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) 1992-2013, 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 := (others => False); 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-defined Restrictions. It is used 105 -- to implement pragma Restrictions (No_Implementation_Restrictions) (which 106 -- 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_05 => 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 -- Subprograms -- 181 ----------------- 182 183 -- Note: several of these subprograms can generate error messages (e.g. 184 -- Check_Restriction). These routines should be called in the analyzer 185 -- rather than the expander, so that the associated error messages are 186 -- correctly generated in semantics only (-gnatc) mode. 187 188 function Abort_Allowed return Boolean; 189 pragma Inline (Abort_Allowed); 190 -- Tests to see if abort is allowed by the current restrictions settings. 191 -- For abort to be allowed, either No_Abort_Statements must be False, 192 -- or Max_Asynchronous_Select_Nesting must be non-zero. 193 194 procedure Check_Compiler_Unit (N : Node_Id); 195 -- If unit N is in a unit that has a pragma Compiler_Unit, then a message 196 -- is posted on node N noting use of a construct that is not permitted in 197 -- the compiler. 198 199 procedure Check_Restricted_Unit (U : Unit_Name_Type; N : Node_Id); 200 -- Checks if loading of unit U is prohibited by the setting of some 201 -- restriction (e.g. No_IO restricts the loading of unit Ada.Text_IO). 202 -- If a restriction exists post error message at the given node. 203 204 procedure Check_Restriction 205 (Msg_Issued : out Boolean; 206 R : Restriction_Id; 207 N : Node_Id; 208 V : Uint := Uint_Minus_1); 209 -- Checks that the given restriction is not set, and if it is set, an 210 -- appropriate message is posted on the given node, in which case 211 -- Msg_Issued is set to True (and False otherwise). Also records the 212 -- violation in the appropriate internal arrays. Note that it is mandatory 213 -- to always use this routine to check if a restriction is violated. Such 214 -- checks must never be done directly by the caller, since otherwise 215 -- violations in the absence of restrictions are not properly recorded. The 216 -- value of V is relevant only for parameter restrictions, and in this case 217 -- indicates the exact count for the violation. If the exact count is not 218 -- known, V is left at its default of -1 which indicates an unknown count. 219 220 procedure Check_Restriction 221 (R : Restriction_Id; 222 N : Node_Id; 223 V : Uint := Uint_Minus_1); 224 -- Wrapper on Check_Restriction with Msg_Issued, with the out-parameter 225 -- being ignored here. 226 227 procedure Check_Restriction_No_Use_Of_Attribute (N : Node_Id); 228 -- N is the node of an attribute definition clause. An error message 229 -- (warning) will be issued if a restriction (warning) was previously set 230 -- for this attribute using Set_No_Use_Of_Attribute. 231 232 procedure Check_Restriction_No_Use_Of_Pragma (N : Node_Id); 233 -- N is the node of a pragma. An error message (warning) will be issued 234 -- if a restriction (warning) was previously set for this pragma using 235 -- Set_No_Use_Of_Pragma. 236 237 procedure Check_Restriction_No_Dependence (U : Node_Id; Err : Node_Id); 238 -- Called when a dependence on a unit is created (either implicitly, or by 239 -- an explicit WITH clause). U is a node for the unit involved, and Err is 240 -- the node to which an error will be attached if necessary. 241 242 procedure Check_Restriction_No_Specification_Of_Aspect (N : Node_Id); 243 -- N is the node id for an N_Aspect_Specification. An error message 244 -- (warning) will be issued if a restriction (warning) was previous set 245 -- for this aspect using Set_No_Specification_Of_Aspect. 246 247 procedure Check_Elaboration_Code_Allowed (N : Node_Id); 248 -- Tests to see if elaboration code is allowed by the current restrictions 249 -- settings. This function is called by Gigi when it needs to define an 250 -- elaboration routine. If elaboration code is not allowed, an error 251 -- message is posted on the node given as argument. 252 253 procedure Check_SPARK_Restriction 254 (Msg : String; 255 N : Node_Id; 256 Force : Boolean := False); 257 -- Node N represents a construct not allowed in SPARK_05 mode. If this is 258 -- a source node, or if the restriction is forced (Force = True), and 259 -- the SPARK_05 restriction is set, then an error is issued on N. Msg 260 -- is appended to the restriction failure message. 261 262 procedure Check_SPARK_Restriction (Msg1, Msg2 : String; N : Node_Id); 263 -- Same as Check_SPARK_Restriction except there is a continuation message 264 -- Msg2 following the initial message Msg1. 265 266 procedure Check_No_Implicit_Aliasing (Obj : Node_Id); 267 -- Obj is a node for which Is_Aliased_View is True, which is being used in 268 -- a context (e.g. 'Access) where no implicit aliasing is allowed if the 269 -- restriction No_Implicit_Aliasing is set. This procedure checks for the 270 -- case where the restriction is active and Obj does not meet the required 271 -- rules for avoiding implicit aliases, and issues a restriction message. 272 273 procedure Check_Implicit_Dynamic_Code_Allowed (N : Node_Id); 274 -- Tests to see if dynamic code generation (dynamically generated 275 -- trampolines, in particular) is allowed by the current restrictions 276 -- settings. This function is called by Gigi when it needs to generate code 277 -- that generates a trampoline. If not allowed, an error message is posted 278 -- on the node given as argument. 279 280 procedure Check_No_Implicit_Heap_Alloc (N : Node_Id); 281 -- Equivalent to Check_Restriction (No_Implicit_Heap_Allocations, N). 282 -- Provided for easy use by back end, which has to check this restriction. 283 284 procedure Check_Obsolescent_2005_Entity (E : Entity_Id; N : Node_Id); 285 -- This routine checks if the entity E is one of the obsolescent entries 286 -- in Ada.Characters.Handling in Ada 2005 and No_Obsolescent_Features 287 -- restriction is active. If so an appropriate message is given. N is 288 -- the node on which the message is to be placed. It's a bit kludgy to 289 -- have this highly specialized routine rather than some wonderful general 290 -- mechanism (e.g. a special pragma) to handle this case, but there are 291 -- only six cases, and it is not worth the effort to do something general. 292 293 procedure Check_Wide_Character_Restriction (E : Entity_Id; N : Node_Id); 294 -- This procedure checks if the No_Wide_Character restriction is active, 295 -- and if so, if N Comes_From_Source, and the root type of E is one of 296 -- [Wide_]Wide_Character or [Wide_]Wide_String, then the restriction 297 -- violation is recorded, and an appropriate message given. 298 299 function Get_Restriction_Id 300 (N : Name_Id) return Restriction_Id; 301 -- Given an identifier name, determines if it is a valid restriction 302 -- identifier, and if so returns the corresponding Restriction_Id value, 303 -- otherwise returns Not_A_Restriction_Id. 304 305 function OK_No_Dependence_Unit_Name (N : Node_Id) return Boolean; 306 -- Used in checking No_Dependence argument of pragma Restrictions or 307 -- pragma Restrictions_Warning, or attribute Restriction_Set. Returns 308 -- True if N has the proper form for a unit name, False otherwise. 309 310 function Is_In_Hidden_Part_In_SPARK (Loc : Source_Ptr) return Boolean; 311 -- Determine if given location is covered by a hidden region range in the 312 -- SPARK hides table. 313 314 function No_Exception_Handlers_Set return Boolean; 315 -- Test to see if current restrictions settings specify that no exception 316 -- handlers are present. This function is called by Gigi when it needs to 317 -- expand an AT END clean up identifier with no exception handler. True 318 -- will be returned if the configurable run-time is activated, and either 319 -- of the restrictions No_Exception_Handlers or No_Exception_Propagation is 320 -- set. In the latter case, the source may contain handlers but they either 321 -- get converted using the local goto transformation or deleted. 322 323 function No_Exception_Propagation_Active return Boolean; 324 -- Test to see if current restrictions settings specify that no 325 -- exception propagation is activated. 326 327 function Process_Restriction_Synonyms (N : Node_Id) return Name_Id; 328 -- Id is a node whose Chars field contains the name of a restriction. 329 -- If it is one of synonyms that we allow for historical purposes (for 330 -- list see System.Rident), then the proper official name is returned. 331 -- Otherwise the Chars field of the argument is returned unchanged. 332 333 function Restriction_Active (R : All_Restrictions) return Boolean; 334 pragma Inline (Restriction_Active); 335 -- Determines if a given restriction is active. This call should only be 336 -- used where the compiled code depends on whether the restriction is 337 -- active. Always use Check_Restriction to record a violation. Note that 338 -- this returns False if we only have a Restriction_Warnings set, since 339 -- restriction warnings should never affect generated code. If you want 340 -- to know if a call to Check_Restriction is needed then use the function 341 -- Restriction_Check_Required instead. 342 343 function Restriction_Check_Required (R : All_Restrictions) return Boolean; 344 pragma Inline (Restriction_Check_Required); 345 -- Determines if either a Restriction_Warnings or Restrictions pragma has 346 -- been given for the specified restriction. If true, then a subsequent 347 -- call to Check_Restriction is required if the restriction is violated. 348 -- This must not be used to guard code generation that depends on whether 349 -- a restriction is active (see Restriction_Active above). Typically it 350 -- is used to avoid complex code to determine if a restriction is violated, 351 -- executing this code only if needed. 352 353 function Restricted_Profile return Boolean; 354 -- Tests if set of restrictions corresponding to Profile (Restricted) is 355 -- currently in effect (set by pragma Profile, or by an appropriate set of 356 -- individual Restrictions pragmas). Returns True only if all the required 357 -- restrictions are set. 358 359 procedure Set_Hidden_Part_In_SPARK (Loc1, Loc2 : Source_Ptr); 360 -- Insert a new hidden region range in the SPARK hides table. The effect 361 -- is to hide any SPARK violation messages which are in the range Loc1 to 362 -- Loc2-1 (i.e. Loc2 is the first location for reenabling checks). 363 364 procedure Set_Profile_Restrictions 365 (P : Profile_Name; 366 N : Node_Id; 367 Warn : Boolean); 368 -- Sets the set of restrictions associated with the given profile name. N 369 -- is the node of the construct to which error messages are to be attached 370 -- as required. Warn is set True for the case of Profile_Warnings where the 371 -- restrictions are set as warnings rather than legality requirements, and 372 -- is also True for Profile if the Treat_Restrictions_As_Warnings flag is 373 -- set. It is false for Profile if this flag is not set. 374 375 procedure Set_Restriction 376 (R : All_Boolean_Restrictions; 377 N : Node_Id); 378 -- N is a node (typically a pragma node) that has the effect of setting 379 -- Boolean restriction R. The restriction is set in Restrictions, and 380 -- also in Main_Restrictions if this is the main unit. 381 382 procedure Set_Restriction 383 (R : All_Parameter_Restrictions; 384 N : Node_Id; 385 V : Integer); 386 -- Similar to the above, except that this is used for the case of a 387 -- parameter restriction, and the corresponding value V is given. 388 389 procedure Set_Restriction_No_Dependence 390 (Unit : Node_Id; 391 Warn : Boolean; 392 Profile : Profile_Name := No_Profile); 393 -- Sets given No_Dependence restriction in table if not there already. Warn 394 -- is True if from Restriction_Warnings, or for Restrictions if the flag 395 -- Treat_Restrictions_As_Warnings is set. False if from Restrictions and 396 -- this flag is not set. Profile is set to a non-default value if the 397 -- No_Dependence restriction comes from a Profile pragma. 398 399 procedure Set_Restriction_No_Specification_Of_Aspect 400 (N : Node_Id; 401 Warning : Boolean); 402 -- N is the node id for an identifier from a pragma Restrictions for the 403 -- No_Specification_Of_Aspect pragma. An error message will be issued if 404 -- the identifier is not a valid aspect name. Warning is set True for the 405 -- case of a Restriction_Warnings pragma specifying this restriction and 406 -- False for a Restrictions pragma specifying this restriction. 407 408 procedure Set_Restriction_No_Use_Of_Attribute 409 (N : Node_Id; 410 Warning : Boolean); 411 -- N is the node id for the identifier in a pragma Restrictions for 412 -- No_Use_Of_Attribute. Caller has verified that this is a valid attribute 413 -- designator. 414 415 procedure Set_Restriction_No_Use_Of_Pragma 416 (N : Node_Id; 417 Warning : Boolean); 418 -- N is the node id for the identifier in a pragma Restrictions for 419 -- No_Use_Of_Pragma. Caller has verified that this is a valid pragma id. 420 421 function Tasking_Allowed return Boolean; 422 pragma Inline (Tasking_Allowed); 423 -- Tests if tasking operations are allowed by the current restrictions 424 -- settings. For tasking to be allowed Max_Tasks must be non-zero. 425 426 ---------------------------------------------- 427 -- Handling of Boolean Compilation Switches -- 428 ---------------------------------------------- 429 430 -- The following declarations are used for proper saving and restoring of 431 -- restrictions for separate compilation units. There are two cases: 432 433 -- For partition-wide restrictions, we just let the restrictions pragmas 434 -- pile up, and we never reset them. We might as well detect what we can 435 -- at compile time. If e.g. a with'ed unit has a restriction for one of 436 -- the partition-wide restrictions, then the binder will enforce it on 437 -- all units in the partition, including the unit with the WITH. Although 438 -- it would not be wrong to leave this till bind time, we might as well 439 -- flag it earlier at compile time. 440 441 -- For non-partition-wide restrictions, we have quite a different state 442 -- of affairs. Here it would be quite wrong to carry a restriction from 443 -- a with'ed unit to another with'ed unit, or from a package spec to the 444 -- package body. This means that we have to reset these non-partition 445 -- wide restrictions at the start of each separate compilation unit. For 446 -- units in the extended main program, we need to reset them all to the 447 -- values set by the configuration pragma file(s). For units not in the 448 -- extended main program, e.g. with'ed units, we might as well reset all 449 -- of these restrictions to off (False). The actual initial values will 450 -- be taken from the config files active when those units are compiled 451 -- as main units. 452 453 type Save_Cunit_Boolean_Restrictions is private; 454 -- Type used for saving and restoring compilation unit restrictions. 455 456 function Cunit_Boolean_Restrictions_Save 457 return Save_Cunit_Boolean_Restrictions; 458 -- This function saves the compilation unit restriction settings, leaving 459 -- then unchanged. This is used e.g. at the start of processing a context 460 -- clause, so that the main unit restrictions can be restored after all 461 -- the with'ed units have been processed. 462 463 procedure Cunit_Boolean_Restrictions_Restore 464 (R : Save_Cunit_Boolean_Restrictions); 465 -- This is the corresponding restore procedure to restore restrictions 466 -- previously saved by Cunit_Boolean_Restrictions_Save. However it does 467 -- not reset No_Elaboration_Code, this stays set if it was set before 468 -- the call, and also if it is set before the call, then the Config 469 -- setting is also updated to include this restriction. This is what 470 -- implements the special handling of No_Elaboration_Code. 471 472 procedure Save_Config_Cunit_Boolean_Restrictions; 473 -- This saves the current compilation unit restrictions in an internal 474 -- variable, and leaves them unchanged. This is called immediately after 475 -- processing the configuration file pragmas, to record the restrictions 476 -- set by these configuration file pragmas. 477 478 procedure Restore_Config_Cunit_Boolean_Restrictions; 479 -- This restores the value saved by the previous call to save config values 480 -- saved by Save_Config_Cunit_Boolean_Restrictions. It is called at the 481 -- start of processing a new unit that is part of the main sources (e.g. 482 -- a package spec when the main unit is a package body). 483 484 procedure Reset_Cunit_Boolean_Restrictions; 485 -- Turns off all non-partition-wide boolean restrictions 486 487 procedure Add_To_Config_Boolean_Restrictions (R : Restriction_Id); 488 -- Add specified restriction to stored configuration boolean restrictions. 489 -- This is used for handling the special case of No_Elaboration_Code. 490 491private 492 type Save_Cunit_Boolean_Restrictions is 493 array (Cunit_Boolean_Restrictions) of Boolean; 494 -- Type used for saving and restoring compilation unit restrictions. 495 -- See Compilation_Unit_Restrictions_[Save|Restore] subprograms. 496 497end Restrict; 498