which
 104    --  uses the information gathered on the bottom-up phase in Analyze). The
 105    --  resolve routines do various other processing, e.g. static evaluation.
 106    --  If a Suppress argument is present, then the resolution is done with the
 107    --  specified check suppressed (can be All_Checks to suppress all checks).
 108
 109    procedure Resolve (N : Node_Id);
 110    --  A version of Resolve where the type to be used for resolution is taken
 111    --  from the Etype (N). This is commonly used in cases where the context
 112    --  does not add anything and the first pass of analysis found the correct
 113    --  expected type.
 114
 115    procedure Resolve_Discrete_Subtype_Indication
 116      (N   : Node_Id;
 117       Typ : Entity_Id);
 118    --  Resolve subtype indications in choices (case statements and aggregates)
 119    --  and in index constraints. Note that the resulting Etype of the subtype_
 120    --  indication node is set to the Etype of the contained range (i.e. an
 121    --  Itype is not constructed for the actual subtype).
 122
 123    procedure Resolve_Entry (Entry_Name : Node_Id);
 124    --  Find name of entry being called, and resolve prefix of name with its
 125    --  own type. For now we assume that the prefix cannot be overloaded and
 126    --  the name of the entry plays no role in the resolution.
 127
 128    function Valid_Conversion
 129      (N           : Node_Id;
 130       Target      : Entity_Id;
 131       Operand     : Node_Id;
 132       Report_Errs : Boolean := True) return Boolean;
 133    --  Verify legality rules given in 4.6 (8-23). Target is the target type
 134    --  of the conversion, which may be an implicit conversion of an actual
 135    --  parameter to an anonymous access type (in which case N denotes the
 136    --  actual parameter and N = Operand). Returns a Boolean result indicating
 137    --  whether the conversion is legal. Reports errors in the case of illegal
 138    --  conversions, unless Report_Errs is False.
 139
 140 private
 141    procedure Resolve_Implicit_Type (N : Node_Id) renames Resolve;
 142    pragma Inline (Resolve_Implicit_Type);
 143    --  We use this renaming to make the application of Inline very explicit to
 144    --  this version, since other versions of Resolve are not inlined.
 145
 146 end Sem_Res;