gcc/ada/sem_prag.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                             S E M _ P R A G                              --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2015, 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 --  Pragma handling is isolated in a separate package
  27 --  (logically this processing belongs in chapter 4)
  28
  29 with Namet;  use Namet;
  30 with Opt;    use Opt;
  31 with Snames; use Snames;
  32 with Types;  use Types;
  33
  34 package Sem_Prag is
  35
  36    --  The following table lists all pragmas that act as an assertion
  37    --  expression.
  38
  39    Assertion_Expression_Pragma : constant array (Pragma_Id) of Boolean :=
  40      (Pragma_Assert               => True,
  41       Pragma_Assert_And_Cut       => True,
  42       Pragma_Assume               => True,
  43       Pragma_Check                => True,
  44       Pragma_Contract_Cases       => True,
  45       Pragma_Initial_Condition    => True,
  46       Pragma_Invariant            => True,
  47       Pragma_Loop_Invariant       => True,
  48       Pragma_Loop_Variant         => True,
  49       Pragma_Post                 => True,
  50       Pragma_Post_Class           => True,
  51       Pragma_Postcondition        => True,
  52       Pragma_Pre                  => True,
  53       Pragma_Pre_Class            => True,
  54       Pragma_Precondition         => True,
  55       Pragma_Predicate            => True,
  56       Pragma_Refined_Post         => True,
  57       Pragma_Test_Case            => True,
  58       Pragma_Type_Invariant       => True,
  59       Pragma_Type_Invariant_Class => True,
  60       others                      => False);
  61
  62    --  The following table lists all the implementation-defined pragmas that
  63    --  may apply to a body stub (no language defined pragmas apply). The table
  64    --  should be synchronized with Aspect_On_Body_Or_Stub_OK in unit Aspects if
  65    --  the pragmas below implement an aspect.
  66
  67    Pragma_On_Body_Or_Stub_OK : constant array (Pragma_Id) of Boolean :=
  68      (Pragma_Refined_Depends => True,
  69       Pragma_Refined_Global  => True,
  70       Pragma_Refined_Post    => True,
  71       Pragma_SPARK_Mode      => True,
  72       Pragma_Warnings        => True,
  73       others                 => False);
  74
  75    -----------------
  76    -- Subprograms --
  77    -----------------
  78
  79    procedure Analyze_Pragma (N : Node_Id);
  80    --  Analyze procedure for pragma reference node N
  81
  82    procedure Analyze_Contract_Cases_In_Decl_Part (N : Node_Id);
  83    --  Perform full analysis and expansion of delayed pragma Contract_Cases
  84
  85    procedure Analyze_Depends_In_Decl_Part (N : Node_Id);
  86    --  Perform full analysis of delayed pragma Depends. This routine is also
  87    --  capable of performing basic analysis of pragma Refined_Depends.
  88
  89    procedure Analyze_External_Property_In_Decl_Part
  90      (N        : Node_Id;
  91       Expr_Val : out Boolean);
  92    --  Perform full analysis of delayed pragmas Async_Readers, Async_Writers,
  93    --  Effective_Reads and Effective_Writes. Flag Expr_Val contains the Boolean
  94    --  argument of the pragma or a default True if no argument is present.
  95
  96    procedure Analyze_Global_In_Decl_Part (N : Node_Id);
  97    --  Perform full analysis of delayed pragma Global. This routine is also
  98    --  capable of performing basic analysis of pragma Refind_Global.
  99
 100    procedure Analyze_Initial_Condition_In_Decl_Part (N : Node_Id);
 101    --  Perform full analysis of delayed pragma Initial_Condition
 102
 103    procedure Analyze_Initializes_In_Decl_Part (N : Node_Id);
 104    --  Perform full analysis of delayed pragma Initializes
 105
 106    procedure Analyze_Pre_Post_Condition_In_Decl_Part (N : Node_Id);
 107    --  Perform preanalysis of [refined] precondition or postcondition pragma
 108    --  N that appears on a subprogram declaration or body [stub].
 109
 110    procedure Analyze_Refined_Depends_In_Decl_Part (N : Node_Id);
 111    --  Preform full analysis of delayed pragma Refined_Depends. This routine
 112    --  uses Analyze_Depends_In_Decl_Part as a starting point, then performs
 113    --  various consistency checks between Depends and Refined_Depends.
 114
 115    procedure Analyze_Refined_Global_In_Decl_Part (N : Node_Id);
 116    --  Perform full analysis of delayed pragma Refined_Global. This routine
 117    --  uses Analyze_Global_In_Decl_Part as a starting point, then performs
 118    --  various consistency checks between Global and Refined_Global.
 119
 120    procedure Analyze_Refined_State_In_Decl_Part (N : Node_Id);
 121    --  Perform full analysis of delayed pragma Refined_State
 122
 123    procedure Analyze_Test_Case_In_Decl_Part (N : Node_Id);
 124    --  Perform preanalysis of pragma Test_Case
 125
 126    procedure Check_Applicable_Policy (N : Node_Id);
 127    --  N is either an N_Aspect or an N_Pragma node. There are two cases. If
 128    --  the name of the aspect or pragma is not one of those recognized as
 129    --  an assertion kind by an Assertion_Policy pragma, then the call has
 130    --  no effect. Note that in the case of a pragma derived from an aspect,
 131    --  the name we use for the purpose of this procedure is the aspect name,
 132    --  which may be different from the pragma name (e.g. Precondition for
 133    --  Pre aspect). In addition, 'Class aspects are recognized (and the
 134    --  corresponding special names used in the processing).
 135    --
 136    --  If the name is a valid assertion kind name, then the Check_Policy pragma
 137    --  chain is checked for a matching entry (or for an Assertion entry which
 138    --  matches all possibilities). If a matching entry is found then the policy
 139    --  is checked. If it is On or Check, then the Is_Checked flag is set in
 140    --  the aspect or pragma node. If it is Off, Ignore, or Disable, then the
 141    --  Is_Ignored flag is set in the aspect or pragma node. Additionally for
 142    --  policy Disable, the Is_Disabled flag is set.
 143    --
 144    --  If no matching Check_Policy pragma is found then the effect depends on
 145    --  whether -gnata was used, if so, then the call has no effect, otherwise
 146    --  Is_Ignored (but not Is_Disabled) is set True.
 147
 148    procedure Check_External_Properties
 149      (Item : Node_Id;
 150       AR   : Boolean;
 151       AW   : Boolean;
 152       ER   : Boolean;
 153       EW   : Boolean);
 154    --  Flags AR, AW, ER and EW denote the static values of external properties
 155    --  Async_Readers, Async_Writers, Effective_Reads and Effective_Writes. Item
 156    --  is the related variable or state. Ensure legality of the combination and
 157    --  issue an error for an illegal combination.
 158
 159    procedure Check_Missing_Part_Of (Item_Id : Entity_Id);
 160    --  Determine whether the placement within the state space of an abstract
 161    --  state, variable or package instantiation denoted by Item_Id requires the
 162    --  use of indicator/option Part_Of. If this is the case, emit an error.
 163
 164    procedure Collect_Subprogram_Inputs_Outputs
 165      (Subp_Id      : Entity_Id;
 166       Synthesize   : Boolean := False;
 167       Subp_Inputs  : in out Elist_Id;
 168       Subp_Outputs : in out Elist_Id;
 169       Global_Seen  : out Boolean);
 170    --  Subsidiary to the analysis of pragmas Depends, Global, Refined_Depends
 171    --  and Refined_Global. The routine is also used by GNATprove. Collect all
 172    --  inputs and outputs of subprogram Subp_Id in lists Subp_Inputs (inputs)
 173    --  and Subp_Outputs (outputs). The inputs and outputs are gathered from:
 174    --    1) The formal parameters of the subprogram
 175    --    2) The items of pragma [Refined_]Global
 176    --         or
 177    --    3) The items of pragma [Refined_]Depends if there is no pragma
 178    --       [Refined_]Global present and flag Synthesize is set to True.
 179    --  If the subprogram has no inputs and/or outputs, then the returned list
 180    --  is No_Elist. Flag Global_Seen is set when the related subprogram has
 181    --  pragma [Refined_]Global.
 182
 183    function Delay_Config_Pragma_Analyze (N : Node_Id) return Boolean;
 184    --  N is a pragma appearing in a configuration pragma file. Most such
 185    --  pragmas are analyzed when the file is read, before parsing and analyzing
 186    --  the main unit. However, the analysis of certain pragmas results in
 187    --  adding information to the compiled main unit, and this cannot be done
 188    --  till the main unit is processed. Such pragmas return True from this
 189    --  function and in Frontend pragmas where Delay_Config_Pragma_Analyze is
 190    --  True have their analysis delayed until after the main program is parsed
 191    --  and analyzed.
 192
 193    function Find_Related_Subprogram_Or_Body
 194      (Prag      : Node_Id;
 195       Do_Checks : Boolean := False) return Node_Id;
 196    --  Subsidiary to the analysis of pragmas Contract_Cases, Depends, Global,
 197    --  Refined_Depends, Refined_Global and Refined_Post and attribute 'Result.
 198    --  Find the declaration of the related subprogram [body or stub] subject
 199    --  to pragma Prag. If flag Do_Checks is set, the routine reports duplicate
 200    --  pragmas and detects improper use of refinement pragmas in stand alone
 201    --  expression functions. The returned value depends on the related pragma
 202    --  as follows:
 203    --    1) Pragmas Contract_Cases, Depends and Global yield the corresponding
 204    --       N_Subprogram_Declaration node or if the pragma applies to a stand
 205    --       alone body, the N_Subprogram_Body node or Empty if illegal.
 206    --    2) Pragmas Refined_Depends, Refined_Global and Refined_Post yield
 207    --       N_Subprogram_Body or N_Subprogram_Body_Stub nodes or Empty if
 208    --       illegal.
 209
 210    function Get_SPARK_Mode_From_Pragma (N : Node_Id) return SPARK_Mode_Type;
 211    --  Given a pragma SPARK_Mode node, return corresponding mode id
 212
 213    procedure Initialize;
 214    --  Initializes data structures used for pragma processing. Must be called
 215    --  before analyzing each new main source program.
 216
 217    function Is_Config_Static_String (Arg : Node_Id) return Boolean;
 218    --  This is called for a configuration pragma that requires either string
 219    --  literal or a concatenation of string literals. We cannot use normal
 220    --  static string processing because it is too early in the case of the
 221    --  pragma appearing in a configuration pragmas file. If Arg is of an
 222    --  appropriate form, then this call obtains the string (doing any necessary
 223    --  concatenations) and places it in Name_Buffer, setting Name_Len to its
 224    --  length, and then returns True. If it is not of the correct form, then an
 225    --  appropriate error message is posted, and False is returned.
 226
 227    function Is_Elaboration_SPARK_Mode (N : Node_Id) return Boolean;
 228    --  Determine whether pragma SPARK_Mode appears in the statement part of a
 229    --  package body.
 230
 231    function Is_Non_Significant_Pragma_Reference (N : Node_Id) return Boolean;
 232    --  The node N is a node for an entity and the issue is whether the
 233    --  occurrence is a reference for the purposes of giving warnings about
 234    --  unreferenced variables. This function returns True if the reference is
 235    --  not a reference from this point of view (e.g. the occurrence in a pragma
 236    --  Pack) and False if it is a real reference (e.g. the occurrence in a
 237    --  pragma Export);
 238
 239    function Is_Pragma_String_Literal (Par : Node_Id) return Boolean;
 240    --  Given an N_Pragma_Argument_Association node, Par, which has the form of
 241    --  an operator symbol, determines whether or not it should be treated as an
 242    --  string literal. This is called by Sem_Ch6.Analyze_Operator_Symbol. If
 243    --  True is returned, the argument is converted to a string literal. If
 244    --  False is returned, then the argument is treated as an entity reference
 245    --  to the operator.
 246
 247    function Is_Private_SPARK_Mode (N : Node_Id) return Boolean;
 248    --  Determine whether pragma SPARK_Mode appears in the private part of a
 249    --  package.
 250
 251    function Is_Valid_Assertion_Kind (Nam : Name_Id) return Boolean;
 252    --  Returns True if Nam is one of the names recognized as a valid assertion
 253    --  kind by the Assertion_Policy pragma. Note that the 'Class cases are
 254    --  represented by the corresponding special names Name_uPre, Name_uPost,
 255    --  Name_uInvariant, and Name_uType_Invariant (_Pre, _Post, _Invariant,
 256    --  and _Type_Invariant).
 257
 258    procedure Process_Compilation_Unit_Pragmas (N : Node_Id);
 259    --  Called at the start of processing compilation unit N to deal with any
 260    --  special issues regarding pragmas. In particular, we have to deal with
 261    --  Suppress_All at this stage, since it can appear after the unit instead
 262    --  of before (actually we allow it to appear anywhere).
 263
 264    procedure Relocate_Pragmas_To_Body
 265      (Subp_Body   : Node_Id;
 266       Target_Body : Node_Id := Empty);
 267    --  Resocate all pragmas that follow and apply to subprogram body Subp_Body
 268    --  to its own declaration list. Candidate pragmas are classified in table
 269    --  Pragma_On_Body_Or_Stub_OK. If Target_Body is set, the pragma are moved
 270    --  to the declarations of Target_Body. This formal should be set when
 271    --  dealing with subprogram body stubs or expression functions.
 272
 273    procedure Set_Encoded_Interface_Name (E : Entity_Id; S : Node_Id);
 274    --  This routine is used to set an encoded interface name. The node S is
 275    --  an N_String_Literal node for the external name to be set, and E is an
 276    --  entity whose Interface_Name field is to be set. In the normal case where
 277    --  S contains a name that is a valid C identifier, then S is simply set as
 278    --  the value of the Interface_Name. Otherwise it is encoded as needed by
 279    --  particular operating systems. See the body for details of the encoding.
 280
 281    function Test_Case_Arg
 282      (Prag        : Node_Id;
 283       Arg_Nam     : Name_Id;
 284       From_Aspect : Boolean := False) return Node_Id;
 285    --  Obtain argument "Name", "Mode", "Ensures" or "Requires" from Test_Case
 286    --  pragma Prag as denoted by Arg_Nam. When From_Aspect is set, an attempt
 287    --  is made to retrieve the argument from the corresponding aspect if there
 288    --  is one. The returned argument has several formats:
 289    --
 290    --    N_Pragma_Argument_Association if retrieved directly from the pragma
 291    --
 292    --    N_Component_Association if retrieved from the corresponding aspect and
 293    --    the argument appears in a named association form.
 294    --
 295    --    An arbitrary expression if retrieved from the corresponding aspect and
 296    --    the argument appears in positional form.
 297    --
 298    --    Empty if there is no such argument
 299
 300 end Sem_Prag;