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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 ------------------------------------------------------------------------------
48 ---------
49 -- Par --
50 ---------
52 function Par
54 is
56 -- Count number of units parsed (relevant only in syntax check only mode,
57 -- since in semantics check mode only a single unit is permitted anyway)
60 -- Variable used to save values of config switches while we parse the
61 -- new unit, to be restored on exit for proper recursive behavior.
64 -- Counter used for constructing loop/block names (see the routine
65 -- Par.Ch5.Get_Loop_Block_Name)
67 --------------------
68 -- Error Recovery --
69 --------------------
71 -- When an error is encountered, a call is made to one of the Error_Msg
72 -- routines to record the error. If the syntax scan is not derailed by the
73 -- error (e.g. a complaint that logical operators are inconsistent in an
74 -- EXPRESSION), then control returns from the Error_Msg call, and the
75 -- parse continues unimpeded.
77 -- If on the other hand, the Error_Msg represents a situation from which
78 -- the parser cannot recover locally, the exception Error_Resync is raised
79 -- immediately after the call to Error_Msg. Handlers for Error_Resync
80 -- are located at strategic points to resynchronize the parse. For example,
81 -- when an error occurs in a statement, the handler skips to the next
82 -- semicolon and continues the scan from there.
84 -- Each parsing procedure contains a note with the heading "Error recovery"
85 -- which shows if it can propagate the Error_Resync exception. In order
86 -- not to propagate the exception, a procedure must either contain its own
87 -- handler for this exception, or it must not call any other routines which
88 -- propagate the exception.
90 -- Note: the arrangement of Error_Resync handlers is such that it should
91 -- never be possible to transfer control through a procedure which made
92 -- an entry in the scope stack, invalidating the contents of the stack.
95 -- Exception raised on error that is not handled locally, see above
98 -- The resynchronization routines in Par.Sync run a risk of getting
99 -- stuck in an infinite loop if they do not skip a token, and the caller
100 -- keeps repeating the same resync call. On the other hand, if they skip
101 -- a token unconditionally, some recovery opportunities are missed. The
102 -- variable Last_Resync_Point records the token location previously set
103 -- by a Resync call, and if a subsequent Resync call occurs at the same
104 -- location, then the Resync routine does guarantee to skip a token.
106 --------------------------------------------
107 -- Handling Semicolon Used in Place of IS --
108 --------------------------------------------
110 -- The following global variables are used in handling the error situation
111 -- of using a semicolon in place of IS in a subprogram declaration as in:
113 -- procedure X (Y : Integer);
114 -- Q : Integer;
115 -- begin
116 -- ...
117 -- end;
119 -- The two contexts in which this can appear are at the outer level, and
120 -- within a declarative region. At the outer level, we know something is
121 -- wrong as soon as we see the Q (or begin, if there are no declarations),
122 -- and we can immediately decide that the semicolon should have been IS.
124 -- The situation in a declarative region is more complex. The declaration
125 -- of Q could belong to the outer region, and we do not know that we have
126 -- an error until we hit the begin. It is still not clear at this point
127 -- from a syntactic point of view that something is wrong, because the
128 -- begin could belong to the enclosing subprogram or package. However, we
129 -- can incorporate a bit of semantic knowledge and note that the body of
130 -- X is missing, so we definitely DO have an error. We diagnose this error
131 -- as semicolon in place of IS on the subprogram line.
133 -- There are two styles for this diagnostic. If the begin immediately
134 -- follows the semicolon, then we can place a flag (IS expected) right
135 -- on the semicolon. Otherwise we do not detect the error until we hit
136 -- the begin which refers back to the line with the semicolon.
138 -- To control the process in the second case, the following global
139 -- variables are set to indicate that we have a subprogram declaration
140 -- whose body is required and has not yet been found. The prefix SIS
141 -- stands for "Subprogram IS" handling.
144 -- Set True to indicate that an entry is active (i.e. that a subprogram
145 -- declaration has been encountered, and no body for this subprogram has
146 -- been encountered). The remaining fields are valid only if this is True.
149 -- Subprogram designator
152 -- Source location of FUNCTION/PROCEDURE keyword
155 -- Column number of FUNCTION/PROCEDURE keyword
158 -- Source location of semicolon at end of subprogram declaration
161 -- Pointer to tree node for subprogram declaration
164 -- Used to save message ID of missing semicolon message (which will be
165 -- modified to missing IS if necessary). Set to No_Error_Msg in the
166 -- normal (non-error) case.
168 -- Five things can happen to an active SIS entry
170 -- 1. If a BEGIN is encountered with an SIS entry active, then we have
171 -- exactly the situation in which we know the body of the subprogram is
172 -- missing. After posting an error message, we change the spec to a body,
173 -- rechaining the declarations that intervened between the spec and BEGIN.
175 -- 2. Another subprogram declaration or body is encountered. In this
176 -- case the entry gets overwritten with the information for the new
177 -- subprogram declaration. We don't catch some nested cases this way,
178 -- but it doesn't seem worth the effort.
180 -- 3. A nested declarative region (e.g. package declaration or package
181 -- body) is encountered. The SIS active indication is reset at the start
182 -- of such a nested region. Again, like case 2, this causes us to miss
183 -- some nested cases, but it doesn't seen worth the effort to stack and
184 -- unstack the SIS information. Maybe we will reconsider this if we ever
185 -- get a complaint about a missed case.
187 -- 4. We encounter a valid pragma INTERFACE or IMPORT that effectively
188 -- supplies the missing body. In this case we reset the entry.
190 -- 5. We encounter the end of the declarative region without encountering
191 -- a BEGIN first. In this situation we simply reset the entry. We know
192 -- that there is a missing body, but it seems more reasonable to let the
193 -- later semantic checking discover this.
195 ----------------------------------------------------
196 -- Handling of Reserved Words Used as Identifiers --
197 ----------------------------------------------------
199 -- Note: throughout the parser, the terms reserved word and keyword
200 -- are used interchangeably to refer to the same set of reserved
201 -- keywords (including until, protected, etc).
203 -- If a reserved word is used in place of an identifier, the parser
204 -- where possible tries to recover gracefully. In particular, if the
205 -- keyword is clearly spelled using identifier casing, e.g. Until in
206 -- a source program using mixed case identifiers and lower case keywords,
207 -- then the keyword is treated as an identifier if it appears in a place
208 -- where an identifier is required.
210 -- The situation is more complex if the keyword is spelled with normal
211 -- keyword casing. In this case, the parser is more reluctant to
212 -- consider it to be intended as an identifier, unless it has some
213 -- further confirmation.
215 -- In the case of an identifier appearing in the identifier list of a
216 -- declaration, the appearance of a comma or colon right after the
217 -- keyword on the same line is taken as confirmation. For an enumeration
218 -- literal, a comma or right paren right after the identifier is also
219 -- treated as adequate confirmation.
221 -- The following type is used in calls to Is_Reserved_Identifier and
222 -- also to P_Defining_Identifier and P_Identifier. The default for all
223 -- these functions is that reserved words in reserved word case are not
224 -- considered to be reserved identifiers. The Id_Check value indicates
225 -- tokens, which if they appear immediately after the identifier, are
226 -- taken as confirming that the use of an identifier was expected
230 -- Default, no special token test
232 C_Comma_Right_Paren,
233 -- Consider as identifier if followed by comma or right paren
235 C_Comma_Colon,
236 -- Consider as identifier if followed by comma or colon
238 C_Do,
239 -- Consider as identifier if followed by DO
241 C_Dot,
242 -- Consider as identifier if followed by period
244 C_Greater_Greater,
245 -- Consider as identifier if followed by >>
247 C_In,
248 -- Consider as identifier if followed by IN
250 C_Is,
251 -- Consider as identifier if followed by IS
253 C_Left_Paren_Semicolon,
254 -- Consider as identifier if followed by left paren or semicolon
256 C_Use,
257 -- Consider as identifier if followed by USE
259 C_Vertical_Bar_Arrow);
260 -- Consider as identifier if followed by | or =>
262 --------------------------------------------
263 -- Handling IS Used in Place of Semicolon --
264 --------------------------------------------
266 -- This is a somewhat trickier situation, and we can't catch it in all
267 -- cases, but we do our best to detect common situations resulting from
268 -- a "cut and paste" operation which forgets to change the IS to semicolon.
269 -- Consider the following example:
271 -- package body X is
272 -- procedure A;
273 -- procedure B is
274 -- procedure C;
275 -- ...
276 -- procedure D is
277 -- begin
278 -- ...
279 -- end;
280 -- begin
281 -- ...
282 -- end;
284 -- The trouble is that the section of text from PROCEDURE B through END;
285 -- constitutes a valid procedure body, and the danger is that we find out
286 -- far too late that something is wrong (indeed most compilers will behave
287 -- uncomfortably on the above example).
289 -- We have two approaches to helping to control this situation. First we
290 -- make every attempt to avoid swallowing the last END; if we can be
291 -- sure that some error will result from doing so. In particular, we won't
292 -- accept the END; unless it is exactly correct (in particular it must not
293 -- have incorrect name tokens), and we won't accept it if it is immediately
294 -- followed by end of file, WITH or SEPARATE (all tokens that unmistakeably
295 -- signal the start of a compilation unit, and which therefore allow us to
296 -- reserve the END; for the outer level.) For more details on this aspect
297 -- of the handling, see package Par.Endh.
299 -- If we can avoid eating up the END; then the result in the absence of
300 -- any additional steps would be to post a missing END referring back to
301 -- the subprogram with the bogus IS. Similarly, if the enclosing package
302 -- has no BEGIN, then the result is a missing BEGIN message, which again
303 -- refers back to the subprogram header.
305 -- Such an error message is not too bad (it's already a big improvement
306 -- over what many parsers do), but it's not ideal, because the declarations
307 -- following the IS have been absorbed into the wrong scope. In the above
308 -- case, this could result for example in a bogus complaint that the body
309 -- of D was missing from the package.
311 -- To catch at least some of these cases, we take the following additional
312 -- steps. First, a subprogram body is marked as having a suspicious IS if
313 -- the declaration line is followed by a line which starts with a symbol
314 -- that can start a declaration in the same column, or to the left of the
315 -- column in which the FUNCTION or PROCEDURE starts (normal style is to
316 -- indent any declarations which really belong a subprogram). If such a
317 -- subprogram encounters a missing BEGIN or missing END, then we decide
318 -- that the IS should have been a semicolon, and the subprogram body node
319 -- is marked (by setting the Bad_Is_Detected flag true. Note that we do
320 -- not do this for library level procedures, only for nested procedures,
321 -- since for library level procedures, we must have a body.
323 -- The processing for a declarative part checks to see if the last
324 -- declaration scanned is marked in this way, and if it is, the tree
325 -- is modified to reflect the IS being interpreted as a semicolon.
327 ---------------------------------------------------
328 -- Parser Type Definitions and Control Variables --
329 ---------------------------------------------------
331 -- The following variable and associated type declaration are used by the
332 -- expression parsing routines to return more detailed information about
333 -- the categorization of a parsed expression.
344 -- The following type is used for calls to P_Subprogram, P_Package, P_Task,
345 -- P_Protected to indicate which of several possibilities is acceptable.
363 Pf_Rec'(F, T, T, T, T, T, F, F);
364 Pf_Decl : constant Pf_Rec :=
367 Pf_Rec'(F, T, T, T, T, F, F, F);
368 Pf_Decl_Pbod : constant Pf_Rec :=
371 Pf_Rec'(F, F, F, T, F, F, F, F);
372 Pf_Spcn : constant Pf_Rec :=
374 -- The above are the only allowed values of Pf_Rec arguments
398 Goto_List : Elist_Id;
399 -- List of goto nodes appearing in the current compilation. Used to
400 -- recognize natural loops and convert them into bona fide loops for
401 -- optimization purposes.
403 Label_List : Elist_Id;
404 -- List of label nodes for labels appearing in the current compilation.
405 -- Used by Par.Labl to construct the corresponding implicit declarations.
407 -----------------
408 -- Scope Table --
409 -----------------
411 -- The scope table, also referred to as the scope stack, is used to
412 -- record the current scope context. It is organized as a stack, with
413 -- inner nested entries corresponding to higher entries on the stack.
414 -- An entry is made when the parser encounters the opening of a nested
415 -- construct (such as a record, task, package etc.), and then package
416 -- Par.Endh uses this stack to deal with END lines (including properly
417 -- dealing with END nesting errors).
419 type SS_End_Type is
420 -- Type of end entry required for this scope. The last two entries are
421 -- used only in the subprogram body case to mark the case of a suspicious
422 -- IS, or a bad IS (i.e. suspicions confirmed by missing BEGIN or END).
423 -- See separate section on dealing with IS used in place of semicolon.
424 -- Note that for many purposes E_Name, E_Suspicious_Is and E_Bad_Is are
425 -- treated the same (E_Suspicious_Is and E_Bad_Is are simply special cases
426 -- of E_Name). They are placed at the end of the enumeration so that a
427 -- test for >= E_Name catches all three cases efficiently.
429 (E_Dummy, -- dummy entry at outer level
430 E_Case, -- END CASE;
431 E_If, -- END IF;
432 E_Loop, -- END LOOP;
433 E_Record, -- END RECORD;
434 E_Return, -- END RETURN;
435 E_Select, -- END SELECT;
436 E_Name, -- END [name];
437 E_Suspicious_Is, -- END [name]; (case of suspicious IS)
438 E_Bad_Is); -- END [name]; (case of bad IS)
440 -- The following describes a single entry in the scope table
442 type Scope_Table_Entry is record
443 Etyp : SS_End_Type;
444 -- Type of end entry, as per above description
446 Lreq : Boolean;
447 -- A flag indicating whether the label, if present, is required to
448 -- appear on the end line. It is referenced only in the case of
449 -- Etyp = E_Name or E_Suspicious_Is where the name may or may not be
450 -- required (yes for labeled block, no in other cases). Note that for
451 -- all cases except begin, the question of whether a label is required
452 -- can be determined from the other fields (for loop, it is required if
453 -- it is present, and for the other constructs it is never required or
454 -- allowed).
456 Ecol : Column_Number;
457 -- Contains the absolute column number (with tabs expanded) of the
458 -- the expected column of the end assuming normal Ada indentation
459 -- usage. If the RM_Column_Check mode is set, this value is used for
460 -- generating error messages about indentation. Otherwise it is used
461 -- only to control heuristic error recovery actions.
463 Labl : Node_Id;
464 -- This field is used only for the LOOP and BEGIN cases, and is the
465 -- Node_Id value of the label name. For all cases except child units,
466 -- this value is an entity whose Chars field contains the name pointer
467 -- that identifies the label uniquely. For the child unit case the Labl
468 -- field references an N_Defining_Program_Unit_Name node for the name.
469 -- For cases other than LOOP or BEGIN, the Label field is set to Error,
470 -- indicating that it is an error to have a label on the end line.
471 -- (this is really a misuse of Error since there is no Error ???)
473 Decl : List_Id;
474 -- Points to the list of declarations (i.e. the declarative part)
475 -- associated with this construct. It is set only in the END [name]
476 -- cases, and is set to No_List for all other cases which do not have a
477 -- declarative unit associated with them. This is used for determining
478 -- the proper location for implicit label declarations.
480 Node : Node_Id;
481 -- Empty except in the case of entries for IF and CASE statements,
482 -- in which case it contains the N_If_Statement or N_Case_Statement
483 -- node. This is used for setting the End_Span field.
485 Sloc : Source_Ptr;
486 -- Source location of the opening token of the construct. This is
487 -- used to refer back to this line in error messages (such as missing
488 -- or incorrect end lines). The Sloc field is not used, and is not set,
489 -- if a label is present (the Labl field provides the text name of the
490 -- label in this case, which is fine for error messages).
492 S_Is : Source_Ptr;
493 -- S_Is is relevant only if Etyp is set to E_Suspicious_Is or
494 -- E_Bad_Is. It records the location of the IS that is considered
495 -- to be suspicious.
497 Junk : Boolean;
498 -- A boolean flag that is set true if the opening entry is the dubious
499 -- result of some prior error, e.g. a record entry where the record
500 -- keyword was missing. It is used to suppress the issuing of a
501 -- corresponding junk complaint about the end line (we do not want
502 -- to complain about a missing end record when there was no record).
503 end record;
505 -- The following declares the scope table itself. The Last field is the
506 -- stack pointer, so that Scope.Table (Scope.Last) is the top entry. The
507 -- oldest entry, at Scope_Stack (0), is a dummy entry with Etyp set to
508 -- E_Dummy, and the other fields undefined. This dummy entry ensures that
509 -- Scope_Stack (Scope_Stack_Ptr).Etyp can always be tested, and that the
510 -- scope stack pointer is always in range.
512 package Scope is new Table.Table (
513 Table_Component_Type => Scope_Table_Entry,
514 Table_Index_Type => Int,
515 Table_Low_Bound => 0,
516 Table_Initial => 50,
517 Table_Increment => 100,
518 Table_Name => "Scope");
520 ---------------------------------
521 -- Parsing Routines by Chapter --
522 ---------------------------------
524 -- Uncommented declarations in this section simply parse the construct
525 -- corresponding to their name, and return an ID value for the Node or
526 -- List that is created.
528 -------------
529 -- Par.Ch2 --
530 -------------
532 package Ch2 is
533 function P_Pragma (Skipping : Boolean := False) return Node_Id;
534 -- Scan out a pragma. If Skipping is True, then the caller is skipping
535 -- the pragma in the context of illegal placement (this is used to avoid
536 -- some junk cascaded messages).
538 function P_Identifier (C : Id_Check := None) return Node_Id;
539 -- Scans out an identifier. The parameter C determines the treatment
540 -- of reserved identifiers. See declaration of Id_Check for details.
542 function P_Pragmas_Opt return List_Id;
543 -- This function scans for a sequence of pragmas in other than a
544 -- declaration sequence or statement sequence context. All pragmas
545 -- can appear except pragmas Assert and Debug, which are only allowed
546 -- in a declaration or statement sequence context.
548 procedure P_Pragmas_Misplaced;
549 -- Skips misplaced pragmas with a complaint
551 procedure P_Pragmas_Opt (List : List_Id);
552 -- Parses optional pragmas and appends them to the List
553 end Ch2;
555 -------------
556 -- Par.Ch3 --
557 -------------
559 package Ch3 is
560 Missing_Begin_Msg : Error_Msg_Id;
561 -- This variable is set by a call to P_Declarative_Part. Normally it
562 -- is set to No_Error_Msg, indicating that no special processing is
563 -- required by the caller. The special case arises when a statement
564 -- is found in the sequence of declarations. In this case the Id of
565 -- the message issued ("declaration expected") is preserved in this
566 -- variable, then the caller can change it to an appropriate missing
567 -- begin message if indeed the BEGIN is missing.
569 function P_Array_Type_Definition return Node_Id;
570 function P_Basic_Declarative_Items return List_Id;
571 function P_Constraint_Opt return Node_Id;
572 function P_Declarative_Part return List_Id;
573 function P_Discrete_Choice_List return List_Id;
574 function P_Discrete_Range return Node_Id;
575 function P_Discrete_Subtype_Definition return Node_Id;
576 function P_Known_Discriminant_Part_Opt return List_Id;
577 function P_Signed_Integer_Type_Definition return Node_Id;
578 function P_Range return Node_Id;
579 function P_Range_Or_Subtype_Mark return Node_Id;
580 function P_Range_Constraint return Node_Id;
581 function P_Record_Definition return Node_Id;
582 function P_Subtype_Mark return Node_Id;
583 function P_Subtype_Mark_Resync return Node_Id;
584 function P_Unknown_Discriminant_Part_Opt return Boolean;
586 function P_Access_Definition
587 (Null_Exclusion_Present : Boolean) return Node_Id;
588 -- Ada 2005 (AI-231/AI-254): The caller parses the null-exclusion part
589 -- and indicates if it was present
591 function P_Access_Type_Definition
592 (Header_Already_Parsed : Boolean := False) return Node_Id;
593 -- Ada 2005 (AI-254): The formal is used to indicate if the caller has
594 -- parsed the null_exclusion part. In this case the caller has also
595 -- removed the ACCESS token
597 procedure P_Component_Items (Decls : List_Id);
598 -- Scan out one or more component items and append them to the
599 -- given list. Only scans out more than one declaration in the
600 -- case where the source has a single declaration with multiple
601 -- defining identifiers.
603 function P_Defining_Identifier (C : Id_Check := None) return Node_Id;
604 -- Scan out a defining identifier. The parameter C controls the
605 -- treatment of errors in case a reserved word is scanned. See the
606 -- declaration of this type for details.
608 function P_Interface_Type_Definition
609 (Abstract_Present : Boolean) return Node_Id;
610 -- Ada 2005 (AI-251): Parse the interface type definition part. Abstract
611 -- Present indicates if the reserved word "abstract" has been previously
612 -- found. It is used to report an error message because interface types
613 -- are by definition abstract tagged. We generate a record_definition
614 -- node if the list of interfaces is empty; otherwise we generate a
615 -- derived_type_definition node (the first interface in this list is the
616 -- ancestor interface).
618 function P_Null_Exclusion
619 (Allow_Anonymous_In_95 : Boolean := False) return Boolean;
620 -- Ada 2005 (AI-231): Parse the null-excluding part. A True result
621 -- indicates that the null-excluding part was present.
622 -- Allow_Anonymous_In_95 is True if we are in a context that allows
623 -- anonymous access types in Ada 95, in which case "not null" is legal
624 -- if it precedes "access".
626 function P_Subtype_Indication
627 (Not_Null_Present : Boolean := False) return Node_Id;
628 -- Ada 2005 (AI-231): The flag Not_Null_Present indicates that the
629 -- null-excluding part has been scanned out and it was present.
631 function Init_Expr_Opt (P : Boolean := False) return Node_Id;
632 -- If an initialization expression is present (:= expression), then
633 -- it is scanned out and returned, otherwise Empty is returned if no
634 -- initialization expression is present. This procedure also handles
635 -- certain common error cases cleanly. The parameter P indicates if
636 -- a right paren can follow the expression (default = no right paren
637 -- allowed).
639 procedure Skip_Declaration (S : List_Id);
640 -- Used when scanning statements to skip past a misplaced declaration
641 -- The declaration is scanned out and appended to the given list.
642 -- Token is known to be a declaration token (in Token_Class_Declk)
643 -- on entry, so there definition is a declaration to be scanned.
645 function P_Subtype_Indication
646 (Subtype_Mark : Node_Id;
647 Not_Null_Present : Boolean := False) return Node_Id;
648 -- This version of P_Subtype_Indication is called when the caller has
649 -- already scanned out the subtype mark which is passed as a parameter.
650 -- Ada 2005 (AI-231): The flag Not_Null_Present indicates that the
651 -- null-excluding part has been scanned out and it was present.
653 function P_Subtype_Mark_Attribute (Type_Node : Node_Id) return Node_Id;
654 -- Parse a subtype mark attribute. The caller has already parsed the
655 -- subtype mark, which is passed in as the argument, and has checked
656 -- that the current token is apostrophe.
657 end Ch3;
659 -------------
660 -- Par.Ch4 --
661 -------------
663 package Ch4 is
664 function P_Aggregate return Node_Id;
665 function P_Expression return Node_Id;
666 function P_Expression_No_Right_Paren return Node_Id;
667 function P_Expression_Or_Range_Attribute return Node_Id;
668 function P_Function_Name return Node_Id;
669 function P_Name return Node_Id;
670 function P_Qualified_Simple_Name return Node_Id;
671 function P_Qualified_Simple_Name_Resync return Node_Id;
672 function P_Simple_Expression return Node_Id;
673 function P_Simple_Expression_Or_Range_Attribute return Node_Id;
675 function P_Qualified_Expression
676 (Subtype_Mark : Node_Id)
677 return Node_Id;
678 -- This routine scans out a qualified expression when the caller has
679 -- already scanned out the name and apostrophe of the construct.
680 end Ch4;
682 -------------
683 -- Par.Ch5 --
684 -------------
686 package Ch5 is
687 function P_Statement_Name (Name_Node : Node_Id) return Node_Id;
688 -- Given a node representing a name (which is a call), converts it
689 -- to the syntactically corresponding procedure call statement.
691 function P_Sequence_Of_Statements (SS_Flags : SS_Rec) return List_Id;
692 -- The argument indicates the acceptable termination tokens.
693 -- See body in Par.Ch5 for details of the use of this parameter.
695 procedure Parse_Decls_Begin_End (Parent : Node_Id);
696 -- Parses declarations and handled statement sequence, setting
697 -- fields of Parent node appropriately.
698 end Ch5;
700 -------------
701 -- Par.Ch6 --
702 -------------
704 package Ch6 is
705 function P_Designator return Node_Id;
706 function P_Defining_Program_Unit_Name return Node_Id;
707 function P_Formal_Part return List_Id;
708 function P_Parameter_Profile return List_Id;
709 function P_Return_Statement return Node_Id;
710 function P_Subprogram_Specification return Node_Id;
712 procedure P_Mode (Node : Node_Id);
713 -- Sets In_Present and/or Out_Present flags in Node scanning past
714 -- IN, OUT or IN OUT tokens in the source.
716 function P_Subprogram (Pf_Flags : Pf_Rec) return Node_Id;
717 -- Scans out any construct starting with either of the keywords
718 -- PROCEDURE or FUNCTION. The parameter indicates which possible
719 -- possible kinds of construct (body, spec, instantiation etc.)
720 -- are permissible in the current context.
721 end Ch6;
723 -------------
724 -- Par.Ch7 --
725 -------------
727 package Ch7 is
728 function P_Package (Pf_Flags : Pf_Rec) return Node_Id;
729 -- Scans out any construct starting with the keyword PACKAGE. The
730 -- parameter indicates which possible kinds of construct (body, spec,
731 -- instantiation etc.) are permissible in the current context.
732 end Ch7;
734 -------------
735 -- Par.Ch8 --
736 -------------
738 package Ch8 is
739 function P_Use_Clause return Node_Id;
740 end Ch8;
742 -------------
743 -- Par.Ch9 --
744 -------------
746 package Ch9 is
747 function P_Abort_Statement return Node_Id;
748 function P_Abortable_Part return Node_Id;
749 function P_Accept_Statement return Node_Id;
750 function P_Delay_Statement return Node_Id;
751 function P_Entry_Body return Node_Id;
752 function P_Protected return Node_Id;
753 function P_Requeue_Statement return Node_Id;
754 function P_Select_Statement return Node_Id;
755 function P_Task return Node_Id;
756 function P_Terminate_Alternative return Node_Id;
757 end Ch9;
759 --------------
760 -- Par.Ch10 --
761 --------------
763 package Ch10 is
764 function P_Compilation_Unit return Node_Id;
765 -- Note: this function scans a single compilation unit, and
766 -- checks that an end of file follows this unit, diagnosing
767 -- any unexpected input as an error, and then skipping it, so
768 -- that Token is set to Tok_EOF on return. An exception is in
769 -- syntax-only mode, where multiple compilation units are
770 -- permitted. In this case, P_Compilation_Unit does not check
771 -- for end of file and there may be more compilation units to
772 -- scan. The caller can uniquely detect this situation by the
773 -- fact that Token is not set to Tok_EOF on return.
774 --
775 -- The Ignore parameter is normally set False. It is set True
776 -- in multiple unit per file mode if we are skipping past a unit
777 -- that we are not interested in.
778 end Ch10;
780 --------------
781 -- Par.Ch11 --
782 --------------
784 package Ch11 is
785 function P_Handled_Sequence_Of_Statements return Node_Id;
786 function P_Raise_Statement return Node_Id;
788 function Parse_Exception_Handlers return List_Id;
789 -- Parses the partial construct EXCEPTION followed by a list of
790 -- exception handlers which appears in a number of productions,
791 -- and returns the list of exception handlers.
792 end Ch11;
794 --------------
795 -- Par.Ch12 --
796 --------------
798 package Ch12 is
799 function P_Generic return Node_Id;
800 function P_Generic_Actual_Part_Opt return List_Id;
801 end Ch12;
803 --------------
804 -- Par.Ch13 --
805 --------------
807 package Ch13 is
808 function P_Representation_Clause return Node_Id;
810 function P_Code_Statement (Subtype_Mark : Node_Id) return Node_Id;
811 -- Function to parse a code statement. The caller has scanned out
812 -- the name to be used as the subtype mark (but has not checked that
813 -- it is suitable for use as a subtype mark, i.e. is either an
814 -- identifier or a selected component). The current token is an
815 -- apostrophe and the following token is either a left paren or
816 -- RANGE (the latter being an error to be caught by P_Code_Statement.
817 end Ch13;
819 -- Note: the parsing for annexe J features (i.e. obsolescent features)
820 -- is found in the logical section where these features would be if
821 -- they were not obsolescent. In particular:
823 -- Delta constraint is parsed by P_Delta_Constraint (3.5.9)
824 -- At clause is parsed by P_At_Clause (13.1)
825 -- Mod clause is parsed by P_Mod_Clause (13.5.1)
827 --------------
828 -- Par.Endh --
829 --------------
831 -- Routines for handling end lines, including scope recovery
833 package Endh is
834 function Check_End return Boolean;
835 -- Called when an end sequence is required. In the absence of an error
836 -- situation, Token contains Tok_End on entry, but in a missing end
837 -- case, this may not be the case. Pop_End_Context is used to determine
838 -- the appropriate action to be taken. The returned result is True if
839 -- an End sequence was encountered and False if no End sequence was
840 -- present. This occurs if the END keyword encountered was determined
841 -- to be improper and deleted (i.e. Pop_End_Context set End_Action to
842 -- Skip_And_Reject). Note that the END sequence includes a semicolon,
843 -- except in the case of END RECORD, where a semicolon follows the END
844 -- RECORD, but is not part of the record type definition itself.
846 procedure End_Skip;
847 -- Skip past an end sequence. On entry Token contains Tok_End, and we
848 -- we know that the end sequence is syntactically incorrect, and that
849 -- an appropriate error message has already been posted. The mission
850 -- is simply to position the scan pointer to be the best guess of the
851 -- position after the end sequence. We do not issue any additional
852 -- error messages while carrying this out.
854 procedure End_Statements (Parent : Node_Id := Empty);
855 -- Called when an end is required or expected to terminate a sequence
856 -- of statements. The caller has already made an appropriate entry in
857 -- the Scope.Table to describe the expected form of the end. This can
858 -- only be used in cases where the only appropriate terminator is end.
859 -- If Parent is non-empty, then if a correct END line is encountered,
860 -- the End_Label field of Parent is set appropriately.
861 end Endh;
863 --------------
864 -- Par.Sync --
865 --------------
867 -- These procedures are used to resynchronize after errors. Following an
868 -- error which is not immediately locally recoverable, the exception
869 -- Error_Resync is raised. The handler for Error_Resync typically calls
870 -- one of these recovery procedures to resynchronize the source position
871 -- to a point from which parsing can be restarted.
873 -- Note: these procedures output an information message that tokens are
874 -- being skipped, but this message is output only if the option for
875 -- Multiple_Errors_Per_Line is set in Options.
877 package Sync is
878 procedure Resync_Choice;
879 -- Used if an error occurs scanning a choice. The scan pointer is
880 -- advanced to the next vertical bar, arrow, or semicolon, whichever
881 -- comes first. We also quit if we encounter an end of file.
883 procedure Resync_Expression;
884 -- Used if an error is detected during the parsing of an expression.
885 -- It skips past tokens until either a token which cannot be part of
886 -- an expression is encountered (an expression terminator), or if a
887 -- comma or right parenthesis or vertical bar is encountered at the
888 -- current parenthesis level (a parenthesis level counter is maintained
889 -- to carry out this test).
891 procedure Resync_Past_Semicolon;
892 -- Used if an error occurs while scanning a sequence of declarations.
893 -- The scan pointer is positioned past the next semicolon and the scan
894 -- resumes. The scan is also resumed on encountering a token which
895 -- starts a declaration (but we make sure to skip at least one token
896 -- in this case, to avoid getting stuck in a loop).
898 procedure Resync_To_Semicolon;
899 -- Similar to Resync_Past_Semicolon, except that the scan pointer is
900 -- left pointing to the semicolon rather than past it.
902 procedure Resync_Past_Semicolon_Or_To_Loop_Or_Then;
903 -- Used if an error occurs while scanning a sequence of statements.
904 -- The scan pointer is positioned past the next semicolon, or to the
905 -- next occurrence of either then or loop, and the scan resumes.
907 procedure Resync_To_When;
908 -- Used when an error occurs scanning an entry index specification.
909 -- The scan pointer is positioned to the next WHEN (or to IS or
910 -- semicolon if either of these appear before WHEN, indicating
911 -- another error has occurred).
913 procedure Resync_Semicolon_List;
914 -- Used if an error occurs while scanning a parenthesized list of items
915 -- separated by semicolons. The scan pointer is advanced to the next
916 -- semicolon or right parenthesis at the outer parenthesis level, or
917 -- to the next is or RETURN keyword occurrence, whichever comes first.
919 procedure Resync_Cunit;
920 -- Synchronize to next token which could be the start of a compilation
921 -- unit, or to the end of file token.
922 end Sync;
924 --------------
925 -- Par.Tchk --
926 --------------
928 -- Routines to check for expected tokens
930 package Tchk is
932 -- Procedures with names of the form T_xxx, where Tok_xxx is a token
933 -- name, check that the current token matches the required token, and
934 -- if so, scan past it. If not, an error is issued indicating that
935 -- the required token is not present (xxx expected). In most cases, the
936 -- scan pointer is not moved in the not-found case, but there are some
937 -- exceptions to this, see for example T_Id, where the scan pointer is
938 -- moved across a literal appearing where an identifier is expected.
940 procedure T_Abort;
941 procedure T_Arrow;
942 procedure T_At;
943 procedure T_Body;
944 procedure T_Box;
945 procedure T_Colon;
946 procedure T_Colon_Equal;
947 procedure T_Comma;
948 procedure T_Dot_Dot;
949 procedure T_For;
950 procedure T_Greater_Greater;
951 procedure T_Identifier;
952 procedure T_In;
953 procedure T_Is;
954 procedure T_Left_Paren;
955 procedure T_Loop;
956 procedure T_Mod;
957 procedure T_New;
958 procedure T_Of;
959 procedure T_Or;
960 procedure T_Private;
961 procedure T_Range;
962 procedure T_Record;
963 procedure T_Right_Paren;
964 procedure T_Semicolon;
965 procedure T_Then;
966 procedure T_Type;
967 procedure T_Use;
968 procedure T_When;
969 procedure T_With;
971 -- Procedures having names of the form TF_xxx, where Tok_xxx is a token
972 -- name check that the current token matches the required token, and
973 -- if so, scan past it. If not, an error message is issued indicating
974 -- that the required token is not present (xxx expected).
976 -- If the missing token is at the end of the line, then control returns
977 -- immediately after posting the message. If there are remaining tokens
978 -- on the current line, a search is conducted to see if the token
979 -- appears later on the current line, as follows:
981 -- A call to Scan_Save is issued and a forward search for the token
982 -- is carried out. If the token is found on the current line before a
983 -- semicolon, then it is scanned out and the scan continues from that
984 -- point. If not the scan is restored to the point where it was missing.
986 procedure TF_Arrow;
987 procedure TF_Is;
988 procedure TF_Loop;
989 procedure TF_Return;
990 procedure TF_Semicolon;
991 procedure TF_Then;
992 procedure TF_Use;
994 -- Procedures with names of the form U_xxx, where Tok_xxx is a token
995 -- name, are just like the corresponding T_xxx procedures except that
996 -- an error message, if given, is unconditional.
998 procedure U_Left_Paren;
999 procedure U_Right_Paren;
1000 end Tchk;
1002 --------------
1003 -- Par.Util --
1004 --------------
1006 package Util is
1007 function Bad_Spelling_Of (T : Token_Type) return Boolean;
1008 -- This function is called in an error situation. It checks if the
1009 -- current token is an identifier whose name is a plausible bad
1010 -- spelling of the given keyword token, and if so, issues an error
1011 -- message, sets Token from T, and returns True. Otherwise Token is
1012 -- unchanged, and False is returned.
1014 procedure Check_Bad_Layout;
1015 -- Check for bad indentation in RM checking mode. Used for statements
1016 -- and declarations. Checks if current token is at start of line and
1017 -- is exdented from the current expected end column, and if so an
1018 -- error message is generated.
1020 procedure Check_Misspelling_Of (T : Token_Type);
1021 pragma Inline (Check_Misspelling_Of);
1022 -- This is similar to the function above, except that it does not
1023 -- return a result. It is typically used in a situation where any
1024 -- identifier is an error, and it makes sense to simply convert it
1025 -- to the given token if it is a plausible misspelling of it.
1027 procedure Check_95_Keyword (Token_95, Next : Token_Type);
1028 -- This routine checks if the token after the current one matches the
1029 -- Next argument. If so, the scan is backed up to the current token
1030 -- and Token_Type is changed to Token_95 after issuing an appropriate
1031 -- error message ("(Ada 83) keyword xx cannot be used"). If not,
1032 -- the scan is backed up with Token_Type unchanged. This routine
1033 -- is used to deal with an attempt to use a 95 keyword in Ada 83
1034 -- mode. The caller has typically checked that the current token,
1035 -- an identifier, matches one of the 95 keywords.
1037 procedure Check_Simple_Expression (E : Node_Id);
1038 -- Given an expression E, that has just been scanned, so that Expr_Form
1039 -- is still set, outputs an error if E is a non-simple expression. E is
1040 -- not modified by this call.
1042 procedure Check_Simple_Expression_In_Ada_83 (E : Node_Id);
1043 -- Like Check_Simple_Expression, except that the error message is only
1044 -- given when operating in Ada 83 mode, and includes "in Ada 83".
1046 function Check_Subtype_Mark (Mark : Node_Id) return Node_Id;
1047 -- Called to check that a node representing a name (or call) is
1048 -- suitable for a subtype mark, i.e, that it is an identifier or
1049 -- a selected component. If so, or if it is already Error, then
1050 -- it is returned unchanged. Otherwise an error message is issued
1051 -- and Error is returned.
1053 function Comma_Present return Boolean;
1054 -- Used in comma delimited lists to determine if a comma is present, or
1055 -- can reasonably be assumed to have been present (an error message is
1056 -- generated in the latter case). If True is returned, the scan has been
1057 -- positioned past the comma. If False is returned, the scan position
1058 -- is unchanged. Note that all comma-delimited lists are terminated by
1059 -- a right paren, so the only legitimate tokens when Comma_Present is
1060 -- called are right paren and comma. If some other token is found, then
1061 -- Comma_Present has the job of deciding whether it is better to pretend
1062 -- a comma was present, post a message for a missing comma and return
1063 -- True, or return False and let the caller diagnose the missing right
1064 -- parenthesis.
1066 procedure Discard_Junk_Node (N : Node_Id);
1067 procedure Discard_Junk_List (L : List_Id);
1068 pragma Inline (Discard_Junk_Node);
1069 pragma Inline (Discard_Junk_List);
1070 -- These procedures do nothing at all, their effect is simply to discard
1071 -- the argument. A typical use is to skip by some junk that is not
1072 -- expected in the current context.
1074 procedure Ignore (T : Token_Type);
1075 -- If current token matches T, then give an error message and skip
1076 -- past it, otherwise the call has no effect at all. T may be any
1077 -- reserved word token, or comma, left or right paren, or semicolon.
1079 function Is_Reserved_Identifier (C : Id_Check := None) return Boolean;
1080 -- Test if current token is a reserved identifier. This test is based
1081 -- on the token being a keyword and being spelled in typical identifier
1082 -- style (i.e. starting with an upper case letter). The parameter C
1083 -- determines the special treatment if a reserved word is encountered
1084 -- that has the normal casing of a reserved word.
1086 procedure Merge_Identifier (Prev : Node_Id; Nxt : Token_Type);
1087 -- Called when the previous token is an identifier (whose Token_Node
1088 -- value is given by Prev) to check if current token is an identifier
1089 -- that can be merged with the previous one adding an underscore. The
1090 -- merge is only attempted if the following token matches Nxt. If all
1091 -- conditions are met, an error message is issued, and the merge is
1092 -- carried out, modifying the Chars field of Prev.
1094 function Next_Token_Is (Tok : Token_Type) return Boolean;
1095 -- Looks at token after current one and returns True if the token type
1096 -- matches Tok. The scan is unconditionally restored on return.
1098 procedure No_Constraint;
1099 -- Called in a place where no constraint is allowed, but one might
1100 -- appear due to a common error (e.g. after the type mark in a procedure
1101 -- parameter. If a constraint is present, an error message is posted,
1102 -- and the constraint is scanned and discarded.
1104 procedure Push_Scope_Stack;
1105 pragma Inline (Push_Scope_Stack);
1106 -- Push a new entry onto the scope stack. Scope.Last (the stack pointer)
1107 -- is incremented. The Junk field is preinitialized to False. The caller
1108 -- is expected to fill in all remaining entries of the new top stack
1109 -- entry at Scope.Table (Scope.Last).
1111 procedure Pop_Scope_Stack;
1112 -- Pop an entry off the top of the scope stack. Scope_Last (the scope
1113 -- table stack pointer) is decremented by one. It is a fatal error to
1114 -- try to pop off the dummy entry at the bottom of the stack (i.e.
1115 -- Scope.Last must be non-zero at the time of call).
1117 function Separate_Present return Boolean;
1118 -- Determines if the current token is either Tok_Separate, or an
1119 -- identifier that is a possible misspelling of "separate" followed
1120 -- by a semicolon. True is returned if so, otherwise False.
1122 procedure Signal_Bad_Attribute;
1123 -- The current token is an identifier that is supposed to be an
1124 -- attribute identifier but is not. This routine posts appropriate
1125 -- error messages, including a check for a near misspelling.
1127 function Token_Is_At_Start_Of_Line return Boolean;
1128 pragma Inline (Token_Is_At_Start_Of_Line);
1129 -- Determines if the current token is the first token on the line
1131 function Token_Is_At_End_Of_Line return Boolean;
1132 -- Determines if the current token is the last token on the line
1133 end Util;
1135 --------------
1136 -- Par.Prag --
1137 --------------
1139 -- The processing for pragmas is split off from chapter 2
1141 function Prag (Pragma_Node : Node_Id; Semi : Source_Ptr) return Node_Id;
1142 -- This function is passed a tree for a pragma that has been scanned out.
1143 -- The pragma is syntactically well formed according to the general syntax
1144 -- for pragmas and the pragma identifier is for one of the recognized
1145 -- pragmas. It performs specific syntactic checks for specific pragmas.
1146 -- The result is the input node if it is OK, or Error otherwise. The
1147 -- reason that this is separated out is to facilitate the addition
1148 -- of implementation defined pragmas. The second parameter records the
1149 -- location of the semicolon following the pragma (this is needed for
1150 -- correct processing of the List and Page pragmas). The returned value
1151 -- is a copy of Pragma_Node, or Error if an error is found. Note that
1152 -- at the point where Prag is called, the right paren ending the pragma
1153 -- has been scanned out, and except in the case of pragma Style_Checks,
1154 -- so has the following semicolon. For Style_Checks, the caller delays
1155 -- the scanning of the semicolon so that it will be scanned using the
1156 -- settings from the Style_Checks pragma preceding it.
1158 --------------
1159 -- Par.Labl --
1160 --------------
1162 procedure Labl;
1163 -- This procedure creates implicit label declarations for all label that
1164 -- are declared in the current unit. Note that this could conceptually
1165 -- be done at the point where the labels are declared, but it is tricky
1166 -- to do it then, since the tree is not hooked up at the point where the
1167 -- label is declared (e.g. a sequence of statements is not yet attached
1168 -- to its containing scope at the point a label in the sequence is found)
1170 --------------
1171 -- Par.Load --
1172 --------------
1174 procedure Load;
1175 -- This procedure loads all subsidiary units that are required by this
1176 -- unit, including with'ed units, specs for bodies, and parents for child
1177 -- units. It does not load bodies for inlined procedures and generics,
1178 -- since we don't know till semantic analysis is complete what is needed.
1180 -----------
1181 -- Stubs --
1182 -----------
1184 -- The package bodies can see all routines defined in all other subpackages
1186 use Ch2;
1187 use Ch3;
1188 use Ch4;
1189 use Ch5;
1190 use Ch6;
1191 use Ch7;
1192 use Ch8;
1193 use Ch9;
1194 use Ch10;
1195 use Ch11;
1196 use Ch12;
1197 use Ch13;
1199 use Endh;
1200 use Tchk;
1201 use Sync;
1202 use Util;
1204 package body Ch2 is separate;
1205 package body Ch3 is separate;
1206 package body Ch4 is separate;
1207 package body Ch5 is separate;
1208 package body Ch6 is separate;
1209 package body Ch7 is separate;
1210 package body Ch8 is separate;
1211 package body Ch9 is separate;
1212 package body Ch10 is separate;
1213 package body Ch11 is separate;
1214 package body Ch12 is separate;
1215 package body Ch13 is separate;
1217 package body Endh is separate;
1218 package body Tchk is separate;
1219 package body Sync is separate;
1220 package body Util is separate;
1222 function Prag (Pragma_Node : Node_Id; Semi : Source_Ptr) return Node_Id
1223 is separate;
1225 procedure Labl is separate;
1226 procedure Load is separate;
1228 -- Start of processing for Par
1230 begin
1232 -- Deal with configuration pragmas case first
1234 if Configuration_Pragmas then
1235 declare
1236 Pragmas : constant List_Id := Empty_List;
1237 P_Node : Node_Id;
1239 begin
1240 loop
1241 if Token = Tok_EOF then
1242 return Pragmas;
1244 elsif Token /= Tok_Pragma then
1245 Error_Msg_SC ("only pragmas allowed in configuration file");
1246 return Error_List;
1248 else
1249 P_Node := P_Pragma;
1251 if Nkind (P_Node) = N_Pragma then
1253 -- Give error if bad pragma
1255 if not Is_Configuration_Pragma_Name (Pragma_Name (P_Node))
1256 and then Pragma_Name (P_Node) /= Name_Source_Reference
1257 then
1258 if Is_Pragma_Name (Pragma_Name (P_Node)) then
1259 Error_Msg_N
1260 ("only configuration pragmas allowed " &
1261 "in configuration file", P_Node);
1262 else
1263 Error_Msg_N
1264 ("unrecognized pragma in configuration file",
1265 P_Node);
1266 end if;
1268 -- Pragma is OK config pragma, so collect it
1270 else
1271 Append (P_Node, Pragmas);
1272 end if;
1273 end if;
1274 end if;
1275 end loop;
1276 end;
1278 -- Normal case of compilation unit
1280 else
1281 Save_Opt_Config_Switches (Save_Config_Switches);
1283 -- The following loop runs more than once in syntax check mode
1284 -- where we allow multiple compilation units in the same file
1285 -- and in Multiple_Unit_Per_file mode where we skip units till
1286 -- we get to the unit we want.
1288 for Ucount in Pos loop
1289 Set_Opt_Config_Switches
1290 (Is_Internal_File_Name (File_Name (Current_Source_File)),
1291 Current_Source_Unit = Main_Unit);
1293 -- Initialize scope table and other parser control variables
1295 Compiler_State := Parsing;
1296 Scope.Init;
1297 Scope.Increment_Last;
1298 Scope.Table (0).Etyp := E_Dummy;
1299 SIS_Entry_Active := False;
1300 Last_Resync_Point := No_Location;
1302 Goto_List := New_Elmt_List;
1303 Label_List := New_Elmt_List;
1305 -- If in multiple unit per file mode, skip past ignored unit
1307 if Ucount < Multiple_Unit_Index then
1309 -- We skip in syntax check only mode, since we don't want
1310 -- to do anything more than skip past the unit and ignore it.
1311 -- This causes processing like setting up a unit table entry
1312 -- to be skipped.
1314 declare
1315 Save_Operating_Mode : constant Operating_Mode_Type :=
1316 Operating_Mode;
1318 Save_Style_Check : constant Boolean := Style_Check;
1320 begin
1321 Operating_Mode := Check_Syntax;
1322 Style_Check := False;
1323 Discard_Node (P_Compilation_Unit);
1324 Operating_Mode := Save_Operating_Mode;
1325 Style_Check := Save_Style_Check;
1327 -- If we are at an end of file, and not yet at the right
1328 -- unit, then we have a fatal error. The unit is missing.
1330 if Token = Tok_EOF then
1331 Error_Msg_SC ("file has too few compilation units");
1332 raise Unrecoverable_Error;
1333 end if;
1334 end;
1336 -- Here if we are not skipping a file in multiple unit per file
1337 -- mode. Parse the unit that we are interested in. Note that in
1338 -- check syntax mode we are interested in all units in the file.
1340 else
1341 declare
1342 Comp_Unit_Node : constant Node_Id := P_Compilation_Unit;
1344 begin
1345 -- If parsing was successful and we are not in check syntax
1346 -- mode, check that language defined units are compiled in
1347 -- GNAT mode. For this purpose we do NOT consider renamings
1348 -- in annex J as predefined. That allows users to compile
1349 -- their own versions of these files, and in particular,
1350 -- in the VMS implementation, the DEC versions can be
1351 -- substituted for the standard Ada 95 versions. Another
1352 -- exception is System.RPC and its children. This allows
1353 -- a user to supply their own communication layer.
1355 if Comp_Unit_Node /= Error
1356 and then Operating_Mode = Generate_Code
1357 and then Current_Source_Unit = Main_Unit
1358 and then not GNAT_Mode
1359 then
1360 declare
1361 Uname : constant String :=
1362 Get_Name_String
1363 (Unit_Name (Current_Source_Unit));
1364 Name : String (1 .. Uname'Length - 2);
1366 begin
1367 -- Because Unit_Name includes "%s" or "%b", we need to
1368 -- strip the last two characters to get the real unit
1369 -- name.
1371 Name := Uname (Uname'First .. Uname'Last - 2);
1373 if Name = "ada" or else
1374 Name = "interfaces" or else
1375 Name = "system"
1376 then
1377 Error_Msg
1378 ("language defined units may not be recompiled",
1379 Sloc (Unit (Comp_Unit_Node)));
1381 elsif Name'Length > 4
1382 and then
1383 Name (Name'First .. Name'First + 3) = "ada."
1384 then
1385 Error_Msg
1386 ("descendents of package Ada " &
1387 "may not be compiled",
1388 Sloc (Unit (Comp_Unit_Node)));
1390 elsif Name'Length > 11
1391 and then
1392 Name (Name'First .. Name'First + 10) = "interfaces."
1393 then
1394 Error_Msg
1395 ("descendents of package Interfaces " &
1396 "may not be compiled",
1397 Sloc (Unit (Comp_Unit_Node)));
1399 elsif Name'Length > 7
1400 and then Name (Name'First .. Name'First + 6) = "system."
1401 and then Name /= "system.rpc"
1402 and then
1403 (Name'Length < 11
1404 or else Name (Name'First .. Name'First + 10) /=
1405 "system.rpc.")
1406 then
1407 Error_Msg
1408 ("descendents of package System " &
1409 "may not be compiled",
1410 Sloc (Unit (Comp_Unit_Node)));
1411 end if;
1412 end;
1413 end if;
1414 end;
1416 -- All done if at end of file
1418 exit when Token = Tok_EOF;
1420 -- If we are not at an end of file, it means we are in syntax
1421 -- check only mode, and we keep the loop going to parse all
1422 -- remaining units in the file.
1424 end if;
1426 Restore_Opt_Config_Switches (Save_Config_Switches);
1427 end loop;
1429 -- Now that we have completely parsed the source file, we can
1430 -- complete the source file table entry.
1432 Complete_Source_File_Entry;
1434 -- An internal error check, the scope stack should now be empty
1436 pragma Assert (Scope.Last = 0);
1438 -- Remaining steps are to create implicit label declarations and to
1439 -- load required subsidiary sources. These steps are required only
1440 -- if we are doing semantic checking.
1442 if Operating_Mode /= Check_Syntax or else Debug_Flag_F then
1443 Par.Labl;
1444 Par.Load;
1445 end if;
1447 -- Restore settings of switches saved on entry
1449 Restore_Opt_Config_Switches (Save_Config_Switches);
1450 Set_Comes_From_Source_Default (False);
1451 return Empty_List;
1452 end if;
1453 end Par;