gcc/ada/sem_ch3.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                              S E M _ C H 3                               --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2014, 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 with Nlists; use Nlists;
  27 with Types;  use Types;
  28
  29 package Sem_Ch3 is
  30    procedure Analyze_Component_Declaration         (N : Node_Id);
  31    procedure Analyze_Full_Type_Declaration         (N : Node_Id);
  32    procedure Analyze_Incomplete_Type_Decl          (N : Node_Id);
  33    procedure Analyze_Itype_Reference               (N : Node_Id);
  34    procedure Analyze_Number_Declaration            (N : Node_Id);
  35    procedure Analyze_Object_Declaration            (N : Node_Id);
  36    procedure Analyze_Others_Choice                 (N : Node_Id);
  37    procedure Analyze_Private_Extension_Declaration (N : Node_Id);
  38    procedure Analyze_Subtype_Indication            (N : Node_Id);
  39    procedure Analyze_Variant_Part                  (N : Node_Id);
  40
  41    procedure Analyze_Subtype_Declaration
  42      (N    : Node_Id;
  43       Skip : Boolean := False);
  44    --  Called to analyze a subtype declaration. The parameter Skip is used for
  45    --  Ada 2005 (AI-412). We set to True in order to avoid reentering the
  46    --  defining identifier of N when analyzing a rewritten incomplete subtype
  47    --  declaration.
  48
  49    function Access_Definition
  50      (Related_Nod : Node_Id;
  51       N           : Node_Id) return Entity_Id;
  52    --  An access definition defines a general access type for a formal
  53    --  parameter. The procedure is called when processing formals, when the
  54    --  current scope is the subprogram. The Implicit type is attached to the
  55    --  Related_Nod put into the enclosing scope, so that the only entities
  56    --  defined in the spec are the formals themselves.
  57
  58    procedure Access_Subprogram_Declaration
  59      (T_Name : Entity_Id;
  60       T_Def  : Node_Id);
  61    --  The subprogram specification yields the signature of an implicit
  62    --  type, whose Ekind is Access_Subprogram_Type. This implicit type is the
  63    --  designated type of the declared access type. In subprogram calls, the
  64    --  signature of the implicit type works like the profile of a regular
  65    --  subprogram.
  66
  67    procedure Add_Internal_Interface_Entities (Tagged_Type : Entity_Id);
  68    --  Add to the list of primitives of Tagged_Type the internal entities
  69    --  associated with covered interface primitives. These entities link the
  70    --  interface primitives with the tagged type primitives that cover them.
  71
  72    procedure Analyze_Declarations (L : List_Id);
  73    --  Called to analyze a list of declarations (in what context ???). Also
  74    --  performs necessary freezing actions (more description needed ???)
  75
  76    procedure Analyze_Interface_Declaration (T : Entity_Id; Def : Node_Id);
  77    --  Analyze an interface declaration or a formal interface declaration
  78
  79    procedure Array_Type_Declaration (T : in out Entity_Id; Def : Node_Id);
  80    --  Process an array type declaration. If the array is constrained, we
  81    --  create an implicit parent array type, with the same index types and
  82    --  component type.
  83
  84    procedure Access_Type_Declaration (T : Entity_Id; Def : Node_Id);
  85    --  Process an access type declaration
  86
  87    procedure Build_Itype_Reference (Ityp : Entity_Id; Nod : Node_Id);
  88    --  Create a reference to an internal type, for use by Gigi. The back-end
  89    --  elaborates itypes on demand, i.e. when their first use is seen. This can
  90    --  lead to scope anomalies if the first use is within a scope that is
  91    --  nested within the scope that contains the point of definition of the
  92    --  itype. The Itype_Reference node forces the elaboration of the itype
  93    --  in the proper scope. The node is inserted after Nod, which is the
  94    --  enclosing declaration that generated Ityp.
  95    --
  96    --  A related mechanism is used during expansion, for itypes created in
  97    --  branches of conditionals. See Ensure_Defined in exp_util. Could both
  98    --  mechanisms be merged ???
  99
 100    procedure Check_Abstract_Overriding (T : Entity_Id);
 101    --  Check that all abstract subprograms inherited from T's parent type have
 102    --  been overridden as required, and that nonabstract subprograms have not
 103    --  been incorrectly overridden with an abstract subprogram.
 104
 105    procedure Check_Aliased_Component_Types (T : Entity_Id);
 106    --  Given an array type or record type T, check that if the type is
 107    --  nonlimited, then the nominal subtype of any components of T that
 108    --  have discriminants must be constrained.
 109
 110    procedure Check_Completion (Body_Id : Node_Id := Empty);
 111    --  At the end of a declarative part, verify that all entities that require
 112    --  completion have received one. If Body_Id is absent, the error indicating
 113    --  a missing completion is placed on the declaration that needs completion.
 114    --  If Body_Id is present, it is the defining identifier of a package body,
 115    --  and errors are posted on that node, rather than on the declarations that
 116    --  require completion in the package declaration.
 117
 118    procedure Check_CPP_Type_Has_No_Defaults (T : Entity_Id);
 119    --  Check that components of imported CPP type T do not have default
 120    --  expressions because the constructor (if any) is on the C++ side.
 121
 122    procedure Derive_Subprogram
 123      (New_Subp     : in out Entity_Id;
 124       Parent_Subp  : Entity_Id;
 125       Derived_Type : Entity_Id;
 126       Parent_Type  : Entity_Id;
 127       Actual_Subp  : Entity_Id := Empty);
 128    --  Derive the subprogram Parent_Subp from Parent_Type, and replace the
 129    --  subsidiary subtypes with the derived type to build the specification of
 130    --  the inherited subprogram (returned in New_Subp). For tagged types, the
 131    --  derived subprogram is aliased to that of the actual (in the case where
 132    --  Actual_Subp is nonempty) rather than to the corresponding subprogram of
 133    --  the parent type.
 134
 135    procedure Derive_Subprograms
 136      (Parent_Type    : Entity_Id;
 137       Derived_Type   : Entity_Id;
 138       Generic_Actual : Entity_Id := Empty);
 139    --  To complete type derivation, collect/retrieve the primitive operations
 140    --  of the parent type, and replace the subsidiary subtypes with the derived
 141    --  type, to build the specs of the inherited ops. For generic actuals, the
 142    --  mapping of the primitive operations to those of the parent type is also
 143    --  done by rederiving the operations within the instance. For tagged types,
 144    --  the derived subprograms are aliased to those of the actual, not those of
 145    --  the ancestor.
 146    --
 147    --  Note: one might expect this to be private to the package body, but there
 148    --  is one rather unusual usage in package Exp_Dist.
 149
 150    function Find_Hidden_Interface
 151      (Src  : Elist_Id;
 152       Dest : Elist_Id) return Entity_Id;
 153    --  Ada 2005: Determine whether the interfaces in list Src are all present
 154    --  in the list Dest. Return the first differing interface, or Empty
 155    --  otherwise.
 156
 157    function Find_Type_Of_Subtype_Indic (S : Node_Id) return Entity_Id;
 158    --  Given a subtype indication S (which is really an N_Subtype_Indication
 159    --  node or a plain N_Identifier), find the type of the subtype mark.
 160
 161    function Find_Type_Name (N : Node_Id) return Entity_Id;
 162    --  Enter the identifier in a type definition, or find the entity already
 163    --  declared, in the case of the full declaration of an incomplete or
 164    --  private type. If the previous declaration is tagged then the class-wide
 165    --  entity is propagated to the identifier to prevent multiple incompatible
 166    --  class-wide types that may be created for self-referential anonymous
 167    --  access components.
 168
 169    function Get_Discriminant_Value
 170      (Discriminant       : Entity_Id;
 171       Typ_For_Constraint : Entity_Id;
 172       Constraint         : Elist_Id) return Node_Id;
 173    --  ??? MORE DOCUMENTATION
 174    --  Given a discriminant somewhere in the Typ_For_Constraint tree and a
 175    --  Constraint, return the value of that discriminant.
 176
 177    function Is_Null_Extension (T : Entity_Id) return Boolean;
 178    --  Returns True if the tagged type T has an N_Full_Type_Declaration that
 179    --  is a null extension, meaning that it has an extension part without any
 180    --  components and does not have a known discriminant part.
 181
 182    function Is_Visible_Component
 183      (C : Entity_Id;
 184       N : Node_Id := Empty) return Boolean;
 185    --  Determines if a record component C is visible in the present context.
 186    --  Note that even though component C could appear in the entity chain of a
 187    --  record type, C may not be visible in the current context. For instance,
 188    --  C may be a component inherited in the full view of a private extension
 189    --  which is not visible in the current context.
 190    --
 191    --  If present, N is the selected component of which C is the selector. If
 192    --  the prefix of N is a type conversion inserted for a discriminant check,
 193    --  C is automatically visible.
 194
 195    procedure Make_Index
 196      (N            : Node_Id;
 197       Related_Nod  : Node_Id;
 198       Related_Id   : Entity_Id := Empty;
 199       Suffix_Index : Nat       := 1;
 200       In_Iter_Schm : Boolean   := False);
 201    --  Process an index that is given in an array declaration, an entry
 202    --  family declaration or a loop iteration. The index is given by an index
 203    --  declaration (a 'box'), or by a discrete range. The later can be the name
 204    --  of a discrete type, or a subtype indication.
 205    --
 206    --  Related_Nod is the node where the potential generated implicit types
 207    --  will be inserted. The next last parameters are used for creating the
 208    --  name. In_Iter_Schm is True if Make_Index is called on the discrete
 209    --  subtype definition in an iteration scheme.
 210
 211    procedure Make_Class_Wide_Type (T : Entity_Id);
 212    --  A Class_Wide_Type is created for each tagged type definition. The
 213    --  attributes of a class-wide type are inherited from those of the type T.
 214    --  If T is introduced by a private declaration, the corresponding class
 215    --  wide type is created at the same time, and therefore there is a private
 216    --  and a full declaration for the class-wide type as well.
 217
 218    function OK_For_Limited_Init_In_05
 219      (Typ : Entity_Id;
 220       Exp : Node_Id) return Boolean;
 221    --  Presuming Exp is an expression of an inherently limited type Typ,
 222    --  returns True if the expression is allowed in an initialization context
 223    --  by the rules of Ada 2005. We use the rule in RM-7.5(2.1/2), "...it is an
 224    --  aggregate, a function_call, or a parenthesized expression or qualified
 225    --  expression whose operand is permitted...". Note that in Ada 95 mode,
 226    --  we sometimes wish to give warnings based on whether the program _would_
 227    --  be legal in Ada 2005. Note that Exp must already have been resolved,
 228    --  so we can know whether it's a function call (as opposed to an indexed
 229    --  component, for example). In the case where Typ is a limited interface's
 230    --  class-wide type, then the expression is allowed to be of any kind if its
 231    --  type is a nonlimited descendant of the interface.
 232
 233    function OK_For_Limited_Init
 234      (Typ : Entity_Id;
 235       Exp : Node_Id) return Boolean;
 236    --  Always False in Ada 95 mode. Equivalent to OK_For_Limited_Init_In_05 in
 237    --  Ada 2005 mode.
 238
 239    procedure Preanalyze_Spec_Expression (N : Node_Id; T : Entity_Id);
 240    --  Default and per object expressions do not freeze their components, and
 241    --  must be analyzed and resolved accordingly. The analysis is done by
 242    --  calling the Preanalyze_And_Resolve routine and setting the global
 243    --  In_Default_Expression flag. See the documentation section entitled
 244    --  "Handling of Default and Per-Object Expressions" in sem.ads for full
 245    --  details. N is the expression to be analyzed, T is the expected type.
 246    --  This mechanism is also used for aspect specifications that have an
 247    --  expression parameter that needs similar preanalysis.
 248
 249    procedure Preanalyze_Assert_Expression (N : Node_Id; T : Entity_Id);
 250    --  Wrapper on Preanalyze_Spec_Expression for assertion expressions, so that
 251    --  In_Assertion_Expr can be properly adjusted.
 252
 253    procedure Preanalyze_Default_Expression (N : Node_Id; T : Entity_Id);
 254    --  Wrapper on Preanalyze_Spec_Expression for default expressions, so that
 255    --  In_Default_Expr can be properly adjusted.
 256
 257    procedure Process_Full_View (N : Node_Id; Full_T, Priv_T : Entity_Id);
 258    --  Process some semantic actions when the full view of a private type is
 259    --  encountered and analyzed. The first action is to create the full views
 260    --  of the dependant private subtypes. The second action is to recopy the
 261    --  primitive operations of the private view (in the tagged case).
 262    --  N is the N_Full_Type_Declaration node.
 263    --
 264    --  Full_T is the full view of the type whose full declaration is in N.
 265    --
 266    --  Priv_T is the private view of the type whose full declaration is in N.
 267
 268    procedure Process_Range_Expr_In_Decl
 269      (R            : Node_Id;
 270       T            : Entity_Id;
 271       Subtyp       : Entity_Id := Empty;
 272       Check_List   : List_Id   := Empty_List;
 273       R_Check_Off  : Boolean   := False;
 274       In_Iter_Schm : Boolean   := False);
 275    --  Process a range expression that appears in a declaration context. The
 276    --  range is analyzed and resolved with the base type of the given type, and
 277    --  an appropriate check for expressions in non-static contexts made on the
 278    --  bounds. R is analyzed and resolved using T, so the caller should if
 279    --  necessary link R into the tree before the call, and in particular in the
 280    --  case of a subtype declaration, it is appropriate to set the parent
 281    --  pointer of R so that the types get properly frozen. Check_List is used
 282    --  when the subprogram is called from Build_Record_Init_Proc and is used to
 283    --  return a set of constraint checking statements generated by the Checks
 284    --  package. R_Check_Off is set to True when the call to Range_Check is to
 285    --  be skipped. In_Iter_Schm is True if Process_Range_Expr_In_Decl is called
 286    --  on the discrete subtype definition in an iteration scheme.
 287    --
 288    --  If Subtyp is given, then the range is for the named subtype Subtyp, and
 289    --  in this case the bounds are captured if necessary using this name.
 290
 291    function Process_Subtype
 292      (S           : Node_Id;
 293       Related_Nod : Node_Id;
 294       Related_Id  : Entity_Id := Empty;
 295       Suffix      : Character := ' ') return Entity_Id;
 296    --  Process a subtype indication S and return corresponding entity.
 297    --  Related_Nod is the node where the potential generated implicit types
 298    --  will be inserted. The Related_Id and Suffix parameters are used to
 299    --  build the associated Implicit type name.
 300
 301    procedure Process_Discriminants
 302      (N    : Node_Id;
 303       Prev : Entity_Id := Empty);
 304    --  Process the discriminants contained in an N_Full_Type_Declaration or
 305    --  N_Incomplete_Type_Decl node N. If the declaration is a completion, Prev
 306    --  is entity on the partial view, on which references are posted. However,
 307    --  note that Process_Discriminants is called for a completion only if
 308    --  partial view had no discriminants (else we just check conformance
 309    --  between the two views and do not call Process_Discriminants again
 310    --  for the completion).
 311
 312    function Replace_Anonymous_Access_To_Protected_Subprogram
 313      (N : Node_Id) return Entity_Id;
 314    --  Ada 2005 (AI-254): Create and decorate an internal full type declaration
 315    --  for an anonymous access to protected subprogram. For a record component
 316    --  declaration, the type is created in the enclosing scope, for an array
 317    --  type declaration or an object declaration it is simply placed ahead of
 318    --  this declaration.
 319
 320    procedure Set_Completion_Referenced (E : Entity_Id);
 321    --  If E is the completion of a private or incomplete  type declaration,
 322    --  or the completion of a deferred constant declaration, mark the entity
 323    --  as referenced. Warnings on unused entities, if needed, go on the
 324    --  partial view.
 325
 326 end Sem_Ch3;