1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- S E M _ A U X -- 6-- -- 7-- S p e c -- 8-- -- 9-- Copyright (C) 1992-2020, 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-- Package containing utility procedures used throughout the compiler. 27 28-- Historical note. Many of the routines here were originally in Einfo, but 29-- Einfo is supposed to be a relatively low level package dealing with the 30-- content of entities in the tree, so this package is used for routines that 31-- require more than minimal semantic knowledge. 32 33with Alloc; 34with Namet; use Namet; 35with Table; 36with Types; use Types; 37 38package Sem_Aux is 39 40 -------------------------------- 41 -- Obsolescent Warnings Table -- 42 -------------------------------- 43 44 -- This table records entities for which a pragma Obsolescent with a 45 -- message argument has been processed. 46 47 type OWT_Record is record 48 Ent : Entity_Id; 49 -- The entity to which the pragma applies 50 51 Msg : String_Id; 52 -- The string containing the message 53 end record; 54 55 package Obsolescent_Warnings is new Table.Table ( 56 Table_Component_Type => OWT_Record, 57 Table_Index_Type => Int, 58 Table_Low_Bound => 0, 59 Table_Initial => Alloc.Obsolescent_Warnings_Initial, 60 Table_Increment => Alloc.Obsolescent_Warnings_Increment, 61 Table_Name => "Obsolescent_Warnings"); 62 63 procedure Initialize; 64 -- Called at the start of compilation of each new main source file to 65 -- initialize the allocation of the Obsolescent_Warnings table. 66 67 ----------------- 68 -- Subprograms -- 69 ----------------- 70 71 function Ancestor_Subtype (Typ : Entity_Id) return Entity_Id; 72 -- The argument Typ is a type or subtype entity. If the argument is a 73 -- subtype then it returns the subtype or type from which the subtype was 74 -- obtained, otherwise it returns Empty. 75 76 -- WARNING: There is a matching C declaration of this subprogram in fe.h 77 78 function Available_View (Ent : Entity_Id) return Entity_Id; 79 -- Ent denotes an abstract state or a type that may come from a limited 80 -- with clause. Return the non-limited view of Ent if there is one or Ent 81 -- if this is not the case. 82 83 function Constant_Value (Ent : Entity_Id) return Node_Id; 84 -- Ent is a variable, constant, named integer, or named real entity. This 85 -- call obtains the initialization expression for the entity. Will return 86 -- Empty for a deferred constant whose full view is not available or 87 -- in some other cases of internal entities, which cannot be treated as 88 -- constants from the point of view of constant folding. Empty is also 89 -- returned for variables with no initialization expression. 90 91 -- WARNING: There is a matching C declaration of this subprogram in fe.h 92 93 function Corresponding_Unsigned_Type (Typ : Entity_Id) return Entity_Id; 94 -- Typ is a signed integer subtype. This routine returns the standard 95 -- unsigned type with the same Esize as the implementation base type of 96 -- Typ, e.g. Long_Integer => Long_Unsigned. 97 98 function Enclosing_Dynamic_Scope (Ent : Entity_Id) return Entity_Id; 99 -- For any entity, Ent, returns the closest dynamic scope in which the 100 -- entity is declared or Standard_Standard for library-level entities. 101 102 function First_Discriminant (Typ : Entity_Id) return Entity_Id; 103 -- Typ is a type with discriminants. The discriminants are the first 104 -- entities declared in the type, so normally this is equivalent to 105 -- First_Entity. The exception arises for tagged types, where the tag 106 -- itself is prepended to the front of the entity chain, so the 107 -- First_Discriminant function steps past the tag if it is present. 108 -- The caller is responsible for checking that the type has discriminants. 109 -- When called on a private type with unknown discriminants, the function 110 -- always returns Empty. 111 112 -- WARNING: There is a matching C declaration of this subprogram in fe.h 113 114 function First_Stored_Discriminant (Typ : Entity_Id) return Entity_Id; 115 -- Typ is a type with discriminants. Gives the first discriminant stored 116 -- in an object of this type. In many cases, these are the same as the 117 -- normal visible discriminants for the type, but in the case of renamed 118 -- discriminants, this is not always the case. 119 -- 120 -- For tagged types, and untagged types which are root types or derived 121 -- types but which do not rename discriminants in their root type, the 122 -- stored discriminants are the same as the actual discriminants of the 123 -- type, and hence this function is the same as First_Discriminant. 124 -- 125 -- For derived untagged types that rename discriminants in the root type 126 -- this is the first of the discriminants that occur in the root type. To 127 -- be precise, in this case stored discriminants are entities attached to 128 -- the entity chain of the derived type which are a copy of the 129 -- discriminants of the root type. Furthermore their Is_Completely_Hidden 130 -- flag is set since although they are actually stored in the object, they 131 -- are not in the set of discriminants that is visible in the type. 132 -- 133 -- For derived untagged types, the set of stored discriminants are the real 134 -- discriminants from Gigi's standpoint, i.e. those that will be stored in 135 -- actual objects of the type. 136 137 -- WARNING: There is a matching C declaration of this subprogram in fe.h 138 139 function First_Subtype (Typ : Entity_Id) return Entity_Id; 140 -- Applies to all types and subtypes. For types, yields the first subtype 141 -- of the type. For subtypes, yields the first subtype of the base type of 142 -- the subtype. 143 144 -- WARNING: There is a matching C declaration of this subprogram in fe.h 145 146 function First_Tag_Component (Typ : Entity_Id) return Entity_Id; 147 -- Typ must be a tagged record type. This function returns the Entity for 148 -- the first _Tag field in the record type. 149 150 function Get_Called_Entity (Call : Node_Id) return Entity_Id; 151 -- Obtain the entity of the entry, operator, or subprogram being invoked 152 -- by call Call. 153 154 function Get_Rep_Item 155 (E : Entity_Id; 156 Nam : Name_Id; 157 Check_Parents : Boolean := True) return Node_Id; 158 -- Searches the Rep_Item chain for a given entity E, for an instance of a 159 -- rep item (pragma, attribute definition clause, or aspect specification) 160 -- whose name matches the given name Nam. If Check_Parents is False then it 161 -- only returns rep item that has been directly specified for E (and not 162 -- inherited from its parents, if any). If one is found, it is returned, 163 -- otherwise Empty is returned. A special case is that when Nam is 164 -- Name_Priority, the call will also find Interrupt_Priority. 165 166 function Get_Rep_Item 167 (E : Entity_Id; 168 Nam1 : Name_Id; 169 Nam2 : 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 one of the given names Nam1 or Nam2. If Check_Parents 174 -- is False then it only returns rep item that has been directly specified 175 -- for E (and not inherited from its parents, if any). If one is found, it 176 -- is returned, otherwise Empty is returned. A special case is that when 177 -- one of the given names is Name_Priority, the call will also find 178 -- Interrupt_Priority. 179 180 function Get_Rep_Pragma 181 (E : Entity_Id; 182 Nam : 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 -- representation pragma whose name matches the given name Nam. If 186 -- Check_Parents is False then it only returns representation pragma that 187 -- has been directly specified for E (and not inherited from its parents, 188 -- if any). If one is found and if it is the first rep item in the list 189 -- that matches Nam, it is returned, otherwise Empty is returned. A special 190 -- case is that when Nam is Name_Priority, the call will also find 191 -- Interrupt_Priority. 192 193 function Get_Rep_Pragma 194 (E : Entity_Id; 195 Nam1 : Name_Id; 196 Nam2 : Name_Id; 197 Check_Parents : Boolean := True) return Node_Id; 198 -- Searches the Rep_Item chain for a given entity E, for an instance of a 199 -- representation pragma whose name matches one of the given names Nam1 or 200 -- Nam2. If Check_Parents is False then it only returns representation 201 -- pragma that has been directly specified for E (and not inherited from 202 -- its parents, if any). If one is found and if it is the first rep item in 203 -- the list that matches one of the given names, it is returned, otherwise 204 -- Empty is returned. A special case is that when one of the given names is 205 -- Name_Priority, the call will also find Interrupt_Priority. 206 207 function Has_Rep_Item 208 (E : Entity_Id; 209 Nam : Name_Id; 210 Check_Parents : Boolean := True) return Boolean; 211 -- Searches the Rep_Item chain for the given entity E, for an instance of a 212 -- rep item (pragma, attribute definition clause, or aspect specification) 213 -- with the given name Nam. If Check_Parents is False then it only checks 214 -- for a rep item that has been directly specified for E (and not inherited 215 -- from its parents, if any). If found then True is returned, otherwise 216 -- False indicates that no matching entry was found. 217 218 function Has_Rep_Item 219 (E : Entity_Id; 220 Nam1 : Name_Id; 221 Nam2 : Name_Id; 222 Check_Parents : Boolean := True) return Boolean; 223 -- Searches the Rep_Item chain for the given entity E, for an instance of a 224 -- rep item (pragma, attribute definition clause, or aspect specification) 225 -- with the given names Nam1 or Nam2. If Check_Parents is False then it 226 -- only checks for a rep item that has been directly specified for E (and 227 -- not inherited from its parents, if any). If found then True is returned, 228 -- otherwise False indicates that no matching entry was found. 229 230 function Has_Rep_Pragma 231 (E : Entity_Id; 232 Nam : Name_Id; 233 Check_Parents : Boolean := True) return Boolean; 234 -- Searches the Rep_Item chain for the given entity E, for an instance of a 235 -- representation pragma with the given name Nam. If Check_Parents is False 236 -- then it only checks for a representation pragma that has been directly 237 -- specified for E (and not inherited from its parents, if any). If found 238 -- and if it is the first rep item in the list that matches Nam then True 239 -- is returned, otherwise False indicates that no matching entry was found. 240 241 function Has_Rep_Pragma 242 (E : Entity_Id; 243 Nam1 : Name_Id; 244 Nam2 : Name_Id; 245 Check_Parents : Boolean := True) return Boolean; 246 -- Searches the Rep_Item chain for the given entity E, for an instance of a 247 -- representation pragma with the given names Nam1 or Nam2. If 248 -- Check_Parents is False then it only checks for a rep item that has been 249 -- directly specified for E (and not inherited from its parents, if any). 250 -- If found and if it is the first rep item in the list that matches one of 251 -- the given names then True is returned, otherwise False indicates that no 252 -- matching entry was found. 253 254 function Has_External_Tag_Rep_Clause (T : Entity_Id) return Boolean; 255 -- Defined in tagged types. Set if an External_Tag rep. clause has been 256 -- given for this type. Use to avoid the generation of the default 257 -- External_Tag. 258 -- 259 -- Note: we used to use an entity flag for this purpose, but that was wrong 260 -- because it was not propagated from the private view to the full view. We 261 -- could have added that propagation, but it would have been an annoying 262 -- irregularity compared to other representation aspects, and the cost of 263 -- looking up the aspect when needed is small. 264 265 function Has_Unconstrained_Elements (T : Entity_Id) return Boolean; 266 -- True if T has discriminants and is unconstrained, or is an array type 267 -- whose element type Has_Unconstrained_Elements. 268 269 function Has_Variant_Part (Typ : Entity_Id) return Boolean; 270 -- Return True if the first subtype of Typ is a discriminated record type 271 -- which has a variant part. False otherwise. 272 273 function In_Generic_Body (Id : Entity_Id) return Boolean; 274 -- Determine whether entity Id appears inside a generic body 275 276 function Initialization_Suppressed (Typ : Entity_Id) return Boolean; 277 pragma Inline (Initialization_Suppressed); 278 -- Returns True if initialization should be suppressed for the given type 279 -- or subtype. This is true if Suppress_Initialization is set either for 280 -- the subtype itself, or for the corresponding base type. 281 282 function Is_Body (N : Node_Id) return Boolean; 283 -- Determine whether an arbitrary node denotes a body 284 285 function Is_By_Copy_Type (Ent : Entity_Id) return Boolean; 286 -- Ent is any entity. Returns True if Ent is a type entity where the type 287 -- is required to be passed by copy, as defined in (RM 6.2(3)). 288 289 function Is_By_Reference_Type (Ent : Entity_Id) return Boolean; 290 -- Ent is any entity. Returns True if Ent is a type entity where the type 291 -- is required to be passed by reference, as defined in (RM 6.2(4-9)). 292 293 -- WARNING: There is a matching C declaration of this subprogram in fe.h 294 295 function Is_Definite_Subtype (T : Entity_Id) return Boolean; 296 -- T is a type entity. Returns True if T is a definite subtype. 297 -- Indefinite subtypes are unconstrained arrays, unconstrained 298 -- discriminated types without defaulted discriminants, class-wide types, 299 -- and types with unknown discriminants. Definite subtypes are all others 300 -- (elementary, constrained composites (including the case of records 301 -- without discriminants), and types with defaulted discriminants). 302 303 function Is_Derived_Type (Ent : Entity_Id) return Boolean; 304 -- Determines if the given entity Ent is a derived type. Result is always 305 -- false if argument is not a type. 306 307 -- WARNING: There is a matching C declaration of this subprogram in fe.h 308 309 function Is_Generic_Formal (E : Entity_Id) return Boolean; 310 -- Determine whether E is a generic formal parameter. In particular this is 311 -- used to set the visibility of generic formals of a generic package 312 -- declared with a box or with partial parameterization. 313 314 function Is_Immutably_Limited_Type (Ent : Entity_Id) return Boolean; 315 -- Implements definition in Ada 2012 RM-7.5 (8.1/3). This differs from the 316 -- following predicate in that an untagged record with immutably limited 317 -- components is NOT by itself immutably limited. This matters, e.g. when 318 -- checking the legality of an access to the current instance. 319 320 function Is_Limited_View (Ent : Entity_Id) return Boolean; 321 -- Ent is any entity. True for a type that is "inherently" limited (i.e. 322 -- cannot become nonlimited). From the Ada 2005 RM-7.5(8.1/2), "a type with 323 -- a part that is of a task, protected, or explicitly limited record type". 324 -- These are the types that are defined as return-by-reference types in Ada 325 -- 95 (see RM95-6.5(11-16)). In Ada 2005, these are the types that require 326 -- build-in-place for function calls. Note that build-in-place is allowed 327 -- for other types, too. This is also used for identifying pure procedures 328 -- whose calls should not be eliminated (RM 10.2.1(18/2)). 329 330 function Is_Limited_Type (Ent : Entity_Id) return Boolean; 331 -- Ent is any entity. Returns true if Ent is a limited type (limited 332 -- private type, limited interface type, task type, protected type, 333 -- composite containing a limited component, or a subtype of any of 334 -- these types). This older routine overlaps with the previous one, this 335 -- should be cleaned up??? 336 337 function Is_Record_Or_Limited_Type (Typ : Entity_Id) return Boolean; 338 -- Return True if Typ requires is a record or limited type. 339 340 function Nearest_Ancestor (Typ : Entity_Id) return Entity_Id; 341 -- Given a subtype Typ, this function finds out the nearest ancestor from 342 -- which constraints and predicates are inherited. There is no simple link 343 -- for doing this, consider: 344 -- 345 -- subtype R is Integer range 1 .. 10; 346 -- type T is new R; 347 -- 348 -- In this case the nearest ancestor is R, but the Etype of T'Base will 349 -- point to R'Base, so we have to go rummaging in the declarations to get 350 -- this information. It is used for making sure we freeze this before we 351 -- freeze Typ, and also for retrieving inherited predicate information. 352 -- For the case of base types or first subtypes, there is no useful entity 353 -- to return, so Empty is returned. 354 -- 355 -- Note: this is similar to Ancestor_Subtype except that it also deals 356 -- with the case of derived types. 357 358 function Nearest_Dynamic_Scope (Ent : Entity_Id) return Entity_Id; 359 -- This is similar to Enclosing_Dynamic_Scope except that if Ent is itself 360 -- a dynamic scope, then it is returned. Otherwise the result is the same 361 -- as that returned by Enclosing_Dynamic_Scope. 362 363 function Next_Tag_Component (Tag : Entity_Id) return Entity_Id; 364 -- Tag must be an entity representing a _Tag field of a tagged record. 365 -- The result returned is the next _Tag field in this record, or Empty 366 -- if this is the last such field. 367 368 function Number_Discriminants (Typ : Entity_Id) return Pos; 369 -- Typ is a type with discriminants, yields number of discriminants in type 370 371 function Object_Type_Has_Constrained_Partial_View 372 (Typ : Entity_Id; 373 Scop : Entity_Id) return Boolean; 374 -- Return True if type of object has attribute Has_Constrained_Partial_View 375 -- set to True; in addition, within a generic body, return True if subtype 376 -- of the object is a descendant of an untagged generic formal private or 377 -- derived type, and the subtype is not an unconstrained array subtype 378 -- (RM 3.3(23.10/3)). 379 380 function Package_Spec (E : Entity_Id) return Node_Id; 381 -- Given an entity for a package spec, return the corresponding package 382 -- spec if any, or else Empty. 383 384 function Package_Specification (E : Entity_Id) return Node_Id; 385 -- Given an entity for a package, return the corresponding package 386 -- specification. 387 388 function Subprogram_Body (E : Entity_Id) return Node_Id; 389 -- Given an entity for a subprogram (spec or body), return the 390 -- corresponding subprogram body if any, or else Empty. 391 392 function Subprogram_Body_Entity (E : Entity_Id) return Entity_Id; 393 -- Given an entity for a subprogram (spec or body), return the entity 394 -- corresponding to the subprogram body, which may be the same as E or 395 -- Empty if no body is available. 396 397 function Subprogram_Spec (E : Entity_Id) return Node_Id; 398 -- Given an entity for a subprogram spec, return the corresponding 399 -- subprogram spec if any, or else Empty. 400 401 function Subprogram_Specification (E : Entity_Id) return Node_Id; 402 -- Given an entity for a subprogram, return the corresponding subprogram 403 -- specification. If the entity is an inherited subprogram without 404 -- specification itself, return the specification of the inherited 405 -- subprogram. 406 407 function Ultimate_Alias (Prim : Entity_Id) return Entity_Id; 408 pragma Inline (Ultimate_Alias); 409 -- Return the last entity in the chain of aliased entities of Prim. If Prim 410 -- has no alias return Prim. 411 412 function Unit_Declaration_Node (Unit_Id : Entity_Id) return Node_Id; 413 -- Unit_Id is the simple name of a program unit, this function returns the 414 -- corresponding xxx_Declaration node for the entity. Also applies to the 415 -- body entities for subprograms, tasks and protected units, in which case 416 -- it returns the subprogram, task or protected body node for it. The unit 417 -- may be a child unit with any number of ancestors. 418 419end Sem_Aux; 420