1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- R E S T R I C T -- 6-- -- 7-- S p e c -- 8-- -- 9-- Copyright (C) 1992-2012, 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-- This package deals with the implementation of the Restrictions pragma 27 28with Namet; use Namet; 29with Rident; use Rident; 30with Table; 31with Types; use Types; 32with Uintp; use Uintp; 33 34package Restrict is 35 36 Restrictions : Restrictions_Info := No_Restrictions; 37 -- This variable records restrictions found in any units in the main 38 -- extended unit, and in the case of restrictions checked for partition 39 -- consistency, restrictions found in any with'ed units, parent specs 40 -- etc., since we may as well check as much as we can at compile time. 41 -- These variables should not be referenced directly by clients. Instead 42 -- use Check_Restriction to record a violation of a restriction, and 43 -- Restriction_Active to test if a given restriction is active. 44 45 Restrictions_Loc : array (All_Restrictions) of Source_Ptr := 46 (others => No_Location); 47 -- Locations of Restrictions pragmas for error message purposes. 48 -- Valid only if corresponding entry in Restrictions is set. A value 49 -- of No_Location is used for implicit restrictions set by another 50 -- pragma, and a value of System_Location is used for restrictions 51 -- set from package Standard by the processing in Targparm. 52 53 Restriction_Profile_Name : array (All_Restrictions) of Profile_Name; 54 -- Entries in this array are valid only if the corresponding restriction 55 -- in Restrictions set. The value is the corresponding profile name if the 56 -- restriction was set by a Profile or Profile_Warnings pragma. The value 57 -- is No_Profile in all other cases. 58 59 Main_Restrictions : Restrictions_Info := No_Restrictions; 60 -- This variable records only restrictions found in any units of the 61 -- main extended unit. These are the variables used for ali file output, 62 -- since we want the binder to be able to accurately diagnose inter-unit 63 -- restriction violations. 64 65 Restriction_Warnings : Rident.Restriction_Flags; 66 -- If one of these flags is set, then it means that violation of the 67 -- corresponding restriction results only in a warning message, not 68 -- in an error message, and the restriction is not otherwise enforced. 69 -- Note that the flags in Restrictions are set to indicate that the 70 -- restriction is set in this case, but Main_Restrictions is never 71 -- set if Restriction_Warnings is set, so this does not look like a 72 -- restriction to the binder. 73 74 -- The following declarations establish a mapping between restriction 75 -- identifiers, and the names of corresponding restriction library units. 76 77 type Unit_Entry is record 78 Res_Id : Restriction_Id; 79 Filenm : String (1 .. 8); 80 end record; 81 82 Unit_Array : constant array (Positive range <>) of Unit_Entry := ( 83 (No_Asynchronous_Control, "a-astaco"), 84 (No_Calendar, "a-calend"), 85 (No_Calendar, "calendar"), 86 (No_Delay, "a-calend"), 87 (No_Delay, "calendar"), 88 (No_Dynamic_Priorities, "a-dynpri"), 89 (No_Finalization, "a-finali"), 90 (No_IO, "a-direio"), 91 (No_IO, "directio"), 92 (No_IO, "a-sequio"), 93 (No_IO, "sequenio"), 94 (No_IO, "a-ststio"), 95 (No_IO, "a-textio"), 96 (No_IO, "text_io "), 97 (No_IO, "a-witeio"), 98 (No_Task_Attributes_Package, "a-tasatt"), 99 (No_Unchecked_Conversion, "a-unccon"), 100 (No_Unchecked_Conversion, "unchconv"), 101 (No_Unchecked_Deallocation, "a-uncdea"), 102 (No_Unchecked_Deallocation, "unchdeal")); 103 104 -- The following map has True for all GNAT pragmas. It is used to 105 -- implement pragma Restrictions (No_Implementation_Restrictions) 106 -- (which is why this restriction itself is excluded from the list). 107 108 Implementation_Restriction : array (All_Restrictions) of Boolean := 109 (Simple_Barriers => True, 110 No_Calendar => True, 111 No_Default_Initialization => True, 112 No_Direct_Boolean_Operators => True, 113 No_Dispatching_Calls => True, 114 No_Dynamic_Attachment => True, 115 No_Elaboration_Code => True, 116 No_Enumeration_Maps => True, 117 No_Entry_Calls_In_Elaboration_Code => True, 118 No_Entry_Queue => True, 119 No_Exception_Handlers => True, 120 No_Exception_Propagation => True, 121 No_Exception_Registration => True, 122 No_Finalization => True, 123 No_Implementation_Attributes => True, 124 No_Implementation_Pragmas => True, 125 No_Implicit_Conditionals => True, 126 No_Implicit_Aliasing => True, 127 No_Implicit_Dynamic_Code => True, 128 No_Implicit_Loops => True, 129 No_Initialize_Scalars => True, 130 No_Local_Protected_Objects => True, 131 No_Protected_Type_Allocators => True, 132 No_Relative_Delay => True, 133 No_Requeue_Statements => True, 134 No_Secondary_Stack => True, 135 No_Select_Statements => True, 136 No_Standard_Storage_Pools => True, 137 No_Stream_Optimizations => True, 138 No_Streams => True, 139 No_Task_Attributes_Package => True, 140 No_Task_Termination => True, 141 No_Tasking => True, 142 No_Wide_Characters => True, 143 Static_Priorities => True, 144 Static_Storage_Size => True, 145 SPARK => True, 146 others => False); 147 148 -- The following table records entries made by Restrictions pragmas 149 -- that specify a parameter for No_Dependence. Each such pragma makes 150 -- an entry in this table. 151 152 -- Note: we have chosen to implement this restriction in the "syntactic" 153 -- form, where we do not check that the named package is a language defined 154 -- package, but instead we allow arbitrary package names. The discussion of 155 -- this issue is not complete in the ARG, but the sense seems to be leaning 156 -- in this direction, which makes more sense to us, since it is much more 157 -- useful, and much easier to implement. 158 159 type ND_Entry is record 160 Unit : Node_Id; 161 -- The unit parameter from the No_Dependence pragma 162 163 Warn : Boolean; 164 -- True if from Restriction_Warnings, False if from Restrictions 165 166 Profile : Profile_Name; 167 -- Set to name of profile from which No_Dependence entry came, or to 168 -- No_Profile if a pragma Restriction set the No_Dependence entry. 169 end record; 170 171 package No_Dependences is new Table.Table ( 172 Table_Component_Type => ND_Entry, 173 Table_Index_Type => Int, 174 Table_Low_Bound => 0, 175 Table_Initial => 200, 176 Table_Increment => 200, 177 Table_Name => "Name_No_Dependences"); 178 179 ------------------------------- 180 -- SPARK Restriction Control -- 181 ------------------------------- 182 183 -- SPARK HIDE directives allow the effect of the SPARK restriction to be 184 -- turned off for a specified region of code, and the following tables are 185 -- the data structures used to keep track of these regions. 186 187 -- The table contains pairs of source locations, the first being the start 188 -- location for hidden region, and the second being the end location. 189 190 -- Note that the start location is included in the hidden region, while 191 -- the end location is excluded from it. (It typically corresponds to the 192 -- next token during scanning.) 193 194 type SPARK_Hide_Entry is record 195 Start : Source_Ptr; 196 Stop : Source_Ptr; 197 end record; 198 199 package SPARK_Hides is new Table.Table ( 200 Table_Component_Type => SPARK_Hide_Entry, 201 Table_Index_Type => Natural, 202 Table_Low_Bound => 1, 203 Table_Initial => 100, 204 Table_Increment => 200, 205 Table_Name => "SPARK Hides"); 206 207 ----------------- 208 -- Subprograms -- 209 ----------------- 210 211 -- Note: several of these subprograms can generate error messages (e.g. 212 -- Check_Restriction). These routines should be called in the analyzer 213 -- rather than the expander, so that the associated error messages are 214 -- correctly generated in semantics only (-gnatc) mode. 215 216 function Abort_Allowed return Boolean; 217 pragma Inline (Abort_Allowed); 218 -- Tests to see if abort is allowed by the current restrictions settings. 219 -- For abort to be allowed, either No_Abort_Statements must be False, 220 -- or Max_Asynchronous_Select_Nesting must be non-zero. 221 222 procedure Check_Compiler_Unit (N : Node_Id); 223 -- If unit N is in a unit that has a pragma Compiler_Unit, then a message 224 -- is posted on node N noting use of a construct that is not permitted in 225 -- the compiler. 226 227 procedure Check_Restricted_Unit (U : Unit_Name_Type; N : Node_Id); 228 -- Checks if loading of unit U is prohibited by the setting of some 229 -- restriction (e.g. No_IO restricts the loading of unit Ada.Text_IO). 230 -- If a restriction exists post error message at the given node. 231 232 procedure Check_Restriction 233 (Msg_Issued : out Boolean; 234 R : Restriction_Id; 235 N : Node_Id; 236 V : Uint := Uint_Minus_1); 237 -- Checks that the given restriction is not set, and if it is set, an 238 -- appropriate message is posted on the given node, in which case 239 -- Msg_Issued is set to True (and False otherwise). Also records the 240 -- violation in the appropriate internal arrays. Note that it is mandatory 241 -- to always use this routine to check if a restriction is violated. Such 242 -- checks must never be done directly by the caller, since otherwise 243 -- violations in the absence of restrictions are not properly recorded. The 244 -- value of V is relevant only for parameter restrictions, and in this case 245 -- indicates the exact count for the violation. If the exact count is not 246 -- known, V is left at its default of -1 which indicates an unknown count. 247 248 procedure Check_Restriction 249 (R : Restriction_Id; 250 N : Node_Id; 251 V : Uint := Uint_Minus_1); 252 -- Wrapper on Check_Restriction with Msg_Issued, with the out-parameter 253 -- being ignored here. 254 255 procedure Check_Restriction_No_Dependence (U : Node_Id; Err : Node_Id); 256 -- Called when a dependence on a unit is created (either implicitly, or by 257 -- an explicit WITH clause). U is a node for the unit involved, and Err is 258 -- the node to which an error will be attached if necessary. 259 260 procedure Check_Restriction_No_Specification_Of_Aspect (N : Node_Id); 261 -- N is the node id for an N_Aspect_Specification. An error message 262 -- (warning) will be issued if a restriction (warning) was previous set 263 -- for this aspect using Set_No_Specification_Of_Aspect. 264 265 procedure Check_Elaboration_Code_Allowed (N : Node_Id); 266 -- Tests to see if elaboration code is allowed by the current restrictions 267 -- settings. This function is called by Gigi when it needs to define an 268 -- elaboration routine. If elaboration code is not allowed, an error 269 -- message is posted on the node given as argument. 270 271 procedure Check_SPARK_Restriction 272 (Msg : String; 273 N : Node_Id; 274 Force : Boolean := False); 275 -- Node N represents a construct not allowed in formal mode. If this is a 276 -- source node, or if the restriction is forced (Force = True), and the 277 -- SPARK restriction is set, then an error is issued on N. Msg is appended 278 -- to the restriction failure message. 279 280 procedure Check_SPARK_Restriction (Msg1, Msg2 : String; N : Node_Id); 281 -- Same as Check_SPARK_Restriction except there is a continuation message 282 -- Msg2 following the initial message Msg1. 283 284 procedure Check_No_Implicit_Aliasing (Obj : Node_Id); 285 -- Obj is a node for which Is_Aliased_View is True, which is being used in 286 -- a context (e.g. 'Access) where no implicit aliasing is allowed if the 287 -- restriction No_Implicit_Aliasing is set. This procedure checks for the 288 -- case where the restriction is active and Obj does not meet the required 289 -- rules for avoiding implicit aliases, and issues a restriction message. 290 291 procedure Check_Implicit_Dynamic_Code_Allowed (N : Node_Id); 292 -- Tests to see if dynamic code generation (dynamically generated 293 -- trampolines, in particular) is allowed by the current restrictions 294 -- settings. This function is called by Gigi when it needs to generate code 295 -- that generates a trampoline. If not allowed, an error message is posted 296 -- on the node given as argument. 297 298 procedure Check_No_Implicit_Heap_Alloc (N : Node_Id); 299 -- Equivalent to Check_Restriction (No_Implicit_Heap_Allocations, N). 300 -- Provided for easy use by back end, which has to check this restriction. 301 302 procedure Check_Obsolescent_2005_Entity (E : Entity_Id; N : Node_Id); 303 -- This routine checks if the entity E is one of the obsolescent entries 304 -- in Ada.Characters.Handling in Ada 2005 and No_Obsolescent_Features 305 -- restriction is active. If so an appropriate message is given. N is 306 -- the node on which the message is to be placed. It's a bit kludgy to 307 -- have this highly specialized routine rather than some wonderful general 308 -- mechanism (e.g. a special pragma) to handle this case, but there are 309 -- only six cases, and it is not worth the effort to do something general. 310 311 procedure Check_Wide_Character_Restriction (E : Entity_Id; N : Node_Id); 312 -- This procedure checks if the No_Wide_Character restriction is active, 313 -- and if so, if N Comes_From_Source, and the root type of E is one of 314 -- [Wide_]Wide_Character or [Wide_]Wide_String, then the restriction 315 -- violation is recorded, and an appropriate message given. 316 317 function Get_Restriction_Id 318 (N : Name_Id) return Restriction_Id; 319 -- Given an identifier name, determines if it is a valid restriction 320 -- identifier, and if so returns the corresponding Restriction_Id value, 321 -- otherwise returns Not_A_Restriction_Id. 322 323 function Is_In_Hidden_Part_In_SPARK (Loc : Source_Ptr) return Boolean; 324 -- Determine if given location is covered by a hidden region range in the 325 -- SPARK hides table. 326 327 function No_Exception_Handlers_Set return Boolean; 328 -- Test to see if current restrictions settings specify that no exception 329 -- handlers are present. This function is called by Gigi when it needs to 330 -- expand an AT END clean up identifier with no exception handler. True 331 -- will be returned if the configurable run-time is activated, and either 332 -- of the restrictions No_Exception_Handlers or No_Exception_Propagation is 333 -- set. In the latter case, the source may contain handlers but they either 334 -- get converted using the local goto transformation or deleted. 335 336 function No_Exception_Propagation_Active return Boolean; 337 -- Test to see if current restrictions settings specify that no 338 -- exception propagation is activated. 339 340 function Process_Restriction_Synonyms (N : Node_Id) return Name_Id; 341 -- Id is a node whose Chars field contains the name of a restriction. 342 -- If it is one of synonyms that we allow for historical purposes (for 343 -- list see System.Rident), then the proper official name is returned. 344 -- Otherwise the Chars field of the argument is returned unchanged. 345 346 function Restriction_Active (R : All_Restrictions) return Boolean; 347 pragma Inline (Restriction_Active); 348 -- Determines if a given restriction is active. This call should only be 349 -- used where the compiled code depends on whether the restriction is 350 -- active. Always use Check_Restriction to record a violation. Note that 351 -- this returns False if we only have a Restriction_Warnings set, since 352 -- restriction warnings should never affect generated code. If you want 353 -- to know if a call to Check_Restriction is needed then use the function 354 -- Restriction_Check_Required instead. 355 356 function Restriction_Check_Required (R : All_Restrictions) return Boolean; 357 pragma Inline (Restriction_Check_Required); 358 -- Determines if either a Restriction_Warnings or Restrictions pragma has 359 -- been given for the specified restriction. If true, then a subsequent 360 -- call to Check_Restriction is required if the restriction is violated. 361 -- This must not be used to guard code generation that depends on whether 362 -- a restriction is active (see Restriction_Active above). Typically it 363 -- is used to avoid complex code to determine if a restriction is violated, 364 -- executing this code only if needed. 365 366 function Restricted_Profile return Boolean; 367 -- Tests if set of restrictions corresponding to Profile (Restricted) is 368 -- currently in effect (set by pragma Profile, or by an appropriate set of 369 -- individual Restrictions pragmas). Returns True only if all the required 370 -- restrictions are set. 371 372 procedure Set_Hidden_Part_In_SPARK (Loc1, Loc2 : Source_Ptr); 373 -- Insert a new hidden region range in the SPARK hides table 374 375 procedure Set_Profile_Restrictions 376 (P : Profile_Name; 377 N : Node_Id; 378 Warn : Boolean); 379 -- Sets the set of restrictions associated with the given profile name. N 380 -- is the node of the construct to which error messages are to be attached 381 -- as required. Warn is set True for the case of Profile_Warnings where the 382 -- restrictions are set as warnings rather than legality requirements, and 383 -- is also True for Profile if the Treat_Restrictions_As_Warnings flag is 384 -- set. It is false for Profile if this flag is not set. 385 386 procedure Set_Restriction 387 (R : All_Boolean_Restrictions; 388 N : Node_Id); 389 -- N is a node (typically a pragma node) that has the effect of setting 390 -- Boolean restriction R. The restriction is set in Restrictions, and 391 -- also in Main_Restrictions if this is the main unit. 392 393 procedure Set_Restriction 394 (R : All_Parameter_Restrictions; 395 N : Node_Id; 396 V : Integer); 397 -- Similar to the above, except that this is used for the case of a 398 -- parameter restriction, and the corresponding value V is given. 399 400 procedure Set_Restriction_No_Dependence 401 (Unit : Node_Id; 402 Warn : Boolean; 403 Profile : Profile_Name := No_Profile); 404 -- Sets given No_Dependence restriction in table if not there already. Warn 405 -- is True if from Restriction_Warnings, or for Restrictions if the flag 406 -- Treat_Restrictions_As_Warnings is set. False if from Restrictions and 407 -- this flag is not set. Profile is set to a non-default value if the 408 -- No_Dependence restriction comes from a Profile pragma. 409 410 procedure Set_Restriction_No_Specification_Of_Aspect 411 (N : Node_Id; 412 Warning : Boolean); 413 -- N is the node id for an identifier from a pragma Restrictions for the 414 -- No_Specification_Of_Aspect pragma. An error message will be issued if 415 -- the identifier is not a valid aspect name. Warning is set True for the 416 -- case of a Restriction_Warnings pragma specifying this restriction and 417 -- False for a Restrictions pragma specifying this restriction. 418 419 function Tasking_Allowed return Boolean; 420 pragma Inline (Tasking_Allowed); 421 -- Tests if tasking operations are allowed by the current restrictions 422 -- settings. For tasking to be allowed Max_Tasks must be non-zero. 423 424 ---------------------------------------------- 425 -- Handling of Boolean Compilation Switches -- 426 ---------------------------------------------- 427 428 -- The following declarations are used for proper saving and restoring of 429 -- restrictions for separate compilation units. There are two cases: 430 431 -- For partition-wide restrictions, we just let the restrictions pragmas 432 -- pile up, and we never reset them. We might as well detect what we can 433 -- at compile time. If e.g. a with'ed unit has a restriction for one of 434 -- the partition-wide restrictions, then the binder will enforce it on 435 -- all units in the partition, including the unit with the WITH. Although 436 -- it would not be wrong to leave this till bind time, we might as well 437 -- flag it earlier at compile time. 438 439 -- For non-partition-wide restrictions, we have quite a different state 440 -- of affairs. Here it would be quite wrong to carry a restriction from 441 -- a with'ed unit to another with'ed unit, or from a package spec to the 442 -- package body. This means that we have to reset these non-partition 443 -- wide restrictions at the start of each separate compilation unit. For 444 -- units in the extended main program, we need to reset them all to the 445 -- values set by the configuration pragma file(s). For units not in the 446 -- extended main program, e.g. with'ed units, we might as well reset all 447 -- of these restrictions to off (False). The actual initial values will 448 -- be taken from the config files active when those units are compiled 449 -- as main units. 450 451 type Save_Cunit_Boolean_Restrictions is private; 452 -- Type used for saving and restoring compilation unit restrictions. 453 454 function Cunit_Boolean_Restrictions_Save 455 return Save_Cunit_Boolean_Restrictions; 456 -- This function saves the compilation unit restriction settings, leaving 457 -- then unchanged. This is used e.g. at the start of processing a context 458 -- clause, so that the main unit restrictions can be restored after all 459 -- the with'ed units have been processed. 460 461 procedure Cunit_Boolean_Restrictions_Restore 462 (R : Save_Cunit_Boolean_Restrictions); 463 -- This is the corresponding restore procedure to restore restrictions 464 -- previously saved by Cunit_Boolean_Restrictions_Save. However it does 465 -- not reset No_Elaboration_Code, this stays set if it was set before 466 -- the call, and also if it is set before the call, then the Config 467 -- setting is also updated to include this restriction. This is what 468 -- implements the special handling of No_Elaboration_Code. 469 470 procedure Save_Config_Cunit_Boolean_Restrictions; 471 -- This saves the current compilation unit restrictions in an internal 472 -- variable, and leaves them unchanged. This is called immediately after 473 -- processing the configuration file pragmas, to record the restrictions 474 -- set by these configuration file pragmas. 475 476 procedure Restore_Config_Cunit_Boolean_Restrictions; 477 -- This restores the value saved by the previous call to save config values 478 -- saved by Save_Config_Cunit_Boolean_Restrictions. It is called at the 479 -- start of processing a new unit that is part of the main sources (e.g. 480 -- a package spec when the main unit is a package body). 481 482 procedure Reset_Cunit_Boolean_Restrictions; 483 -- Turns off all non-partition-wide boolean restrictions 484 485 procedure Add_To_Config_Boolean_Restrictions (R : Restriction_Id); 486 -- Add specified restriction to stored configuration boolean restrictions. 487 -- This is used for handling the special case of No_Elaboration_Code. 488 489private 490 type Save_Cunit_Boolean_Restrictions is 491 array (Cunit_Boolean_Restrictions) of Boolean; 492 -- Type used for saving and restoring compilation unit restrictions. 493 -- See Compilation_Unit_Restrictions_[Save|Restore] subprograms. 494 495end Restrict; 496