1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- P A R -- 6-- -- 7-- B o d y -- 8-- -- 9-- Copyright (C) 1992-2015, 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 Snames; use Snames; 49with Style; 50with Stylesw; use Stylesw; 51with Table; 52with Tbuild; use Tbuild; 53 54--------- 55-- Par -- 56--------- 57 58function Par (Configuration_Pragmas : Boolean) return List_Id is 59 60 Num_Library_Units : Natural := 0; 61 -- Count number of units parsed (relevant only in syntax check only mode, 62 -- since in semantics check mode only a single unit is permitted anyway). 63 64 Save_Config_Switches : Config_Switches_Type; 65 -- Variable used to save values of config switches while we parse the 66 -- new unit, to be restored on exit for proper recursive behavior. 67 68 Loop_Block_Count : Nat := 0; 69 -- Counter used for constructing loop/block names (see the routine 70 -- Par.Ch5.Get_Loop_Block_Name). 71 72 Inside_Record_Definition : Boolean := False; 73 -- Flag set True within a record definition. Used to control warning 74 -- for redefinition of standard entities (not issued for field names). 75 76 -------------------- 77 -- Error Recovery -- 78 -------------------- 79 80 -- When an error is encountered, a call is made to one of the Error_Msg 81 -- routines to record the error. If the syntax scan is not derailed by the 82 -- error (e.g. a complaint that logical operators are inconsistent in an 83 -- EXPRESSION), then control returns from the Error_Msg call, and the 84 -- parse continues unimpeded. 85 86 -- If on the other hand, the Error_Msg represents a situation from which 87 -- the parser cannot recover locally, the exception Error_Resync is raised 88 -- immediately after the call to Error_Msg. Handlers for Error_Resync 89 -- are located at strategic points to resynchronize the parse. For example, 90 -- when an error occurs in a statement, the handler skips to the next 91 -- semicolon and continues the scan from there. 92 93 -- Each parsing procedure contains a note with the heading "Error recovery" 94 -- which shows if it can propagate the Error_Resync exception. In order 95 -- not to propagate the exception, a procedure must either contain its own 96 -- handler for this exception, or it must not call any other routines which 97 -- propagate the exception. 98 99 -- Note: the arrangement of Error_Resync handlers is such that it should 100 -- never be possible to transfer control through a procedure which made 101 -- an entry in the scope stack, invalidating the contents of the stack. 102 103 Error_Resync : exception; 104 -- Exception raised on error that is not handled locally, see above 105 106 Last_Resync_Point : Source_Ptr; 107 -- The resynchronization routines in Par.Sync run a risk of getting 108 -- stuck in an infinite loop if they do not skip a token, and the caller 109 -- keeps repeating the same resync call. On the other hand, if they skip 110 -- a token unconditionally, some recovery opportunities are missed. The 111 -- variable Last_Resync_Point records the token location previously set 112 -- by a Resync call, and if a subsequent Resync call occurs at the same 113 -- location, then the Resync routine does guarantee to skip a token. 114 115 -------------------------------------------- 116 -- Handling Semicolon Used in Place of IS -- 117 -------------------------------------------- 118 119 -- The following global variables are used in handling the error situation 120 -- of using a semicolon in place of IS in a subprogram declaration as in: 121 122 -- procedure X (Y : Integer); 123 -- Q : Integer; 124 -- begin 125 -- ... 126 -- end; 127 128 -- The two contexts in which this can appear are at the outer level, and 129 -- within a declarative region. At the outer level, we know something is 130 -- wrong as soon as we see the Q (or begin, if there are no declarations), 131 -- and we can immediately decide that the semicolon should have been IS. 132 133 -- The situation in a declarative region is more complex. The declaration 134 -- of Q could belong to the outer region, and we do not know that we have 135 -- an error until we hit the begin. It is still not clear at this point 136 -- from a syntactic point of view that something is wrong, because the 137 -- begin could belong to the enclosing subprogram or package. However, we 138 -- can incorporate a bit of semantic knowledge and note that the body of 139 -- X is missing, so we definitely DO have an error. We diagnose this error 140 -- as semicolon in place of IS on the subprogram line. 141 142 -- There are two styles for this diagnostic. If the begin immediately 143 -- follows the semicolon, then we can place a flag (IS expected) right 144 -- on the semicolon. Otherwise we do not detect the error until we hit 145 -- the begin which refers back to the line with the semicolon. 146 147 -- To control the process in the second case, the following global 148 -- variables are set to indicate that we have a subprogram declaration 149 -- whose body is required and has not yet been found. The prefix SIS 150 -- stands for "Subprogram IS" handling. 151 152 SIS_Entry_Active : Boolean := False; 153 -- Set True to indicate that an entry is active (i.e. that a subprogram 154 -- declaration has been encountered, and no body for this subprogram has 155 -- been encountered). The remaining fields are valid only if this is True. 156 157 SIS_Labl : Node_Id; 158 -- Subprogram designator 159 160 SIS_Sloc : Source_Ptr; 161 -- Source location of FUNCTION/PROCEDURE keyword 162 163 SIS_Ecol : Column_Number; 164 -- Column number of FUNCTION/PROCEDURE keyword 165 166 SIS_Semicolon_Sloc : Source_Ptr; 167 -- Source location of semicolon at end of subprogram declaration 168 169 SIS_Declaration_Node : Node_Id; 170 -- Pointer to tree node for subprogram declaration 171 172 SIS_Missing_Semicolon_Message : Error_Msg_Id; 173 -- Used to save message ID of missing semicolon message (which will be 174 -- modified to missing IS if necessary). Set to No_Error_Msg in the 175 -- normal (non-error) case. 176 177 -- Five things can happen to an active SIS entry 178 179 -- 1. If a BEGIN is encountered with an SIS entry active, then we have 180 -- exactly the situation in which we know the body of the subprogram is 181 -- missing. After posting an error message, we change the spec to a body, 182 -- rechaining the declarations that intervened between the spec and BEGIN. 183 184 -- 2. Another subprogram declaration or body is encountered. In this 185 -- case the entry gets overwritten with the information for the new 186 -- subprogram declaration. We don't catch some nested cases this way, 187 -- but it doesn't seem worth the effort. 188 189 -- 3. A nested declarative region (e.g. package declaration or package 190 -- body) is encountered. The SIS active indication is reset at the start 191 -- of such a nested region. Again, like case 2, this causes us to miss 192 -- some nested cases, but it doesn't seen worth the effort to stack and 193 -- unstack the SIS information. Maybe we will reconsider this if we ever 194 -- get a complaint about a missed case. 195 196 -- 4. We encounter a valid pragma INTERFACE or IMPORT that effectively 197 -- supplies the missing body. In this case we reset the entry. 198 199 -- 5. We encounter the end of the declarative region without encountering 200 -- a BEGIN first. In this situation we simply reset the entry. We know 201 -- that there is a missing body, but it seems more reasonable to let the 202 -- later semantic checking discover this. 203 204 ---------------------------------------------------- 205 -- Handling of Reserved Words Used as Identifiers -- 206 ---------------------------------------------------- 207 208 -- Note: throughout the parser, the terms reserved word and keyword are 209 -- used interchangeably to refer to the same set of reserved keywords 210 -- (including until, protected, etc). 211 212 -- If a reserved word is used in place of an identifier, the parser where 213 -- possible tries to recover gracefully. In particular, if the keyword is 214 -- clearly spelled using identifier casing, e.g. Until in a source program 215 -- using mixed case identifiers and lower case keywords, then the keyword 216 -- is treated as an identifier if it appears in a place where an identifier 217 -- is required. 218 219 -- The situation is more complex if the keyword is spelled with normal 220 -- keyword casing. In this case, the parser is more reluctant to consider 221 -- it to be intended as an identifier, unless it has some further 222 -- confirmation. 223 224 -- In the case of an identifier appearing in the identifier list of a 225 -- declaration, the appearance of a comma or colon right after the keyword 226 -- on the same line is taken as confirmation. For an enumeration literal, 227 -- a comma or right paren right after the identifier is also treated as 228 -- adequate confirmation. 229 230 -- The following type is used in calls to Is_Reserved_Identifier and 231 -- also to P_Defining_Identifier and P_Identifier. The default for all 232 -- these functions is that reserved words in reserved word case are not 233 -- considered to be reserved identifiers. The Id_Check value indicates 234 -- tokens, which if they appear immediately after the identifier, are 235 -- taken as confirming that the use of an identifier was expected 236 237 type Id_Check is 238 (None, 239 -- Default, no special token test 240 241 C_Comma_Right_Paren, 242 -- Consider as identifier if followed by comma or right paren 243 244 C_Comma_Colon, 245 -- Consider as identifier if followed by comma or colon 246 247 C_Do, 248 -- Consider as identifier if followed by DO 249 250 C_Dot, 251 -- Consider as identifier if followed by period 252 253 C_Greater_Greater, 254 -- Consider as identifier if followed by >> 255 256 C_In, 257 -- Consider as identifier if followed by IN 258 259 C_Is, 260 -- Consider as identifier if followed by IS 261 262 C_Left_Paren_Semicolon, 263 -- Consider as identifier if followed by left paren or semicolon 264 265 C_Use, 266 -- Consider as identifier if followed by USE 267 268 C_Vertical_Bar_Arrow); 269 -- Consider as identifier if followed by | or => 270 271 -------------------------------------------- 272 -- Handling IS Used in Place of Semicolon -- 273 -------------------------------------------- 274 275 -- This is a somewhat trickier situation, and we can't catch it in all 276 -- cases, but we do our best to detect common situations resulting from 277 -- a "cut and paste" operation which forgets to change the IS to semicolon. 278 -- Consider the following example: 279 280 -- package body X is 281 -- procedure A; 282 -- procedure B is 283 -- procedure C; 284 -- ... 285 -- procedure D is 286 -- begin 287 -- ... 288 -- end; 289 -- begin 290 -- ... 291 -- end; 292 293 -- The trouble is that the section of text from PROCEDURE B through END; 294 -- constitutes a valid procedure body, and the danger is that we find out 295 -- far too late that something is wrong (indeed most compilers will behave 296 -- uncomfortably on the above example). 297 298 -- We have two approaches to helping to control this situation. First we 299 -- make every attempt to avoid swallowing the last END; if we can be sure 300 -- that some error will result from doing so. In particular, we won't 301 -- accept the END; unless it is exactly correct (in particular it must not 302 -- have incorrect name tokens), and we won't accept it if it is immediately 303 -- followed by end of file, WITH or SEPARATE (all tokens that unmistakeably 304 -- signal the start of a compilation unit, and which therefore allow us to 305 -- reserve the END; for the outer level.) For more details on this aspect 306 -- of the handling, see package Par.Endh. 307 308 -- If we can avoid eating up the END; then the result in the absence of 309 -- any additional steps would be to post a missing END referring back to 310 -- the subprogram with the bogus IS. Similarly, if the enclosing package 311 -- has no BEGIN, then the result is a missing BEGIN message, which again 312 -- refers back to the subprogram header. 313 314 -- Such an error message is not too bad (it's already a big improvement 315 -- over what many parsers do), but it's not ideal, because the declarations 316 -- following the IS have been absorbed into the wrong scope. In the above 317 -- case, this could result for example in a bogus complaint that the body 318 -- of D was missing from the package. 319 320 -- To catch at least some of these cases, we take the following additional 321 -- steps. First, a subprogram body is marked as having a suspicious IS if 322 -- the declaration line is followed by a line which starts with a symbol 323 -- that can start a declaration in the same column, or to the left of the 324 -- column in which the FUNCTION or PROCEDURE starts (normal style is to 325 -- indent any declarations which really belong a subprogram). If such a 326 -- subprogram encounters a missing BEGIN or missing END, then we decide 327 -- that the IS should have been a semicolon, and the subprogram body node 328 -- is marked (by setting the Bad_Is_Detected flag true. Note that we do 329 -- not do this for library level procedures, only for nested procedures, 330 -- since for library level procedures, we must have a body. 331 332 -- The processing for a declarative part checks to see if the last 333 -- declaration scanned is marked in this way, and if it is, the tree 334 -- is modified to reflect the IS being interpreted as a semicolon. 335 336 --------------------------------------------------- 337 -- Parser Type Definitions and Control Variables -- 338 --------------------------------------------------- 339 340 -- The following variable and associated type declaration are used by the 341 -- expression parsing routines to return more detailed information about 342 -- the categorization of a parsed expression. 343 344 type Expr_Form_Type is ( 345 EF_Simple_Name, -- Simple name, i.e. possibly qualified identifier 346 EF_Name, -- Simple expression which could also be a name 347 EF_Simple, -- Simple expression which is not call or name 348 EF_Range_Attr, -- Range attribute reference 349 EF_Non_Simple); -- Expression that is not a simple expression 350 351 Expr_Form : Expr_Form_Type; 352 353 -- The following type is used for calls to P_Subprogram, P_Package, P_Task, 354 -- P_Protected to indicate which of several possibilities is acceptable. 355 356 type Pf_Rec is record 357 Spcn : Boolean; -- True if specification OK 358 Decl : Boolean; -- True if declaration OK 359 Gins : Boolean; -- True if generic instantiation OK 360 Pbod : Boolean; -- True if proper body OK 361 Rnam : Boolean; -- True if renaming declaration OK 362 Stub : Boolean; -- True if body stub OK 363 Pexp : Boolean; -- True if parameterized expression OK 364 Fil2 : Boolean; -- Filler to fill to 8 bits 365 end record; 366 pragma Pack (Pf_Rec); 367 368 function T return Boolean renames True; 369 function F return Boolean renames False; 370 371 Pf_Decl_Gins_Pbod_Rnam_Stub_Pexp : constant Pf_Rec := 372 Pf_Rec'(F, T, T, T, T, T, T, F); 373 Pf_Decl_Pexp : constant Pf_Rec := 374 Pf_Rec'(F, T, F, F, F, F, T, F); 375 Pf_Decl_Gins_Pbod_Rnam_Pexp : constant Pf_Rec := 376 Pf_Rec'(F, T, T, T, T, F, T, F); 377 Pf_Decl_Pbod_Pexp : constant Pf_Rec := 378 Pf_Rec'(F, T, F, T, F, F, T, F); 379 Pf_Pbod_Pexp : constant Pf_Rec := 380 Pf_Rec'(F, F, F, T, F, F, T, F); 381 Pf_Spcn : constant Pf_Rec := 382 Pf_Rec'(T, F, F, F, F, F, F, F); 383 -- The above are the only allowed values of Pf_Rec arguments 384 385 type SS_Rec is record 386 Eftm : Boolean; -- ELSIF can terminate sequence 387 Eltm : Boolean; -- ELSE can terminate sequence 388 Extm : Boolean; -- EXCEPTION can terminate sequence 389 Ortm : Boolean; -- OR can terminate sequence 390 Sreq : Boolean; -- at least one statement required 391 Tatm : Boolean; -- THEN ABORT can terminate sequence 392 Whtm : Boolean; -- WHEN can terminate sequence 393 Unco : Boolean; -- Unconditional terminate after one statement 394 end record; 395 pragma Pack (SS_Rec); 396 397 SS_Eftm_Eltm_Sreq : constant SS_Rec := SS_Rec'(T, T, F, F, T, F, F, F); 398 SS_Eltm_Ortm_Tatm : constant SS_Rec := SS_Rec'(F, T, F, T, F, T, F, F); 399 SS_Extm_Sreq : constant SS_Rec := SS_Rec'(F, F, T, F, T, F, F, F); 400 SS_None : constant SS_Rec := SS_Rec'(F, F, F, F, F, F, F, F); 401 SS_Ortm_Sreq : constant SS_Rec := SS_Rec'(F, F, F, T, T, F, F, F); 402 SS_Sreq : constant SS_Rec := SS_Rec'(F, F, F, F, T, F, F, F); 403 SS_Sreq_Whtm : constant SS_Rec := SS_Rec'(F, F, F, F, T, F, T, F); 404 SS_Whtm : constant SS_Rec := SS_Rec'(F, F, F, F, F, F, T, F); 405 SS_Unco : constant SS_Rec := SS_Rec'(F, F, F, F, F, F, F, T); 406 407 Goto_List : Elist_Id; 408 -- List of goto nodes appearing in the current compilation. Used to 409 -- recognize natural loops and convert them into bona fide loops for 410 -- optimization purposes. 411 412 Label_List : Elist_Id; 413 -- List of label nodes for labels appearing in the current compilation. 414 -- Used by Par.Labl to construct the corresponding implicit declarations. 415 416 ----------------- 417 -- Scope Table -- 418 ----------------- 419 420 -- The scope table, also referred to as the scope stack, is used to record 421 -- the current scope context. It is organized as a stack, with inner nested 422 -- entries corresponding to higher entries on the stack. An entry is made 423 -- when the parser encounters the opening of a nested construct (such as a 424 -- record, task, package etc.), and then package Par.Endh uses this stack 425 -- to deal with END lines (including properly dealing with END nesting 426 -- errors). 427 428 type SS_End_Type is 429 -- Type of end entry required for this scope. The last two entries are 430 -- used only in the subprogram body case to mark the case of a suspicious 431 -- IS, or a bad IS (i.e. suspicions confirmed by missing BEGIN or END). 432 -- See separate section on dealing with IS used in place of semicolon. 433 -- Note that for many purposes E_Name, E_Suspicious_Is and E_Bad_Is are 434 -- treated the same (E_Suspicious_Is and E_Bad_Is are simply special cases 435 -- of E_Name). They are placed at the end of the enumeration so that a 436 -- test for >= E_Name catches all three cases efficiently. 437 438 (E_Dummy, -- dummy entry at outer level 439 E_Case, -- END CASE; 440 E_If, -- END IF; 441 E_Loop, -- END LOOP; 442 E_Record, -- END RECORD; 443 E_Return, -- END RETURN; 444 E_Select, -- END SELECT; 445 E_Name, -- END [name]; 446 E_Suspicious_Is, -- END [name]; (case of suspicious IS) 447 E_Bad_Is); -- END [name]; (case of bad IS) 448 449 -- The following describes a single entry in the scope table 450 451 type Scope_Table_Entry is record 452 Etyp : SS_End_Type; 453 -- Type of end entry, as per above description 454 455 Lreq : Boolean; 456 -- A flag indicating whether the label, if present, is required to 457 -- appear on the end line. It is referenced only in the case of Etyp is 458 -- equal to E_Name or E_Suspicious_Is where the name may or may not be 459 -- required (yes for labeled block, no in other cases). Note that for 460 -- all cases except begin, the question of whether a label is required 461 -- can be determined from the other fields (for loop, it is required if 462 -- it is present, and for the other constructs it is never required or 463 -- allowed). 464 465 Ecol : Column_Number; 466 -- Contains the absolute column number (with tabs expanded) of the 467 -- expected column of the end assuming normal Ada indentation usage. If 468 -- the RM_Column_Check mode is set, this value is used for generating 469 -- error messages about indentation. Otherwise it is used only to 470 -- control heuristic error recovery actions. This value is zero origin. 471 472 Labl : Node_Id; 473 -- This field is used to provide the name of the construct being parsed 474 -- and indirectly its kind. For loops and blocks, the field contains the 475 -- source name or the generated one. For package specifications, bodies, 476 -- subprogram specifications and bodies the field holds the correponding 477 -- program unit name. For task declarations and bodies, protected types 478 -- and bodies, and accept statements the field hold the name of the type 479 -- or operation. For if-statements, case-statements, and selects, the 480 -- field is initialized to Error. 481 482 -- Note: this is a bit of an odd (mis)use of Error, since there is no 483 -- Error, but we use this value as a place holder to indicate that it 484 -- is an error to have a label on the end line. 485 486 -- Whenever the field is a name, it is attached to the parent node of 487 -- the construct being parsed. Thus the parent node indicates the kind 488 -- of construct whose parse tree is being built. This is used in error 489 -- recovery. 490 491 Decl : List_Id; 492 -- Points to the list of declarations (i.e. the declarative part) 493 -- associated with this construct. It is set only in the END [name] 494 -- cases, and is set to No_List for all other cases which do not have a 495 -- declarative unit associated with them. This is used for determining 496 -- the proper location for implicit label declarations. 497 498 Node : Node_Id; 499 -- Empty except in the case of entries for IF and CASE statements, in 500 -- which case it contains the N_If_Statement or N_Case_Statement node. 501 -- This is used for setting the End_Span field. 502 503 Sloc : Source_Ptr; 504 -- Source location of the opening token of the construct. This is used 505 -- to refer back to this line in error messages (such as missing or 506 -- incorrect end lines). The Sloc field is not used, and is not set, if 507 -- a label is present (the Labl field provides the text name of the 508 -- label in this case, which is fine for error messages). 509 510 S_Is : Source_Ptr; 511 -- S_Is is relevant only if Etyp is set to E_Suspicious_Is or E_Bad_Is. 512 -- It records the location of the IS that is considered to be 513 -- suspicious. 514 515 Junk : Boolean; 516 -- A boolean flag that is set true if the opening entry is the dubious 517 -- result of some prior error, e.g. a record entry where the record 518 -- keyword was missing. It is used to suppress the issuing of a 519 -- corresponding junk complaint about the end line (we do not want 520 -- to complain about a missing end record when there was no record). 521 end record; 522 523 -- The following declares the scope table itself. The Last field is the 524 -- stack pointer, so that Scope.Table (Scope.Last) is the top entry. The 525 -- oldest entry, at Scope_Stack (0), is a dummy entry with Etyp set to 526 -- E_Dummy, and the other fields undefined. This dummy entry ensures that 527 -- Scope_Stack (Scope_Stack_Ptr).Etyp can always be tested, and that the 528 -- scope stack pointer is always in range. 529 530 package Scope is new Table.Table ( 531 Table_Component_Type => Scope_Table_Entry, 532 Table_Index_Type => Int, 533 Table_Low_Bound => 0, 534 Table_Initial => 50, 535 Table_Increment => 100, 536 Table_Name => "Scope"); 537 538 ------------------------------------------ 539 -- Table for Handling Suspicious Labels -- 540 ------------------------------------------ 541 542 -- This is a special data structure which is used to deal very spefifically 543 -- with the following error case 544 545 -- label; 546 -- loop 547 -- ... 548 -- end loop label; 549 550 -- Similar cases apply to FOR, WHILE, DECLARE, or BEGIN 551 552 -- In each case the opening line looks like a procedure call because of 553 -- the semicolon. And the end line looks illegal because of an unexpected 554 -- label. If we did nothing special, we would just diagnose the label on 555 -- the end as unexpected. But that does not help point to the real error 556 -- which is that the semicolon after label should be a colon. 557 558 -- To deal with this, we build an entry in the Suspicious_Labels table 559 -- whenever we encounter an identifier followed by a semicolon, followed 560 -- by one of LOOP, FOR, WHILE, DECLARE, BEGIN. Then this entry is used to 561 -- issue the right message when we hit the END that confirms that this was 562 -- a bad label. 563 564 type Suspicious_Label_Entry is record 565 Proc_Call : Node_Id; 566 -- Node for the procedure call statement built for the label; construct 567 568 Semicolon_Loc : Source_Ptr; 569 -- Location of the possibly wrong semicolon 570 571 Start_Token : Source_Ptr; 572 -- Source location of the LOOP, FOR, WHILE, DECLARE, BEGIN token 573 end record; 574 575 package Suspicious_Labels is new Table.Table ( 576 Table_Component_Type => Suspicious_Label_Entry, 577 Table_Index_Type => Int, 578 Table_Low_Bound => 1, 579 Table_Initial => 50, 580 Table_Increment => 100, 581 Table_Name => "Suspicious_Labels"); 582 583 -- Now when we are about to issue a message complaining about an END label 584 -- that should not be there because it appears to end a construct that has 585 -- no label, we first search the suspicious labels table entry, using the 586 -- source location stored in the scope table as a key. If we find a match, 587 -- then we check that the label on the end matches the name in the call, 588 -- and if so, we issue a message saying the semicolon should be a colon. 589 590 -- Quite a bit of work, but really helpful in the case where it helps, and 591 -- the need for this is based on actual experience with tracking down this 592 -- kind of error (the eye often easily mistakes semicolon for colon). 593 594 -- Note: we actually have enough information to patch up the tree, but 595 -- this may not be worth the effort. Also we could deal with the same 596 -- situation for EXIT with a label, but for now don't bother with that. 597 598 --------------------------------- 599 -- Parsing Routines by Chapter -- 600 --------------------------------- 601 602 -- Uncommented declarations in this section simply parse the construct 603 -- corresponding to their name, and return an ID value for the Node or 604 -- List that is created. 605 606 ------------- 607 -- Par.Ch2 -- 608 ------------- 609 610 package Ch2 is 611 function P_Pragma (Skipping : Boolean := False) return Node_Id; 612 -- Scan out a pragma. If Skipping is True, then the caller is skipping 613 -- the pragma in the context of illegal placement (this is used to avoid 614 -- some junk cascaded messages). Some pragmas must be dealt with during 615 -- the parsing phase (e.g. pragma Page, since we can generate a listing 616 -- in syntax only mode). It is possible that the parser uses the rescan 617 -- logic (using Save/Restore_Scan_State) with the effect of calling this 618 -- procedure more than once for the same pragma. All parse-time pragma 619 -- handling must be prepared to handle such multiple calls correctly. 620 621 function P_Identifier (C : Id_Check := None) return Node_Id; 622 -- Scans out an identifier. The parameter C determines the treatment 623 -- of reserved identifiers. See declaration of Id_Check for details. 624 625 function P_Pragmas_Opt return List_Id; 626 -- This function scans for a sequence of pragmas in other than a 627 -- declaration sequence or statement sequence context. All pragmas 628 -- can appear except pragmas Assert and Debug, which are only allowed 629 -- in a declaration or statement sequence context. 630 631 procedure P_Pragmas_Misplaced; 632 -- Skips misplaced pragmas with a complaint 633 634 procedure P_Pragmas_Opt (List : List_Id); 635 -- Parses optional pragmas and appends them to the List 636 end Ch2; 637 638 ------------- 639 -- Par.Ch3 -- 640 ------------- 641 642 package Ch3 is 643 Missing_Begin_Msg : Error_Msg_Id; 644 -- This variable is set by a call to P_Declarative_Part. Normally it 645 -- is set to No_Error_Msg, indicating that no special processing is 646 -- required by the caller. The special case arises when a statement 647 -- is found in the sequence of declarations. In this case the Id of 648 -- the message issued ("declaration expected") is preserved in this 649 -- variable, then the caller can change it to an appropriate missing 650 -- begin message if indeed the BEGIN is missing. 651 652 function P_Array_Type_Definition return Node_Id; 653 function P_Basic_Declarative_Items return List_Id; 654 function P_Constraint_Opt return Node_Id; 655 function P_Declarative_Part return List_Id; 656 function P_Discrete_Choice_List return List_Id; 657 function P_Discrete_Range return Node_Id; 658 function P_Discrete_Subtype_Definition return Node_Id; 659 function P_Known_Discriminant_Part_Opt return List_Id; 660 function P_Signed_Integer_Type_Definition return Node_Id; 661 function P_Range return Node_Id; 662 function P_Range_Constraint return Node_Id; 663 function P_Record_Definition return Node_Id; 664 function P_Subtype_Mark return Node_Id; 665 function P_Subtype_Mark_Resync return Node_Id; 666 function P_Unknown_Discriminant_Part_Opt return Boolean; 667 668 function P_Access_Definition 669 (Null_Exclusion_Present : Boolean) return Node_Id; 670 -- Ada 2005 (AI-231/AI-254): The caller parses the null-exclusion part 671 -- and indicates if it was present 672 673 function P_Access_Type_Definition 674 (Header_Already_Parsed : Boolean := False) return Node_Id; 675 -- Ada 2005 (AI-254): The formal is used to indicate if the caller has 676 -- parsed the null_exclusion part. In this case the caller has also 677 -- removed the ACCESS token 678 679 procedure P_Component_Items (Decls : List_Id); 680 -- Scan out one or more component items and append them to the given 681 -- list. Only scans out more than one declaration in the case where the 682 -- source has a single declaration with multiple defining identifiers. 683 684 function P_Defining_Identifier (C : Id_Check := None) return Node_Id; 685 -- Scan out a defining identifier. The parameter C controls the 686 -- treatment of errors in case a reserved word is scanned. See the 687 -- declaration of this type for details. 688 689 function P_Interface_Type_Definition 690 (Abstract_Present : Boolean) return Node_Id; 691 -- Ada 2005 (AI-251): Parse the interface type definition part. Abstract 692 -- Present indicates if the reserved word "abstract" has been previously 693 -- found. It is used to report an error message because interface types 694 -- are by definition abstract tagged. We generate a record_definition 695 -- node if the list of interfaces is empty; otherwise we generate a 696 -- derived_type_definition node (the first interface in this list is the 697 -- ancestor interface). 698 699 function P_Null_Exclusion 700 (Allow_Anonymous_In_95 : Boolean := False) return Boolean; 701 -- Ada 2005 (AI-231): Parse the null-excluding part. A True result 702 -- indicates that the null-excluding part was present. 703 -- 704 -- Allow_Anonymous_In_95 is True if we are in a context that allows 705 -- anonymous access types in Ada 95, in which case "not null" is legal 706 -- if it precedes "access". 707 708 function P_Subtype_Indication 709 (Not_Null_Present : Boolean := False) return Node_Id; 710 -- Ada 2005 (AI-231): The flag Not_Null_Present indicates that the 711 -- null-excluding part has been scanned out and it was present. 712 713 function P_Range_Or_Subtype_Mark 714 (Allow_Simple_Expression : Boolean := False) return Node_Id; 715 -- Scans out a range or subtype mark, and also permits a general simple 716 -- expression if Allow_Simple_Expression is set to True. 717 718 function Init_Expr_Opt (P : Boolean := False) return Node_Id; 719 -- If an initialization expression is present (:= expression), then 720 -- it is scanned out and returned, otherwise Empty is returned if no 721 -- initialization expression is present. This procedure also handles 722 -- certain common error cases cleanly. The parameter P indicates if 723 -- a right paren can follow the expression (default = no right paren 724 -- allowed). 725 726 procedure Skip_Declaration (S : List_Id); 727 -- Used when scanning statements to skip past a misplaced declaration 728 -- The declaration is scanned out and appended to the given list. 729 -- Token is known to be a declaration token (in Token_Class_Declk) 730 -- on entry, so there definition is a declaration to be scanned. 731 732 function P_Subtype_Indication 733 (Subtype_Mark : Node_Id; 734 Not_Null_Present : Boolean := False) return Node_Id; 735 -- This version of P_Subtype_Indication is called when the caller has 736 -- already scanned out the subtype mark which is passed as a parameter. 737 -- Ada 2005 (AI-231): The flag Not_Null_Present indicates that the 738 -- null-excluding part has been scanned out and it was present. 739 740 function P_Subtype_Mark_Attribute (Type_Node : Node_Id) return Node_Id; 741 -- Parse a subtype mark attribute. The caller has already parsed the 742 -- subtype mark, which is passed in as the argument, and has checked 743 -- that the current token is apostrophe. 744 end Ch3; 745 746 ------------- 747 -- Par.Ch4 -- 748 ------------- 749 750 package Ch4 is 751 function P_Aggregate return Node_Id; 752 function P_Expression return Node_Id; 753 function P_Expression_Or_Range_Attribute return Node_Id; 754 function P_Function_Name return Node_Id; 755 function P_Name return Node_Id; 756 function P_Qualified_Simple_Name return Node_Id; 757 function P_Qualified_Simple_Name_Resync return Node_Id; 758 function P_Simple_Expression return Node_Id; 759 function P_Simple_Expression_Or_Range_Attribute return Node_Id; 760 761 function P_Case_Expression return Node_Id; 762 -- Scans out a case expression. Called with Token pointing to the CASE 763 -- keyword, and returns pointing to the terminating right parent, 764 -- semicolon, or comma, but does not consume this terminating token. 765 766 function P_Expression_If_OK return Node_Id; 767 -- Scans out an expression allowing an unparenthesized case expression, 768 -- if expression, or quantified expression to appear without enclosing 769 -- parentheses. However, if such an expression is not preceded by a left 770 -- paren, and followed by a right paren, an error message will be output 771 -- noting that parenthesization is required. 772 773 function P_Expression_No_Right_Paren return Node_Id; 774 -- Scans out an expression in contexts where the expression cannot be 775 -- terminated by a right paren (gives better error recovery if an errant 776 -- right paren is found after the expression). 777 778 function P_Expression_Or_Range_Attribute_If_OK return Node_Id; 779 -- Scans out an expression or range attribute where a conditional 780 -- expression is permitted to appear without surrounding parentheses. 781 -- However, if such an expression is not preceded by a left paren, and 782 -- followed by a right paren, an error message will be output noting 783 -- that parenthesization is required. 784 785 function P_If_Expression return Node_Id; 786 -- Scans out an if expression. Called with Token pointing to the 787 -- IF keyword, and returns pointing to the terminating right paren, 788 -- semicolon or comma, but does not consume this terminating token. 789 790 function P_Qualified_Expression (Subtype_Mark : Node_Id) return Node_Id; 791 -- This routine scans out a qualified expression when the caller has 792 -- already scanned out the name and apostrophe of the construct. 793 794 function P_Quantified_Expression return Node_Id; 795 -- This routine scans out a quantified expression when the caller has 796 -- already scanned out the keyword "for" of the construct. 797 end Ch4; 798 799 ------------- 800 -- Par.Ch5 -- 801 ------------- 802 803 package Ch5 is 804 function P_Condition return Node_Id; 805 -- Scan out and return a condition. Note that an error is given if 806 -- the condition is followed by a right parenthesis. 807 808 function P_Condition (Cond : Node_Id) return Node_Id; 809 -- Similar to the above, but the caller has already scanned out the 810 -- conditional expression and passes it as an argument. This form of 811 -- the call does not check for a following right parenthesis. 812 813 function P_Loop_Parameter_Specification return Node_Id; 814 -- Used in loop constructs and quantified expressions. 815 816 function P_Sequence_Of_Statements (SS_Flags : SS_Rec) return List_Id; 817 -- The argument indicates the acceptable termination tokens. 818 -- See body in Par.Ch5 for details of the use of this parameter. 819 820 procedure Parse_Decls_Begin_End (Parent : Node_Id); 821 -- Parses declarations and handled statement sequence, setting 822 -- fields of Parent node appropriately. 823 end Ch5; 824 825 ------------- 826 -- Par.Ch6 -- 827 ------------- 828 829 package Ch6 is 830 function P_Designator return Node_Id; 831 function P_Defining_Program_Unit_Name return Node_Id; 832 function P_Formal_Part return List_Id; 833 function P_Parameter_Profile return List_Id; 834 function P_Return_Statement return Node_Id; 835 function P_Subprogram_Specification return Node_Id; 836 837 procedure P_Mode (Node : Node_Id); 838 -- Sets In_Present and/or Out_Present flags in Node scanning past IN, 839 -- OUT or IN OUT tokens in the source. 840 841 function P_Subprogram (Pf_Flags : Pf_Rec) return Node_Id; 842 -- Scans out any construct starting with either of the keywords 843 -- PROCEDURE or FUNCTION. The parameter indicates which possible 844 -- possible kinds of construct (body, spec, instantiation etc.) 845 -- are permissible in the current context. 846 end Ch6; 847 848 ------------- 849 -- Par.Ch7 -- 850 ------------- 851 852 package Ch7 is 853 function P_Package (Pf_Flags : Pf_Rec) return Node_Id; 854 -- Scans out any construct starting with the keyword PACKAGE. The 855 -- parameter indicates which possible kinds of construct (body, spec, 856 -- instantiation etc.) are permissible in the current context. 857 end Ch7; 858 859 ------------- 860 -- Par.Ch8 -- 861 ------------- 862 863 package Ch8 is 864 function P_Use_Clause return Node_Id; 865 end Ch8; 866 867 ------------- 868 -- Par.Ch9 -- 869 ------------- 870 871 package Ch9 is 872 function P_Abort_Statement return Node_Id; 873 function P_Abortable_Part return Node_Id; 874 function P_Accept_Statement return Node_Id; 875 function P_Delay_Statement return Node_Id; 876 function P_Entry_Body return Node_Id; 877 function P_Protected return Node_Id; 878 function P_Requeue_Statement return Node_Id; 879 function P_Select_Statement return Node_Id; 880 function P_Task return Node_Id; 881 function P_Terminate_Alternative return Node_Id; 882 end Ch9; 883 884 -------------- 885 -- Par.Ch10 -- 886 -------------- 887 888 package Ch10 is 889 function P_Compilation_Unit return Node_Id; 890 -- Note: this function scans a single compilation unit, and checks that 891 -- an end of file follows this unit, diagnosing any unexpected input as 892 -- an error, and then skipping it, so that Token is set to Tok_EOF on 893 -- return. An exception is in syntax-only mode, where multiple 894 -- compilation units are permitted. In this case, P_Compilation_Unit 895 -- does not check for end of file and there may be more compilation 896 -- units to scan. The caller can uniquely detect this situation by the 897 -- fact that Token is not set to Tok_EOF on return. 898 -- 899 -- What about multiple unit/file capability that now exists??? 900 -- 901 -- The Ignore parameter is normally set False. It is set True in the 902 -- multiple unit per file mode if we are skipping past a unit that we 903 -- are not interested in. 904 end Ch10; 905 906 -------------- 907 -- Par.Ch11 -- 908 -------------- 909 910 package Ch11 is 911 function P_Handled_Sequence_Of_Statements return Node_Id; 912 function P_Raise_Expression return Node_Id; 913 function P_Raise_Statement return Node_Id; 914 915 function Parse_Exception_Handlers return List_Id; 916 -- Parses the partial construct EXCEPTION followed by a list of 917 -- exception handlers which appears in a number of productions, and 918 -- returns the list of exception handlers. 919 end Ch11; 920 921 -------------- 922 -- Par.Ch12 -- 923 -------------- 924 925 package Ch12 is 926 function P_Generic return Node_Id; 927 function P_Generic_Actual_Part_Opt return List_Id; 928 end Ch12; 929 930 -------------- 931 -- Par.Ch13 -- 932 -------------- 933 934 package Ch13 is 935 function P_Representation_Clause return Node_Id; 936 937 function Aspect_Specifications_Present 938 (Strict : Boolean := Ada_Version < Ada_2012) return Boolean; 939 -- This function tests whether the next keyword is WITH followed by 940 -- something that looks reasonably like an aspect specification. If so, 941 -- True is returned. Otherwise False is returned. In either case control 942 -- returns with the token pointer unchanged (i.e. pointing to the WITH 943 -- token in the case where True is returned). This function takes care 944 -- of generating appropriate messages if aspect specifications appear 945 -- in versions of Ada prior to Ada 2012. The parameter strict can be 946 -- set to True, to be rather strict about considering something to be 947 -- an aspect specification. If Strict is False, then the circuitry is 948 -- rather more generous in considering something ill-formed to be an 949 -- attempt at an aspect specification. The default is more strict for 950 -- Ada versions before Ada 2012 (where aspect specifications are not 951 -- permitted). Note: this routine never checks the terminator token 952 -- for aspects so it does not matter whether the aspect specifications 953 -- are terminated by semicolon or some other character. 954 -- 955 -- Note: This function also handles the case of WHEN used where WITH 956 -- was intended, and in that case posts an error and returns True. 957 958 procedure P_Aspect_Specifications 959 (Decl : Node_Id; 960 Semicolon : Boolean := True); 961 -- This procedure scans out a series of aspect spefications. If argument 962 -- Semicolon is True, a terminating semicolon is also scanned. If this 963 -- argument is False, the scan pointer is left pointing past the aspects 964 -- and the caller must check for a proper terminator. 965 -- 966 -- P_Aspect_Specifications is called with the current token pointing 967 -- to either a WITH keyword starting an aspect specification, or an 968 -- instance of what shpould be a terminator token. In the former case, 969 -- the aspect specifications are scanned out including the terminator 970 -- token if it is a semicolon, and the Has_Aspect_Specifications 971 -- flag is set in the given declaration node. A list of aspects 972 -- is built and stored for this declaration node using a call to 973 -- Set_Aspect_Specifications. If no WITH keyword is present, then this 974 -- call has no effect other than scanning out the terminator if it is a 975 -- semicolon (with the exception that it detects WHEN used in place of 976 -- WITH). 977 978 -- If Decl is Error on entry, any scanned aspect specifications are 979 -- ignored and a message is output saying aspect specifications not 980 -- permitted here. If Decl is Empty, then scanned aspect specifications 981 -- are also ignored, but no error message is given (this is used when 982 -- the caller has already taken care of the error message). 983 984 function Get_Aspect_Specifications 985 (Semicolon : Boolean := True) return List_Id; 986 -- Parse a list of aspects but do not attach them to a declaration node. 987 -- Subsidiary to P_Aspect_Specifications procedure. Used when parsing 988 -- a subprogram specification that may be a declaration or a body. 989 -- Semicolon has the same meaning as for P_Aspect_Specifications above. 990 991 function P_Code_Statement (Subtype_Mark : Node_Id) return Node_Id; 992 -- Function to parse a code statement. The caller has scanned out 993 -- the name to be used as the subtype mark (but has not checked that 994 -- it is suitable for use as a subtype mark, i.e. is either an 995 -- identifier or a selected component). The current token is an 996 -- apostrophe and the following token is either a left paren or 997 -- RANGE (the latter being an error to be caught by P_Code_Statement. 998 end Ch13; 999 1000 -- Note: the parsing for annexe J features (i.e. obsolescent features) 1001 -- is found in the logical section where these features would be if 1002 -- they were not obsolescent. In particular: 1003 1004 -- Delta constraint is parsed by P_Delta_Constraint (3.5.9) 1005 -- At clause is parsed by P_At_Clause (13.1) 1006 -- Mod clause is parsed by P_Mod_Clause (13.5.1) 1007 1008 -------------- 1009 -- Par.Endh -- 1010 -------------- 1011 1012 -- Routines for handling end lines, including scope recovery 1013 1014 package Endh is 1015 function Check_End 1016 (Decl : Node_Id := Empty; 1017 Is_Loc : Source_Ptr := No_Location) return Boolean; 1018 -- Called when an end sequence is required. In the absence of an error 1019 -- situation, Token contains Tok_End on entry, but in a missing end 1020 -- case, this may not be the case. Pop_End_Context is used to determine 1021 -- the appropriate action to be taken. The returned result is True if 1022 -- an End sequence was encountered and False if no End sequence was 1023 -- present. This occurs if the END keyword encountered was determined 1024 -- to be improper and deleted (i.e. Pop_End_Context set End_Action to 1025 -- Skip_And_Reject). Note that the END sequence includes a semicolon, 1026 -- except in the case of END RECORD, where a semicolon follows the END 1027 -- RECORD, but is not part of the record type definition itself. 1028 -- 1029 -- If Decl is non-empty, then aspect specifications are permitted 1030 -- following the end, and Decl is the declaration node with which 1031 -- these aspect specifications are to be associated. If Decl is empty, 1032 -- then aspect specifications are not permitted and will generate an 1033 -- error message. 1034 -- 1035 -- Is_Loc is set to other than the default only for the case of a 1036 -- package declaration. It points to the IS keyword of the declaration, 1037 -- and is used to specialize the error messages for misplaced aspect 1038 -- specifications in this case. Note that Decl is always Empty if Is_Loc 1039 -- is set. 1040 1041 procedure End_Skip; 1042 -- Skip past an end sequence. On entry Token contains Tok_End, and we 1043 -- we know that the end sequence is syntactically incorrect, and that 1044 -- an appropriate error message has already been posted. The mission 1045 -- is simply to position the scan pointer to be the best guess of the 1046 -- position after the end sequence. We do not issue any additional 1047 -- error messages while carrying this out. 1048 1049 procedure End_Statements 1050 (Parent : Node_Id := Empty; 1051 Decl : Node_Id := Empty; 1052 Is_Sloc : Source_Ptr := No_Location); 1053 -- Called when an end is required or expected to terminate a sequence 1054 -- of statements. The caller has already made an appropriate entry in 1055 -- the Scope.Table to describe the expected form of the end. This can 1056 -- only be used in cases where the only appropriate terminator is end. 1057 -- If Parent is non-empty, then if a correct END line is encountered, 1058 -- the End_Label field of Parent is set appropriately. 1059 -- 1060 -- If Decl is non-null, then it is a declaration node, and aspect 1061 -- specifications are permitted after the end statement. These aspect 1062 -- specifications, if present, are stored in this declaration node. 1063 -- If Decl is null, then aspect specifications are not permitted after 1064 -- the end statement. 1065 -- 1066 -- In the case where Decl is null, Is_Sloc determines the handling. If 1067 -- it is set to No_Location, then aspect specifications are ignored and 1068 -- an error message is given. Is_Sloc is used in the package declaration 1069 -- case to point to the IS, and is used to specialize the error emssages 1070 -- issued in this case. 1071 end Endh; 1072 1073 -------------- 1074 -- Par.Sync -- 1075 -------------- 1076 1077 -- These procedures are used to resynchronize after errors. Following an 1078 -- error which is not immediately locally recoverable, the exception 1079 -- Error_Resync is raised. The handler for Error_Resync typically calls 1080 -- one of these recovery procedures to resynchronize the source position 1081 -- to a point from which parsing can be restarted. 1082 1083 -- Note: these procedures output an information message that tokens are 1084 -- being skipped, but this message is output only if the option for 1085 -- Multiple_Errors_Per_Line is set in Options. 1086 1087 package Sync is 1088 procedure Resync_Choice; 1089 -- Used if an error occurs scanning a choice. The scan pointer is 1090 -- advanced to the next vertical bar, arrow, or semicolon, whichever 1091 -- comes first. We also quit if we encounter an end of file. 1092 1093 procedure Resync_Cunit; 1094 -- Synchronize to next token which could be the start of a compilation 1095 -- unit, or to the end of file token. 1096 1097 procedure Resync_Expression; 1098 -- Used if an error is detected during the parsing of an expression. 1099 -- It skips past tokens until either a token which cannot be part of 1100 -- an expression is encountered (an expression terminator), or if a 1101 -- comma or right parenthesis or vertical bar is encountered at the 1102 -- current parenthesis level (a parenthesis level counter is maintained 1103 -- to carry out this test). 1104 1105 procedure Resync_Past_Malformed_Aspect; 1106 -- Used when parsing aspect specifications to skip a malformed aspect. 1107 -- The scan pointer is positioned next to a comma, a semicolon or "is" 1108 -- when the aspect applies to a body. 1109 1110 procedure Resync_Past_Semicolon; 1111 -- Used if an error occurs while scanning a sequence of declarations. 1112 -- The scan pointer is positioned past the next semicolon and the scan 1113 -- resumes. The scan is also resumed on encountering a token which 1114 -- starts a declaration (but we make sure to skip at least one token 1115 -- in this case, to avoid getting stuck in a loop). 1116 1117 procedure Resync_Past_Semicolon_Or_To_Loop_Or_Then; 1118 -- Used if an error occurs while scanning a sequence of statements. The 1119 -- scan pointer is positioned past the next semicolon, or to the next 1120 -- occurrence of either then or loop, and the scan resumes. 1121 1122 procedure Resync_Semicolon_List; 1123 -- Used if an error occurs while scanning a parenthesized list of items 1124 -- separated by semicolons. The scan pointer is advanced to the next 1125 -- semicolon or right parenthesis at the outer parenthesis level, or 1126 -- to the next is or RETURN keyword occurrence, whichever comes first. 1127 1128 procedure Resync_To_Semicolon; 1129 -- Similar to Resync_Past_Semicolon, except that the scan pointer is 1130 -- left pointing to the semicolon rather than past it. 1131 1132 procedure Resync_To_When; 1133 -- Used when an error occurs scanning an entry index specification. The 1134 -- scan pointer is positioned to the next WHEN (or to IS or semicolon if 1135 -- either of these appear before WHEN, indicating another error has 1136 -- occurred). 1137 end Sync; 1138 1139 -------------- 1140 -- Par.Tchk -- 1141 -------------- 1142 1143 -- Routines to check for expected tokens 1144 1145 package Tchk is 1146 1147 -- Procedures with names of the form T_xxx, where Tok_xxx is a token 1148 -- name, check that the current token matches the required token, and 1149 -- if so, scan past it. If not, an error is issued indicating that 1150 -- the required token is not present (xxx expected). In most cases, the 1151 -- scan pointer is not moved in the not-found case, but there are some 1152 -- exceptions to this, see for example T_Id, where the scan pointer is 1153 -- moved across a literal appearing where an identifier is expected. 1154 1155 procedure T_Abort; 1156 procedure T_Arrow; 1157 procedure T_At; 1158 procedure T_Body; 1159 procedure T_Box; 1160 procedure T_Colon; 1161 procedure T_Colon_Equal; 1162 procedure T_Comma; 1163 procedure T_Dot_Dot; 1164 procedure T_For; 1165 procedure T_Greater_Greater; 1166 procedure T_Identifier; 1167 procedure T_In; 1168 procedure T_Is; 1169 procedure T_Left_Paren; 1170 procedure T_Loop; 1171 procedure T_Mod; 1172 procedure T_New; 1173 procedure T_Of; 1174 procedure T_Or; 1175 procedure T_Private; 1176 procedure T_Range; 1177 procedure T_Record; 1178 procedure T_Right_Paren; 1179 procedure T_Semicolon; 1180 procedure T_Then; 1181 procedure T_Type; 1182 procedure T_Use; 1183 procedure T_When; 1184 procedure T_With; 1185 1186 -- Procedures having names of the form TF_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 message is issued indicating 1189 -- that the required token is not present (xxx expected). 1190 1191 -- If the missing token is at the end of the line, then control returns 1192 -- immediately after posting the message. If there are remaining tokens 1193 -- on the current line, a search is conducted to see if the token 1194 -- appears later on the current line, as follows: 1195 1196 -- A call to Scan_Save is issued and a forward search for the token 1197 -- is carried out. If the token is found on the current line before a 1198 -- semicolon, then it is scanned out and the scan continues from that 1199 -- point. If not the scan is restored to the point where it was missing. 1200 1201 procedure TF_Arrow; 1202 procedure TF_Is; 1203 procedure TF_Loop; 1204 procedure TF_Return; 1205 procedure TF_Semicolon; 1206 procedure TF_Then; 1207 procedure TF_Use; 1208 1209 -- Procedures with names of the form U_xxx, where Tok_xxx is a token 1210 -- name, are just like the corresponding T_xxx procedures except that 1211 -- an error message, if given, is unconditional. 1212 1213 procedure U_Left_Paren; 1214 procedure U_Right_Paren; 1215 end Tchk; 1216 1217 -------------- 1218 -- Par.Util -- 1219 -------------- 1220 1221 package Util is 1222 function Bad_Spelling_Of (T : Token_Type) return Boolean; 1223 -- This function is called in an error situation. It checks if the 1224 -- current token is an identifier whose name is a plausible bad 1225 -- spelling of the given keyword token, and if so, issues an error 1226 -- message, sets Token from T, and returns True. Otherwise Token is 1227 -- unchanged, and False is returned. 1228 1229 procedure Check_Bad_Layout; 1230 -- Check for bad indentation in RM checking mode. Used for statements 1231 -- and declarations. Checks if current token is at start of line and 1232 -- is exdented from the current expected end column, and if so an 1233 -- error message is generated. 1234 1235 procedure Check_Misspelling_Of (T : Token_Type); 1236 pragma Inline (Check_Misspelling_Of); 1237 -- This is similar to the function above, except that it does not 1238 -- return a result. It is typically used in a situation where any 1239 -- identifier is an error, and it makes sense to simply convert it 1240 -- to the given token if it is a plausible misspelling of it. 1241 1242 procedure Check_95_Keyword (Token_95, Next : Token_Type); 1243 -- This routine checks if the token after the current one matches the 1244 -- Next argument. If so, the scan is backed up to the current token 1245 -- and Token_Type is changed to Token_95 after issuing an appropriate 1246 -- error message ("(Ada 83) keyword xx cannot be used"). If not, 1247 -- the scan is backed up with Token_Type unchanged. This routine 1248 -- is used to deal with an attempt to use a 95 keyword in Ada 83 1249 -- mode. The caller has typically checked that the current token, 1250 -- an identifier, matches one of the 95 keywords. 1251 1252 procedure Check_Future_Keyword; 1253 -- Emit a warning if the current token is a valid identifier in the 1254 -- language version in use, but is a reserved word in a later language 1255 -- version (unless the language version in use is Ada 83). 1256 1257 procedure Check_Simple_Expression (E : Node_Id); 1258 -- Given an expression E, that has just been scanned, so that Expr_Form 1259 -- is still set, outputs an error if E is a non-simple expression. E is 1260 -- not modified by this call. 1261 1262 procedure Check_Simple_Expression_In_Ada_83 (E : Node_Id); 1263 -- Like Check_Simple_Expression, except that the error message is only 1264 -- given when operating in Ada 83 mode, and includes "in Ada 83". 1265 1266 function Check_Subtype_Mark (Mark : Node_Id) return Node_Id; 1267 -- Called to check that a node representing a name (or call) is 1268 -- suitable for a subtype mark, i.e, that it is an identifier or 1269 -- a selected component. If so, or if it is already Error, then 1270 -- it is returned unchanged. Otherwise an error message is issued 1271 -- and Error is returned. 1272 1273 function Comma_Present return Boolean; 1274 -- Used in comma delimited lists to determine if a comma is present, or 1275 -- can reasonably be assumed to have been present (an error message is 1276 -- generated in the latter case). If True is returned, the scan has been 1277 -- positioned past the comma. If False is returned, the scan position 1278 -- is unchanged. Note that all comma-delimited lists are terminated by 1279 -- a right paren, so the only legitimate tokens when Comma_Present is 1280 -- called are right paren and comma. If some other token is found, then 1281 -- Comma_Present has the job of deciding whether it is better to pretend 1282 -- a comma was present, post a message for a missing comma and return 1283 -- True, or return False and let the caller diagnose the missing right 1284 -- parenthesis. 1285 1286 procedure Discard_Junk_Node (N : Node_Id); 1287 procedure Discard_Junk_List (L : List_Id); 1288 pragma Inline (Discard_Junk_Node); 1289 pragma Inline (Discard_Junk_List); 1290 -- These procedures do nothing at all, their effect is simply to discard 1291 -- the argument. A typical use is to skip by some junk that is not 1292 -- expected in the current context. 1293 1294 procedure Ignore (T : Token_Type); 1295 -- If current token matches T, then give an error message and skip 1296 -- past it, otherwise the call has no effect at all. T may be any 1297 -- reserved word token, or comma, left or right paren, or semicolon. 1298 1299 function Is_Reserved_Identifier (C : Id_Check := None) return Boolean; 1300 -- Test if current token is a reserved identifier. This test is based 1301 -- on the token being a keyword and being spelled in typical identifier 1302 -- style (i.e. starting with an upper case letter). The parameter C 1303 -- determines the special treatment if a reserved word is encountered 1304 -- that has the normal casing of a reserved word. 1305 1306 procedure Merge_Identifier (Prev : Node_Id; Nxt : Token_Type); 1307 -- Called when the previous token is an identifier (whose Token_Node 1308 -- value is given by Prev) to check if current token is an identifier 1309 -- that can be merged with the previous one adding an underscore. The 1310 -- merge is only attempted if the following token matches Nxt. If all 1311 -- conditions are met, an error message is issued, and the merge is 1312 -- carried out, modifying the Chars field of Prev. 1313 1314 function Next_Token_Is (Tok : Token_Type) return Boolean; 1315 -- Looks at token after current one and returns True if the token type 1316 -- matches Tok. The scan is unconditionally restored on return. 1317 1318 procedure No_Constraint; 1319 -- Called in a place where no constraint is allowed, but one might 1320 -- appear due to a common error (e.g. after the type mark in a procedure 1321 -- parameter. If a constraint is present, an error message is posted, 1322 -- and the constraint is scanned and discarded. 1323 1324 procedure Push_Scope_Stack; 1325 pragma Inline (Push_Scope_Stack); 1326 -- Push a new entry onto the scope stack. Scope.Last (the stack pointer) 1327 -- is incremented. The Junk field is preinitialized to False. The caller 1328 -- is expected to fill in all remaining entries of the new top stack 1329 -- entry at Scope.Table (Scope.Last). 1330 1331 procedure Pop_Scope_Stack; 1332 -- Pop an entry off the top of the scope stack. Scope_Last (the scope 1333 -- table stack pointer) is decremented by one. It is a fatal error to 1334 -- try to pop off the dummy entry at the bottom of the stack (i.e. 1335 -- Scope.Last must be non-zero at the time of call). 1336 1337 function Separate_Present return Boolean; 1338 -- Determines if the current token is either Tok_Separate, or an 1339 -- identifier that is a possible misspelling of "separate" followed 1340 -- by a semicolon. True is returned if so, otherwise False. 1341 1342 procedure Signal_Bad_Attribute; 1343 -- The current token is an identifier that is supposed to be an 1344 -- attribute identifier but is not. This routine posts appropriate 1345 -- error messages, including a check for a near misspelling. 1346 1347 function Token_Is_At_Start_Of_Line return Boolean; 1348 pragma Inline (Token_Is_At_Start_Of_Line); 1349 -- Determines if the current token is the first token on the line 1350 1351 function Token_Is_At_End_Of_Line return Boolean; 1352 -- Determines if the current token is the last token on the line 1353 1354 procedure Warn_If_Standard_Redefinition (N : Node_Id); 1355 -- Issues a warning if Warn_On_Standard_Redefinition is set True, and 1356 -- the Node N (which is a Defining_Identifier node with the Chars field 1357 -- set) is a renaming of an entity in package Standard. 1358 1359 end Util; 1360 1361 -------------- 1362 -- Par.Prag -- 1363 -------------- 1364 1365 -- The processing for pragmas is split off from chapter 2 1366 1367 function Prag (Pragma_Node : Node_Id; Semi : Source_Ptr) return Node_Id; 1368 -- This function is passed a tree for a pragma that has been scanned out. 1369 -- The pragma is syntactically well formed according to the general syntax 1370 -- for pragmas and the pragma identifier is for one of the recognized 1371 -- pragmas. It performs specific syntactic checks for specific pragmas. 1372 -- The result is the input node if it is OK, or Error otherwise. The 1373 -- reason that this is separated out is to facilitate the addition 1374 -- of implementation defined pragmas. The second parameter records the 1375 -- location of the semicolon following the pragma (this is needed for 1376 -- correct processing of the List and Page pragmas). The returned value 1377 -- is a copy of Pragma_Node, or Error if an error is found. Note that 1378 -- at the point where Prag is called, the right paren ending the pragma 1379 -- has been scanned out, and except in the case of pragma Style_Checks, 1380 -- so has the following semicolon. For Style_Checks, the caller delays 1381 -- the scanning of the semicolon so that it will be scanned using the 1382 -- settings from the Style_Checks pragma preceding it. 1383 1384 -------------- 1385 -- Par.Labl -- 1386 -------------- 1387 1388 procedure Labl; 1389 -- This procedure creates implicit label declarations for all labels that 1390 -- are declared in the current unit. Note that this could conceptually be 1391 -- done at the point where the labels are declared, but it is tricky to do 1392 -- it then, since the tree is not hooked up at the point where the label is 1393 -- declared (e.g. a sequence of statements is not yet attached to its 1394 -- containing scope at the point a label in the sequence is found). 1395 1396 -------------- 1397 -- Par.Load -- 1398 -------------- 1399 1400 procedure Load; 1401 -- This procedure loads all subsidiary units that are required by this 1402 -- unit, including with'ed units, specs for bodies, and parents for child 1403 -- units. It does not load bodies for inlined procedures and generics, 1404 -- since we don't know till semantic analysis is complete what is needed. 1405 1406 ----------- 1407 -- Stubs -- 1408 ----------- 1409 1410 -- The package bodies can see all routines defined in all other subpackages 1411 1412 use Ch2; 1413 use Ch3; 1414 use Ch4; 1415 use Ch5; 1416 use Ch6; 1417 use Ch7; 1418 use Ch8; 1419 use Ch9; 1420 use Ch10; 1421 use Ch11; 1422 use Ch12; 1423 use Ch13; 1424 1425 use Endh; 1426 use Tchk; 1427 use Sync; 1428 use Util; 1429 1430 package body Ch2 is separate; 1431 package body Ch3 is separate; 1432 package body Ch4 is separate; 1433 package body Ch5 is separate; 1434 package body Ch6 is separate; 1435 package body Ch7 is separate; 1436 package body Ch8 is separate; 1437 package body Ch9 is separate; 1438 package body Ch10 is separate; 1439 package body Ch11 is separate; 1440 package body Ch12 is separate; 1441 package body Ch13 is separate; 1442 1443 package body Endh is separate; 1444 package body Tchk is separate; 1445 package body Sync is separate; 1446 package body Util is separate; 1447 1448 function Prag (Pragma_Node : Node_Id; Semi : Source_Ptr) return Node_Id 1449 is separate; 1450 1451 procedure Labl is separate; 1452 procedure Load is separate; 1453 1454-- Start of processing for Par 1455 1456begin 1457 Compiler_State := Parsing; 1458 1459 -- Deal with configuration pragmas case first 1460 1461 if Configuration_Pragmas then 1462 declare 1463 Pragmas : constant List_Id := Empty_List; 1464 P_Node : Node_Id; 1465 1466 begin 1467 loop 1468 if Token = Tok_EOF then 1469 Compiler_State := Analyzing; 1470 return Pragmas; 1471 1472 elsif Token /= Tok_Pragma then 1473 Error_Msg_SC ("only pragmas allowed in configuration file"); 1474 Compiler_State := Analyzing; 1475 return Error_List; 1476 1477 else 1478 P_Node := P_Pragma; 1479 1480 if Nkind (P_Node) = N_Pragma then 1481 1482 -- Give error if bad pragma 1483 1484 if not Is_Configuration_Pragma_Name (Pragma_Name (P_Node)) 1485 and then Pragma_Name (P_Node) /= Name_Source_Reference 1486 then 1487 if Is_Pragma_Name (Pragma_Name (P_Node)) then 1488 Error_Msg_N 1489 ("only configuration pragmas allowed " & 1490 "in configuration file", P_Node); 1491 else 1492 Error_Msg_N 1493 ("unrecognized pragma in configuration file", 1494 P_Node); 1495 end if; 1496 1497 -- Pragma is OK config pragma, so collect it 1498 1499 else 1500 Append (P_Node, Pragmas); 1501 end if; 1502 end if; 1503 end if; 1504 end loop; 1505 end; 1506 1507 -- Normal case of compilation unit 1508 1509 else 1510 Save_Opt_Config_Switches (Save_Config_Switches); 1511 1512 -- The following loop runs more than once in syntax check mode 1513 -- where we allow multiple compilation units in the same file 1514 -- and in Multiple_Unit_Per_file mode where we skip units till 1515 -- we get to the unit we want. 1516 1517 for Ucount in Pos loop 1518 Set_Opt_Config_Switches 1519 (Is_Internal_File_Name (File_Name (Current_Source_File)), 1520 Current_Source_Unit = Main_Unit); 1521 1522 -- Initialize scope table and other parser control variables 1523 1524 Compiler_State := Parsing; 1525 Scope.Init; 1526 Scope.Increment_Last; 1527 Scope.Table (0).Etyp := E_Dummy; 1528 SIS_Entry_Active := False; 1529 Last_Resync_Point := No_Location; 1530 1531 Goto_List := New_Elmt_List; 1532 Label_List := New_Elmt_List; 1533 1534 -- If in multiple unit per file mode, skip past ignored unit 1535 1536 if Ucount < Multiple_Unit_Index then 1537 1538 -- We skip in syntax check only mode, since we don't want to do 1539 -- anything more than skip past the unit and ignore it. This means 1540 -- we skip processing like setting up a unit table entry. 1541 1542 declare 1543 Save_Operating_Mode : constant Operating_Mode_Type := 1544 Operating_Mode; 1545 1546 Save_Style_Check : constant Boolean := Style_Check; 1547 1548 begin 1549 Operating_Mode := Check_Syntax; 1550 Style_Check := False; 1551 Discard_Node (P_Compilation_Unit); 1552 Operating_Mode := Save_Operating_Mode; 1553 Style_Check := Save_Style_Check; 1554 1555 -- If we are at an end of file, and not yet at the right unit, 1556 -- then we have a fatal error. The unit is missing. 1557 1558 if Token = Tok_EOF then 1559 Error_Msg_SC ("file has too few compilation units"); 1560 raise Unrecoverable_Error; 1561 end if; 1562 end; 1563 1564 -- Here if we are not skipping a file in multiple unit per file mode. 1565 -- Parse the unit that we are interested in. Note that in check 1566 -- syntax mode we are interested in all units in the file. 1567 1568 else 1569 declare 1570 Comp_Unit_Node : constant Node_Id := P_Compilation_Unit; 1571 1572 begin 1573 -- If parsing was successful and we are not in check syntax 1574 -- mode, check that language-defined units are compiled in GNAT 1575 -- mode. For this purpose we do NOT consider renamings in annex 1576 -- J as predefined. That allows users to compile their own 1577 -- versions of these files. Another exception is System.RPC 1578 -- and its children. This allows a user to supply their own 1579 -- communication layer. 1580 -- Similarly, we do not generate an error in CodePeer mode, 1581 -- to allow users to analyze third-party compiler packages. 1582 1583 if Comp_Unit_Node /= Error 1584 and then Operating_Mode = Generate_Code 1585 and then Current_Source_Unit = Main_Unit 1586 and then not GNAT_Mode 1587 and then not CodePeer_Mode 1588 then 1589 declare 1590 Uname : constant String := 1591 Get_Name_String 1592 (Unit_Name (Current_Source_Unit)); 1593 Name : String (1 .. Uname'Length - 2); 1594 1595 begin 1596 -- Because Unit_Name includes "%s"/"%b", we need to strip 1597 -- the last two characters to get the real unit name. 1598 1599 Name := Uname (Uname'First .. Uname'Last - 2); 1600 1601 if Name = "ada" or else 1602 Name = "interfaces" or else 1603 Name = "system" 1604 then 1605 Error_Msg 1606 ("language-defined units cannot be recompiled", 1607 Sloc (Unit (Comp_Unit_Node))); 1608 1609 elsif Name'Length > 4 1610 and then 1611 Name (Name'First .. Name'First + 3) = "ada." 1612 then 1613 Error_Msg 1614 ("user-defined descendents of package Ada " & 1615 "are not allowed", 1616 Sloc (Unit (Comp_Unit_Node))); 1617 1618 elsif Name'Length > 11 1619 and then 1620 Name (Name'First .. Name'First + 10) = "interfaces." 1621 then 1622 Error_Msg 1623 ("user-defined descendents of package Interfaces " & 1624 "are not allowed", 1625 Sloc (Unit (Comp_Unit_Node))); 1626 1627 elsif Name'Length > 7 1628 and then Name (Name'First .. Name'First + 6) = "system." 1629 and then Name /= "system.rpc" 1630 and then 1631 (Name'Length < 11 1632 or else Name (Name'First .. Name'First + 10) /= 1633 "system.rpc.") 1634 then 1635 Error_Msg 1636 ("user-defined descendents of package System " & 1637 "are not allowed", 1638 Sloc (Unit (Comp_Unit_Node))); 1639 end if; 1640 end; 1641 end if; 1642 end; 1643 1644 -- All done if at end of file 1645 1646 exit when Token = Tok_EOF; 1647 1648 -- If we are not at an end of file, it means we are in syntax 1649 -- check only mode, and we keep the loop going to parse all 1650 -- remaining units in the file. 1651 1652 end if; 1653 1654 Restore_Opt_Config_Switches (Save_Config_Switches); 1655 end loop; 1656 1657 -- Now that we have completely parsed the source file, we can complete 1658 -- the source file table entry. 1659 1660 Complete_Source_File_Entry; 1661 1662 -- An internal error check, the scope stack should now be empty 1663 1664 pragma Assert (Scope.Last = 0); 1665 1666 -- Here we make the SCO table entries for the main unit 1667 1668 if Generate_SCO then 1669 SCO_Record_Raw (Main_Unit); 1670 end if; 1671 1672 -- Remaining steps are to create implicit label declarations and to load 1673 -- required subsidiary sources. These steps are required only if we are 1674 -- doing semantic checking. 1675 1676 if Operating_Mode /= Check_Syntax or else Debug_Flag_F then 1677 Par.Labl; 1678 Par.Load; 1679 end if; 1680 1681 -- Restore settings of switches saved on entry 1682 1683 Restore_Opt_Config_Switches (Save_Config_Switches); 1684 Set_Comes_From_Source_Default (False); 1685 Compiler_State := Analyzing; 1686 return Empty_List; 1687 end if; 1688end Par; 1689