1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- S E M _ A U X -- 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-- As a special exception, if other files instantiate generics from this -- 22-- unit, or you link this unit with other files to produce an executable, -- 23-- this unit does not by itself cause the resulting executable to be -- 24-- covered by the GNU General Public License. This exception does not -- 25-- however invalidate any other reasons why the executable file might be -- 26-- covered by the GNU Public License. -- 27-- -- 28-- GNAT was originally developed by the GNAT team at New York University. -- 29-- Extensive contributions were provided by Ada Core Technologies Inc. -- 30-- -- 31------------------------------------------------------------------------------ 32 33-- Package containing utility procedures used throughout the compiler, 34-- and also by ASIS so dependencies are limited to ASIS included packages. 35 36-- Historical note. Many of the routines here were originally in Einfo, but 37-- Einfo is supposed to be a relatively low level package dealing with the 38-- content of entities in the tree, so this package is used for routines that 39-- require more than minimal semantic knowledge. 40 41with Alloc; use Alloc; 42with Namet; use Namet; 43with Table; 44with Types; use Types; 45with Sinfo; use Sinfo; 46 47package Sem_Aux is 48 49 -------------------------------- 50 -- Obsolescent Warnings Table -- 51 -------------------------------- 52 53 -- This table records entities for which a pragma Obsolescent with a 54 -- message argument has been processed. 55 56 type OWT_Record is record 57 Ent : Entity_Id; 58 -- The entity to which the pragma applies 59 60 Msg : String_Id; 61 -- The string containing the message 62 end record; 63 64 package Obsolescent_Warnings is new Table.Table ( 65 Table_Component_Type => OWT_Record, 66 Table_Index_Type => Int, 67 Table_Low_Bound => 0, 68 Table_Initial => Alloc.Obsolescent_Warnings_Initial, 69 Table_Increment => Alloc.Obsolescent_Warnings_Increment, 70 Table_Name => "Obsolescent_Warnings"); 71 72 procedure Initialize; 73 -- Called at the start of compilation of each new main source file to 74 -- initialize the allocation of the Obsolescent_Warnings table. Note that 75 -- Initialize must not be called if Tree_Read is used. 76 77 procedure Tree_Read; 78 -- Initializes Obsolescent_Warnings table from current tree file using the 79 -- relevant Table.Tree_Read routine. 80 81 procedure Tree_Write; 82 -- Writes out Obsolescent_Warnings table to current tree file using the 83 -- relevant Table.Tree_Write routine. 84 85 ----------------- 86 -- Subprograms -- 87 ----------------- 88 89 function Ancestor_Subtype (Typ : Entity_Id) return Entity_Id; 90 -- The argument Id is a type or subtype entity. If the argument is a 91 -- subtype then it returns the subtype or type from which the subtype was 92 -- obtained, otherwise it returns Empty. 93 94 function Available_View (Ent : Entity_Id) return Entity_Id; 95 -- Ent denotes an abstract state or a type that may come from a limited 96 -- with clause. Return the non-limited view of Ent if there is one or Ent 97 -- if this is not the case. 98 99 function Constant_Value (Ent : Entity_Id) return Node_Id; 100 -- Ent is a variable, constant, named integer, or named real entity. This 101 -- call obtains the initialization expression for the entity. Will return 102 -- Empty for a deferred constant whose full view is not available or 103 -- in some other cases of internal entities, which cannot be treated as 104 -- constants from the point of view of constant folding. Empty is also 105 -- returned for variables with no initialization expression. 106 107 function Corresponding_Unsigned_Type (Typ : Entity_Id) return Entity_Id; 108 -- Typ is a signed integer subtype. This routine returns the standard 109 -- unsigned type with the same Esize as the implementation base type of 110 -- Typ, e.g. Long_Integer => Long_Unsigned. 111 112 function Enclosing_Dynamic_Scope (Ent : Entity_Id) return Entity_Id; 113 -- For any entity, Ent, returns the closest dynamic scope in which the 114 -- entity is declared or Standard_Standard for library-level entities. 115 116 function First_Discriminant (Typ : Entity_Id) return Entity_Id; 117 -- Typ is a type with discriminants. The discriminants are the first 118 -- entities declared in the type, so normally this is equivalent to 119 -- First_Entity. The exception arises for tagged types, where the tag 120 -- itself is prepended to the front of the entity chain, so the 121 -- First_Discriminant function steps past the tag if it is present. 122 123 function First_Stored_Discriminant (Typ : Entity_Id) return Entity_Id; 124 -- Typ is a type with discriminants. Gives the first discriminant stored 125 -- in an object of this type. In many cases, these are the same as the 126 -- normal visible discriminants for the type, but in the case of renamed 127 -- discriminants, this is not always the case. 128 -- 129 -- For tagged types, and untagged types which are root types or derived 130 -- types but which do not rename discriminants in their root type, the 131 -- stored discriminants are the same as the actual discriminants of the 132 -- type, and hence this function is the same as First_Discriminant. 133 -- 134 -- For derived untagged types that rename discriminants in the root type 135 -- this is the first of the discriminants that occur in the root type. To 136 -- be precise, in this case stored discriminants are entities attached to 137 -- the entity chain of the derived type which are a copy of the 138 -- discriminants of the root type. Furthermore their Is_Completely_Hidden 139 -- flag is set since although they are actually stored in the object, they 140 -- are not in the set of discriminants that is visible in the type. 141 -- 142 -- For derived untagged types, the set of stored discriminants are the real 143 -- discriminants from Gigi's standpoint, i.e. those that will be stored in 144 -- actual objects of the type. 145 146 function First_Subtype (Typ : Entity_Id) return Entity_Id; 147 -- Applies to all types and subtypes. For types, yields the first subtype 148 -- of the type. For subtypes, yields the first subtype of the base type of 149 -- the subtype. 150 151 function First_Tag_Component (Typ : Entity_Id) return Entity_Id; 152 -- Typ must be a tagged record type. This function returns the Entity for 153 -- the first _Tag field in the record type. 154 155 function Get_Binary_Nkind (Op : Entity_Id) return Node_Kind; 156 -- Op must be an entity with an Ekind of E_Operator. This function returns 157 -- the Nkind value that would be used to construct a binary operator node 158 -- referencing this entity. It is an error to call this function if Ekind 159 -- (Op) /= E_Operator. 160 161 function Get_Unary_Nkind (Op : Entity_Id) return Node_Kind; 162 -- Op must be an entity with an Ekind of E_Operator. This function returns 163 -- the Nkind value that would be used to construct a unary operator node 164 -- referencing this entity. It is an error to call this function if Ekind 165 -- (Op) /= E_Operator. 166 167 function Get_Rep_Item 168 (E : Entity_Id; 169 Nam : Name_Id; 170 Check_Parents : Boolean := True) return Node_Id; 171 -- Searches the Rep_Item chain for a given entity E, for an instance of a 172 -- rep item (pragma, attribute definition clause, or aspect specification) 173 -- whose name matches the given name Nam. If Check_Parents is False then it 174 -- only returns rep item that has been directly specified for E (and not 175 -- inherited from its parents, if any). If one is found, it is returned, 176 -- otherwise Empty is returned. A special case is that when Nam is 177 -- Name_Priority, the call will also find Interrupt_Priority. 178 179 function Get_Rep_Item 180 (E : Entity_Id; 181 Nam1 : Name_Id; 182 Nam2 : Name_Id; 183 Check_Parents : Boolean := True) return Node_Id; 184 -- Searches the Rep_Item chain for a given entity E, for an instance of a 185 -- rep item (pragma, attribute definition clause, or aspect specification) 186 -- whose name matches one of the given names Nam1 or Nam2. If Check_Parents 187 -- is False then it only returns rep item that has been directly specified 188 -- for E (and not inherited from its parents, if any). If one is found, it 189 -- is returned, otherwise Empty is returned. A special case is that when 190 -- one of the given names is Name_Priority, the call will also find 191 -- Interrupt_Priority. 192 193 function Get_Rep_Pragma 194 (E : Entity_Id; 195 Nam : Name_Id; 196 Check_Parents : Boolean := True) return Node_Id; 197 -- Searches the Rep_Item chain for a given entity E, for an instance of a 198 -- representation pragma whose name matches the given name Nam. If 199 -- Check_Parents is False then it only returns representation pragma that 200 -- has been directly specified for E (and not inherited from its parents, 201 -- if any). If one is found and if it is the first rep item in the list 202 -- that matches Nam, it is returned, otherwise Empty is returned. A special 203 -- case is that when Nam is Name_Priority, the call will also find 204 -- Interrupt_Priority. 205 206 function Get_Rep_Pragma 207 (E : Entity_Id; 208 Nam1 : Name_Id; 209 Nam2 : Name_Id; 210 Check_Parents : Boolean := True) return Node_Id; 211 -- Searches the Rep_Item chain for a given entity E, for an instance of a 212 -- representation pragma whose name matches one of the given names Nam1 or 213 -- Nam2. If Check_Parents is False then it only returns representation 214 -- pragma that has been directly specified for E (and not inherited from 215 -- its parents, if any). If one is found and if it is the first rep item in 216 -- the list that matches one of the given names, it is returned, otherwise 217 -- Empty is returned. A special case is that when one of the given names is 218 -- Name_Priority, the call will also find Interrupt_Priority. 219 220 function Has_Rep_Item 221 (E : Entity_Id; 222 Nam : Name_Id; 223 Check_Parents : Boolean := True) return Boolean; 224 -- Searches the Rep_Item chain for the given entity E, for an instance of a 225 -- rep item (pragma, attribute definition clause, or aspect specification) 226 -- with the given name Nam. If Check_Parents is False then it only checks 227 -- for a rep item that has been directly specified for E (and not inherited 228 -- from its parents, if any). If found then True is returned, otherwise 229 -- False indicates that no matching entry was found. 230 231 function Has_Rep_Item 232 (E : Entity_Id; 233 Nam1 : Name_Id; 234 Nam2 : Name_Id; 235 Check_Parents : Boolean := True) return Boolean; 236 -- Searches the Rep_Item chain for the given entity E, for an instance of a 237 -- rep item (pragma, attribute definition clause, or aspect specification) 238 -- with the given names Nam1 or Nam2. If Check_Parents is False then it 239 -- only checks for a rep item that has been directly specified for E (and 240 -- not inherited from its parents, if any). If found then True is returned, 241 -- otherwise False indicates that no matching entry was found. 242 243 function Has_Rep_Pragma 244 (E : Entity_Id; 245 Nam : Name_Id; 246 Check_Parents : Boolean := True) return Boolean; 247 -- Searches the Rep_Item chain for the given entity E, for an instance of a 248 -- representation pragma with the given name Nam. If Check_Parents is False 249 -- then it only checks for a representation pragma that has been directly 250 -- specified for E (and not inherited from its parents, if any). If found 251 -- and if it is the first rep item in the list that matches Nam then True 252 -- is returned, otherwise False indicates that no matching entry was found. 253 254 function Has_Rep_Pragma 255 (E : Entity_Id; 256 Nam1 : Name_Id; 257 Nam2 : Name_Id; 258 Check_Parents : Boolean := True) return Boolean; 259 -- Searches the Rep_Item chain for the given entity E, for an instance of a 260 -- representation pragma with the given names Nam1 or Nam2. If 261 -- Check_Parents is False then it only checks for a rep item that has been 262 -- directly specified for E (and not inherited from its parents, if any). 263 -- If found and if it is the first rep item in the list that matches one of 264 -- the given names then True is returned, otherwise False indicates that no 265 -- matching entry was found. 266 267 function Has_External_Tag_Rep_Clause (T : Entity_Id) return Boolean; 268 -- Defined in tagged types. Set if an External_Tag rep. clause has been 269 -- given for this type. Use to avoid the generation of the default 270 -- External_Tag. 271 -- 272 -- Note: we used to use an entity flag for this purpose, but that was wrong 273 -- because it was not propagated from the private view to the full view. We 274 -- could have added that propagation, but it would have been an annoying 275 -- irregularity compared to other representation aspects, and the cost of 276 -- looking up the aspect when needed is small. 277 278 function Has_Unconstrained_Elements (T : Entity_Id) return Boolean; 279 -- True if T has discriminants and is unconstrained, or is an array type 280 -- whose element type Has_Unconstrained_Elements. 281 282 function Has_Variant_Part (Typ : Entity_Id) return Boolean; 283 -- Return True if the first subtype of Typ is a discriminated record type 284 -- which has a variant part. False otherwise. 285 286 function In_Generic_Body (Id : Entity_Id) return Boolean; 287 -- Determine whether entity Id appears inside a generic body 288 289 function Initialization_Suppressed (Typ : Entity_Id) return Boolean; 290 pragma Inline (Initialization_Suppressed); 291 -- Returns True if initialization should be suppressed for the given type 292 -- or subtype. This is true if Suppress_Initialization is set either for 293 -- the subtype itself, or for the corresponding base type. 294 295 function Is_Body (N : Node_Id) return Boolean; 296 -- Determine whether an arbitrary node denotes a body 297 298 function Is_By_Copy_Type (Ent : Entity_Id) return Boolean; 299 -- Ent is any entity. Returns True if Ent is a type entity where the type 300 -- is required to be passed by copy, as defined in (RM 6.2(3)). 301 302 function Is_By_Reference_Type (Ent : Entity_Id) return Boolean; 303 -- Ent is any entity. Returns True if Ent is a type entity where the type 304 -- is required to be passed by reference, as defined in (RM 6.2(4-9)). 305 306 function Is_Derived_Type (Ent : Entity_Id) return Boolean; 307 -- Determines if the given entity Ent is a derived type. Result is always 308 -- false if argument is not a type. 309 310 function Is_Generic_Formal (E : Entity_Id) return Boolean; 311 -- Determine whether E is a generic formal parameter. In particular this is 312 -- used to set the visibility of generic formals of a generic package 313 -- declared with a box or with partial parameterization. 314 315 function Is_Indefinite_Subtype (Ent : Entity_Id) return Boolean; 316 -- Ent is any entity. Determines if given entity is an unconstrained array 317 -- type or subtype, a discriminated record type or subtype with no initial 318 -- discriminant values or a class wide type or subtype and returns True if 319 -- so. False for other type entities, or any entities that are not types. 320 321 function Is_Immutably_Limited_Type (Ent : Entity_Id) return Boolean; 322 -- Implements definition in Ada 2012 RM-7.5 (8.1/3). This differs from the 323 -- following predicate in that an untagged record with immutably limited 324 -- components is NOT by itself immutably limited. This matters, e.g. when 325 -- checking the legality of an access to the current instance. 326 327 function Is_Limited_View (Ent : Entity_Id) return Boolean; 328 -- Ent is any entity. True for a type that is "inherently" limited (i.e. 329 -- cannot become nonlimited). From the Ada 2005 RM-7.5(8.1/2), "a type with 330 -- a part that is of a task, protected, or explicitly limited record type". 331 -- These are the types that are defined as return-by-reference types in Ada 332 -- 95 (see RM95-6.5(11-16)). In Ada 2005, these are the types that require 333 -- build-in-place for function calls. Note that build-in-place is allowed 334 -- for other types, too. This is also used for identifying pure procedures 335 -- whose calls should not be eliminated (RM 10.2.1(18/2)). 336 337 function Is_Limited_Type (Ent : Entity_Id) return Boolean; 338 -- Ent is any entity. Returns true if Ent is a limited type (limited 339 -- private type, limited interface type, task type, protected type, 340 -- composite containing a limited component, or a subtype of any of 341 -- these types). This older routine overlaps with the previous one, this 342 -- should be cleaned up??? 343 344 function Nearest_Ancestor (Typ : Entity_Id) return Entity_Id; 345 -- Given a subtype Typ, this function finds out the nearest ancestor from 346 -- which constraints and predicates are inherited. There is no simple link 347 -- for doing this, consider: 348 -- 349 -- subtype R is Integer range 1 .. 10; 350 -- type T is new R; 351 -- 352 -- In this case the nearest ancestor is R, but the Etype of T'Base will 353 -- point to R'Base, so we have to go rummaging in the declarations to get 354 -- this information. It is used for making sure we freeze this before we 355 -- freeze Typ, and also for retrieving inherited predicate information. 356 -- For the case of base types or first subtypes, there is no useful entity 357 -- to return, so Empty is returned. 358 -- 359 -- Note: this is similar to Ancestor_Subtype except that it also deals 360 -- with the case of derived types. 361 362 function Nearest_Dynamic_Scope (Ent : Entity_Id) return Entity_Id; 363 -- This is similar to Enclosing_Dynamic_Scope except that if Ent is itself 364 -- a dynamic scope, then it is returned. Otherwise the result is the same 365 -- as that returned by Enclosing_Dynamic_Scope. 366 367 function Next_Tag_Component (Tag : Entity_Id) return Entity_Id; 368 -- Tag must be an entity representing a _Tag field of a tagged record. 369 -- The result returned is the next _Tag field in this record, or Empty 370 -- if this is the last such field. 371 372 function Number_Discriminants (Typ : Entity_Id) return Pos; 373 -- Typ is a type with discriminants, yields number of discriminants in type 374 375 function Object_Type_Has_Constrained_Partial_View 376 (Typ : Entity_Id; 377 Scop : Entity_Id) return Boolean; 378 -- Return True if type of object has attribute Has_Constrained_Partial_View 379 -- set to True; in addition, within a generic body, return True if subtype 380 -- of the object is a descendant of an untagged generic formal private or 381 -- derived type, and the subtype is not an unconstrained array subtype 382 -- (RM 3.3(23.10/3)). 383 384 function Ultimate_Alias (Prim : Entity_Id) return Entity_Id; 385 pragma Inline (Ultimate_Alias); 386 -- Return the last entity in the chain of aliased entities of Prim. If Prim 387 -- has no alias return Prim. 388 389 function Unit_Declaration_Node (Unit_Id : Entity_Id) return Node_Id; 390 -- Unit_Id is the simple name of a program unit, this function returns the 391 -- corresponding xxx_Declaration node for the entity. Also applies to the 392 -- body entities for subprograms, tasks and protected units, in which case 393 -- it returns the subprogram, task or protected body node for it. The unit 394 -- may be a child unit with any number of ancestors. 395 396 function Package_Specification (Pack_Id : Entity_Id) return Node_Id; 397 -- Given an entity for a package or generic package, return corresponding 398 -- package specification. Simplifies handling of child units, and better 399 -- than the old idiom: Specification (Unit_Declaration_Node (Pack_Id)). 400 401end Sem_Aux; 402