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
26with Nlists; use Nlists;
27with Types;  use Types;
28
29package 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
326end Sem_Ch3;
327