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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) 1992-2008, 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 ------------------------------------------------------------------------------
49 ---------
50 -- Par --
51 ---------
53 function Par
55 is
57 -- Count number of units parsed (relevant only in syntax check only mode,
58 -- since in semantics check mode only a single unit is permitted anyway)
61 -- Variable used to save values of config switches while we parse the
62 -- new unit, to be restored on exit for proper recursive behavior.
65 -- Counter used for constructing loop/block names (see the routine
66 -- Par.Ch5.Get_Loop_Block_Name)
68 --------------------
69 -- Error Recovery --
70 --------------------
72 -- When an error is encountered, a call is made to one of the Error_Msg
73 -- routines to record the error. If the syntax scan is not derailed by the
74 -- error (e.g. a complaint that logical operators are inconsistent in an
75 -- EXPRESSION), then control returns from the Error_Msg call, and the
76 -- parse continues unimpeded.
78 -- If on the other hand, the Error_Msg represents a situation from which
79 -- the parser cannot recover locally, the exception Error_Resync is raised
80 -- immediately after the call to Error_Msg. Handlers for Error_Resync
81 -- are located at strategic points to resynchronize the parse. For example,
82 -- when an error occurs in a statement, the handler skips to the next
83 -- semicolon and continues the scan from there.
85 -- Each parsing procedure contains a note with the heading "Error recovery"
86 -- which shows if it can propagate the Error_Resync exception. In order
87 -- not to propagate the exception, a procedure must either contain its own
88 -- handler for this exception, or it must not call any other routines which
89 -- propagate the exception.
91 -- Note: the arrangement of Error_Resync handlers is such that it should
92 -- never be possible to transfer control through a procedure which made
93 -- an entry in the scope stack, invalidating the contents of the stack.
96 -- Exception raised on error that is not handled locally, see above
99 -- The resynchronization routines in Par.Sync run a risk of getting
100 -- stuck in an infinite loop if they do not skip a token, and the caller
101 -- keeps repeating the same resync call. On the other hand, if they skip
102 -- a token unconditionally, some recovery opportunities are missed. The
103 -- variable Last_Resync_Point records the token location previously set
104 -- by a Resync call, and if a subsequent Resync call occurs at the same
105 -- location, then the Resync routine does guarantee to skip a token.
107 --------------------------------------------
108 -- Handling Semicolon Used in Place of IS --
109 --------------------------------------------
111 -- The following global variables are used in handling the error situation
112 -- of using a semicolon in place of IS in a subprogram declaration as in:
114 -- procedure X (Y : Integer);
115 -- Q : Integer;
116 -- begin
117 -- ...
118 -- end;
120 -- The two contexts in which this can appear are at the outer level, and
121 -- within a declarative region. At the outer level, we know something is
122 -- wrong as soon as we see the Q (or begin, if there are no declarations),
123 -- and we can immediately decide that the semicolon should have been IS.
125 -- The situation in a declarative region is more complex. The declaration
126 -- of Q could belong to the outer region, and we do not know that we have
127 -- an error until we hit the begin. It is still not clear at this point
128 -- from a syntactic point of view that something is wrong, because the
129 -- begin could belong to the enclosing subprogram or package. However, we
130 -- can incorporate a bit of semantic knowledge and note that the body of
131 -- X is missing, so we definitely DO have an error. We diagnose this error
132 -- as semicolon in place of IS on the subprogram line.
134 -- There are two styles for this diagnostic. If the begin immediately
135 -- follows the semicolon, then we can place a flag (IS expected) right
136 -- on the semicolon. Otherwise we do not detect the error until we hit
137 -- the begin which refers back to the line with the semicolon.
139 -- To control the process in the second case, the following global
140 -- variables are set to indicate that we have a subprogram declaration
141 -- whose body is required and has not yet been found. The prefix SIS
142 -- stands for "Subprogram IS" handling.
145 -- Set True to indicate that an entry is active (i.e. that a subprogram
146 -- declaration has been encountered, and no body for this subprogram has
147 -- been encountered). The remaining fields are valid only if this is True.
150 -- Subprogram designator
153 -- Source location of FUNCTION/PROCEDURE keyword
156 -- Column number of FUNCTION/PROCEDURE keyword
159 -- Source location of semicolon at end of subprogram declaration
162 -- Pointer to tree node for subprogram declaration
165 -- Used to save message ID of missing semicolon message (which will be
166 -- modified to missing IS if necessary). Set to No_Error_Msg in the
167 -- normal (non-error) case.
169 -- Five things can happen to an active SIS entry
171 -- 1. If a BEGIN is encountered with an SIS entry active, then we have
172 -- exactly the situation in which we know the body of the subprogram is
173 -- missing. After posting an error message, we change the spec to a body,
174 -- rechaining the declarations that intervened between the spec and BEGIN.
176 -- 2. Another subprogram declaration or body is encountered. In this
177 -- case the entry gets overwritten with the information for the new
178 -- subprogram declaration. We don't catch some nested cases this way,
179 -- but it doesn't seem worth the effort.
181 -- 3. A nested declarative region (e.g. package declaration or package
182 -- body) is encountered. The SIS active indication is reset at the start
183 -- of such a nested region. Again, like case 2, this causes us to miss
184 -- some nested cases, but it doesn't seen worth the effort to stack and
185 -- unstack the SIS information. Maybe we will reconsider this if we ever
186 -- get a complaint about a missed case.
188 -- 4. We encounter a valid pragma INTERFACE or IMPORT that effectively
189 -- supplies the missing body. In this case we reset the entry.
191 -- 5. We encounter the end of the declarative region without encountering
192 -- a BEGIN first. In this situation we simply reset the entry. We know
193 -- that there is a missing body, but it seems more reasonable to let the
194 -- later semantic checking discover this.
196 ----------------------------------------------------
197 -- Handling of Reserved Words Used as Identifiers --
198 ----------------------------------------------------
200 -- Note: throughout the parser, the terms reserved word and keyword
201 -- are used interchangeably to refer to the same set of reserved
202 -- keywords (including until, protected, etc).
204 -- If a reserved word is used in place of an identifier, the parser
205 -- where possible tries to recover gracefully. In particular, if the
206 -- keyword is clearly spelled using identifier casing, e.g. Until in
207 -- a source program using mixed case identifiers and lower case keywords,
208 -- then the keyword is treated as an identifier if it appears in a place
209 -- where an identifier is required.
211 -- The situation is more complex if the keyword is spelled with normal
212 -- keyword casing. In this case, the parser is more reluctant to
213 -- consider it to be intended as an identifier, unless it has some
214 -- further confirmation.
216 -- In the case of an identifier appearing in the identifier list of a
217 -- declaration, the appearance of a comma or colon right after the
218 -- keyword on the same line is taken as confirmation. For an enumeration
219 -- literal, a comma or right paren right after the identifier is also
220 -- treated as adequate confirmation.
222 -- The following type is used in calls to Is_Reserved_Identifier and
223 -- also to P_Defining_Identifier and P_Identifier. The default for all
224 -- these functions is that reserved words in reserved word case are not
225 -- considered to be reserved identifiers. The Id_Check value indicates
226 -- tokens, which if they appear immediately after the identifier, are
227 -- taken as confirming that the use of an identifier was expected
231 -- Default, no special token test
233 C_Comma_Right_Paren,
234 -- Consider as identifier if followed by comma or right paren
236 C_Comma_Colon,
237 -- Consider as identifier if followed by comma or colon
239 C_Do,
240 -- Consider as identifier if followed by DO
242 C_Dot,
243 -- Consider as identifier if followed by period
245 C_Greater_Greater,
246 -- Consider as identifier if followed by >>
248 C_In,
249 -- Consider as identifier if followed by IN
251 C_Is,
252 -- Consider as identifier if followed by IS
254 C_Left_Paren_Semicolon,
255 -- Consider as identifier if followed by left paren or semicolon
257 C_Use,
258 -- Consider as identifier if followed by USE
260 C_Vertical_Bar_Arrow);
261 -- Consider as identifier if followed by | or =>
263 --------------------------------------------
264 -- Handling IS Used in Place of Semicolon --
265 --------------------------------------------
267 -- This is a somewhat trickier situation, and we can't catch it in all
268 -- cases, but we do our best to detect common situations resulting from
269 -- a "cut and paste" operation which forgets to change the IS to semicolon.
270 -- Consider the following example:
272 -- package body X is
273 -- procedure A;
274 -- procedure B is
275 -- procedure C;
276 -- ...
277 -- procedure D is
278 -- begin
279 -- ...
280 -- end;
281 -- begin
282 -- ...
283 -- end;
285 -- The trouble is that the section of text from PROCEDURE B through END;
286 -- constitutes a valid procedure body, and the danger is that we find out
287 -- far too late that something is wrong (indeed most compilers will behave
288 -- uncomfortably on the above example).
290 -- We have two approaches to helping to control this situation. First we
291 -- make every attempt to avoid swallowing the last END; if we can be
292 -- sure that some error will result from doing so. In particular, we won't
293 -- accept the END; unless it is exactly correct (in particular it must not
294 -- have incorrect name tokens), and we won't accept it if it is immediately
295 -- followed by end of file, WITH or SEPARATE (all tokens that unmistakeably
296 -- signal the start of a compilation unit, and which therefore allow us to
297 -- reserve the END; for the outer level.) For more details on this aspect
298 -- of the handling, see package Par.Endh.
300 -- If we can avoid eating up the END; then the result in the absence of
301 -- any additional steps would be to post a missing END referring back to
302 -- the subprogram with the bogus IS. Similarly, if the enclosing package
303 -- has no BEGIN, then the result is a missing BEGIN message, which again
304 -- refers back to the subprogram header.
306 -- Such an error message is not too bad (it's already a big improvement
307 -- over what many parsers do), but it's not ideal, because the declarations
308 -- following the IS have been absorbed into the wrong scope. In the above
309 -- case, this could result for example in a bogus complaint that the body
310 -- of D was missing from the package.
312 -- To catch at least some of these cases, we take the following additional
313 -- steps. First, a subprogram body is marked as having a suspicious IS if
314 -- the declaration line is followed by a line which starts with a symbol
315 -- that can start a declaration in the same column, or to the left of the
316 -- column in which the FUNCTION or PROCEDURE starts (normal style is to
317 -- indent any declarations which really belong a subprogram). If such a
318 -- subprogram encounters a missing BEGIN or missing END, then we decide
319 -- that the IS should have been a semicolon, and the subprogram body node
320 -- is marked (by setting the Bad_Is_Detected flag true. Note that we do
321 -- not do this for library level procedures, only for nested procedures,
322 -- since for library level procedures, we must have a body.
324 -- The processing for a declarative part checks to see if the last
325 -- declaration scanned is marked in this way, and if it is, the tree
326 -- is modified to reflect the IS being interpreted as a semicolon.
328 ---------------------------------------------------
329 -- Parser Type Definitions and Control Variables --
330 ---------------------------------------------------
332 -- The following variable and associated type declaration are used by the
333 -- expression parsing routines to return more detailed information about
334 -- the categorization of a parsed expression.
345 -- The following type is used for calls to P_Subprogram, P_Package, P_Task,
346 -- P_Protected to indicate which of several possibilities is acceptable.
364 Pf_Rec'(F, T, T, T, T, T, F, F);
365 Pf_Decl : constant Pf_Rec :=
368 Pf_Rec'(F, T, T, T, T, F, F, F);
369 Pf_Decl_Pbod : constant Pf_Rec :=
372 Pf_Rec'(F, F, F, T, F, F, F, F);
373 Pf_Spcn : constant Pf_Rec :=
375 -- The above are the only allowed values of Pf_Rec arguments
399 Goto_List : Elist_Id;
400 -- List of goto nodes appearing in the current compilation. Used to
401 -- recognize natural loops and convert them into bona fide loops for
402 -- optimization purposes.
404 Label_List : Elist_Id;
405 -- List of label nodes for labels appearing in the current compilation.
406 -- Used by Par.Labl to construct the corresponding implicit declarations.
408 -----------------
409 -- Scope Table --
410 -----------------
412 -- The scope table, also referred to as the scope stack, is used to
413 -- record the current scope context. It is organized as a stack, with
414 -- inner nested entries corresponding to higher entries on the stack.
415 -- An entry is made when the parser encounters the opening of a nested
416 -- construct (such as a record, task, package etc.), and then package
417 -- Par.Endh uses this stack to deal with END lines (including properly
418 -- dealing with END nesting errors).
420 type SS_End_Type is
421 -- Type of end entry required for this scope. The last two entries are
422 -- used only in the subprogram body case to mark the case of a suspicious
423 -- IS, or a bad IS (i.e. suspicions confirmed by missing BEGIN or END).
424 -- See separate section on dealing with IS used in place of semicolon.
425 -- Note that for many purposes E_Name, E_Suspicious_Is and E_Bad_Is are
426 -- treated the same (E_Suspicious_Is and E_Bad_Is are simply special cases
427 -- of E_Name). They are placed at the end of the enumeration so that a
428 -- test for >= E_Name catches all three cases efficiently.
430 (E_Dummy, -- dummy entry at outer level
431 E_Case, -- END CASE;
432 E_If, -- END IF;
433 E_Loop, -- END LOOP;
434 E_Record, -- END RECORD;
435 E_Return, -- END RETURN;
436 E_Select, -- END SELECT;
437 E_Name, -- END [name];
438 E_Suspicious_Is, -- END [name]; (case of suspicious IS)
439 E_Bad_Is); -- END [name]; (case of bad IS)
441 -- The following describes a single entry in the scope table
443 type Scope_Table_Entry is record
444 Etyp : SS_End_Type;
445 -- Type of end entry, as per above description
447 Lreq : Boolean;
448 -- A flag indicating whether the label, if present, is required to
449 -- appear on the end line. It is referenced only in the case of
450 -- Etyp = E_Name or E_Suspicious_Is where the name may or may not be
451 -- required (yes for labeled block, no in other cases). Note that for
452 -- all cases except begin, the question of whether a label is required
453 -- can be determined from the other fields (for loop, it is required if
454 -- it is present, and for the other constructs it is never required or
455 -- allowed).
457 Ecol : Column_Number;
458 -- Contains the absolute column number (with tabs expanded) of the
459 -- the expected column of the end assuming normal Ada indentation
460 -- usage. If the RM_Column_Check mode is set, this value is used for
461 -- generating error messages about indentation. Otherwise it is used
462 -- only to control heuristic error recovery actions.
464 Labl : Node_Id;
465 -- This field is used only for the LOOP and BEGIN cases, and is the
466 -- Node_Id value of the label name. For all cases except child units,
467 -- this value is an entity whose Chars field contains the name pointer
468 -- that identifies the label uniquely. For the child unit case the Labl
469 -- field references an N_Defining_Program_Unit_Name node for the name.
470 -- For cases other than LOOP or BEGIN, the Label field is set to Error,
471 -- indicating that it is an error to have a label on the end line.
472 -- (this is really a misuse of Error since there is no Error ???)
474 Decl : List_Id;
475 -- Points to the list of declarations (i.e. the declarative part)
476 -- associated with this construct. It is set only in the END [name]
477 -- cases, and is set to No_List for all other cases which do not have a
478 -- declarative unit associated with them. This is used for determining
479 -- the proper location for implicit label declarations.
481 Node : Node_Id;
482 -- Empty except in the case of entries for IF and CASE statements,
483 -- in which case it contains the N_If_Statement or N_Case_Statement
484 -- node. This is used for setting the End_Span field.
486 Sloc : Source_Ptr;
487 -- Source location of the opening token of the construct. This is
488 -- used to refer back to this line in error messages (such as missing
489 -- or incorrect end lines). The Sloc field is not used, and is not set,
490 -- if a label is present (the Labl field provides the text name of the
491 -- label in this case, which is fine for error messages).
493 S_Is : Source_Ptr;
494 -- S_Is is relevant only if Etyp is set to E_Suspicious_Is or
495 -- E_Bad_Is. It records the location of the IS that is considered
496 -- to be suspicious.
498 Junk : Boolean;
499 -- A boolean flag that is set true if the opening entry is the dubious
500 -- result of some prior error, e.g. a record entry where the record
501 -- keyword was missing. It is used to suppress the issuing of a
502 -- corresponding junk complaint about the end line (we do not want
503 -- to complain about a missing end record when there was no record).
504 end record;
506 -- The following declares the scope table itself. The Last field is the
507 -- stack pointer, so that Scope.Table (Scope.Last) is the top entry. The
508 -- oldest entry, at Scope_Stack (0), is a dummy entry with Etyp set to
509 -- E_Dummy, and the other fields undefined. This dummy entry ensures that
510 -- Scope_Stack (Scope_Stack_Ptr).Etyp can always be tested, and that the
511 -- scope stack pointer is always in range.
513 package Scope is new Table.Table (
514 Table_Component_Type => Scope_Table_Entry,
515 Table_Index_Type => Int,
516 Table_Low_Bound => 0,
517 Table_Initial => 50,
518 Table_Increment => 100,
519 Table_Name => "Scope");
521 ---------------------------------
522 -- Parsing Routines by Chapter --
523 ---------------------------------
525 -- Uncommented declarations in this section simply parse the construct
526 -- corresponding to their name, and return an ID value for the Node or
527 -- List that is created.
529 -------------
530 -- Par.Ch2 --
531 -------------
533 package Ch2 is
534 function P_Pragma (Skipping : Boolean := False) return Node_Id;
535 -- Scan out a pragma. If Skipping is True, then the caller is skipping
536 -- the pragma in the context of illegal placement (this is used to avoid
537 -- some junk cascaded messages).
539 function P_Identifier (C : Id_Check := None) return Node_Id;
540 -- Scans out an identifier. The parameter C determines the treatment
541 -- of reserved identifiers. See declaration of Id_Check for details.
543 function P_Pragmas_Opt return List_Id;
544 -- This function scans for a sequence of pragmas in other than a
545 -- declaration sequence or statement sequence context. All pragmas
546 -- can appear except pragmas Assert and Debug, which are only allowed
547 -- in a declaration or statement sequence context.
549 procedure P_Pragmas_Misplaced;
550 -- Skips misplaced pragmas with a complaint
552 procedure P_Pragmas_Opt (List : List_Id);
553 -- Parses optional pragmas and appends them to the List
554 end Ch2;
556 -------------
557 -- Par.Ch3 --
558 -------------
560 package Ch3 is
561 Missing_Begin_Msg : Error_Msg_Id;
562 -- This variable is set by a call to P_Declarative_Part. Normally it
563 -- is set to No_Error_Msg, indicating that no special processing is
564 -- required by the caller. The special case arises when a statement
565 -- is found in the sequence of declarations. In this case the Id of
566 -- the message issued ("declaration expected") is preserved in this
567 -- variable, then the caller can change it to an appropriate missing
568 -- begin message if indeed the BEGIN is missing.
570 function P_Array_Type_Definition return Node_Id;
571 function P_Basic_Declarative_Items return List_Id;
572 function P_Constraint_Opt return Node_Id;
573 function P_Declarative_Part return List_Id;
574 function P_Discrete_Choice_List return List_Id;
575 function P_Discrete_Range return Node_Id;
576 function P_Discrete_Subtype_Definition return Node_Id;
577 function P_Known_Discriminant_Part_Opt return List_Id;
578 function P_Signed_Integer_Type_Definition return Node_Id;
579 function P_Range return Node_Id;
580 function P_Range_Or_Subtype_Mark return Node_Id;
581 function P_Range_Constraint return Node_Id;
582 function P_Record_Definition return Node_Id;
583 function P_Subtype_Mark return Node_Id;
584 function P_Subtype_Mark_Resync return Node_Id;
585 function P_Unknown_Discriminant_Part_Opt return Boolean;
587 function P_Access_Definition
588 (Null_Exclusion_Present : Boolean) return Node_Id;
589 -- Ada 2005 (AI-231/AI-254): The caller parses the null-exclusion part
590 -- and indicates if it was present
592 function P_Access_Type_Definition
593 (Header_Already_Parsed : Boolean := False) return Node_Id;
594 -- Ada 2005 (AI-254): The formal is used to indicate if the caller has
595 -- parsed the null_exclusion part. In this case the caller has also
596 -- removed the ACCESS token
598 procedure P_Component_Items (Decls : List_Id);
599 -- Scan out one or more component items and append them to the
600 -- given list. Only scans out more than one declaration in the
601 -- case where the source has a single declaration with multiple
602 -- defining identifiers.
604 function P_Defining_Identifier (C : Id_Check := None) return Node_Id;
605 -- Scan out a defining identifier. The parameter C controls the
606 -- treatment of errors in case a reserved word is scanned. See the
607 -- declaration of this type for details.
609 function P_Interface_Type_Definition
610 (Abstract_Present : Boolean) return Node_Id;
611 -- Ada 2005 (AI-251): Parse the interface type definition part. Abstract
612 -- Present indicates if the reserved word "abstract" has been previously
613 -- found. It is used to report an error message because interface types
614 -- are by definition abstract tagged. We generate a record_definition
615 -- node if the list of interfaces is empty; otherwise we generate a
616 -- derived_type_definition node (the first interface in this list is the
617 -- ancestor interface).
619 function P_Null_Exclusion
620 (Allow_Anonymous_In_95 : Boolean := False) return Boolean;
621 -- Ada 2005 (AI-231): Parse the null-excluding part. A True result
622 -- indicates that the null-excluding part was present.
623 -- Allow_Anonymous_In_95 is True if we are in a context that allows
624 -- anonymous access types in Ada 95, in which case "not null" is legal
625 -- if it precedes "access".
627 function P_Subtype_Indication
628 (Not_Null_Present : Boolean := False) return Node_Id;
629 -- Ada 2005 (AI-231): The flag Not_Null_Present indicates that the
630 -- null-excluding part has been scanned out and it was present.
632 function Init_Expr_Opt (P : Boolean := False) return Node_Id;
633 -- If an initialization expression is present (:= expression), then
634 -- it is scanned out and returned, otherwise Empty is returned if no
635 -- initialization expression is present. This procedure also handles
636 -- certain common error cases cleanly. The parameter P indicates if
637 -- a right paren can follow the expression (default = no right paren
638 -- allowed).
640 procedure Skip_Declaration (S : List_Id);
641 -- Used when scanning statements to skip past a misplaced declaration
642 -- The declaration is scanned out and appended to the given list.
643 -- Token is known to be a declaration token (in Token_Class_Declk)
644 -- on entry, so there definition is a declaration to be scanned.
646 function P_Subtype_Indication
647 (Subtype_Mark : Node_Id;
648 Not_Null_Present : Boolean := False) return Node_Id;
649 -- This version of P_Subtype_Indication is called when the caller has
650 -- already scanned out the subtype mark which is passed as a parameter.
651 -- Ada 2005 (AI-231): The flag Not_Null_Present indicates that the
652 -- null-excluding part has been scanned out and it was present.
654 function P_Subtype_Mark_Attribute (Type_Node : Node_Id) return Node_Id;
655 -- Parse a subtype mark attribute. The caller has already parsed the
656 -- subtype mark, which is passed in as the argument, and has checked
657 -- that the current token is apostrophe.
658 end Ch3;
660 -------------
661 -- Par.Ch4 --
662 -------------
664 package Ch4 is
665 function P_Aggregate return Node_Id;
666 function P_Expression return Node_Id;
667 function P_Expression_No_Right_Paren return Node_Id;
668 function P_Expression_Or_Range_Attribute return Node_Id;
669 function P_Function_Name return Node_Id;
670 function P_Name return Node_Id;
671 function P_Qualified_Simple_Name return Node_Id;
672 function P_Qualified_Simple_Name_Resync return Node_Id;
673 function P_Simple_Expression return Node_Id;
674 function P_Simple_Expression_Or_Range_Attribute return Node_Id;
676 function P_Qualified_Expression
677 (Subtype_Mark : Node_Id)
678 return Node_Id;
679 -- This routine scans out a qualified expression when the caller has
680 -- already scanned out the name and apostrophe of the construct.
681 end Ch4;
683 -------------
684 -- Par.Ch5 --
685 -------------
687 package Ch5 is
688 function P_Statement_Name (Name_Node : Node_Id) return Node_Id;
689 -- Given a node representing a name (which is a call), converts it
690 -- to the syntactically corresponding procedure call statement.
692 function P_Sequence_Of_Statements (SS_Flags : SS_Rec) return List_Id;
693 -- The argument indicates the acceptable termination tokens.
694 -- See body in Par.Ch5 for details of the use of this parameter.
696 procedure Parse_Decls_Begin_End (Parent : Node_Id);
697 -- Parses declarations and handled statement sequence, setting
698 -- fields of Parent node appropriately.
699 end Ch5;
701 -------------
702 -- Par.Ch6 --
703 -------------
705 package Ch6 is
706 function P_Designator return Node_Id;
707 function P_Defining_Program_Unit_Name return Node_Id;
708 function P_Formal_Part return List_Id;
709 function P_Parameter_Profile return List_Id;
710 function P_Return_Statement return Node_Id;
711 function P_Subprogram_Specification return Node_Id;
713 procedure P_Mode (Node : Node_Id);
714 -- Sets In_Present and/or Out_Present flags in Node scanning past
715 -- IN, OUT or IN OUT tokens in the source.
717 function P_Subprogram (Pf_Flags : Pf_Rec) return Node_Id;
718 -- Scans out any construct starting with either of the keywords
719 -- PROCEDURE or FUNCTION. The parameter indicates which possible
720 -- possible kinds of construct (body, spec, instantiation etc.)
721 -- are permissible in the current context.
722 end Ch6;
724 -------------
725 -- Par.Ch7 --
726 -------------
728 package Ch7 is
729 function P_Package (Pf_Flags : Pf_Rec) return Node_Id;
730 -- Scans out any construct starting with the keyword PACKAGE. The
731 -- parameter indicates which possible kinds of construct (body, spec,
732 -- instantiation etc.) are permissible in the current context.
733 end Ch7;
735 -------------
736 -- Par.Ch8 --
737 -------------
739 package Ch8 is
740 function P_Use_Clause return Node_Id;
741 end Ch8;
743 -------------
744 -- Par.Ch9 --
745 -------------
747 package Ch9 is
748 function P_Abort_Statement return Node_Id;
749 function P_Abortable_Part return Node_Id;
750 function P_Accept_Statement return Node_Id;
751 function P_Delay_Statement return Node_Id;
752 function P_Entry_Body return Node_Id;
753 function P_Protected return Node_Id;
754 function P_Requeue_Statement return Node_Id;
755 function P_Select_Statement return Node_Id;
756 function P_Task return Node_Id;
757 function P_Terminate_Alternative return Node_Id;
758 end Ch9;
760 --------------
761 -- Par.Ch10 --
762 --------------
764 package Ch10 is
765 function P_Compilation_Unit return Node_Id;
766 -- Note: this function scans a single compilation unit, and
767 -- checks that an end of file follows this unit, diagnosing
768 -- any unexpected input as an error, and then skipping it, so
769 -- that Token is set to Tok_EOF on return. An exception is in
770 -- syntax-only mode, where multiple compilation units are
771 -- permitted. In this case, P_Compilation_Unit does not check
772 -- for end of file and there may be more compilation units to
773 -- scan. The caller can uniquely detect this situation by the
774 -- fact that Token is not set to Tok_EOF on return.
775 --
776 -- The Ignore parameter is normally set False. It is set True
777 -- in multiple unit per file mode if we are skipping past a unit
778 -- that we are not interested in.
779 end Ch10;
781 --------------
782 -- Par.Ch11 --
783 --------------
785 package Ch11 is
786 function P_Handled_Sequence_Of_Statements return Node_Id;
787 function P_Raise_Statement return Node_Id;
789 function Parse_Exception_Handlers return List_Id;
790 -- Parses the partial construct EXCEPTION followed by a list of
791 -- exception handlers which appears in a number of productions,
792 -- and returns the list of exception handlers.
793 end Ch11;
795 --------------
796 -- Par.Ch12 --
797 --------------
799 package Ch12 is
800 function P_Generic return Node_Id;
801 function P_Generic_Actual_Part_Opt return List_Id;
802 end Ch12;
804 --------------
805 -- Par.Ch13 --
806 --------------
808 package Ch13 is
809 function P_Representation_Clause return Node_Id;
811 function P_Code_Statement (Subtype_Mark : Node_Id) return Node_Id;
812 -- Function to parse a code statement. The caller has scanned out
813 -- the name to be used as the subtype mark (but has not checked that
814 -- it is suitable for use as a subtype mark, i.e. is either an
815 -- identifier or a selected component). The current token is an
816 -- apostrophe and the following token is either a left paren or
817 -- RANGE (the latter being an error to be caught by P_Code_Statement.
818 end Ch13;
820 -- Note: the parsing for annexe J features (i.e. obsolescent features)
821 -- is found in the logical section where these features would be if
822 -- they were not obsolescent. In particular:
824 -- Delta constraint is parsed by P_Delta_Constraint (3.5.9)
825 -- At clause is parsed by P_At_Clause (13.1)
826 -- Mod clause is parsed by P_Mod_Clause (13.5.1)
828 --------------
829 -- Par.Endh --
830 --------------
832 -- Routines for handling end lines, including scope recovery
834 package Endh is
835 function Check_End return Boolean;
836 -- Called when an end sequence is required. In the absence of an error
837 -- situation, Token contains Tok_End on entry, but in a missing end
838 -- case, this may not be the case. Pop_End_Context is used to determine
839 -- the appropriate action to be taken. The returned result is True if
840 -- an End sequence was encountered and False if no End sequence was
841 -- present. This occurs if the END keyword encountered was determined
842 -- to be improper and deleted (i.e. Pop_End_Context set End_Action to
843 -- Skip_And_Reject). Note that the END sequence includes a semicolon,
844 -- except in the case of END RECORD, where a semicolon follows the END
845 -- RECORD, but is not part of the record type definition itself.
847 procedure End_Skip;
848 -- Skip past an end sequence. On entry Token contains Tok_End, and we
849 -- we know that the end sequence is syntactically incorrect, and that
850 -- an appropriate error message has already been posted. The mission
851 -- is simply to position the scan pointer to be the best guess of the
852 -- position after the end sequence. We do not issue any additional
853 -- error messages while carrying this out.
855 procedure End_Statements (Parent : Node_Id := Empty);
856 -- Called when an end is required or expected to terminate a sequence
857 -- of statements. The caller has already made an appropriate entry in
858 -- the Scope.Table to describe the expected form of the end. This can
859 -- only be used in cases where the only appropriate terminator is end.
860 -- If Parent is non-empty, then if a correct END line is encountered,
861 -- the End_Label field of Parent is set appropriately.
862 end Endh;
864 --------------
865 -- Par.Sync --
866 --------------
868 -- These procedures are used to resynchronize after errors. Following an
869 -- error which is not immediately locally recoverable, the exception
870 -- Error_Resync is raised. The handler for Error_Resync typically calls
871 -- one of these recovery procedures to resynchronize the source position
872 -- to a point from which parsing can be restarted.
874 -- Note: these procedures output an information message that tokens are
875 -- being skipped, but this message is output only if the option for
876 -- Multiple_Errors_Per_Line is set in Options.
878 package Sync is
879 procedure Resync_Choice;
880 -- Used if an error occurs scanning a choice. The scan pointer is
881 -- advanced to the next vertical bar, arrow, or semicolon, whichever
882 -- comes first. We also quit if we encounter an end of file.
884 procedure Resync_Expression;
885 -- Used if an error is detected during the parsing of an expression.
886 -- It skips past tokens until either a token which cannot be part of
887 -- an expression is encountered (an expression terminator), or if a
888 -- comma or right parenthesis or vertical bar is encountered at the
889 -- current parenthesis level (a parenthesis level counter is maintained
890 -- to carry out this test).
892 procedure Resync_Past_Semicolon;
893 -- Used if an error occurs while scanning a sequence of declarations.
894 -- The scan pointer is positioned past the next semicolon and the scan
895 -- resumes. The scan is also resumed on encountering a token which
896 -- starts a declaration (but we make sure to skip at least one token
897 -- in this case, to avoid getting stuck in a loop).
899 procedure Resync_To_Semicolon;
900 -- Similar to Resync_Past_Semicolon, except that the scan pointer is
901 -- left pointing to the semicolon rather than past it.
903 procedure Resync_Past_Semicolon_Or_To_Loop_Or_Then;
904 -- Used if an error occurs while scanning a sequence of statements.
905 -- The scan pointer is positioned past the next semicolon, or to the
906 -- next occurrence of either then or loop, and the scan resumes.
908 procedure Resync_To_When;
909 -- Used when an error occurs scanning an entry index specification.
910 -- The scan pointer is positioned to the next WHEN (or to IS or
911 -- semicolon if either of these appear before WHEN, indicating
912 -- another error has occurred).
914 procedure Resync_Semicolon_List;
915 -- Used if an error occurs while scanning a parenthesized list of items
916 -- separated by semicolons. The scan pointer is advanced to the next
917 -- semicolon or right parenthesis at the outer parenthesis level, or
918 -- to the next is or RETURN keyword occurrence, whichever comes first.
920 procedure Resync_Cunit;
921 -- Synchronize to next token which could be the start of a compilation
922 -- unit, or to the end of file token.
923 end Sync;
925 --------------
926 -- Par.Tchk --
927 --------------
929 -- Routines to check for expected tokens
931 package Tchk is
933 -- Procedures with names of the form T_xxx, where Tok_xxx is a token
934 -- name, check that the current token matches the required token, and
935 -- if so, scan past it. If not, an error is issued indicating that
936 -- the required token is not present (xxx expected). In most cases, the
937 -- scan pointer is not moved in the not-found case, but there are some
938 -- exceptions to this, see for example T_Id, where the scan pointer is
939 -- moved across a literal appearing where an identifier is expected.
941 procedure T_Abort;
942 procedure T_Arrow;
943 procedure T_At;
944 procedure T_Body;
945 procedure T_Box;
946 procedure T_Colon;
947 procedure T_Colon_Equal;
948 procedure T_Comma;
949 procedure T_Dot_Dot;
950 procedure T_For;
951 procedure T_Greater_Greater;
952 procedure T_Identifier;
953 procedure T_In;
954 procedure T_Is;
955 procedure T_Left_Paren;
956 procedure T_Loop;
957 procedure T_Mod;
958 procedure T_New;
959 procedure T_Of;
960 procedure T_Or;
961 procedure T_Private;
962 procedure T_Range;
963 procedure T_Record;
964 procedure T_Right_Paren;
965 procedure T_Semicolon;
966 procedure T_Then;
967 procedure T_Type;
968 procedure T_Use;
969 procedure T_When;
970 procedure T_With;
972 -- Procedures having names of the form TF_xxx, where Tok_xxx is a token
973 -- name check that the current token matches the required token, and
974 -- if so, scan past it. If not, an error message is issued indicating
975 -- that the required token is not present (xxx expected).
977 -- If the missing token is at the end of the line, then control returns
978 -- immediately after posting the message. If there are remaining tokens
979 -- on the current line, a search is conducted to see if the token
980 -- appears later on the current line, as follows:
982 -- A call to Scan_Save is issued and a forward search for the token
983 -- is carried out. If the token is found on the current line before a
984 -- semicolon, then it is scanned out and the scan continues from that
985 -- point. If not the scan is restored to the point where it was missing.
987 procedure TF_Arrow;
988 procedure TF_Is;
989 procedure TF_Loop;
990 procedure TF_Return;
991 procedure TF_Semicolon;
992 procedure TF_Then;
993 procedure TF_Use;
995 -- Procedures with names of the form U_xxx, where Tok_xxx is a token
996 -- name, are just like the corresponding T_xxx procedures except that
997 -- an error message, if given, is unconditional.
999 procedure U_Left_Paren;
1000 procedure U_Right_Paren;
1001 end Tchk;
1003 --------------
1004 -- Par.Util --
1005 --------------
1007 package Util is
1008 function Bad_Spelling_Of (T : Token_Type) return Boolean;
1009 -- This function is called in an error situation. It checks if the
1010 -- current token is an identifier whose name is a plausible bad
1011 -- spelling of the given keyword token, and if so, issues an error
1012 -- message, sets Token from T, and returns True. Otherwise Token is
1013 -- unchanged, and False is returned.
1015 procedure Check_Bad_Layout;
1016 -- Check for bad indentation in RM checking mode. Used for statements
1017 -- and declarations. Checks if current token is at start of line and
1018 -- is exdented from the current expected end column, and if so an
1019 -- error message is generated.
1021 procedure Check_Misspelling_Of (T : Token_Type);
1022 pragma Inline (Check_Misspelling_Of);
1023 -- This is similar to the function above, except that it does not
1024 -- return a result. It is typically used in a situation where any
1025 -- identifier is an error, and it makes sense to simply convert it
1026 -- to the given token if it is a plausible misspelling of it.
1028 procedure Check_95_Keyword (Token_95, Next : Token_Type);
1029 -- This routine checks if the token after the current one matches the
1030 -- Next argument. If so, the scan is backed up to the current token
1031 -- and Token_Type is changed to Token_95 after issuing an appropriate
1032 -- error message ("(Ada 83) keyword xx cannot be used"). If not,
1033 -- the scan is backed up with Token_Type unchanged. This routine
1034 -- is used to deal with an attempt to use a 95 keyword in Ada 83
1035 -- mode. The caller has typically checked that the current token,
1036 -- an identifier, matches one of the 95 keywords.
1038 procedure Check_Simple_Expression (E : Node_Id);
1039 -- Given an expression E, that has just been scanned, so that Expr_Form
1040 -- is still set, outputs an error if E is a non-simple expression. E is
1041 -- not modified by this call.
1043 procedure Check_Simple_Expression_In_Ada_83 (E : Node_Id);
1044 -- Like Check_Simple_Expression, except that the error message is only
1045 -- given when operating in Ada 83 mode, and includes "in Ada 83".
1047 function Check_Subtype_Mark (Mark : Node_Id) return Node_Id;
1048 -- Called to check that a node representing a name (or call) is
1049 -- suitable for a subtype mark, i.e, that it is an identifier or
1050 -- a selected component. If so, or if it is already Error, then
1051 -- it is returned unchanged. Otherwise an error message is issued
1052 -- and Error is returned.
1054 function Comma_Present return Boolean;
1055 -- Used in comma delimited lists to determine if a comma is present, or
1056 -- can reasonably be assumed to have been present (an error message is
1057 -- generated in the latter case). If True is returned, the scan has been
1058 -- positioned past the comma. If False is returned, the scan position
1059 -- is unchanged. Note that all comma-delimited lists are terminated by
1060 -- a right paren, so the only legitimate tokens when Comma_Present is
1061 -- called are right paren and comma. If some other token is found, then
1062 -- Comma_Present has the job of deciding whether it is better to pretend
1063 -- a comma was present, post a message for a missing comma and return
1064 -- True, or return False and let the caller diagnose the missing right
1065 -- parenthesis.
1067 procedure Discard_Junk_Node (N : Node_Id);
1068 procedure Discard_Junk_List (L : List_Id);
1069 pragma Inline (Discard_Junk_Node);
1070 pragma Inline (Discard_Junk_List);
1071 -- These procedures do nothing at all, their effect is simply to discard
1072 -- the argument. A typical use is to skip by some junk that is not
1073 -- expected in the current context.
1075 procedure Ignore (T : Token_Type);
1076 -- If current token matches T, then give an error message and skip
1077 -- past it, otherwise the call has no effect at all. T may be any
1078 -- reserved word token, or comma, left or right paren, or semicolon.
1080 function Is_Reserved_Identifier (C : Id_Check := None) return Boolean;
1081 -- Test if current token is a reserved identifier. This test is based
1082 -- on the token being a keyword and being spelled in typical identifier
1083 -- style (i.e. starting with an upper case letter). The parameter C
1084 -- determines the special treatment if a reserved word is encountered
1085 -- that has the normal casing of a reserved word.
1087 procedure Merge_Identifier (Prev : Node_Id; Nxt : Token_Type);
1088 -- Called when the previous token is an identifier (whose Token_Node
1089 -- value is given by Prev) to check if current token is an identifier
1090 -- that can be merged with the previous one adding an underscore. The
1091 -- merge is only attempted if the following token matches Nxt. If all
1092 -- conditions are met, an error message is issued, and the merge is
1093 -- carried out, modifying the Chars field of Prev.
1095 function Next_Token_Is (Tok : Token_Type) return Boolean;
1096 -- Looks at token after current one and returns True if the token type
1097 -- matches Tok. The scan is unconditionally restored on return.
1099 procedure No_Constraint;
1100 -- Called in a place where no constraint is allowed, but one might
1101 -- appear due to a common error (e.g. after the type mark in a procedure
1102 -- parameter. If a constraint is present, an error message is posted,
1103 -- and the constraint is scanned and discarded.
1105 procedure Push_Scope_Stack;
1106 pragma Inline (Push_Scope_Stack);
1107 -- Push a new entry onto the scope stack. Scope.Last (the stack pointer)
1108 -- is incremented. The Junk field is preinitialized to False. The caller
1109 -- is expected to fill in all remaining entries of the new top stack
1110 -- entry at Scope.Table (Scope.Last).
1112 procedure Pop_Scope_Stack;
1113 -- Pop an entry off the top of the scope stack. Scope_Last (the scope
1114 -- table stack pointer) is decremented by one. It is a fatal error to
1115 -- try to pop off the dummy entry at the bottom of the stack (i.e.
1116 -- Scope.Last must be non-zero at the time of call).
1118 function Separate_Present return Boolean;
1119 -- Determines if the current token is either Tok_Separate, or an
1120 -- identifier that is a possible misspelling of "separate" followed
1121 -- by a semicolon. True is returned if so, otherwise False.
1123 procedure Signal_Bad_Attribute;
1124 -- The current token is an identifier that is supposed to be an
1125 -- attribute identifier but is not. This routine posts appropriate
1126 -- error messages, including a check for a near misspelling.
1128 function Token_Is_At_Start_Of_Line return Boolean;
1129 pragma Inline (Token_Is_At_Start_Of_Line);
1130 -- Determines if the current token is the first token on the line
1132 function Token_Is_At_End_Of_Line return Boolean;
1133 -- Determines if the current token is the last token on the line
1134 end Util;
1136 --------------
1137 -- Par.Prag --
1138 --------------
1140 -- The processing for pragmas is split off from chapter 2
1142 function Prag (Pragma_Node : Node_Id; Semi : Source_Ptr) return Node_Id;
1143 -- This function is passed a tree for a pragma that has been scanned out.
1144 -- The pragma is syntactically well formed according to the general syntax
1145 -- for pragmas and the pragma identifier is for one of the recognized
1146 -- pragmas. It performs specific syntactic checks for specific pragmas.
1147 -- The result is the input node if it is OK, or Error otherwise. The
1148 -- reason that this is separated out is to facilitate the addition
1149 -- of implementation defined pragmas. The second parameter records the
1150 -- location of the semicolon following the pragma (this is needed for
1151 -- correct processing of the List and Page pragmas). The returned value
1152 -- is a copy of Pragma_Node, or Error if an error is found. Note that
1153 -- at the point where Prag is called, the right paren ending the pragma
1154 -- has been scanned out, and except in the case of pragma Style_Checks,
1155 -- so has the following semicolon. For Style_Checks, the caller delays
1156 -- the scanning of the semicolon so that it will be scanned using the
1157 -- settings from the Style_Checks pragma preceding it.
1159 --------------
1160 -- Par.Labl --
1161 --------------
1163 procedure Labl;
1164 -- This procedure creates implicit label declarations for all label that
1165 -- are declared in the current unit. Note that this could conceptually
1166 -- be done at the point where the labels are declared, but it is tricky
1167 -- to do it then, since the tree is not hooked up at the point where the
1168 -- label is declared (e.g. a sequence of statements is not yet attached
1169 -- to its containing scope at the point a label in the sequence is found)
1171 --------------
1172 -- Par.Load --
1173 --------------
1175 procedure Load;
1176 -- This procedure loads all subsidiary units that are required by this
1177 -- unit, including with'ed units, specs for bodies, and parents for child
1178 -- units. It does not load bodies for inlined procedures and generics,
1179 -- since we don't know till semantic analysis is complete what is needed.
1181 -----------
1182 -- Stubs --
1183 -----------
1185 -- The package bodies can see all routines defined in all other subpackages
1187 use Ch2;
1188 use Ch3;
1189 use Ch4;
1190 use Ch5;
1191 use Ch6;
1192 use Ch7;
1193 use Ch8;
1194 use Ch9;
1195 use Ch10;
1196 use Ch11;
1197 use Ch12;
1198 use Ch13;
1200 use Endh;
1201 use Tchk;
1202 use Sync;
1203 use Util;
1205 package body Ch2 is separate;
1206 package body Ch3 is separate;
1207 package body Ch4 is separate;
1208 package body Ch5 is separate;
1209 package body Ch6 is separate;
1210 package body Ch7 is separate;
1211 package body Ch8 is separate;
1212 package body Ch9 is separate;
1213 package body Ch10 is separate;
1214 package body Ch11 is separate;
1215 package body Ch12 is separate;
1216 package body Ch13 is separate;
1218 package body Endh is separate;
1219 package body Tchk is separate;
1220 package body Sync is separate;
1221 package body Util is separate;
1223 function Prag (Pragma_Node : Node_Id; Semi : Source_Ptr) return Node_Id
1224 is separate;
1226 procedure Labl is separate;
1227 procedure Load is separate;
1229 -- Start of processing for Par
1231 begin
1233 -- Deal with configuration pragmas case first
1235 if Configuration_Pragmas then
1236 declare
1237 Pragmas : constant List_Id := Empty_List;
1238 P_Node : Node_Id;
1240 begin
1241 loop
1242 if Token = Tok_EOF then
1243 return Pragmas;
1245 elsif Token /= Tok_Pragma then
1246 Error_Msg_SC ("only pragmas allowed in configuration file");
1247 return Error_List;
1249 else
1250 P_Node := P_Pragma;
1252 if Nkind (P_Node) = N_Pragma then
1254 -- Give error if bad pragma
1256 if not Is_Configuration_Pragma_Name (Pragma_Name (P_Node))
1257 and then Pragma_Name (P_Node) /= Name_Source_Reference
1258 then
1259 if Is_Pragma_Name (Pragma_Name (P_Node)) then
1260 Error_Msg_N
1261 ("only configuration pragmas allowed " &
1262 "in configuration file", P_Node);
1263 else
1264 Error_Msg_N
1265 ("unrecognized pragma in configuration file",
1266 P_Node);
1267 end if;
1269 -- Pragma is OK config pragma, so collect it
1271 else
1272 Append (P_Node, Pragmas);
1273 end if;
1274 end if;
1275 end if;
1276 end loop;
1277 end;
1279 -- Normal case of compilation unit
1281 else
1282 Save_Opt_Config_Switches (Save_Config_Switches);
1284 -- The following loop runs more than once in syntax check mode
1285 -- where we allow multiple compilation units in the same file
1286 -- and in Multiple_Unit_Per_file mode where we skip units till
1287 -- we get to the unit we want.
1289 for Ucount in Pos loop
1290 Set_Opt_Config_Switches
1291 (Is_Internal_File_Name (File_Name (Current_Source_File)),
1292 Current_Source_Unit = Main_Unit);
1294 -- Initialize scope table and other parser control variables
1296 Compiler_State := Parsing;
1297 Scope.Init;
1298 Scope.Increment_Last;
1299 Scope.Table (0).Etyp := E_Dummy;
1300 SIS_Entry_Active := False;
1301 Last_Resync_Point := No_Location;
1303 Goto_List := New_Elmt_List;
1304 Label_List := New_Elmt_List;
1306 -- If in multiple unit per file mode, skip past ignored unit
1308 if Ucount < Multiple_Unit_Index then
1310 -- We skip in syntax check only mode, since we don't want
1311 -- to do anything more than skip past the unit and ignore it.
1312 -- This causes processing like setting up a unit table entry
1313 -- to be skipped.
1315 declare
1316 Save_Operating_Mode : constant Operating_Mode_Type :=
1317 Operating_Mode;
1319 Save_Style_Check : constant Boolean := Style_Check;
1321 begin
1322 Operating_Mode := Check_Syntax;
1323 Style_Check := False;
1324 Discard_Node (P_Compilation_Unit);
1325 Operating_Mode := Save_Operating_Mode;
1326 Style_Check := Save_Style_Check;
1328 -- If we are at an end of file, and not yet at the right
1329 -- unit, then we have a fatal error. The unit is missing.
1331 if Token = Tok_EOF then
1332 Error_Msg_SC ("file has too few compilation units");
1333 raise Unrecoverable_Error;
1334 end if;
1335 end;
1337 -- Here if we are not skipping a file in multiple unit per file
1338 -- mode. Parse the unit that we are interested in. Note that in
1339 -- check syntax mode we are interested in all units in the file.
1341 else
1342 declare
1343 Comp_Unit_Node : constant Node_Id := P_Compilation_Unit;
1345 begin
1346 -- If parsing was successful and we are not in check syntax
1347 -- mode, check that language defined units are compiled in
1348 -- GNAT mode. For this purpose we do NOT consider renamings
1349 -- in annex J as predefined. That allows users to compile
1350 -- their own versions of these files, and in particular,
1351 -- in the VMS implementation, the DEC versions can be
1352 -- substituted for the standard Ada 95 versions. Another
1353 -- exception is System.RPC and its children. This allows
1354 -- a user to supply their own communication layer.
1356 if Comp_Unit_Node /= Error
1357 and then Operating_Mode = Generate_Code
1358 and then Current_Source_Unit = Main_Unit
1359 and then not GNAT_Mode
1360 then
1361 declare
1362 Uname : constant String :=
1363 Get_Name_String
1364 (Unit_Name (Current_Source_Unit));
1365 Name : String (1 .. Uname'Length - 2);
1367 begin
1368 -- Because Unit_Name includes "%s" or "%b", we need to
1369 -- strip the last two characters to get the real unit
1370 -- name.
1372 Name := Uname (Uname'First .. Uname'Last - 2);
1374 if Name = "ada" or else
1375 Name = "interfaces" or else
1376 Name = "system"
1377 then
1378 Error_Msg
1379 ("language defined units may not be recompiled",
1380 Sloc (Unit (Comp_Unit_Node)));
1382 elsif Name'Length > 4
1383 and then
1384 Name (Name'First .. Name'First + 3) = "ada."
1385 then
1386 Error_Msg
1387 ("descendents of package Ada " &
1388 "may not be compiled",
1389 Sloc (Unit (Comp_Unit_Node)));
1391 elsif Name'Length > 11
1392 and then
1393 Name (Name'First .. Name'First + 10) = "interfaces."
1394 then
1395 Error_Msg
1396 ("descendents of package Interfaces " &
1397 "may not be compiled",
1398 Sloc (Unit (Comp_Unit_Node)));
1400 elsif Name'Length > 7
1401 and then Name (Name'First .. Name'First + 6) = "system."
1402 and then Name /= "system.rpc"
1403 and then
1404 (Name'Length < 11
1405 or else Name (Name'First .. Name'First + 10) /=
1406 "system.rpc.")
1407 then
1408 Error_Msg
1409 ("descendents of package System " &
1410 "may not be compiled",
1411 Sloc (Unit (Comp_Unit_Node)));
1412 end if;
1413 end;
1414 end if;
1415 end;
1417 -- All done if at end of file
1419 exit when Token = Tok_EOF;
1421 -- If we are not at an end of file, it means we are in syntax
1422 -- check only mode, and we keep the loop going to parse all
1423 -- remaining units in the file.
1425 end if;
1427 Restore_Opt_Config_Switches (Save_Config_Switches);
1428 end loop;
1430 -- Now that we have completely parsed the source file, we can
1431 -- complete the source file table entry.
1433 Complete_Source_File_Entry;
1435 -- An internal error check, the scope stack should now be empty
1437 pragma Assert (Scope.Last = 0);
1439 -- Remaining steps are to create implicit label declarations and to
1440 -- load required subsidiary sources. These steps are required only
1441 -- if we are doing semantic checking.
1443 if Operating_Mode /= Check_Syntax or else Debug_Flag_F then
1444 Par.Labl;
1445 Par.Load;
1446 end if;
1448 -- Restore settings of switches saved on entry
1450 Restore_Opt_Config_Switches (Save_Config_Switches);
1451 Set_Comes_From_Source_Default (False);
1452 return Empty_List;
1453 end if;
1454 end Par;