1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- P A R -- 6-- -- 7-- B o d y -- 8-- -- 9-- Copyright (C) 1992-2021, 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 Aspects; use Aspects; 27with Atree; use Atree; 28with Casing; use Casing; 29with Debug; use Debug; 30with Elists; use Elists; 31with Errout; use Errout; 32with Fname; use Fname; 33with Lib; use Lib; 34with Namet; use Namet; 35with Namet.Sp; use Namet.Sp; 36with Nlists; use Nlists; 37with Nmake; use Nmake; 38with Opt; use Opt; 39with Output; use Output; 40with Par_SCO; use Par_SCO; 41with Restrict; use Restrict; 42with Scans; use Scans; 43with Scn; use Scn; 44with Sem_Util; use Sem_Util; 45with Sinput; use Sinput; 46with Sinput.L; use Sinput.L; 47with Sinfo; use Sinfo; 48with Sinfo.Nodes; use Sinfo.Nodes; 49with Sinfo.Utils; use Sinfo.Utils; 50with Snames; use Snames; 51with Style; 52with Stylesw; use Stylesw; 53with Table; 54with Tbuild; use Tbuild; 55 56--------- 57-- Par -- 58--------- 59 60function Par (Configuration_Pragmas : Boolean) return List_Id is 61 62 Inside_Record_Definition : Boolean := False; 63 -- True within a record definition. Used to control warning for 64 -- redefinition of standard entities (not issued for field names). 65 66 Loop_Block_Count : Nat := 0; 67 -- Counter used for constructing loop/block names (see the routine 68 -- Par.Ch5.Get_Loop_Block_Name). 69 70 Num_Library_Units : Natural := 0; 71 -- Count number of units parsed (relevant only in syntax check only mode, 72 -- since in semantics check mode only a single unit is permitted anyway). 73 74 Save_Config_Attrs : Config_Switches_Type; 75 -- Variable used to save values of config switches while we parse the 76 -- new unit, to be restored on exit for proper recursive behavior. 77 78 -------------------- 79 -- Error Recovery -- 80 -------------------- 81 82 -- When an error is encountered, a call is made to one of the Error_Msg 83 -- routines to record the error. If the syntax scan is not derailed by the 84 -- error (e.g. a complaint that logical operators are inconsistent in an 85 -- EXPRESSION), then control returns from the Error_Msg call, and the 86 -- parse continues unimpeded. 87 88 -- If on the other hand, the Error_Msg represents a situation from which 89 -- the parser cannot recover locally, the exception Error_Resync is raised 90 -- immediately after the call to Error_Msg. Handlers for Error_Resync 91 -- are located at strategic points to resynchronize the parse. For example, 92 -- when an error occurs in a statement, the handler skips to the next 93 -- semicolon and continues the scan from there. 94 95 -- Each parsing procedure contains a note with the heading "Error recovery" 96 -- which shows if it can propagate the Error_Resync exception. In order 97 -- not to propagate the exception, a procedure must either contain its own 98 -- handler for this exception, or it must not call any other routines which 99 -- propagate the exception. 100 101 -- Note: the arrangement of Error_Resync handlers is such that it should 102 -- never be possible to transfer control through a procedure which made 103 -- an entry in the scope stack, invalidating the contents of the stack. 104 105 Error_Resync : exception; 106 -- Exception raised on error that is not handled locally, see above 107 108 Last_Resync_Point : Source_Ptr; 109 -- The resynchronization routines in Par.Sync run a risk of getting 110 -- stuck in an infinite loop if they do not skip a token, and the caller 111 -- keeps repeating the same resync call. On the other hand, if they skip 112 -- a token unconditionally, some recovery opportunities are missed. The 113 -- variable Last_Resync_Point records the token location previously set 114 -- by a Resync call, and if a subsequent Resync call occurs at the same 115 -- location, then the Resync routine does guarantee to skip a token. 116 117 -------------------------------------------- 118 -- Handling Semicolon Used in Place of IS -- 119 -------------------------------------------- 120 121 -- The following global variables are used in handling the error situation 122 -- of using a semicolon in place of IS in a subprogram declaration as in: 123 124 -- procedure X (Y : Integer); 125 -- Q : Integer; 126 -- begin 127 -- ... 128 -- end; 129 130 -- The two contexts in which this can appear are at the outer level, and 131 -- within a declarative region. At the outer level, we know something is 132 -- wrong as soon as we see the Q (or begin, if there are no declarations), 133 -- and we can immediately decide that the semicolon should have been IS. 134 135 -- The situation in a declarative region is more complex. The declaration 136 -- of Q could belong to the outer region, and we do not know that we have 137 -- an error until we hit the begin. It is still not clear at this point 138 -- from a syntactic point of view that something is wrong, because the 139 -- begin could belong to the enclosing subprogram or package. However, we 140 -- can incorporate a bit of semantic knowledge and note that the body of 141 -- X is missing, so we definitely DO have an error. We diagnose this error 142 -- as semicolon in place of IS on the subprogram line. 143 144 -- There are two styles for this diagnostic. If the begin immediately 145 -- follows the semicolon, then we can place a flag (IS expected) right 146 -- on the semicolon. Otherwise we do not detect the error until we hit 147 -- the begin which refers back to the line with the semicolon. 148 149 -- To control the process in the second case, the following global 150 -- variables are set to indicate that we have a subprogram declaration 151 -- whose body is required and has not yet been found. The prefix SIS 152 -- stands for "Subprogram IS" handling. 153 154 SIS_Entry_Active : Boolean := False; 155 -- Set True to indicate that an entry is active (i.e. that a subprogram 156 -- declaration has been encountered, and no body for this subprogram 157 -- has been encountered). The remaining variables other than 158 -- SIS_Aspect_Import_Seen are valid only if this is True. 159 160 SIS_Aspect_Import_Seen : Boolean := False; 161 -- If this is True when a subprogram declaration has been encountered, we 162 -- do not set SIS_Entry_Active, because the Import means there is no body. 163 -- Set False at the start of P_Subprogram, set True when an Import aspect 164 -- specification is seen, and used when P_Subprogram finds a subprogram 165 -- declaration. This is necessary because the aspects are parsed before 166 -- we know we have a subprogram declaration. 167 168 SIS_Labl : Node_Id; 169 -- Subprogram designator 170 171 SIS_Sloc : Source_Ptr; 172 -- Source location of FUNCTION/PROCEDURE keyword 173 174 SIS_Ecol : Column_Number; 175 -- Column number of FUNCTION/PROCEDURE keyword 176 177 SIS_Semicolon_Sloc : Source_Ptr; 178 -- Source location of semicolon at end of subprogram declaration 179 180 SIS_Declaration_Node : Node_Id; 181 -- Pointer to tree node for subprogram declaration 182 183 SIS_Missing_Semicolon_Message : Error_Msg_Id; 184 -- Used to save message ID of missing semicolon message (which will be 185 -- modified to missing IS if necessary). Set to No_Error_Msg in the 186 -- normal (non-error) case. 187 188 -- Five things can happen to an active SIS entry 189 190 -- 1. If a BEGIN is encountered with an SIS entry active, then we have 191 -- exactly the situation in which we know the body of the subprogram is 192 -- missing. After posting an error message, we change the spec to a body, 193 -- rechaining the declarations that intervened between the spec and BEGIN. 194 195 -- 2. Another subprogram declaration or body is encountered. In this 196 -- case the entry gets overwritten with the information for the new 197 -- subprogram declaration. We don't catch some nested cases this way, 198 -- but it doesn't seem worth the effort. 199 200 -- 3. A nested declarative region (e.g. package declaration or package 201 -- body) is encountered. The SIS active indication is reset at the start 202 -- of such a nested region. Again, like case 2, this causes us to miss 203 -- some nested cases, but it doesn't seen worth the effort to stack and 204 -- unstack the SIS information. Maybe we will reconsider this if we ever 205 -- get a complaint about a missed case. 206 207 -- 4. We encounter a valid pragma INTERFACE or IMPORT that effectively 208 -- supplies the missing body. In this case we reset the entry. 209 210 -- 5. We encounter the end of the declarative region without encountering 211 -- a BEGIN first. In this situation we simply reset the entry. We know 212 -- that there is a missing body, but it seems more reasonable to let the 213 -- later semantic checking discover this. 214 215 ---------------------------------------------------- 216 -- Handling of Reserved Words Used as Identifiers -- 217 ---------------------------------------------------- 218 219 -- Note: throughout the parser, the terms reserved word and keyword are 220 -- used interchangeably to refer to the same set of reserved keywords 221 -- (including until, protected, etc). 222 223 -- If a reserved word is used in place of an identifier, the parser where 224 -- possible tries to recover gracefully. In particular, if the keyword is 225 -- clearly spelled using identifier casing, e.g. Until in a source program 226 -- using mixed case identifiers and lower case keywords, then the keyword 227 -- is treated as an identifier if it appears in a place where an identifier 228 -- is required. 229 230 -- The situation is more complex if the keyword is spelled with normal 231 -- keyword casing. In this case, the parser is more reluctant to consider 232 -- it to be intended as an identifier, unless it has some further 233 -- confirmation. 234 235 -- In the case of an identifier appearing in the identifier list of a 236 -- declaration, the appearance of a comma or colon right after the keyword 237 -- on the same line is taken as confirmation. For an enumeration literal, 238 -- a comma or right paren right after the identifier is also treated as 239 -- adequate confirmation. 240 241 -- The following type is used in calls to Is_Reserved_Identifier and 242 -- also to P_Defining_Identifier and P_Identifier. The default for all 243 -- these functions is that reserved words in reserved word case are not 244 -- considered to be reserved identifiers. The Id_Check value indicates 245 -- tokens, which if they appear immediately after the identifier, are 246 -- taken as confirming that the use of an identifier was expected 247 248 type Id_Check is 249 (None, 250 -- Default, no special token test 251 252 C_Comma_Right_Paren, 253 -- Consider as identifier if followed by comma or right paren 254 255 C_Comma_Colon, 256 -- Consider as identifier if followed by comma or colon 257 258 C_Do, 259 -- Consider as identifier if followed by DO 260 261 C_Dot, 262 -- Consider as identifier if followed by period 263 264 C_Greater_Greater, 265 -- Consider as identifier if followed by >> 266 267 C_In, 268 -- Consider as identifier if followed by IN 269 270 C_Is, 271 -- Consider as identifier if followed by IS 272 273 C_Left_Paren_Semicolon, 274 -- Consider as identifier if followed by left paren or semicolon 275 276 C_Use, 277 -- Consider as identifier if followed by USE 278 279 C_Vertical_Bar_Arrow); 280 -- Consider as identifier if followed by | or => 281 282 -------------------------------------------- 283 -- Handling IS Used in Place of Semicolon -- 284 -------------------------------------------- 285 286 -- This is a somewhat trickier situation, and we can't catch it in all 287 -- cases, but we do our best to detect common situations resulting from 288 -- a "cut and paste" operation which forgets to change the IS to semicolon. 289 -- Consider the following example: 290 291 -- package body X is 292 -- procedure A; 293 -- procedure B is 294 -- procedure C; 295 -- ... 296 -- procedure D is 297 -- begin 298 -- ... 299 -- end; 300 -- begin 301 -- ... 302 -- end; 303 304 -- The trouble is that the section of text from PROCEDURE B through END; 305 -- constitutes a valid procedure body, and the danger is that we find out 306 -- far too late that something is wrong (indeed most compilers will behave 307 -- uncomfortably on the above example). 308 309 -- We have two approaches to helping to control this situation. First we 310 -- make every attempt to avoid swallowing the last END; if we can be sure 311 -- that some error will result from doing so. In particular, we won't 312 -- accept the END; unless it is exactly correct (in particular it must not 313 -- have incorrect name tokens), and we won't accept it if it is immediately 314 -- followed by end of file, WITH or SEPARATE (all tokens that unmistakeably 315 -- signal the start of a compilation unit, and which therefore allow us to 316 -- reserve the END; for the outer level.) For more details on this aspect 317 -- of the handling, see package Par.Endh. 318 319 -- If we can avoid eating up the END; then the result in the absence of 320 -- any additional steps would be to post a missing END referring back to 321 -- the subprogram with the bogus IS. Similarly, if the enclosing package 322 -- has no BEGIN, then the result is a missing BEGIN message, which again 323 -- refers back to the subprogram header. 324 325 -- Such an error message is not too bad (it's already a big improvement 326 -- over what many parsers do), but it's not ideal, because the declarations 327 -- following the IS have been absorbed into the wrong scope. In the above 328 -- case, this could result for example in a bogus complaint that the body 329 -- of D was missing from the package. 330 331 -- To catch at least some of these cases, we take the following additional 332 -- steps. First, a subprogram body is marked as having a suspicious IS if 333 -- the declaration line is followed by a line which starts with a symbol 334 -- that can start a declaration in the same column, or to the left of the 335 -- column in which the FUNCTION or PROCEDURE starts (normal style is to 336 -- indent any declarations which really belong a subprogram). If such a 337 -- subprogram encounters a missing BEGIN or missing END, then we decide 338 -- that the IS should have been a semicolon, and the subprogram body node 339 -- is marked (by setting the Bad_Is_Detected flag true. Note that we do 340 -- not do this for library level procedures, only for nested procedures, 341 -- since for library level procedures, we must have a body. 342 343 -- The processing for a declarative part checks to see if the last 344 -- declaration scanned is marked in this way, and if it is, the tree 345 -- is modified to reflect the IS being interpreted as a semicolon. 346 347 --------------------------------------------------- 348 -- Parser Type Definitions and Control Variables -- 349 --------------------------------------------------- 350 351 -- The following variable and associated type declaration are used by the 352 -- expression parsing routines to return more detailed information about 353 -- the categorization of a parsed expression. 354 355 type Expr_Form_Type is ( 356 EF_Simple_Name, -- Simple name, i.e. possibly qualified identifier 357 EF_Name, -- Simple expression which could also be a name 358 EF_Simple, -- Simple expression which is not call or name 359 EF_Range_Attr, -- Range attribute reference 360 EF_Non_Simple); -- Expression that is not a simple expression 361 362 Expr_Form : Expr_Form_Type; 363 364 -- The following type is used for calls to P_Subprogram, P_Package, P_Task, 365 -- P_Protected to indicate which of several possibilities is acceptable. 366 367 type Pf_Rec is record 368 Spcn : Boolean; -- True if specification OK 369 Decl : Boolean; -- True if declaration OK 370 Gins : Boolean; -- True if generic instantiation OK 371 Pbod : Boolean; -- True if proper body OK 372 Rnam : Boolean; -- True if renaming declaration OK 373 Stub : Boolean; -- True if body stub OK 374 Pexp : Boolean; -- True if parameterized expression OK 375 Fil2 : Boolean; -- Filler to fill to 8 bits 376 end record; 377 pragma Pack (Pf_Rec); 378 379 function T return Boolean renames True; 380 function F return Boolean renames False; 381 382 Pf_Decl_Gins_Pbod_Rnam_Stub_Pexp : constant Pf_Rec := 383 Pf_Rec'(F, T, T, T, T, T, T, F); 384 Pf_Decl_Pexp : constant Pf_Rec := 385 Pf_Rec'(F, T, F, F, F, F, T, F); 386 Pf_Decl_Gins_Pbod_Rnam_Pexp : constant Pf_Rec := 387 Pf_Rec'(F, T, T, T, T, F, T, F); 388 Pf_Decl_Pbod_Pexp : constant Pf_Rec := 389 Pf_Rec'(F, T, F, T, F, F, T, F); 390 Pf_Pbod_Pexp : constant Pf_Rec := 391 Pf_Rec'(F, F, F, T, F, F, T, F); 392 Pf_Spcn : constant Pf_Rec := 393 Pf_Rec'(T, F, F, F, F, F, F, F); 394 -- The above are the only allowed values of Pf_Rec arguments 395 396 type SS_Rec is record 397 Eftm : Boolean; -- ELSIF can terminate sequence 398 Eltm : Boolean; -- ELSE can terminate sequence 399 Extm : Boolean; -- EXCEPTION can terminate sequence 400 Ortm : Boolean; -- OR can terminate sequence 401 Sreq : Boolean; -- at least one statement required 402 Tatm : Boolean; -- THEN ABORT can terminate sequence 403 Whtm : Boolean; -- WHEN can terminate sequence 404 Unco : Boolean; -- Unconditional terminate after one statement 405 end record; 406 pragma Pack (SS_Rec); 407 408 SS_Eftm_Eltm_Sreq : constant SS_Rec := SS_Rec'(T, T, F, F, T, F, F, F); 409 SS_Eltm_Ortm_Tatm : constant SS_Rec := SS_Rec'(F, T, F, T, F, T, F, F); 410 SS_Extm_Sreq : constant SS_Rec := SS_Rec'(F, F, T, F, T, F, F, F); 411 SS_None : constant SS_Rec := SS_Rec'(F, F, F, F, F, F, F, F); 412 SS_Ortm_Sreq : constant SS_Rec := SS_Rec'(F, F, F, T, T, F, F, F); 413 SS_Sreq : constant SS_Rec := SS_Rec'(F, F, F, F, T, F, F, F); 414 SS_Sreq_Whtm : constant SS_Rec := SS_Rec'(F, F, F, F, T, F, T, F); 415 SS_Whtm : constant SS_Rec := SS_Rec'(F, F, F, F, F, F, T, F); 416 SS_Unco : constant SS_Rec := SS_Rec'(F, F, F, F, F, F, F, T); 417 418 Goto_List : Elist_Id; 419 -- List of goto nodes appearing in the current compilation. Used to 420 -- recognize natural loops and convert them into bona fide loops for 421 -- optimization purposes. 422 423 Label_List : Elist_Id; 424 -- List of label nodes for labels appearing in the current compilation. 425 -- Used by Par.Labl to construct the corresponding implicit declarations. 426 427 ----------------- 428 -- Scope Table -- 429 ----------------- 430 431 -- The scope table, also referred to as the scope stack, is used to record 432 -- the current scope context. It is organized as a stack, with inner nested 433 -- entries corresponding to higher entries on the stack. An entry is made 434 -- when the parser encounters the opening of a nested construct (such as a 435 -- record, task, package etc.), and then package Par.Endh uses this stack 436 -- to deal with END lines (including properly dealing with END nesting 437 -- errors). 438 439 type SS_End_Type is 440 -- Type of end entry required for this scope. The last two entries are 441 -- used only in the subprogram body case to mark the case of a suspicious 442 -- IS, or a bad IS (i.e. suspicions confirmed by missing BEGIN or END). 443 -- See separate section on dealing with IS used in place of semicolon. 444 -- Note that for many purposes E_Name, E_Suspicious_Is and E_Bad_Is are 445 -- treated the same (E_Suspicious_Is and E_Bad_Is are simply special cases 446 -- of E_Name). They are placed at the end of the enumeration so that a 447 -- test for >= E_Name catches all three cases efficiently. 448 449 (E_Dummy, -- dummy entry at outer level 450 E_Case, -- END CASE; 451 E_If, -- END IF; 452 E_Loop, -- END LOOP; 453 E_Record, -- END RECORD; 454 E_Return, -- END RETURN; 455 E_Select, -- END SELECT; 456 E_Name, -- END [name]; 457 E_Suspicious_Is, -- END [name]; (case of suspicious IS) 458 E_Bad_Is); -- END [name]; (case of bad IS) 459 460 -- The following describes a single entry in the scope table 461 462 type Scope_Table_Entry is record 463 Etyp : SS_End_Type; 464 -- Type of end entry, as per above description 465 466 Lreq : Boolean; 467 -- A flag indicating whether the label, if present, is required to 468 -- appear on the end line. It is referenced only in the case of Etyp is 469 -- equal to E_Name or E_Suspicious_Is where the name may or may not be 470 -- required (yes for labeled block, no in other cases). Note that for 471 -- all cases except begin, the question of whether a label is required 472 -- can be determined from the other fields (for loop, it is required if 473 -- it is present, and for the other constructs it is never required or 474 -- allowed). 475 476 Ecol : Column_Number; 477 -- Contains the absolute column number (with tabs expanded) of the 478 -- expected column of the end assuming normal Ada indentation usage. If 479 -- the RM_Column_Check mode is set, this value is used for generating 480 -- error messages about indentation. Otherwise it is used only to 481 -- control heuristic error recovery actions. This value is zero origin. 482 483 Labl : Node_Id; 484 -- This field is used to provide the name of the construct being parsed 485 -- and indirectly its kind. For loops and blocks, the field contains the 486 -- source name or the generated one. For package specifications, bodies, 487 -- subprogram specifications and bodies the field holds the correponding 488 -- program unit name. For task declarations and bodies, protected types 489 -- and bodies, and accept statements the field hold the name of the type 490 -- or operation. For if-statements, case-statements, return statements, 491 -- and selects, the field is initialized to Error. 492 493 -- Note: this is a bit of an odd (mis)use of Error, since there is no 494 -- Error, but we use this value as a place holder to indicate that it 495 -- is an error to have a label on the end line. 496 497 -- Whenever the field is a name, it is attached to the parent node of 498 -- the construct being parsed. Thus the parent node indicates the kind 499 -- of construct whose parse tree is being built. This is used in error 500 -- recovery. 501 502 Decl : List_Id; 503 -- Points to the list of declarations (i.e. the declarative part) 504 -- associated with this construct. It is set only in the END [name] 505 -- cases, and is set to No_List for all other cases which do not have a 506 -- declarative unit associated with them. This is used for determining 507 -- the proper location for implicit label declarations. 508 509 Node : Node_Id; 510 -- Empty except in the case of entries for IF and CASE statements, in 511 -- which case it contains the N_If_Statement or N_Case_Statement node. 512 -- This is used for setting the End_Span field. 513 514 Sloc : Source_Ptr; 515 -- Source location of the opening token of the construct. This is used 516 -- to refer back to this line in error messages (such as missing or 517 -- incorrect end lines). The Sloc field is not used, and is not set, if 518 -- a label is present (the Labl field provides the text name of the 519 -- label in this case, which is fine for error messages). 520 521 S_Is : Source_Ptr; 522 -- S_Is is relevant only if Etyp is set to E_Suspicious_Is or E_Bad_Is. 523 -- It records the location of the IS that is considered to be 524 -- suspicious. 525 526 Junk : Boolean; 527 -- A boolean flag that is set true if the opening entry is the dubious 528 -- result of some prior error, e.g. a record entry where the record 529 -- keyword was missing. It is used to suppress the issuing of a 530 -- corresponding junk complaint about the end line (we do not want 531 -- to complain about a missing end record when there was no record). 532 end record; 533 534 -- The following declares the scope table itself. The Last field is the 535 -- stack pointer, so that Scope.Table (Scope.Last) is the top entry. The 536 -- oldest entry, at Scope_Stack (0), is a dummy entry with Etyp set to 537 -- E_Dummy, and the other fields undefined. This dummy entry ensures that 538 -- Scope_Stack (Scope_Stack_Ptr).Etyp can always be tested, and that the 539 -- scope stack pointer is always in range. 540 541 package Scope is new Table.Table ( 542 Table_Component_Type => Scope_Table_Entry, 543 Table_Index_Type => Int, 544 Table_Low_Bound => 0, 545 Table_Initial => 50, 546 Table_Increment => 100, 547 Table_Name => "Scope"); 548 549 type Scope_Table_Entry_Ptr is access all Scope_Table_Entry; 550 551 function Scopes (Index : Int) return Scope_Table_Entry_Ptr; 552 -- Return the indicated Scope_Table_Entry. We use a pointer for 553 -- efficiency. Callers should not save the pointer, but should do things 554 -- like Scopes (Scope.Last).Something. Note that there is one place in 555 -- Par.Ch5 that indexes the stack out of bounds, and can't call this. 556 557 function Scopes (Index : Int) return Scope_Table_Entry_Ptr is 558 begin 559 pragma Assert (Index in Scope.First .. Scope.Last); 560 return Scope.Table (Index)'Unrestricted_Access; 561 end Scopes; 562 563 ------------------------------------------ 564 -- Table for Handling Suspicious Labels -- 565 ------------------------------------------ 566 567 -- This is a special data structure which is used to deal very spefifically 568 -- with the following error case 569 570 -- label; 571 -- loop 572 -- ... 573 -- end loop label; 574 575 -- Similar cases apply to FOR, WHILE, DECLARE, or BEGIN 576 577 -- In each case the opening line looks like a procedure call because of 578 -- the semicolon. And the end line looks illegal because of an unexpected 579 -- label. If we did nothing special, we would just diagnose the label on 580 -- the end as unexpected. But that does not help point to the real error 581 -- which is that the semicolon after label should be a colon. 582 583 -- To deal with this, we build an entry in the Suspicious_Labels table 584 -- whenever we encounter an identifier followed by a semicolon, followed 585 -- by one of LOOP, FOR, WHILE, DECLARE, BEGIN. Then this entry is used to 586 -- issue the right message when we hit the END that confirms that this was 587 -- a bad label. 588 589 type Suspicious_Label_Entry is record 590 Proc_Call : Node_Id; 591 -- Node for the procedure call statement built for the label; construct 592 593 Semicolon_Loc : Source_Ptr; 594 -- Location of the possibly wrong semicolon 595 596 Start_Token : Source_Ptr; 597 -- Source location of the LOOP, FOR, WHILE, DECLARE, BEGIN token 598 end record; 599 600 package Suspicious_Labels is new Table.Table ( 601 Table_Component_Type => Suspicious_Label_Entry, 602 Table_Index_Type => Int, 603 Table_Low_Bound => 1, 604 Table_Initial => 50, 605 Table_Increment => 100, 606 Table_Name => "Suspicious_Labels"); 607 608 -- Now when we are about to issue a message complaining about an END label 609 -- that should not be there because it appears to end a construct that has 610 -- no label, we first search the suspicious labels table entry, using the 611 -- source location stored in the scope table as a key. If we find a match, 612 -- then we check that the label on the end matches the name in the call, 613 -- and if so, we issue a message saying the semicolon should be a colon. 614 615 -- Quite a bit of work, but really helpful in the case where it helps, and 616 -- the need for this is based on actual experience with tracking down this 617 -- kind of error (the eye often easily mistakes semicolon for colon). 618 619 -- Note: we actually have enough information to patch up the tree, but 620 -- this may not be worth the effort. Also we could deal with the same 621 -- situation for EXIT with a label, but for now don't bother with that. 622 623 Current_Assign_Node : Node_Id := Empty; 624 -- This is the node of the current assignment statement being compiled. 625 -- It is used to record the presence of target_names on its RHS. This 626 -- context-dependent trick simplifies the analysis of such nodes, where 627 -- the RHS must first be analyzed with expansion disabled. 628 629 --------------------------------- 630 -- Parsing Routines by Chapter -- 631 --------------------------------- 632 633 -- Uncommented declarations in this section simply parse the construct 634 -- corresponding to their name, and return an ID value for the Node or 635 -- List that is created. 636 637 ------------- 638 -- Par.Ch2 -- 639 ------------- 640 641 package Ch2 is 642 function P_Pragma (Skipping : Boolean := False) return Node_Id; 643 -- Scan out a pragma. If Skipping is True, then the caller is skipping 644 -- the pragma in the context of illegal placement (this is used to avoid 645 -- some junk cascaded messages). Some pragmas must be dealt with during 646 -- the parsing phase (e.g. pragma Page, since we can generate a listing 647 -- in syntax only mode). It is possible that the parser uses the rescan 648 -- logic (using Save/Restore_Scan_State) with the effect of calling this 649 -- procedure more than once for the same pragma. All parse-time pragma 650 -- handling must be prepared to handle such multiple calls correctly. 651 652 function P_Identifier (C : Id_Check := None) return Node_Id; 653 -- Scans out an identifier. The parameter C determines the treatment 654 -- of reserved identifiers. See declaration of Id_Check for details. 655 656 function P_Pragmas_Opt return List_Id; 657 -- This function scans for a sequence of pragmas in other than a 658 -- declaration sequence or statement sequence context. All pragmas 659 -- can appear except pragmas Assert and Debug, which are only allowed 660 -- in a declaration or statement sequence context. 661 662 procedure P_Pragmas_Misplaced; 663 -- Skips misplaced pragmas with a complaint 664 665 procedure P_Pragmas_Opt (List : List_Id); 666 -- Parses optional pragmas and appends them to the List 667 end Ch2; 668 669 ------------- 670 -- Par.Ch3 -- 671 ------------- 672 673 package Ch3 is 674 Missing_Begin_Msg : Error_Msg_Id; 675 -- This variable is set by a call to P_Declarative_Part. Normally it 676 -- is set to No_Error_Msg, indicating that no special processing is 677 -- required by the caller. The special case arises when a statement 678 -- is found in the sequence of declarations. In this case the Id of 679 -- the message issued ("declaration expected") is preserved in this 680 -- variable, then the caller can change it to an appropriate missing 681 -- begin message if indeed the BEGIN is missing. 682 683 function P_Array_Type_Definition return Node_Id; 684 function P_Constraint_Opt return Node_Id; 685 function P_Declarative_Part return List_Id; 686 function P_Discrete_Choice_List return List_Id; 687 function P_Discrete_Range return Node_Id; 688 function P_Discrete_Subtype_Definition return Node_Id; 689 function P_Known_Discriminant_Part_Opt return List_Id; 690 function P_Signed_Integer_Type_Definition return Node_Id; 691 function P_Range return Node_Id; 692 function P_Range_Constraint return Node_Id; 693 function P_Record_Definition return Node_Id; 694 function P_Subtype_Mark return Node_Id; 695 function P_Subtype_Mark_Resync return Node_Id; 696 function P_Unknown_Discriminant_Part_Opt return Boolean; 697 698 function P_Basic_Declarative_Items 699 (Declare_Expression : Boolean) return List_Id; 700 -- Used to parse the declarative items in a package visible or 701 -- private part (in which case Declare_Expression is False), and 702 -- the declare_items of a declare_expression (in which case 703 -- Declare_Expression is True). Declare_Expression is used to 704 -- affect the wording of error messages, and to control style 705 -- checking. 706 707 function P_Access_Definition 708 (Null_Exclusion_Present : Boolean) return Node_Id; 709 -- Ada 2005 (AI-231/AI-254): The caller parses the null-exclusion part 710 -- and indicates if it was present 711 712 function P_Access_Type_Definition 713 (Header_Already_Parsed : Boolean := False) return Node_Id; 714 -- Ada 2005 (AI-254): The formal is used to indicate if the caller has 715 -- parsed the null_exclusion part. In this case the caller has also 716 -- removed the ACCESS token 717 718 procedure P_Component_Items (Decls : List_Id); 719 -- Scan out one or more component items and append them to the given 720 -- list. Only scans out more than one declaration in the case where the 721 -- source has a single declaration with multiple defining identifiers. 722 723 function P_Defining_Identifier (C : Id_Check := None) return Node_Id; 724 -- Scan out a defining identifier. The parameter C controls the 725 -- treatment of errors in case a reserved word is scanned. See the 726 -- declaration of this type for details. 727 728 function P_Interface_Type_Definition 729 (Abstract_Present : Boolean) return Node_Id; 730 -- Ada 2005 (AI-251): Parse the interface type definition part. Abstract 731 -- Present indicates if the reserved word "abstract" has been previously 732 -- found. It is used to report an error message because interface types 733 -- are by definition abstract tagged. We generate a record_definition 734 -- node if the list of interfaces is empty; otherwise we generate a 735 -- derived_type_definition node (the first interface in this list is the 736 -- ancestor interface). 737 738 function P_Null_Exclusion 739 (Allow_Anonymous_In_95 : Boolean := False) return Boolean; 740 -- Ada 2005 (AI-231): Parse the null-excluding part. A True result 741 -- indicates that the null-excluding part was present. 742 -- 743 -- Allow_Anonymous_In_95 is True if we are in a context that allows 744 -- anonymous access types in Ada 95, in which case "not null" is legal 745 -- if it precedes "access". 746 747 function P_Subtype_Indication 748 (Not_Null_Present : Boolean := False) return Node_Id; 749 -- Ada 2005 (AI-231): The flag Not_Null_Present indicates that the 750 -- null-excluding part has been scanned out and it was present. 751 752 function P_Range_Or_Subtype_Mark 753 (Allow_Simple_Expression : Boolean := False) return Node_Id; 754 -- Scans out a range or subtype mark, and also permits a general simple 755 -- expression if Allow_Simple_Expression is set to True. 756 757 function Init_Expr_Opt (P : Boolean := False) return Node_Id; 758 -- If an initialization expression is present (:= expression), then 759 -- it is scanned out and returned, otherwise Empty is returned if no 760 -- initialization expression is present. This procedure also handles 761 -- certain common error cases cleanly. The parameter P indicates if 762 -- a right paren can follow the expression (default = no right paren 763 -- allowed). 764 765 procedure Skip_Declaration (S : List_Id); 766 -- Used when scanning statements to skip past a misplaced declaration 767 -- The declaration is scanned out and appended to the given list. 768 -- Token is known to be a declaration token (in Token_Class_Declk) 769 -- on entry, so there definition is a declaration to be scanned. 770 771 function P_Subtype_Indication 772 (Subtype_Mark : Node_Id; 773 Not_Null_Present : Boolean := False) return Node_Id; 774 -- This version of P_Subtype_Indication is called when the caller has 775 -- already scanned out the subtype mark which is passed as a parameter. 776 -- Ada 2005 (AI-231): The flag Not_Null_Present indicates that the 777 -- null-excluding part has been scanned out and it was present. 778 779 function P_Subtype_Mark_Attribute (Type_Node : Node_Id) return Node_Id; 780 -- Parse a subtype mark attribute. The caller has already parsed the 781 -- subtype mark, which is passed in as the argument, and has checked 782 -- that the current token is apostrophe. 783 end Ch3; 784 785 ------------- 786 -- Par.Ch4 -- 787 ------------- 788 789 package Ch4 is 790 function P_Aggregate return Node_Id; 791 function P_Expression return Node_Id; 792 function P_Expression_Or_Range_Attribute return Node_Id; 793 function P_Function_Name return Node_Id; 794 function P_Name return Node_Id; 795 function P_Qualified_Simple_Name return Node_Id; 796 function P_Qualified_Simple_Name_Resync return Node_Id; 797 function P_Simple_Expression return Node_Id; 798 function P_Simple_Expression_Or_Range_Attribute return Node_Id; 799 800 function P_Expression_If_OK return Node_Id; 801 -- Scans out an expression allowing an unparenthesized case expression, 802 -- if expression, or quantified expression to appear without enclosing 803 -- parentheses. However, if such an expression is not preceded by a left 804 -- paren, and followed by a right paren, an error message will be output 805 -- noting that parenthesization is required. 806 807 function P_Expression_No_Right_Paren return Node_Id; 808 -- Scans out an expression in contexts where the expression cannot be 809 -- terminated by a right paren (gives better error recovery if an errant 810 -- right paren is found after the expression). 811 812 function P_Expression_Or_Range_Attribute_If_OK return Node_Id; 813 -- Scans out an expression or range attribute where a conditional 814 -- expression is permitted to appear without surrounding parentheses. 815 -- However, if such an expression is not preceded by a left paren, and 816 -- followed by a right paren, an error message will be output noting 817 -- that parenthesization is required. 818 819 function P_If_Expression return Node_Id; 820 -- Scans out an if expression. Called with Token pointing to the 821 -- IF keyword, and returns pointing to the terminating right paren, 822 -- semicolon or comma, but does not consume this terminating token. 823 824 function P_Qualified_Expression (Subtype_Mark : Node_Id) return Node_Id; 825 -- This routine scans out a qualified expression when the caller has 826 -- already scanned out the name and apostrophe of the construct. 827 828 function P_Quantified_Expression return Node_Id; 829 -- This routine scans out a quantified expression when the caller has 830 -- already scanned out the keyword "for" of the construct. 831 end Ch4; 832 833 ------------- 834 -- Par.Ch5 -- 835 ------------- 836 837 package Ch5 is 838 function P_Condition return Node_Id; 839 -- Scan out and return a condition. Note that an error is given if 840 -- the condition is followed by a right parenthesis. 841 842 function P_Condition (Cond : Node_Id) return Node_Id; 843 -- Similar to the above, but the caller has already scanned out the 844 -- conditional expression and passes it as an argument. This form of 845 -- the call does not check for a following right parenthesis. 846 847 function P_Iterator_Specification (Def_Id : Node_Id) return Node_Id; 848 -- Parse an iterator specification. The defining identifier has already 849 -- been scanned, as it is the common prefix between loop and iterator 850 -- specification. 851 852 function P_Loop_Parameter_Specification return Node_Id; 853 -- Used in loop constructs and quantified expressions. 854 855 function P_Sequence_Of_Statements (SS_Flags : SS_Rec) return List_Id; 856 -- The argument indicates the acceptable termination tokens. 857 -- See body in Par.Ch5 for details of the use of this parameter. 858 859 procedure Parse_Decls_Begin_End (Parent : Node_Id); 860 -- Parses declarations and handled statement sequence, setting 861 -- fields of Parent node appropriately. 862 end Ch5; 863 864 ------------- 865 -- Par.Ch6 -- 866 ------------- 867 868 package Ch6 is 869 function P_Designator return Node_Id; 870 function P_Defining_Program_Unit_Name return Node_Id; 871 function P_Formal_Part return List_Id; 872 function P_Parameter_Profile return List_Id; 873 function P_Return_Statement return Node_Id; 874 function P_Subprogram_Specification return Node_Id; 875 876 procedure P_Mode (Node : Node_Id); 877 -- Sets In_Present and/or Out_Present flags in Node scanning past IN, 878 -- OUT or IN OUT tokens in the source. 879 880 function P_Subprogram (Pf_Flags : Pf_Rec) return Node_Id; 881 -- Scans out any construct starting with either of the keywords 882 -- PROCEDURE or FUNCTION. The parameter indicates which possible 883 -- possible kinds of construct (body, spec, instantiation etc.) 884 -- are permissible in the current context. 885 end Ch6; 886 887 ------------- 888 -- Par.Ch7 -- 889 ------------- 890 891 package Ch7 is 892 function P_Package (Pf_Flags : Pf_Rec) return Node_Id; 893 -- Scans out any construct starting with the keyword PACKAGE. The 894 -- parameter indicates which possible kinds of construct (body, spec, 895 -- instantiation etc.) are permissible in the current context. 896 end Ch7; 897 898 ------------- 899 -- Par.Ch8 -- 900 ------------- 901 902 package Ch8 is 903 procedure P_Use_Clause (Item_List : List_Id); 904 end Ch8; 905 906 ------------- 907 -- Par.Ch9 -- 908 ------------- 909 910 package Ch9 is 911 function P_Abort_Statement return Node_Id; 912 function P_Abortable_Part return Node_Id; 913 function P_Accept_Statement return Node_Id; 914 function P_Delay_Statement return Node_Id; 915 function P_Entry_Body return Node_Id; 916 function P_Protected return Node_Id; 917 function P_Requeue_Statement return Node_Id; 918 function P_Select_Statement return Node_Id; 919 function P_Task return Node_Id; 920 function P_Terminate_Alternative return Node_Id; 921 end Ch9; 922 923 -------------- 924 -- Par.Ch10 -- 925 -------------- 926 927 package Ch10 is 928 function P_Compilation_Unit return Node_Id; 929 -- Note: this function scans a single compilation unit, and checks that 930 -- an end of file follows this unit, diagnosing any unexpected input as 931 -- an error, and then skipping it, so that Token is set to Tok_EOF on 932 -- return. An exception is in syntax-only mode, where multiple 933 -- compilation units are permitted. In this case, P_Compilation_Unit 934 -- does not check for end of file and there may be more compilation 935 -- units to scan. The caller can uniquely detect this situation by the 936 -- fact that Token is not set to Tok_EOF on return. 937 -- 938 -- What about multiple unit/file capability that now exists??? 939 -- 940 -- The Ignore parameter is normally set False. It is set True in the 941 -- multiple unit per file mode if we are skipping past a unit that we 942 -- are not interested in. 943 end Ch10; 944 945 -------------- 946 -- Par.Ch11 -- 947 -------------- 948 949 package Ch11 is 950 function P_Handled_Sequence_Of_Statements return Node_Id; 951 function P_Raise_Expression return Node_Id; 952 function P_Raise_Statement return Node_Id; 953 954 function Parse_Exception_Handlers return List_Id; 955 -- Parses the partial construct EXCEPTION followed by a list of 956 -- exception handlers which appears in a number of productions, and 957 -- returns the list of exception handlers. 958 end Ch11; 959 960 -------------- 961 -- Par.Ch12 -- 962 -------------- 963 964 package Ch12 is 965 function P_Generic return Node_Id; 966 function P_Generic_Actual_Part_Opt return List_Id; 967 end Ch12; 968 969 -------------- 970 -- Par.Ch13 -- 971 -------------- 972 973 package Ch13 is 974 function P_Representation_Clause return Node_Id; 975 976 function Aspect_Specifications_Present 977 (Strict : Boolean := Ada_Version < Ada_2012) return Boolean; 978 -- This function tests whether the next keyword is WITH followed by 979 -- something that looks reasonably like an aspect specification. If so, 980 -- True is returned. Otherwise False is returned. In either case control 981 -- returns with the token pointer unchanged (i.e. pointing to the WITH 982 -- token in the case where True is returned). This function takes care 983 -- of generating appropriate messages if aspect specifications appear 984 -- in versions of Ada prior to Ada 2012. The parameter strict can be 985 -- set to True, to be rather strict about considering something to be 986 -- an aspect specification. If Strict is False, then the circuitry is 987 -- rather more generous in considering something ill-formed to be an 988 -- attempt at an aspect specification. The default is more strict for 989 -- Ada versions before Ada 2012 (where aspect specifications are not 990 -- permitted). Note: this routine never checks the terminator token 991 -- for aspects so it does not matter whether the aspect specifications 992 -- are terminated by semicolon or some other character. 993 -- 994 -- Note: This function also handles the case of WHEN used where WITH 995 -- was intended, and in that case posts an error and returns True. 996 997 procedure P_Aspect_Specifications 998 (Decl : Node_Id; 999 Semicolon : Boolean := True); 1000 -- This procedure scans out a series of aspect specifications. If 1001 -- argument Semicolon is True, a terminating semicolon is also scanned. 1002 -- If this argument is False, the scan pointer is left pointing past the 1003 -- aspects and the caller must check for a proper terminator. 1004 -- 1005 -- P_Aspect_Specifications is called with the current token pointing 1006 -- to either a WITH keyword starting an aspect specification, or an 1007 -- instance of what shpould be a terminator token. In the former case, 1008 -- the aspect specifications are scanned out including the terminator 1009 -- token if it is a semicolon, and the Has_Aspect_Specifications 1010 -- flag is set in the given declaration node. A list of aspects 1011 -- is built and stored for this declaration node using a call to 1012 -- Set_Aspect_Specifications. If no WITH keyword is present, then this 1013 -- call has no effect other than scanning out the terminator if it is a 1014 -- semicolon (with the exception that it detects WHEN used in place of 1015 -- WITH). 1016 1017 -- If Decl is Error on entry, any scanned aspect specifications are 1018 -- ignored and a message is output saying aspect specifications not 1019 -- permitted here. If Decl is Empty, then scanned aspect specifications 1020 -- are also ignored, but no error message is given (this is used when 1021 -- the caller has already taken care of the error message). 1022 1023 function Get_Aspect_Specifications 1024 (Semicolon : Boolean := True) return List_Id; 1025 -- Parse a list of aspects but do not attach them to a declaration node. 1026 -- Subsidiary to P_Aspect_Specifications procedure. Used when parsing 1027 -- a subprogram specification that may be a declaration or a body. 1028 -- Semicolon has the same meaning as for P_Aspect_Specifications above. 1029 1030 function P_Code_Statement (Subtype_Mark : Node_Id) return Node_Id; 1031 -- Function to parse a code statement. The caller has scanned out 1032 -- the name to be used as the subtype mark (but has not checked that 1033 -- it is suitable for use as a subtype mark, i.e. is either an 1034 -- identifier or a selected component). The current token is an 1035 -- apostrophe and the following token is either a left paren or 1036 -- RANGE (the latter being an error to be caught by P_Code_Statement. 1037 end Ch13; 1038 1039 -- Note: the parsing for annexe J features (i.e. obsolescent features) 1040 -- is found in the logical section where these features would be if 1041 -- they were not obsolescent. In particular: 1042 1043 -- Delta constraint is parsed by P_Delta_Constraint (3.5.9) 1044 -- At clause is parsed by P_At_Clause (13.1) 1045 -- Mod clause is parsed by P_Mod_Clause (13.5.1) 1046 1047 -------------- 1048 -- Par.Endh -- 1049 -------------- 1050 1051 -- Routines for handling end lines, including scope recovery 1052 1053 package Endh is 1054 function Check_End 1055 (Decl : Node_Id := Empty; 1056 Is_Loc : Source_Ptr := No_Location) return Boolean; 1057 -- Called when an end sequence is required. In the absence of an error 1058 -- situation, Token contains Tok_End on entry, but in a missing end 1059 -- case, this may not be the case. Pop_End_Context is used to determine 1060 -- the appropriate action to be taken. The returned result is True if 1061 -- an End sequence was encountered and False if no End sequence was 1062 -- present. This occurs if the END keyword encountered was determined 1063 -- to be improper and deleted (i.e. Pop_End_Context set End_Action to 1064 -- Skip_And_Reject). Note that the END sequence includes a semicolon, 1065 -- except in the case of END RECORD, where a semicolon follows the END 1066 -- RECORD, but is not part of the record type definition itself. 1067 -- 1068 -- If Decl is non-empty, then aspect specifications are permitted 1069 -- following the end, and Decl is the declaration node with which 1070 -- these aspect specifications are to be associated. If Decl is empty, 1071 -- then aspect specifications are not permitted and will generate an 1072 -- error message. 1073 -- 1074 -- Is_Loc is set to other than the default only for the case of a 1075 -- package declaration. It points to the IS keyword of the declaration, 1076 -- and is used to specialize the error messages for misplaced aspect 1077 -- specifications in this case. Note that Decl is always Empty if Is_Loc 1078 -- is set. 1079 1080 procedure End_Skip; 1081 -- Skip past an end sequence. On entry Token contains Tok_End, and we 1082 -- we know that the end sequence is syntactically incorrect, and that 1083 -- an appropriate error message has already been posted. The mission 1084 -- is simply to position the scan pointer to be the best guess of the 1085 -- position after the end sequence. We do not issue any additional 1086 -- error messages while carrying this out. 1087 1088 procedure End_Statements 1089 (Parent : Node_Id := Empty; 1090 Decl : Node_Id := Empty; 1091 Is_Sloc : Source_Ptr := No_Location); 1092 -- Called when an end is required or expected to terminate a sequence 1093 -- of statements. The caller has already made an appropriate entry in 1094 -- the Scope.Table to describe the expected form of the end. This can 1095 -- only be used in cases where the only appropriate terminator is end. 1096 -- If Parent is non-empty, then if a correct END line is encountered, 1097 -- the End_Label field of Parent is set appropriately. 1098 -- 1099 -- If Decl is non-null, then it is a declaration node, and aspect 1100 -- specifications are permitted after the end statement. These aspect 1101 -- specifications, if present, are stored in this declaration node. 1102 -- If Decl is null, then aspect specifications are not permitted after 1103 -- the end statement. 1104 -- 1105 -- In the case where Decl is null, Is_Sloc determines the handling. If 1106 -- it is set to No_Location, then aspect specifications are ignored and 1107 -- an error message is given. Is_Sloc is used in the package declaration 1108 -- case to point to the IS, and is used to specialize the error emssages 1109 -- issued in this case. 1110 end Endh; 1111 1112 -------------- 1113 -- Par.Sync -- 1114 -------------- 1115 1116 -- These procedures are used to resynchronize after errors. Following an 1117 -- error which is not immediately locally recoverable, the exception 1118 -- Error_Resync is raised. The handler for Error_Resync typically calls 1119 -- one of these recovery procedures to resynchronize the source position 1120 -- to a point from which parsing can be restarted. 1121 1122 -- Note: these procedures output an information message that tokens are 1123 -- being skipped, but this message is output only if the option for 1124 -- Multiple_Errors_Per_Line is set in Options. 1125 1126 package Sync is 1127 procedure Resync_Choice; 1128 -- Used if an error occurs scanning a choice. The scan pointer is 1129 -- advanced to the next vertical bar, arrow, or semicolon, whichever 1130 -- comes first. We also quit if we encounter an end of file. 1131 1132 procedure Resync_Cunit; 1133 -- Synchronize to next token which could be the start of a compilation 1134 -- unit, or to the end of file token. 1135 1136 procedure Resync_Expression; 1137 -- Used if an error is detected during the parsing of an expression. 1138 -- It skips past tokens until either a token which cannot be part of 1139 -- an expression is encountered (an expression terminator), or if a 1140 -- comma or right parenthesis or vertical bar is encountered at the 1141 -- current parenthesis level (a parenthesis level counter is maintained 1142 -- to carry out this test). 1143 1144 procedure Resync_Past_Malformed_Aspect; 1145 -- Used when parsing aspect specifications to skip a malformed aspect. 1146 -- The scan pointer is positioned next to a comma, a semicolon or "is" 1147 -- when the aspect applies to a body. 1148 1149 procedure Resync_Past_Semicolon; 1150 -- Used if an error occurs while scanning a sequence of declarations. 1151 -- The scan pointer is positioned past the next semicolon and the scan 1152 -- resumes. The scan is also resumed on encountering a token which 1153 -- starts a declaration (but we make sure to skip at least one token 1154 -- in this case, to avoid getting stuck in a loop). 1155 1156 procedure Resync_Past_Semicolon_Or_To_Loop_Or_Then; 1157 -- Used if an error occurs while scanning a sequence of statements. The 1158 -- scan pointer is positioned past the next semicolon, or to the next 1159 -- occurrence of either then or loop, and the scan resumes. 1160 1161 procedure Resync_Semicolon_List; 1162 -- Used if an error occurs while scanning a parenthesized list of items 1163 -- separated by semicolons. The scan pointer is advanced to the next 1164 -- semicolon or right parenthesis at the outer parenthesis level, or 1165 -- to the next is or RETURN keyword occurrence, whichever comes first. 1166 1167 procedure Resync_To_Semicolon; 1168 -- Similar to Resync_Past_Semicolon, except that the scan pointer is 1169 -- left pointing to the semicolon rather than past it. 1170 1171 procedure Resync_To_When; 1172 -- Used when an error occurs scanning an entry index specification. The 1173 -- scan pointer is positioned to the next WHEN (or to IS or semicolon if 1174 -- either of these appear before WHEN, indicating another error has 1175 -- occurred). 1176 end Sync; 1177 1178 -------------- 1179 -- Par.Tchk -- 1180 -------------- 1181 1182 -- Routines to check for expected tokens 1183 1184 package Tchk is 1185 1186 -- Procedures with names of the form T_xxx, where Tok_xxx is a token 1187 -- name, check that the current token matches the required token, and 1188 -- if so, scan past it. If not, an error is issued indicating that 1189 -- the required token is not present (xxx expected). In most cases, the 1190 -- scan pointer is not moved in the not-found case, but there are some 1191 -- exceptions to this, see for example T_Id, where the scan pointer is 1192 -- moved across a literal appearing where an identifier is expected. 1193 1194 procedure T_Abort; 1195 procedure T_Arrow; 1196 procedure T_At; 1197 procedure T_Body; 1198 procedure T_Box; 1199 procedure T_Colon; 1200 procedure T_Colon_Equal; 1201 procedure T_Comma; 1202 procedure T_Dot_Dot; 1203 procedure T_For; 1204 procedure T_Greater_Greater; 1205 procedure T_Identifier; 1206 procedure T_In; 1207 procedure T_Is; 1208 procedure T_Left_Paren; 1209 procedure T_Loop; 1210 procedure T_Mod; 1211 procedure T_New; 1212 procedure T_Of; 1213 procedure T_Or; 1214 procedure T_Private; 1215 procedure T_Range; 1216 procedure T_Record; 1217 procedure T_Right_Bracket; 1218 procedure T_Right_Paren; 1219 procedure T_Semicolon; 1220 procedure T_Then; 1221 procedure T_Type; 1222 procedure T_Use; 1223 procedure T_When; 1224 procedure T_With; 1225 1226 -- Procedures having names of the form TF_xxx, where Tok_xxx is a token 1227 -- name check that the current token matches the required token, and 1228 -- if so, scan past it. If not, an error message is issued indicating 1229 -- that the required token is not present (xxx expected). 1230 1231 -- If the missing token is at the end of the line, then control returns 1232 -- immediately after posting the message. If there are remaining tokens 1233 -- on the current line, a search is conducted to see if the token 1234 -- appears later on the current line, as follows: 1235 1236 -- A call to Scan_Save is issued and a forward search for the token 1237 -- is carried out. If the token is found on the current line before a 1238 -- semicolon, then it is scanned out and the scan continues from that 1239 -- point. If not the scan is restored to the point where it was missing. 1240 1241 procedure TF_Arrow; 1242 procedure TF_Is; 1243 procedure TF_Loop; 1244 procedure TF_Return; 1245 procedure TF_Semicolon; 1246 procedure TF_Then; 1247 procedure TF_Use; 1248 1249 -- Procedures with names of the form U_xxx, where Tok_xxx is a token 1250 -- name, are just like the corresponding T_xxx procedures except that 1251 -- an error message, if given, is unconditional. 1252 1253 procedure U_Left_Paren; 1254 procedure U_Right_Paren; 1255 end Tchk; 1256 1257 -------------- 1258 -- Par.Util -- 1259 -------------- 1260 1261 package Util is 1262 function Bad_Spelling_Of (T : Token_Type) return Boolean; 1263 -- This function is called in an error situation. It checks if the 1264 -- current token is an identifier whose name is a plausible bad 1265 -- spelling of the given keyword token, and if so, issues an error 1266 -- message, sets Token from T, and returns True. Otherwise Token is 1267 -- unchanged, and False is returned. 1268 1269 procedure Check_Bad_Layout; 1270 -- Check for bad indentation in RM checking mode. Used for statements 1271 -- and declarations. Checks if current token is at start of line and 1272 -- is exdented from the current expected end column, and if so an 1273 -- error message is generated. 1274 1275 procedure Check_Misspelling_Of (T : Token_Type); 1276 pragma Inline (Check_Misspelling_Of); 1277 -- This is similar to the function above, except that it does not 1278 -- return a result. It is typically used in a situation where any 1279 -- identifier is an error, and it makes sense to simply convert it 1280 -- to the given token if it is a plausible misspelling of it. 1281 1282 procedure Check_95_Keyword (Token_95, Next : Token_Type); 1283 -- This routine checks if the token after the current one matches the 1284 -- Next argument. If so, the scan is backed up to the current token 1285 -- and Token_Type is changed to Token_95 after issuing an appropriate 1286 -- error message ("(Ada 83) keyword xx cannot be used"). If not, 1287 -- the scan is backed up with Token_Type unchanged. This routine 1288 -- is used to deal with an attempt to use a 95 keyword in Ada 83 1289 -- mode. The caller has typically checked that the current token, 1290 -- an identifier, matches one of the 95 keywords. 1291 1292 procedure Check_Future_Keyword; 1293 -- Emit a warning if the current token is a valid identifier in the 1294 -- language version in use, but is a reserved word in a later language 1295 -- version (unless the language version in use is Ada 83). 1296 1297 procedure Check_Simple_Expression (E : Node_Id); 1298 -- Given an expression E, that has just been scanned, so that Expr_Form 1299 -- is still set, outputs an error if E is a non-simple expression. E is 1300 -- not modified by this call. 1301 1302 procedure Check_Simple_Expression_In_Ada_83 (E : Node_Id); 1303 -- Like Check_Simple_Expression, except that the error message is only 1304 -- given when operating in Ada 83 mode, and includes "in Ada 83". 1305 1306 function Check_Subtype_Mark (Mark : Node_Id) return Node_Id; 1307 -- Called to check that a node representing a name (or call) is 1308 -- suitable for a subtype mark, i.e, that it is an identifier or 1309 -- a selected component. If so, or if it is already Error, then 1310 -- it is returned unchanged. Otherwise an error message is issued 1311 -- and Error is returned. 1312 1313 function Comma_Present return Boolean; 1314 -- Used in comma delimited lists to determine if a comma is present, or 1315 -- can reasonably be assumed to have been present (an error message is 1316 -- generated in the latter case). If True is returned, the scan has been 1317 -- positioned past the comma. If False is returned, the scan position 1318 -- is unchanged. Note that all comma-delimited lists are terminated by 1319 -- a right paren, so the only legitimate tokens when Comma_Present is 1320 -- called are right paren and comma. If some other token is found, then 1321 -- Comma_Present has the job of deciding whether it is better to pretend 1322 -- a comma was present, post a message for a missing comma and return 1323 -- True, or return False and let the caller diagnose the missing right 1324 -- parenthesis. 1325 1326 procedure Discard_Junk_Node (N : Node_Id); 1327 procedure Discard_Junk_List (L : List_Id); 1328 pragma Inline (Discard_Junk_Node); 1329 pragma Inline (Discard_Junk_List); 1330 -- These procedures do nothing at all, their effect is simply to discard 1331 -- the argument. A typical use is to skip by some junk that is not 1332 -- expected in the current context. 1333 1334 procedure Ignore (T : Token_Type); 1335 -- If current token matches T, then give an error message and skip 1336 -- past it, otherwise the call has no effect at all. T may be any 1337 -- reserved word token, or comma, left or right paren, or semicolon. 1338 1339 function Is_Reserved_Identifier (C : Id_Check := None) return Boolean; 1340 -- Test if current token is a reserved identifier. This test is based 1341 -- on the token being a keyword and being spelled in typical identifier 1342 -- style (i.e. starting with an upper case letter). The parameter C 1343 -- determines the special treatment if a reserved word is encountered 1344 -- that has the normal casing of a reserved word. 1345 1346 procedure Merge_Identifier (Prev : Node_Id; Nxt : Token_Type); 1347 -- Called when the previous token is an identifier (whose Token_Node 1348 -- value is given by Prev) to check if current token is an identifier 1349 -- that can be merged with the previous one adding an underscore. The 1350 -- merge is only attempted if the following token matches Nxt. If all 1351 -- conditions are met, an error message is issued, and the merge is 1352 -- carried out, modifying the Chars field of Prev. 1353 1354 function Missing_Semicolon_On_When return Boolean; 1355 -- This function deals with the following specialized situations 1356 -- 1357 -- when 'x' => 1358 -- exit/return [identifier] 1359 -- when 'y' => 1360 -- 1361 -- This looks like a messed up EXIT WHEN or RETURN WHEN, when in fact 1362 -- the problem is a missing semicolon. It is called with Token pointing 1363 -- to the WHEN token, and returns True if a semicolon is missing before 1364 -- the WHEN as in the above example. 1365 1366 function Next_Token_Is (Tok : Token_Type) return Boolean; 1367 -- Looks at token after current one and returns True if the token type 1368 -- matches Tok. The scan is unconditionally restored on return. 1369 1370 procedure No_Constraint; 1371 -- Called in a place where no constraint is allowed, but one might 1372 -- appear due to a common error (e.g. after the type mark in a procedure 1373 -- parameter. If a constraint is present, an error message is posted, 1374 -- and the constraint is scanned and discarded. 1375 1376 procedure Push_Scope_Stack; 1377 pragma Inline (Push_Scope_Stack); 1378 -- Push a new entry onto the scope stack. Scope.Last (the stack pointer) 1379 -- is incremented. The Junk field is preinitialized to False. The caller 1380 -- is expected to fill in all remaining entries of the new top stack 1381 -- entry at Scopes (Scope.Last). 1382 1383 procedure Pop_Scope_Stack; 1384 -- Pop an entry off the top of the scope stack. Scope_Last (the scope 1385 -- table stack pointer) is decremented by one. It is a fatal error to 1386 -- try to pop off the dummy entry at the bottom of the stack (i.e. 1387 -- Scope.Last must be non-zero at the time of call). 1388 1389 function Separate_Present return Boolean; 1390 -- Determines if the current token is either Tok_Separate, or an 1391 -- identifier that is a possible misspelling of "separate" followed 1392 -- by a semicolon. True is returned if so, otherwise False. 1393 1394 procedure Signal_Bad_Attribute; 1395 -- The current token is an identifier that is supposed to be an 1396 -- attribute identifier but is not. This routine posts appropriate 1397 -- error messages, including a check for a near misspelling. 1398 1399 function Token_Is_At_Start_Of_Line return Boolean; 1400 pragma Inline (Token_Is_At_Start_Of_Line); 1401 -- Determines if the current token is the first token on the line 1402 1403 function Token_Is_At_End_Of_Line return Boolean; 1404 -- Determines if the current token is the last token on the line 1405 1406 procedure Warn_If_Standard_Redefinition (N : Node_Id); 1407 -- Issues a warning if Warn_On_Standard_Redefinition is set True, and 1408 -- the Node N (which is a Defining_Identifier node with the Chars field 1409 -- set) is a renaming of an entity in package Standard. 1410 1411 end Util; 1412 1413 -------------- 1414 -- Par.Prag -- 1415 -------------- 1416 1417 -- The processing for pragmas is split off from chapter 2 1418 1419 function Prag (Pragma_Node : Node_Id; Semi : Source_Ptr) return Node_Id; 1420 -- This function is passed a tree for a pragma that has been scanned out. 1421 -- The pragma is syntactically well formed according to the general syntax 1422 -- for pragmas and the pragma identifier is for one of the recognized 1423 -- pragmas. It performs specific syntactic checks for specific pragmas. 1424 -- The result is the input node if it is OK, or Error otherwise. The 1425 -- reason that this is separated out is to facilitate the addition 1426 -- of implementation defined pragmas. The second parameter records the 1427 -- location of the semicolon following the pragma (this is needed for 1428 -- correct processing of the List and Page pragmas). The returned value 1429 -- is a copy of Pragma_Node, or Error if an error is found. Note that 1430 -- at the point where Prag is called, the right paren ending the pragma 1431 -- has been scanned out, and except in the case of pragma Style_Checks, 1432 -- so has the following semicolon. For Style_Checks, the caller delays 1433 -- the scanning of the semicolon so that it will be scanned using the 1434 -- settings from the Style_Checks pragma preceding it. 1435 1436 -------------- 1437 -- Par.Labl -- 1438 -------------- 1439 1440 procedure Labl; 1441 -- This procedure creates implicit label declarations for all labels that 1442 -- are declared in the current unit. Note that this could conceptually be 1443 -- done at the point where the labels are declared, but it is tricky to do 1444 -- it then, since the tree is not hooked up at the point where the label is 1445 -- declared (e.g. a sequence of statements is not yet attached to its 1446 -- containing scope at the point a label in the sequence is found). 1447 1448 -------------- 1449 -- Par.Load -- 1450 -------------- 1451 1452 procedure Load; 1453 -- This procedure loads all subsidiary units that are required by this 1454 -- unit, including with'ed units, specs for bodies, and parents for child 1455 -- units. It does not load bodies for inlined procedures and generics, 1456 -- since we don't know till semantic analysis is complete what is needed. 1457 1458 ----------- 1459 -- Stubs -- 1460 ----------- 1461 1462 -- The package bodies can see all routines defined in all other subpackages 1463 1464 use Ch2; 1465 use Ch3; 1466 use Ch4; 1467 use Ch5; 1468 use Ch6; 1469 use Ch7; 1470 use Ch8; 1471 use Ch9; 1472 use Ch10; 1473 use Ch11; 1474 use Ch12; 1475 use Ch13; 1476 1477 use Endh; 1478 use Tchk; 1479 use Sync; 1480 use Util; 1481 1482 package body Ch2 is separate; 1483 package body Ch3 is separate; 1484 package body Ch4 is separate; 1485 package body Ch5 is separate; 1486 package body Ch6 is separate; 1487 package body Ch7 is separate; 1488 package body Ch8 is separate; 1489 package body Ch9 is separate; 1490 package body Ch10 is separate; 1491 package body Ch11 is separate; 1492 package body Ch12 is separate; 1493 package body Ch13 is separate; 1494 1495 package body Endh is separate; 1496 package body Tchk is separate; 1497 package body Sync is separate; 1498 package body Util is separate; 1499 1500 function Prag (Pragma_Node : Node_Id; Semi : Source_Ptr) return Node_Id 1501 is separate; 1502 1503 procedure Labl is separate; 1504 procedure Load is separate; 1505 1506 Result : List_Id := Empty_List; 1507 1508-- Start of processing for Par 1509 1510begin 1511 Compiler_State := Parsing; 1512 1513 -- Deal with configuration pragmas case first 1514 1515 if Configuration_Pragmas then 1516 declare 1517 Pragmas : constant List_Id := Empty_List; 1518 P_Node : Node_Id; 1519 1520 begin 1521 loop 1522 if Token = Tok_EOF then 1523 Result := Pragmas; 1524 exit; 1525 1526 elsif Token /= Tok_Pragma then 1527 Error_Msg_SC ("only pragmas allowed in configuration file"); 1528 Result := Error_List; 1529 exit; 1530 1531 else 1532 P_Node := P_Pragma; 1533 1534 if Nkind (P_Node) = N_Pragma then 1535 1536 -- Give error if bad pragma 1537 1538 if not Is_Configuration_Pragma_Name 1539 (Pragma_Name_Unmapped (P_Node)) 1540 and then 1541 Pragma_Name_Unmapped (P_Node) /= Name_Source_Reference 1542 then 1543 if Is_Pragma_Name (Pragma_Name_Unmapped (P_Node)) then 1544 Error_Msg_N 1545 ("only configuration pragmas allowed " & 1546 "in configuration file", P_Node); 1547 else 1548 Error_Msg_N 1549 ("unrecognized pragma in configuration file", 1550 P_Node); 1551 end if; 1552 1553 -- Pragma is OK config pragma, so collect it 1554 1555 else 1556 Append (P_Node, Pragmas); 1557 end if; 1558 end if; 1559 end if; 1560 end loop; 1561 end; 1562 1563 if Config_Files_Store_Basename then 1564 Complete_Source_File_Entry; 1565 end if; 1566 1567 -- Normal case of compilation unit 1568 1569 else 1570 Save_Config_Attrs := Save_Config_Switches; 1571 1572 -- The following loop runs more than once in syntax check mode 1573 -- where we allow multiple compilation units in the same file 1574 -- and in Multiple_Unit_Per_file mode where we skip units till 1575 -- we get to the unit we want. 1576 1577 for Ucount in Pos loop 1578 Set_Config_Switches 1579 (Is_Internal_Unit (Current_Source_Unit), 1580 Main_Unit => Current_Source_Unit = Main_Unit); 1581 1582 -- Initialize scope table and other parser control variables 1583 1584 Compiler_State := Parsing; 1585 Scope.Init; 1586 Scope.Increment_Last; 1587 Scopes (0).Etyp := E_Dummy; 1588 SIS_Entry_Active := False; 1589 Last_Resync_Point := No_Location; 1590 1591 Goto_List := New_Elmt_List; 1592 Label_List := New_Elmt_List; 1593 1594 -- If in multiple unit per file mode, skip past ignored unit 1595 1596 if Ucount < Multiple_Unit_Index then 1597 1598 -- We skip in syntax check only mode, since we don't want to do 1599 -- anything more than skip past the unit and ignore it. This means 1600 -- we skip processing like setting up a unit table entry. 1601 1602 declare 1603 Save_Operating_Mode : constant Operating_Mode_Type := 1604 Operating_Mode; 1605 1606 Save_Style_Check : constant Boolean := Style_Check; 1607 1608 begin 1609 Operating_Mode := Check_Syntax; 1610 Style_Check := False; 1611 Discard_Node (P_Compilation_Unit); 1612 Operating_Mode := Save_Operating_Mode; 1613 Style_Check := Save_Style_Check; 1614 1615 -- If we are at an end of file, and not yet at the right unit, 1616 -- then we have a fatal error. The unit is missing. 1617 1618 if Token = Tok_EOF then 1619 Error_Msg_SC ("file has too few compilation units"); 1620 raise Unrecoverable_Error; 1621 end if; 1622 end; 1623 1624 -- Here if we are not skipping a file in multiple unit per file mode. 1625 -- Parse the unit that we are interested in. Note that in check 1626 -- syntax mode we are interested in all units in the file. 1627 1628 else 1629 declare 1630 Comp_Unit_Node : constant Node_Id := P_Compilation_Unit; 1631 1632 begin 1633 -- If parsing was successful and we are not in check syntax 1634 -- mode, check that language-defined units are compiled in GNAT 1635 -- mode. For this purpose we do NOT consider renamings in annex 1636 -- J as predefined. That allows users to compile their own 1637 -- versions of these files. Another exception is System.RPC 1638 -- and its children. This allows a user to supply their own 1639 -- communication layer. 1640 -- Similarly, we do not generate an error in CodePeer mode, 1641 -- to allow users to analyze third-party compiler packages. 1642 1643 if Comp_Unit_Node /= Error 1644 and then Operating_Mode = Generate_Code 1645 and then Current_Source_Unit = Main_Unit 1646 and then not GNAT_Mode 1647 and then not CodePeer_Mode 1648 then 1649 declare 1650 Uname : constant String := 1651 Get_Name_String 1652 (Unit_Name (Current_Source_Unit)); 1653 Name : String renames 1654 Uname (Uname'First .. Uname'Last - 2); 1655 -- Because Unit_Name includes "%s"/"%b", we need to strip 1656 -- the last two characters to get the real unit name. 1657 1658 begin 1659 if Name = "ada" or else 1660 Name = "interfaces" or else 1661 Name = "system" 1662 then 1663 Error_Msg 1664 ("language-defined units cannot be recompiled", 1665 Sloc (Unit (Comp_Unit_Node))); 1666 1667 elsif Name'Length > 4 1668 and then 1669 Name (Name'First .. Name'First + 3) = "ada." 1670 then 1671 Error_Msg 1672 ("user-defined descendants of package Ada " & 1673 "are not allowed", 1674 Sloc (Unit (Comp_Unit_Node))); 1675 1676 elsif Name'Length > 11 1677 and then 1678 Name (Name'First .. Name'First + 10) = "interfaces." 1679 then 1680 Error_Msg 1681 ("user-defined descendants of package Interfaces " & 1682 "are not allowed", 1683 Sloc (Unit (Comp_Unit_Node))); 1684 1685 elsif Name'Length > 7 1686 and then Name (Name'First .. Name'First + 6) = "system." 1687 and then Name /= "system.rpc" 1688 and then 1689 (Name'Length < 11 1690 or else Name (Name'First .. Name'First + 10) /= 1691 "system.rpc.") 1692 then 1693 Error_Msg 1694 ("user-defined descendants of package System " & 1695 "are not allowed", 1696 Sloc (Unit (Comp_Unit_Node))); 1697 end if; 1698 end; 1699 end if; 1700 end; 1701 1702 -- All done if at end of file 1703 1704 exit when Token = Tok_EOF; 1705 1706 -- If we are not at an end of file, it means we are in syntax 1707 -- check only mode, and we keep the loop going to parse all 1708 -- remaining units in the file. 1709 1710 end if; 1711 1712 Restore_Config_Switches (Save_Config_Attrs); 1713 end loop; 1714 1715 -- Now that we have completely parsed the source file, we can complete 1716 -- the source file table entry. 1717 1718 Complete_Source_File_Entry; 1719 1720 -- An internal error check, the scope stack should now be empty 1721 1722 pragma Assert (Scope.Last = 0); 1723 1724 -- Here we make the SCO table entries for the main unit 1725 1726 if Generate_SCO then 1727 SCO_Record_Raw (Main_Unit); 1728 end if; 1729 1730 -- Remaining steps are to create implicit label declarations and to load 1731 -- required subsidiary sources. These steps are required only if we are 1732 -- doing semantic checking. 1733 1734 if Operating_Mode /= Check_Syntax or else Debug_Flag_F then 1735 Par.Labl; 1736 Par.Load; 1737 end if; 1738 1739 -- Restore settings of switches saved on entry 1740 1741 Restore_Config_Switches (Save_Config_Attrs); 1742 Set_Comes_From_Source_Default (False); 1743 end if; 1744 1745 Compiler_State := Analyzing; 1746 Current_Source_File := No_Source_File; 1747 return Result; 1748end Par; 1749