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1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- P A R --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 1992-2022, 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 ------------------------------------------------------------------------------
56 ---------
57 -- Par --
58 ---------
63 -- True within a record definition. Used to control warning for
64 -- redefinition of standard entities (not issued for field names).
67 -- Counter used for constructing loop/block names (see the routine
68 -- Par.Ch5.Get_Loop_Block_Name).
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).
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.
78 --------------------
79 -- Error Recovery --
80 --------------------
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.
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.
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.
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.
106 -- Exception raised on error that is not handled locally, see above
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.
117 --------------------------------------------
118 -- Handling Semicolon Used in Place of IS --
119 --------------------------------------------
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:
124 -- procedure X (Y : Integer);
125 -- Q : Integer;
126 -- begin
127 -- ...
128 -- end;
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.
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.
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.
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.
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.
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.
169 -- Subprogram designator
172 -- Source location of FUNCTION/PROCEDURE keyword
175 -- Column number of FUNCTION/PROCEDURE keyword
178 -- Source location of semicolon at end of subprogram declaration
181 -- Pointer to tree node for subprogram declaration
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.
188 -- Five things can happen to an active SIS entry
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.
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.
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.
207 -- 4. We encounter a valid pragma INTERFACE or IMPORT that effectively
208 -- supplies the missing body. In this case we reset the entry.
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.
215 ----------------------------------------------------
216 -- Handling of Reserved Words Used as Identifiers --
217 ----------------------------------------------------
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).
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.
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.
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.
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
250 -- Default, no special token test
252 C_Comma_Right_Paren,
253 -- Consider as identifier if followed by comma or right paren
255 C_Comma_Colon,
256 -- Consider as identifier if followed by comma or colon
258 C_Do,
259 -- Consider as identifier if followed by DO
261 C_Dot,
262 -- Consider as identifier if followed by period
264 C_Greater_Greater,
265 -- Consider as identifier if followed by >>
267 C_In,
268 -- Consider as identifier if followed by IN
270 C_Is,
271 -- Consider as identifier if followed by IS
273 C_Left_Paren_Semicolon,
274 -- Consider as identifier if followed by left paren or semicolon
276 C_Use,
277 -- Consider as identifier if followed by USE
279 C_Vertical_Bar_Arrow);
280 -- Consider as identifier if followed by | or =>
282 --------------------------------------------
283 -- Handling IS Used in Place of Semicolon --
284 --------------------------------------------
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:
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;
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).
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.
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.
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.
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.
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.
347 ---------------------------------------------------
348 -- Parser Type Definitions and Control Variables --
349 ---------------------------------------------------
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.
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.
383 Pf_Rec'(F, T, T, T, T, T, T, F);
384 Pf_Decl_Pexp : constant Pf_Rec :=
387 Pf_Rec'(F, T, T, T, T, F, T, F);
388 Pf_Decl_Pbod_Pexp : constant Pf_Rec :=
391 Pf_Rec'(F, F, F, T, F, F, T, F);
392 Pf_Spcn : constant Pf_Rec :=
394 -- The above are the only allowed values of Pf_Rec arguments
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.
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.
427 -----------------
428 -- Scope Table --
429 -----------------
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).
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.
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)
460 -- The following describes a single entry in the scope table
462 type Scope_Table_Entry is record
463 Etyp : SS_End_Type;
464 -- Type of end entry, as per above description
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).
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.
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
488 -- corresponding program unit name. For task declarations and bodies,
489 -- protected types and bodies, and accept statements the field hold the
490 -- name of the type or operation. For if-statements, case-statements,
491 -- return statements, and selects, the field is initialized to Error.
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.
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.
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.
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.
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).
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.
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;
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.
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");
549 type Scope_Table_Entry_Ptr is access all Scope_Table_Entry;
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.
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;
563 ------------------------------------------
564 -- Table for Handling Suspicious Labels --
565 ------------------------------------------
567 -- This is a special data structure which is used to deal very specifically
568 -- with the following error case
570 -- label;
571 -- loop
572 -- ...
573 -- end loop label;
575 -- Similar cases apply to FOR, WHILE, DECLARE, or BEGIN
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.
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.
589 type Suspicious_Label_Entry is record
590 Proc_Call : Node_Id;
591 -- Node for the procedure call statement built for the label; construct
593 Semicolon_Loc : Source_Ptr;
594 -- Location of the possibly wrong semicolon
596 Start_Token : Source_Ptr;
597 -- Source location of the LOOP, FOR, WHILE, DECLARE, BEGIN token
598 end record;
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");
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.
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).
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.
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.
629 ---------------------------------
630 -- Parsing Routines by Chapter --
631 ---------------------------------
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.
637 -------------
638 -- Par.Ch2 --
639 -------------
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.
652 function P_Identifier
653 (C : Id_Check := None;
654 Force_Msg : Boolean := False) return Node_Id;
655 -- Scans out an identifier. The parameter C determines the treatment
656 -- of reserved identifiers. See declaration of Id_Check for details.
658 -- An appropriate error message, pointing to the token, is also issued
659 -- if either this is the first occurrence of misuse of this identifier,
660 -- or if Force_Msg is True.
662 function P_Pragmas_Opt return List_Id;
663 -- This function scans for a sequence of pragmas in other than a
664 -- declaration sequence or statement sequence context. All pragmas
665 -- can appear except pragmas Assert and Debug, which are only allowed
666 -- in a declaration or statement sequence context.
668 procedure P_Pragmas_Misplaced;
669 -- Skips misplaced pragmas with a complaint
671 procedure P_Pragmas_Opt (List : List_Id);
672 -- Parses optional pragmas and appends them to the List
673 end Ch2;
675 -------------
676 -- Par.Ch3 --
677 -------------
679 package Ch3 is
680 Missing_Begin_Msg : Error_Msg_Id;
681 -- This variable is set by a call to P_Declarative_Part. Normally it
682 -- is set to No_Error_Msg, indicating that no special processing is
683 -- required by the caller. The special case arises when a statement
684 -- is found in the sequence of declarations. In this case the Id of
685 -- the message issued ("declaration expected") is preserved in this
686 -- variable, then the caller can change it to an appropriate missing
687 -- begin message if indeed the BEGIN is missing.
689 function P_Array_Type_Definition return Node_Id;
690 function P_Constraint_Opt return Node_Id;
691 function P_Declarative_Part return List_Id;
692 function P_Discrete_Choice_List return List_Id;
693 function P_Discrete_Range return Node_Id;
694 function P_Discrete_Subtype_Definition return Node_Id;
695 function P_Known_Discriminant_Part_Opt return List_Id;
696 function P_Signed_Integer_Type_Definition return Node_Id;
697 function P_Range return Node_Id;
698 function P_Range_Constraint return Node_Id;
699 function P_Record_Definition return Node_Id;
700 function P_Subtype_Mark return Node_Id;
701 function P_Subtype_Mark_Resync return Node_Id;
702 function P_Unknown_Discriminant_Part_Opt return Boolean;
704 function P_Basic_Declarative_Items
705 (Declare_Expression : Boolean) return List_Id;
706 -- Used to parse the declarative items in a package visible or
707 -- private part (in which case Declare_Expression is False), and
708 -- the declare_items of a declare_expression (in which case
709 -- Declare_Expression is True). Declare_Expression is used to
710 -- affect the wording of error messages, and to control style
711 -- checking.
713 function P_Access_Definition
714 (Null_Exclusion_Present : Boolean) return Node_Id;
715 -- Ada 2005 (AI-231/AI-254): The caller parses the null-exclusion part
716 -- and indicates if it was present
718 function P_Access_Type_Definition
719 (Header_Already_Parsed : Boolean := False) return Node_Id;
720 -- Ada 2005 (AI-254): The formal is used to indicate if the caller has
721 -- parsed the null_exclusion part. In this case the caller has also
722 -- removed the ACCESS token
724 procedure P_Component_Items (Decls : List_Id);
725 -- Scan out one or more component items and append them to the given
726 -- list. Only scans out more than one declaration in the case where the
727 -- source has a single declaration with multiple defining identifiers.
729 function P_Defining_Identifier (C : Id_Check := None) return Node_Id;
730 -- Scan out a defining identifier. The parameter C controls the
731 -- treatment of errors in case a reserved word is scanned. See the
732 -- declaration of this type for details.
734 function P_Interface_Type_Definition
735 (Abstract_Present : Boolean) return Node_Id;
736 -- Ada 2005 (AI-251): Parse the interface type definition part. Abstract
737 -- Present indicates if the reserved word "abstract" has been previously
738 -- found. It is used to report an error message because interface types
739 -- are by definition abstract tagged. We generate a record_definition
740 -- node if the list of interfaces is empty; otherwise we generate a
741 -- derived_type_definition node (the first interface in this list is the
742 -- ancestor interface).
744 function P_Null_Exclusion
745 (Allow_Anonymous_In_95 : Boolean := False) return Boolean;
746 -- Ada 2005 (AI-231): Parse the null-excluding part. A True result
747 -- indicates that the null-excluding part was present.
748 --
749 -- Allow_Anonymous_In_95 is True if we are in a context that allows
750 -- anonymous access types in Ada 95, in which case "not null" is legal
751 -- if it precedes "access".
753 function P_Subtype_Indication
754 (Not_Null_Present : Boolean := False) return Node_Id;
755 -- Ada 2005 (AI-231): The flag Not_Null_Present indicates that the
756 -- null-excluding part has been scanned out and it was present.
758 function P_Range_Or_Subtype_Mark
759 (Allow_Simple_Expression : Boolean := False) return Node_Id;
760 -- Scans out a range or subtype mark, and also permits a general simple
761 -- expression if Allow_Simple_Expression is set to True.
763 function Init_Expr_Opt (P : Boolean := False) return Node_Id;
764 -- If an initialization expression is present (:= expression), then
765 -- it is scanned out and returned, otherwise Empty is returned if no
766 -- initialization expression is present. This procedure also handles
767 -- certain common error cases cleanly. The parameter P indicates if
768 -- a right paren can follow the expression (default = no right paren
769 -- allowed).
771 procedure Skip_Declaration (S : List_Id);
772 -- Used when scanning statements to skip past a misplaced declaration
773 -- The declaration is scanned out and appended to the given list.
774 -- Token is known to be a declaration token (in Token_Class_Declk)
775 -- on entry, so there definition is a declaration to be scanned.
777 function P_Subtype_Indication
778 (Subtype_Mark : Node_Id;
779 Not_Null_Present : Boolean := False) return Node_Id;
780 -- This version of P_Subtype_Indication is called when the caller has
781 -- already scanned out the subtype mark which is passed as a parameter.
782 -- Ada 2005 (AI-231): The flag Not_Null_Present indicates that the
783 -- null-excluding part has been scanned out and it was present.
785 function P_Subtype_Mark_Attribute (Type_Node : Node_Id) return Node_Id;
786 -- Parse a subtype mark attribute. The caller has already parsed the
787 -- subtype mark, which is passed in as the argument, and has checked
788 -- that the current token is apostrophe.
789 end Ch3;
791 -------------
792 -- Par.Ch4 --
793 -------------
795 package Ch4 is
796 function P_Aggregate return Node_Id;
797 function P_Expression return Node_Id;
798 function P_Expression_Or_Range_Attribute return Node_Id;
799 function P_Function_Name return Node_Id;
800 function P_Name return Node_Id;
801 function P_Qualified_Simple_Name return Node_Id;
802 function P_Qualified_Simple_Name_Resync return Node_Id;
803 function P_Simple_Expression return Node_Id;
804 function P_Simple_Expression_Or_Range_Attribute return Node_Id;
806 function P_Expression_If_OK return Node_Id;
807 -- Scans out an expression allowing an unparenthesized case expression,
808 -- if expression, or quantified expression to appear without enclosing
809 -- parentheses. However, if such an expression is not preceded by a left
810 -- paren, and followed by a right paren, an error message will be output
811 -- noting that parenthesization is required.
813 function P_Expression_No_Right_Paren return Node_Id;
814 -- Scans out an expression in contexts where the expression cannot be
815 -- terminated by a right paren (gives better error recovery if an errant
816 -- right paren is found after the expression).
818 function P_Expression_Or_Range_Attribute_If_OK return Node_Id;
819 -- Scans out an expression or range attribute where a conditional
820 -- expression is permitted to appear without surrounding parentheses.
821 -- However, if such an expression is not preceded by a left paren, and
822 -- followed by a right paren, an error message will be output noting
823 -- that parenthesization is required.
825 function P_If_Expression return Node_Id;
826 -- Scans out an if expression. Called with Token pointing to the
827 -- IF keyword, and returns pointing to the terminating right paren,
828 -- semicolon or comma, but does not consume this terminating token.
830 function P_Qualified_Expression (Subtype_Mark : Node_Id) return Node_Id;
831 -- This routine scans out a qualified expression when the caller has
832 -- already scanned out the name and apostrophe of the construct.
834 function P_Quantified_Expression return Node_Id;
835 -- This routine scans out a quantified expression when the caller has
836 -- already scanned out the keyword "for" of the construct.
837 end Ch4;
839 -------------
840 -- Par.Ch5 --
841 -------------
843 package Ch5 is
844 function P_Condition return Node_Id;
845 -- Scan out and return a condition. Note that an error is given if
846 -- the condition is followed by a right parenthesis.
848 function P_Condition (Cond : Node_Id) return Node_Id;
849 -- Similar to the above, but the caller has already scanned out the
850 -- conditional expression and passes it as an argument. This form of
851 -- the call does not check for a following right parenthesis.
853 function P_Iterator_Specification (Def_Id : Node_Id) return Node_Id;
854 -- Parse an iterator specification. The defining identifier has already
855 -- been scanned, as it is the common prefix between loop and iterator
856 -- specification.
858 function P_Loop_Parameter_Specification return Node_Id;
859 -- Used in loop constructs and quantified expressions.
861 function P_Sequence_Of_Statements (SS_Flags : SS_Rec) return List_Id;
862 -- The argument indicates the acceptable termination tokens.
863 -- See body in Par.Ch5 for details of the use of this parameter.
865 procedure Parse_Decls_Begin_End (Parent : Node_Id);
866 -- Parses declarations and handled statement sequence, setting
867 -- fields of Parent node appropriately.
868 end Ch5;
870 -------------
871 -- Par.Ch6 --
872 -------------
874 package Ch6 is
875 function P_Designator return Node_Id;
876 function P_Defining_Program_Unit_Name return Node_Id;
877 function P_Formal_Part return List_Id;
878 function P_Parameter_Profile return List_Id;
879 function P_Return_Statement return Node_Id;
880 function P_Subprogram_Specification return Node_Id;
882 procedure P_Mode (Node : Node_Id);
883 -- Sets In_Present and/or Out_Present flags in Node scanning past IN,
884 -- OUT or IN OUT tokens in the source.
886 function P_Subprogram (Pf_Flags : Pf_Rec) return Node_Id;
887 -- Scans out any construct starting with either of the keywords
888 -- PROCEDURE or FUNCTION. The parameter indicates which possible
889 -- possible kinds of construct (body, spec, instantiation etc.)
890 -- are permissible in the current context.
891 end Ch6;
893 -------------
894 -- Par.Ch7 --
895 -------------
897 package Ch7 is
898 function P_Package (Pf_Flags : Pf_Rec) return Node_Id;
899 -- Scans out any construct starting with the keyword PACKAGE. The
900 -- parameter indicates which possible kinds of construct (body, spec,
901 -- instantiation etc.) are permissible in the current context.
902 end Ch7;
904 -------------
905 -- Par.Ch8 --
906 -------------
908 package Ch8 is
909 procedure P_Use_Clause (Item_List : List_Id);
910 end Ch8;
912 -------------
913 -- Par.Ch9 --
914 -------------
916 package Ch9 is
917 function P_Abort_Statement return Node_Id;
918 function P_Abortable_Part return Node_Id;
919 function P_Accept_Statement return Node_Id;
920 function P_Delay_Statement return Node_Id;
921 function P_Entry_Body return Node_Id;
922 function P_Protected return Node_Id;
923 function P_Requeue_Statement return Node_Id;
924 function P_Select_Statement return Node_Id;
925 function P_Task return Node_Id;
926 function P_Terminate_Alternative return Node_Id;
927 end Ch9;
929 --------------
930 -- Par.Ch10 --
931 --------------
933 package Ch10 is
934 function P_Compilation_Unit return Node_Id;
935 -- Note: this function scans a single compilation unit, and checks that
936 -- an end of file follows this unit, diagnosing any unexpected input as
937 -- an error, and then skipping it, so that Token is set to Tok_EOF on
938 -- return. An exception is in syntax-only mode, where multiple
939 -- compilation units are permitted. In this case, P_Compilation_Unit
940 -- does not check for end of file and there may be more compilation
941 -- units to scan. The caller can uniquely detect this situation by the
942 -- fact that Token is not set to Tok_EOF on return.
943 --
944 -- What about multiple unit/file capability that now exists???
945 --
946 -- The Ignore parameter is normally set False. It is set True in the
947 -- multiple unit per file mode if we are skipping past a unit that we
948 -- are not interested in.
949 end Ch10;
951 --------------
952 -- Par.Ch11 --
953 --------------
955 package Ch11 is
956 function P_Handled_Sequence_Of_Statements return Node_Id;
957 function P_Raise_Expression return Node_Id;
958 function P_Raise_Statement return Node_Id;
960 function Parse_Exception_Handlers return List_Id;
961 -- Parses the partial construct EXCEPTION followed by a list of
962 -- exception handlers which appears in a number of productions, and
963 -- returns the list of exception handlers.
964 end Ch11;
966 --------------
967 -- Par.Ch12 --
968 --------------
970 package Ch12 is
971 function P_Generic return Node_Id;
972 function P_Generic_Actual_Part_Opt return List_Id;
973 end Ch12;
975 --------------
976 -- Par.Ch13 --
977 --------------
979 package Ch13 is
980 function P_Representation_Clause return Node_Id;
982 function Aspect_Specifications_Present
983 (Strict : Boolean := Ada_Version < Ada_2012) return Boolean;
984 -- This function tests whether the next keyword is WITH followed by
985 -- something that looks reasonably like an aspect specification. If so,
986 -- True is returned. Otherwise False is returned. In either case control
987 -- returns with the token pointer unchanged (i.e. pointing to the WITH
988 -- token in the case where True is returned). This function takes care
989 -- of generating appropriate messages if aspect specifications appear
990 -- in versions of Ada prior to Ada 2012. The parameter strict can be
991 -- set to True, to be rather strict about considering something to be
992 -- an aspect specification. If Strict is False, then the circuitry is
993 -- rather more generous in considering something ill-formed to be an
994 -- attempt at an aspect specification. The default is more strict for
995 -- Ada versions before Ada 2012 (where aspect specifications are not
996 -- permitted). Note: this routine never checks the terminator token
997 -- for aspects so it does not matter whether the aspect specifications
998 -- are terminated by semicolon or some other character.
999 --
1000 -- Note: This function also handles the case of WHEN used where WITH
1001 -- was intended, and in that case posts an error and returns True.
1003 procedure P_Aspect_Specifications
1004 (Decl : Node_Id;
1005 Semicolon : Boolean := True);
1006 -- This procedure scans out a series of aspect specifications. If
1007 -- argument Semicolon is True, a terminating semicolon is also scanned.
1008 -- If this argument is False, the scan pointer is left pointing past the
1009 -- aspects and the caller must check for a proper terminator.
1010 --
1011 -- P_Aspect_Specifications is called with the current token pointing
1012 -- to either a WITH keyword starting an aspect specification, or an
1013 -- instance of what shpould be a terminator token. In the former case,
1014 -- the aspect specifications are scanned out including the terminator
1015 -- token if it is a semicolon, and the Has_Aspect_Specifications
1016 -- flag is set in the given declaration node. A list of aspects
1017 -- is built and stored for this declaration node using a call to
1018 -- Set_Aspect_Specifications. If no WITH keyword is present, then this
1019 -- call has no effect other than scanning out the terminator if it is a
1020 -- semicolon (with the exception that it detects WHEN used in place of
1021 -- WITH).
1023 -- If Decl is Error on entry, any scanned aspect specifications are
1024 -- ignored and a message is output saying aspect specifications not
1025 -- permitted here. If Decl is Empty, then scanned aspect specifications
1026 -- are also ignored, but no error message is given (this is used when
1027 -- the caller has already taken care of the error message).
1029 function Get_Aspect_Specifications
1030 (Semicolon : Boolean := True) return List_Id;
1031 -- Parse a list of aspects but do not attach them to a declaration node.
1032 -- Subsidiary to P_Aspect_Specifications procedure. Used when parsing
1033 -- a subprogram specification that may be a declaration or a body.
1034 -- Semicolon has the same meaning as for P_Aspect_Specifications above.
1036 function P_Code_Statement (Subtype_Mark : Node_Id) return Node_Id;
1037 -- Function to parse a code statement. The caller has scanned out
1038 -- the name to be used as the subtype mark (but has not checked that
1039 -- it is suitable for use as a subtype mark, i.e. is either an
1040 -- identifier or a selected component). The current token is an
1041 -- apostrophe and the following token is either a left paren or
1042 -- RANGE (the latter being an error to be caught by P_Code_Statement.
1043 end Ch13;
1045 -- Note: the parsing for annexe J features (i.e. obsolescent features)
1046 -- is found in the logical section where these features would be if
1047 -- they were not obsolescent. In particular:
1049 -- Delta constraint is parsed by P_Delta_Constraint (3.5.9)
1050 -- At clause is parsed by P_At_Clause (13.1)
1051 -- Mod clause is parsed by P_Mod_Clause (13.5.1)
1053 --------------
1054 -- Par.Endh --
1055 --------------
1057 -- Routines for handling end lines, including scope recovery
1059 package Endh is
1060 function Check_End
1061 (Decl : Node_Id := Empty;
1062 Is_Loc : Source_Ptr := No_Location) return Boolean;
1063 -- Called when an end sequence is required. In the absence of an error
1064 -- situation, Token contains Tok_End on entry, but in a missing end
1065 -- case, this may not be the case. Pop_End_Context is used to determine
1066 -- the appropriate action to be taken. The returned result is True if
1067 -- an End sequence was encountered and False if no End sequence was
1068 -- present. This occurs if the END keyword encountered was determined
1069 -- to be improper and deleted (i.e. Pop_End_Context set End_Action to
1070 -- Skip_And_Reject). Note that the END sequence includes a semicolon,
1071 -- except in the case of END RECORD, where a semicolon follows the END
1072 -- RECORD, but is not part of the record type definition itself.
1073 --
1074 -- If Decl is non-empty, then aspect specifications are permitted
1075 -- following the end, and Decl is the declaration node with which
1076 -- these aspect specifications are to be associated. If Decl is empty,
1077 -- then aspect specifications are not permitted and will generate an
1078 -- error message.
1079 --
1080 -- Is_Loc is set to other than the default only for the case of a
1081 -- package declaration. It points to the IS keyword of the declaration,
1082 -- and is used to specialize the error messages for misplaced aspect
1083 -- specifications in this case. Note that Decl is always Empty if Is_Loc
1084 -- is set.
1086 procedure End_Skip;
1087 -- Skip past an end sequence. On entry Token contains Tok_End, and we
1088 -- we know that the end sequence is syntactically incorrect, and that
1089 -- an appropriate error message has already been posted. The mission
1090 -- is simply to position the scan pointer to be the best guess of the
1091 -- position after the end sequence. We do not issue any additional
1092 -- error messages while carrying this out.
1094 procedure End_Statements
1095 (Parent : Node_Id := Empty;
1096 Decl : Node_Id := Empty;
1097 Is_Sloc : Source_Ptr := No_Location);
1098 -- Called when an end is required or expected to terminate a sequence
1099 -- of statements. The caller has already made an appropriate entry in
1100 -- the Scope.Table to describe the expected form of the end. This can
1101 -- only be used in cases where the only appropriate terminator is end.
1102 -- If Parent is non-empty, then if a correct END line is encountered,
1103 -- the End_Label field of Parent is set appropriately.
1104 --
1105 -- If Decl is non-null, then it is a declaration node, and aspect
1106 -- specifications are permitted after the end statement. These aspect
1107 -- specifications, if present, are stored in this declaration node.
1108 -- If Decl is null, then aspect specifications are not permitted after
1109 -- the end statement.
1110 --
1111 -- In the case where Decl is null, Is_Sloc determines the handling. If
1112 -- it is set to No_Location, then aspect specifications are ignored and
1113 -- an error message is given. Is_Sloc is used in the package declaration
1114 -- case to point to the IS, and is used to specialize the error emssages
1115 -- issued in this case.
1116 end Endh;
1118 --------------
1119 -- Par.Sync --
1120 --------------
1122 -- These procedures are used to resynchronize after errors. Following an
1123 -- error which is not immediately locally recoverable, the exception
1124 -- Error_Resync is raised. The handler for Error_Resync typically calls
1125 -- one of these recovery procedures to resynchronize the source position
1126 -- to a point from which parsing can be restarted.
1128 -- Note: these procedures output an information message that tokens are
1129 -- being skipped, but this message is output only if the option for
1130 -- Multiple_Errors_Per_Line is set in Options.
1132 package Sync is
1133 procedure Resync_Choice;
1134 -- Used if an error occurs scanning a choice. The scan pointer is
1135 -- advanced to the next vertical bar, arrow, or semicolon, whichever
1136 -- comes first. We also quit if we encounter an end of file.
1138 procedure Resync_Cunit;
1139 -- Synchronize to next token which could be the start of a compilation
1140 -- unit, or to the end of file token.
1142 procedure Resync_Expression;
1143 -- Used if an error is detected during the parsing of an expression.
1144 -- It skips past tokens until either a token which cannot be part of
1145 -- an expression is encountered (an expression terminator), or if a
1146 -- comma or right parenthesis or vertical bar is encountered at the
1147 -- current parenthesis level (a parenthesis level counter is maintained
1148 -- to carry out this test).
1150 procedure Resync_Past_Malformed_Aspect;
1151 -- Used when parsing aspect specifications to skip a malformed aspect.
1152 -- The scan pointer is positioned next to a comma, a semicolon or "is"
1153 -- when the aspect applies to a body.
1155 procedure Resync_Past_Semicolon;
1156 -- Used if an error occurs while scanning a sequence of declarations.
1157 -- The scan pointer is positioned past the next semicolon and the scan
1158 -- resumes. The scan is also resumed on encountering a token which
1159 -- starts a declaration (but we make sure to skip at least one token
1160 -- in this case, to avoid getting stuck in a loop).
1162 procedure Resync_Past_Semicolon_Or_To_Loop_Or_Then;
1163 -- Used if an error occurs while scanning a sequence of statements. The
1164 -- scan pointer is positioned past the next semicolon, or to the next
1165 -- occurrence of either then or loop, and the scan resumes.
1167 procedure Resync_Semicolon_List;
1168 -- Used if an error occurs while scanning a parenthesized list of items
1169 -- separated by semicolons. The scan pointer is advanced to the next
1170 -- semicolon or right parenthesis at the outer parenthesis level, or
1171 -- to the next is or RETURN keyword occurrence, whichever comes first.
1173 procedure Resync_To_Semicolon;
1174 -- Similar to Resync_Past_Semicolon, except that the scan pointer is
1175 -- left pointing to the semicolon rather than past it.
1177 procedure Resync_To_When;
1178 -- Used when an error occurs scanning an entry index specification. The
1179 -- scan pointer is positioned to the next WHEN (or to IS or semicolon if
1180 -- either of these appear before WHEN, indicating another error has
1181 -- occurred).
1182 end Sync;
1184 --------------
1185 -- Par.Tchk --
1186 --------------
1188 -- Routines to check for expected tokens
1190 package Tchk is
1192 -- Procedures with names of the form T_xxx, where Tok_xxx is a token
1193 -- name, check that the current token matches the required token, and
1194 -- if so, scan past it. If not, an error is issued indicating that
1195 -- the required token is not present (xxx expected). In most cases, the
1196 -- scan pointer is not moved in the not-found case, but there are some
1197 -- exceptions to this, see for example T_Id, where the scan pointer is
1198 -- moved across a literal appearing where an identifier is expected.
1200 procedure T_Abort;
1201 procedure T_Arrow;
1202 procedure T_At;
1203 procedure T_Body;
1204 procedure T_Box;
1205 procedure T_Colon;
1206 procedure T_Colon_Equal;
1207 procedure T_Comma;
1208 procedure T_Dot_Dot;
1209 procedure T_For;
1210 procedure T_Greater_Greater;
1211 procedure T_Identifier;
1212 procedure T_In;
1213 procedure T_Is;
1214 procedure T_Left_Paren;
1215 procedure T_Loop;
1216 procedure T_Mod;
1217 procedure T_New;
1218 procedure T_Of;
1219 procedure T_Or;
1220 procedure T_Private;
1221 procedure T_Range;
1222 procedure T_Record;
1223 procedure T_Right_Bracket;
1224 procedure T_Right_Paren;
1225 procedure T_Semicolon;
1226 procedure T_Then;
1227 procedure T_Type;
1228 procedure T_Use;
1229 procedure T_When;
1230 procedure T_With;
1232 -- Procedures having names of the form TF_xxx, where Tok_xxx is a token
1233 -- name check that the current token matches the required token, and
1234 -- if so, scan past it. If not, an error message is issued indicating
1235 -- that the required token is not present (xxx expected).
1237 -- If the missing token is at the end of the line, then control returns
1238 -- immediately after posting the message. If there are remaining tokens
1239 -- on the current line, a search is conducted to see if the token
1240 -- appears later on the current line, as follows:
1242 -- A call to Scan_Save is issued and a forward search for the token
1243 -- is carried out. If the token is found on the current line before a
1244 -- semicolon, then it is scanned out and the scan continues from that
1245 -- point. If not the scan is restored to the point where it was missing.
1247 procedure TF_Arrow;
1248 procedure TF_Is;
1249 procedure TF_Loop;
1250 procedure TF_Return;
1251 procedure TF_Semicolon;
1252 procedure TF_Then;
1253 procedure TF_Use;
1255 -- Procedures with names of the form U_xxx, where Tok_xxx is a token
1256 -- name, are just like the corresponding T_xxx procedures except that
1257 -- an error message, if given, is unconditional.
1259 procedure U_Left_Paren;
1260 procedure U_Right_Paren;
1261 end Tchk;
1263 --------------
1264 -- Par.Util --
1265 --------------
1267 package Util is
1268 function Bad_Spelling_Of (T : Token_Type) return Boolean;
1269 -- This function is called in an error situation. It checks if the
1270 -- current token is an identifier whose name is a plausible bad
1271 -- spelling of the given keyword token, and if so, issues an error
1272 -- message, sets Token from T, and returns True. Otherwise Token is
1273 -- unchanged, and False is returned.
1275 procedure Check_Bad_Layout;
1276 -- Check for bad indentation in RM checking mode. Used for statements
1277 -- and declarations. Checks if current token is at start of line and
1278 -- is exdented from the current expected end column, and if so an
1279 -- error message is generated.
1281 procedure Check_Misspelling_Of (T : Token_Type);
1282 pragma Inline (Check_Misspelling_Of);
1283 -- This is similar to the function above, except that it does not
1284 -- return a result. It is typically used in a situation where any
1285 -- identifier is an error, and it makes sense to simply convert it
1286 -- to the given token if it is a plausible misspelling of it.
1288 procedure Check_95_Keyword (Token_95, Next : Token_Type);
1289 -- This routine checks if the token after the current one matches the
1290 -- Next argument. If so, the scan is backed up to the current token
1291 -- and Token_Type is changed to Token_95 after issuing an appropriate
1292 -- error message ("(Ada 83) keyword xx cannot be used"). If not,
1293 -- the scan is backed up with Token_Type unchanged. This routine
1294 -- is used to deal with an attempt to use a 95 keyword in Ada 83
1295 -- mode. The caller has typically checked that the current token,
1296 -- an identifier, matches one of the 95 keywords.
1298 procedure Check_Future_Keyword;
1299 -- Emit a warning if the current token is a valid identifier in the
1300 -- language version in use, but is a reserved word in a later language
1301 -- version (unless the language version in use is Ada 83).
1303 procedure Check_Simple_Expression (E : Node_Id);
1304 -- Given an expression E, that has just been scanned, so that Expr_Form
1305 -- is still set, outputs an error if E is a non-simple expression. E is
1306 -- not modified by this call.
1308 procedure Check_Simple_Expression_In_Ada_83 (E : Node_Id);
1309 -- Like Check_Simple_Expression, except that the error message is only
1310 -- given when operating in Ada 83 mode, and includes "in Ada 83".
1312 function Check_Subtype_Mark (Mark : Node_Id) return Node_Id;
1313 -- Called to check that a node representing a name (or call) is
1314 -- suitable for a subtype mark, i.e, that it is an identifier or
1315 -- a selected component. If so, or if it is already Error, then
1316 -- it is returned unchanged. Otherwise an error message is issued
1317 -- and Error is returned.
1319 function Comma_Present return Boolean;
1320 -- Used in comma delimited lists to determine if a comma is present, or
1321 -- can reasonably be assumed to have been present (an error message is
1322 -- generated in the latter case). If True is returned, the scan has been
1323 -- positioned past the comma. If False is returned, the scan position
1324 -- is unchanged. Note that all comma-delimited lists are terminated by
1325 -- a right paren, so the only legitimate tokens when Comma_Present is
1326 -- called are right paren and comma. If some other token is found, then
1327 -- Comma_Present has the job of deciding whether it is better to pretend
1328 -- a comma was present, post a message for a missing comma and return
1329 -- True, or return False and let the caller diagnose the missing right
1330 -- parenthesis.
1332 procedure Discard_Junk_Node (N : Node_Id);
1333 procedure Discard_Junk_List (L : List_Id);
1334 pragma Inline (Discard_Junk_Node);
1335 pragma Inline (Discard_Junk_List);
1336 -- These procedures do nothing at all, their effect is simply to discard
1337 -- the argument. A typical use is to skip by some junk that is not
1338 -- expected in the current context.
1340 procedure Ignore (T : Token_Type);
1341 -- If current token matches T, then give an error message and skip
1342 -- past it, otherwise the call has no effect at all. T may be any
1343 -- reserved word token, or comma, left or right paren, or semicolon.
1345 function Is_Reserved_Identifier (C : Id_Check := None) return Boolean;
1346 -- Test if current token is a reserved identifier. This test is based
1347 -- on the token being a keyword and being spelled in typical identifier
1348 -- style (i.e. starting with an upper case letter). The parameter C
1349 -- determines the special treatment if a reserved word is encountered
1350 -- that has the normal casing of a reserved word.
1352 procedure Merge_Identifier (Prev : Node_Id; Nxt : Token_Type);
1353 -- Called when the previous token is an identifier (whose Token_Node
1354 -- value is given by Prev) to check if current token is an identifier
1355 -- that can be merged with the previous one adding an underscore. The
1356 -- merge is only attempted if the following token matches Nxt. If all
1357 -- conditions are met, an error message is issued, and the merge is
1358 -- carried out, modifying the Chars field of Prev.
1360 function Missing_Semicolon_On_When return Boolean;
1361 -- This function deals with the following specialized situations
1362 --
1364 -- exit/return [identifier]
1366 --
1367 -- This looks like a messed up EXIT WHEN or RETURN WHEN, when in fact
1368 -- the problem is a missing semicolon. It is called with Token pointing
1369 -- to the WHEN token, and returns True if a semicolon is missing before
1370 -- the WHEN as in the above example.
1372 function Next_Token_Is (Tok : Token_Type) return Boolean;
1373 -- Looks at token after current one and returns True if the token type
1374 -- matches Tok. The scan is unconditionally restored on return.
1376 procedure No_Constraint;
1377 -- Called in a place where no constraint is allowed, but one might
1378 -- appear due to a common error (e.g. after the type mark in a procedure
1379 -- parameter. If a constraint is present, an error message is posted,
1380 -- and the constraint is scanned and discarded.
1382 procedure Push_Scope_Stack;
1383 pragma Inline (Push_Scope_Stack);
1384 -- Push a new entry onto the scope stack. Scope.Last (the stack pointer)
1385 -- is incremented. The Junk field is preinitialized to False. The caller
1386 -- is expected to fill in all remaining entries of the new top stack
1387 -- entry at Scopes (Scope.Last).
1389 procedure Pop_Scope_Stack;
1390 -- Pop an entry off the top of the scope stack. Scope_Last (the scope
1391 -- table stack pointer) is decremented by one. It is a fatal error to
1392 -- try to pop off the dummy entry at the bottom of the stack (i.e.
1393 -- Scope.Last must be non-zero at the time of call).
1395 function Separate_Present return Boolean;
1396 -- Determines if the current token is either Tok_Separate, or an
1397 -- identifier that is a possible misspelling of "separate" followed
1398 -- by a semicolon. True is returned if so, otherwise False.
1400 procedure Signal_Bad_Attribute;
1401 -- The current token is an identifier that is supposed to be an
1402 -- attribute identifier but is not. This routine posts appropriate
1403 -- error messages, including a check for a near misspelling.
1405 function Token_Is_At_Start_Of_Line return Boolean;
1406 pragma Inline (Token_Is_At_Start_Of_Line);
1407 -- Determines if the current token is the first token on the line
1409 function Token_Is_At_End_Of_Line return Boolean;
1410 -- Determines if the current token is the last token on the line
1412 procedure Warn_If_Standard_Redefinition (N : Node_Id);
1413 -- Issues a warning if Warn_On_Standard_Redefinition is set True, and
1414 -- the Node N (which is a Defining_Identifier node with the Chars field
1415 -- set) is a renaming of an entity in package Standard.
1417 end Util;
1419 --------------
1420 -- Par.Prag --
1421 --------------
1423 -- The processing for pragmas is split off from chapter 2
1425 function Prag (Pragma_Node : Node_Id; Semi : Source_Ptr) return Node_Id;
1426 -- This function is passed a tree for a pragma that has been scanned out.
1427 -- The pragma is syntactically well formed according to the general syntax
1428 -- for pragmas and the pragma identifier is for one of the recognized
1429 -- pragmas. It performs specific syntactic checks for specific pragmas.
1430 -- The result is the input node if it is OK, or Error otherwise. The
1431 -- reason that this is separated out is to facilitate the addition
1432 -- of implementation defined pragmas. The second parameter records the
1433 -- location of the semicolon following the pragma (this is needed for
1434 -- correct processing of the List and Page pragmas). The returned value
1435 -- is a copy of Pragma_Node, or Error if an error is found. Note that
1436 -- at the point where Prag is called, the right paren ending the pragma
1437 -- has been scanned out, and except in the case of pragma Style_Checks,
1438 -- so has the following semicolon. For Style_Checks, the caller delays
1439 -- the scanning of the semicolon so that it will be scanned using the
1440 -- settings from the Style_Checks pragma preceding it.
1442 --------------
1443 -- Par.Labl --
1444 --------------
1446 procedure Labl;
1447 -- This procedure creates implicit label declarations for all labels that
1448 -- are declared in the current unit. Note that this could conceptually be
1449 -- done at the point where the labels are declared, but it is tricky to do
1450 -- it then, since the tree is not hooked up at the point where the label is
1451 -- declared (e.g. a sequence of statements is not yet attached to its
1452 -- containing scope at the point a label in the sequence is found).
1454 --------------
1455 -- Par.Load --
1456 --------------
1458 procedure Load;
1459 -- This procedure loads all subsidiary units that are required by this
1460 -- unit, including with'ed units, specs for bodies, and parents for child
1461 -- units. It does not load bodies for inlined procedures and generics,
1462 -- since we don't know till semantic analysis is complete what is needed.
1464 -----------
1465 -- Stubs --
1466 -----------
1468 -- The package bodies can see all routines defined in all other subpackages
1470 use Ch2;
1471 use Ch3;
1472 use Ch4;
1473 use Ch5;
1474 use Ch6;
1475 use Ch7;
1476 use Ch8;
1477 use Ch9;
1478 use Ch10;
1479 use Ch11;
1480 use Ch12;
1481 use Ch13;
1483 use Endh;
1484 use Tchk;
1485 use Sync;
1486 use Util;
1488 package body Ch2 is separate;
1489 package body Ch3 is separate;
1490 package body Ch4 is separate;
1491 package body Ch5 is separate;
1492 package body Ch6 is separate;
1493 package body Ch7 is separate;
1494 package body Ch8 is separate;
1495 package body Ch9 is separate;
1496 package body Ch10 is separate;
1497 package body Ch11 is separate;
1498 package body Ch12 is separate;
1499 package body Ch13 is separate;
1501 package body Endh is separate;
1502 package body Tchk is separate;
1503 package body Sync is separate;
1504 package body Util is separate;
1506 function Prag (Pragma_Node : Node_Id; Semi : Source_Ptr) return Node_Id
1507 is separate;
1509 procedure Labl is separate;
1510 procedure Load is separate;
1512 Result : List_Id := Empty_List;
1514 -- Start of processing for Par
1516 begin
1517 Compiler_State := Parsing;
1519 -- Deal with configuration pragmas case first
1521 if Configuration_Pragmas then
1522 declare
1523 Pragmas : constant List_Id := Empty_List;
1524 P_Node : Node_Id;
1526 begin
1527 loop
1528 if Token = Tok_EOF then
1529 Result := Pragmas;
1530 exit;
1532 elsif Token /= Tok_Pragma then
1533 Error_Msg_SC ("only pragmas allowed in configuration file");
1534 Result := Error_List;
1535 exit;
1537 else
1538 P_Node := P_Pragma;
1540 if Nkind (P_Node) = N_Pragma then
1542 -- Give error if bad pragma
1544 if not Is_Configuration_Pragma_Name
1545 (Pragma_Name_Unmapped (P_Node))
1546 and then
1547 Pragma_Name_Unmapped (P_Node) /= Name_Source_Reference
1548 then
1549 if Is_Pragma_Name (Pragma_Name_Unmapped (P_Node)) then
1550 Error_Msg_N
1551 ("only configuration pragmas allowed " &
1552 "in configuration file", P_Node);
1553 else
1554 Error_Msg_N
1555 ("unrecognized pragma in configuration file",
1556 P_Node);
1557 end if;
1559 -- Pragma is OK config pragma, so collect it
1561 else
1562 Append (P_Node, Pragmas);
1563 end if;
1564 end if;
1565 end if;
1566 end loop;
1567 end;
1569 if Config_Files_Store_Basename then
1570 Complete_Source_File_Entry;
1571 end if;
1573 -- Normal case of compilation unit
1575 else
1576 Save_Config_Attrs := Save_Config_Switches;
1578 -- The following loop runs more than once in syntax check mode
1579 -- where we allow multiple compilation units in the same file
1580 -- and in Multiple_Unit_Per_file mode where we skip units till
1581 -- we get to the unit we want.
1583 for Ucount in Pos loop
1584 Set_Config_Switches
1585 (Is_Internal_Unit (Current_Source_Unit),
1586 Main_Unit => Current_Source_Unit = Main_Unit);
1588 -- Initialize scope table and other parser control variables
1590 Compiler_State := Parsing;
1591 Scope.Init;
1592 Scope.Increment_Last;
1593 Scopes (0).Etyp := E_Dummy;
1594 SIS_Entry_Active := False;
1595 Last_Resync_Point := No_Location;
1597 Goto_List := New_Elmt_List;
1598 Label_List := New_Elmt_List;
1600 -- If in multiple unit per file mode, skip past ignored unit
1602 if Ucount < Multiple_Unit_Index then
1604 -- We skip in syntax check only mode, since we don't want to do
1605 -- anything more than skip past the unit and ignore it. This means
1606 -- we skip processing like setting up a unit table entry.
1608 declare
1609 Save_Operating_Mode : constant Operating_Mode_Type :=
1610 Operating_Mode;
1612 Save_Style_Check : constant Boolean := Style_Check;
1614 begin
1615 Operating_Mode := Check_Syntax;
1616 Style_Check := False;
1617 Discard_Node (P_Compilation_Unit);
1618 Operating_Mode := Save_Operating_Mode;
1619 Style_Check := Save_Style_Check;
1621 -- If we are at an end of file, and not yet at the right unit,
1622 -- then we have a fatal error. The unit is missing.
1624 if Token = Tok_EOF then
1625 Error_Msg_SC ("file has too few compilation units");
1626 raise Unrecoverable_Error;
1627 end if;
1628 end;
1630 -- Here if we are not skipping a file in multiple unit per file mode.
1631 -- Parse the unit that we are interested in. Note that in check
1632 -- syntax mode we are interested in all units in the file.
1634 else
1635 declare
1636 Comp_Unit_Node : constant Node_Id := P_Compilation_Unit;
1638 begin
1639 -- If parsing was successful and we are not in check syntax
1640 -- mode, check that language-defined units are compiled in GNAT
1641 -- mode. For this purpose we do NOT consider renamings in annex
1642 -- J as predefined. That allows users to compile their own
1643 -- versions of these files. Another exception is System.RPC
1644 -- and its children. This allows a user to supply their own
1645 -- communication layer.
1646 -- Similarly, we do not generate an error in CodePeer mode,
1647 -- to allow users to analyze third-party compiler packages.
1649 if Comp_Unit_Node /= Error
1650 and then Operating_Mode = Generate_Code
1651 and then Current_Source_Unit = Main_Unit
1652 and then not GNAT_Mode
1653 and then not CodePeer_Mode
1654 then
1655 declare
1656 Uname : constant String :=
1657 Get_Name_String
1658 (Unit_Name (Current_Source_Unit));
1659 Name : String renames
1660 Uname (Uname'First .. Uname'Last - 2);
1661 -- Because Unit_Name includes "%s"/"%b", we need to strip
1662 -- the last two characters to get the real unit name.
1664 begin
1665 if Name = "ada" or else
1666 Name = "interfaces" or else
1667 Name = "system"
1668 then
1669 Error_Msg
1670 ("language-defined units cannot be recompiled",
1671 Sloc (Unit (Comp_Unit_Node)));
1673 elsif Name'Length > 4
1674 and then
1675 Name (Name'First .. Name'First + 3) = "ada."
1676 then
1677 Error_Msg
1678 ("user-defined descendants of package Ada " &
1679 "are not allowed",
1680 Sloc (Unit (Comp_Unit_Node)));
1682 elsif Name'Length > 11
1683 and then
1684 Name (Name'First .. Name'First + 10) = "interfaces."
1685 then
1686 Error_Msg
1687 ("user-defined descendants of package Interfaces " &
1688 "are not allowed",
1689 Sloc (Unit (Comp_Unit_Node)));
1691 elsif Name'Length > 7
1692 and then Name (Name'First .. Name'First + 6) = "system."
1693 and then Name /= "system.rpc"
1694 and then
1695 (Name'Length < 11
1696 or else Name (Name'First .. Name'First + 10) /=
1697 "system.rpc.")
1698 then
1699 Error_Msg
1700 ("user-defined descendants of package System " &
1701 "are not allowed",
1702 Sloc (Unit (Comp_Unit_Node)));
1703 end if;
1704 end;
1705 end if;
1706 end;
1708 -- All done if at end of file
1710 exit when Token = Tok_EOF;
1712 -- If we are not at an end of file, it means we are in syntax
1713 -- check only mode, and we keep the loop going to parse all
1714 -- remaining units in the file.
1716 end if;
1718 Restore_Config_Switches (Save_Config_Attrs);
1719 end loop;
1721 -- Now that we have completely parsed the source file, we can complete
1722 -- the source file table entry.
1724 Complete_Source_File_Entry;
1726 -- An internal error check, the scope stack should now be empty
1728 pragma Assert (Scope.Last = 0);
1730 -- Here we make the SCO table entries for the main unit
1732 if Generate_SCO then
1733 SCO_Record_Raw (Main_Unit);
1734 end if;
1736 -- Remaining steps are to create implicit label declarations and to load
1737 -- required subsidiary sources. These steps are required only if we are
1738 -- doing semantic checking.
1740 if Operating_Mode /= Check_Syntax or else Debug_Flag_F then
1741 Par.Labl;
1742 Par.Load;
1743 end if;
1745 -- Restore settings of switches saved on entry
1747 Restore_Config_Switches (Save_Config_Attrs);
1748 Set_Comes_From_Source_Default (False);
1749 end if;
1751 Compiler_State := Analyzing;
1752 Current_Source_File := No_Source_File;
1753 return Result;
1754 end Par;