1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2002, Free Software Foundation, Inc. --
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 2, 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 COPYING. If not, write --
19 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
20 -- MA 02111-1307, USA. --
22 -- GNAT was originally developed by the GNAT team at New York University. --
23 -- Extensive contributions were provided by Ada Core Technologies Inc. --
25 ------------------------------------------------------------------------------
27 with Stringt; use Stringt;
28 with Uintp; use Uintp;
30 with GNAT.Spelling_Checker; use GNAT.Spelling_Checker;
39 type End_Action_Type is (
40 -- Type used to describe the result of the Pop_End_Context call
43 -- Current end sequence is entirely c correct. In this case Token and
44 -- the scan pointer are left pointing past the end sequence (i.e. they
45 -- are unchanged from the values set on entry to Pop_End_Context).
48 -- Current end sequence is to be left in place to satisfy some outer
49 -- scope. Token and the scan pointer are set to point to the end
50 -- token, and should be left there. A message has been generated
51 -- indicating a missing end sequence. This status is also used for
52 -- the case when no end token is present.
55 -- The end sequence is incorrect (and an error message has been
56 -- posted), but it will still be accepted. In this case Token and
57 -- the scan pointer point back to the end token, and the caller
58 -- should skip past the end sequence before proceeding.
61 -- The end sequence is judged to belong to an unrecognized inner
62 -- scope. An appropriate message has been issued and the caller
63 -- should skip past the end sequence and then proceed as though
64 -- no end sequence had been encountered.
66 End_Action : End_Action_Type;
67 -- The variable set by Pop_End_Context call showing which of the four
68 -- decisions described above is judged the best.
70 End_Sloc : Source_Ptr;
71 -- Source location of END token
74 -- Set False if error is found in END line
76 End_Column : Column_Number;
79 End_Type : SS_End_Type;
80 -- Type of END expected. The special value E_Dummy is set to indicate that
81 -- no END token was present (so a missing END inserted message is needed)
84 -- Node_Id value for explicit name on END line, or for compiler supplied
85 -- name in the case where an optional name is not given. Empty if no name
86 -- appears. If non-empty, then it is either an N_Designator node for a
87 -- child unit or a node with a Chars field identifying the actual label.
89 End_Labl_Present : Boolean;
90 -- Indicates that the value in End_Labl was for an explicit label.
93 -- Set True if the entry is syntactically correct
96 -- Set True if the keyword in the END sequence matches, or if neither
97 -- the END sequence nor the END stack entry has a keyword.
100 -- Set True if both the END sequence and the END stack entry contained
101 -- labels (other than No_Name or Error_Name) and the labels matched.
102 -- This is a stronger condition than SYNTAX_OK, since it means that a
103 -- label was present, even in a case where it was optional. Note that
104 -- the case of no label required, and no label present does NOT set
105 -- Label_OK to True, it is True only if a positive label match is found.
108 -- Column_OK is set True if the END sequence appears in the expected column
110 Scan_State : Saved_Scan_State;
111 -- Save state at start of END sequence, in case we decide not to eat it up
113 -----------------------
114 -- Local Subprograms --
115 -----------------------
117 procedure Evaluate_End_Entry (SS_Index : Nat);
118 -- Compare scanned END entry (as recorded by a prior call to P_End_Scan)
119 -- with a specified entry in the scope stack (the single parameter is the
120 -- entry index in the scope stack). Note that Scan is not called. The above
121 -- variables xxx_OK are set to indicate the result of the evaluation.
123 function Explicit_Start_Label (SS_Index : Nat) return Boolean;
124 -- Determines whether the specified entry in the scope stack has an
125 -- explicit start label (i.e. one other than one that was created by
126 -- the parser when no explicit label was present)
128 procedure Output_End_Deleted;
129 -- Output a message complaining that the current END structure does not
130 -- match anything and is being deleted.
132 procedure Output_End_Expected (Ins : Boolean);
133 -- Output a message at the start of the current token which is always an
134 -- END, complaining that the END is not of the right form. The message
135 -- indicates the expected form. The information for the message is taken
136 -- from the top entry in the scope stack. The Ins parameter is True if
137 -- an end is being inserted, and false if an existing end is being
138 -- replaced. Note that in the case of a suspicious IS for the Ins case,
139 -- we do not output the message, but instead simply mark the scope stack
140 -- entry as being a case of a bad IS.
142 procedure Output_End_Missing;
143 -- Output a message just before the current token, complaining that the
144 -- END is not of the right form. The message indicates the expected form.
145 -- The information for the message is taken from the top entry in the
146 -- scope stack. Note that in the case of a suspicious IS, we do not output
147 -- the message, but instead simply mark the scope stack entry as a bad IS.
149 procedure Pop_End_Context;
150 -- Pop_End_Context is called after processing a construct, to pop the
151 -- top entry off the end stack. It decides on the appropriate action to
152 -- to take, signalling the result by setting End_Action as described in
153 -- the global variable section.
155 function Same_Label (Label1, Label2 : Node_Id) return Boolean;
156 -- This function compares the two names associated with the given nodes.
157 -- If they are both simple (i.e. have Chars fields), then they have to
158 -- be the same name. Otherwise they must both be N_Selected_Component
159 -- nodes, referring to the same set of names, or Label1 is an N_Designator
160 -- referring to the same set of names as the N_Defining_Program_Unit_Name
161 -- in Label2. Any other combination returns False. This routine is used
162 -- to compare the End_Labl scanned from the End line with the saved label
163 -- value in the scope stack.
169 function Check_End return Boolean is
170 Name_On_Separate_Line : Boolean;
171 -- Set True if the name on an END line is on a separate source line
172 -- from the END. This is highly suspicious, but is allowed. The point
173 -- is that we want to make sure that we don't just have a missing
174 -- semicolon misleading us into swallowing an identifier from the
177 Name_Scan_State : Saved_Scan_State;
178 -- Save state at start of name if Name_On_Separate_Line is TRUE
180 Span_Node : constant Node_Id := Scope.Table (Scope.Last).Node;
183 End_Labl_Present := False;
186 -- Our first task is to scan out the END sequence if one is present.
187 -- If none is present, signal by setting End_Type to E_Dummy.
189 if Token /= Tok_End then
193 Save_Scan_State (Scan_State); -- at END
194 End_Sloc := Token_Ptr;
195 End_Column := Start_Column;
199 -- Set End_Span if expected. note that this will be useless
200 -- if we do not have the right ending keyword, but in this
201 -- case we have a malformed program anyway, and the setting
202 -- of End_Span will simply be unreliable in this case anyway.
204 if Present (Span_Node) then
205 Set_End_Location (Span_Node, Token_Ptr);
208 -- Cases of keywords where no label is allowed
210 if Token = Tok_Case then
214 elsif Token = Tok_If then
218 elsif Token = Tok_Record then
219 End_Type := E_Record;
222 elsif Token = Tok_Select then
223 End_Type := E_Select;
226 -- Cases which do allow labels
231 if Token = Tok_Loop then
235 -- FOR or WHILE allowed (signalling error) to substitute for LOOP
236 -- if on the same line as the END
238 elsif (Token = Tok_For or else Token = Tok_While)
239 and then not Token_Is_At_Start_Of_Line
241 Scan; -- past FOR or WHILE
245 -- Cases with no keyword
251 -- Now see if a name is present
253 if Token = Tok_Identifier or else
254 Token = Tok_String_Literal or else
255 Token = Tok_Operator_Symbol
257 if Token_Is_At_Start_Of_Line then
258 Name_On_Separate_Line := True;
259 Save_Scan_State (Name_Scan_State);
261 Name_On_Separate_Line := False;
264 End_Labl := P_Designator;
265 End_Labl_Present := True;
267 -- We have now scanned out a name. Here is where we do a check
268 -- to catch the cases like:
273 -- where the missing semicolon might make us swallow up the X
274 -- as a bogus end label. In a situation like this, where the
275 -- apparent name is on a separate line, we accept it only if
276 -- it matches the label and is followed by a semicolon.
278 if Name_On_Separate_Line then
279 if Token /= Tok_Semicolon or else
280 not Same_Label (End_Labl, Scope.Table (Scope.Last).Labl)
282 Restore_Scan_State (Name_Scan_State);
284 End_Labl_Present := False;
288 -- Here for case of name allowed, but no name present. We will
289 -- supply an implicit matching name, with source location set
290 -- to the scan location past the END token.
293 End_Labl := Scope.Table (Scope.Last).Labl;
295 if End_Labl > Empty_Or_Error then
297 -- The task here is to construct a designator from the
298 -- opening label, with the components all marked as not
299 -- from source, and Is_End_Label set in the identifier
300 -- or operator symbol. The location for all components
301 -- is the curent token location.
303 -- Case of child unit name
305 if Nkind (End_Labl) = N_Defining_Program_Unit_Name then
307 Eref : constant Node_Id :=
308 Make_Identifier (Token_Ptr,
310 Chars (Defining_Identifier (End_Labl)));
312 function Copy_Name (N : Node_Id) return Node_Id;
313 -- Copies a selected component or identifier
319 function Copy_Name (N : Node_Id) return Node_Id is
323 if Nkind (N) = N_Selected_Component then
325 Make_Selected_Component (Token_Ptr,
327 Copy_Name (Prefix (N)),
329 Copy_Name (Selector_Name (N)));
333 Make_Identifier (Token_Ptr,
335 Set_Comes_From_Source (N, False);
340 -- Start of processing for Child_End
343 Set_Comes_From_Source (Eref, False);
346 Make_Designator (Token_Ptr,
347 Name => Copy_Name (Name (End_Labl)),
351 -- Simple identifier case
353 elsif Nkind (End_Labl) = N_Defining_Identifier
354 or else Nkind (End_Labl) = N_Identifier
357 Make_Identifier (Token_Ptr,
358 Chars => Chars (End_Labl));
360 elsif Nkind (End_Labl) = N_Defining_Operator_Symbol
361 or else Nkind (End_Labl) = N_Operator_Symbol
363 Get_Decoded_Name_String (Chars (End_Labl));
366 Make_Operator_Symbol (Token_Ptr,
367 Chars => Chars (End_Labl),
368 Strval => String_From_Name_Buffer);
371 Set_Comes_From_Source (End_Labl, False);
372 End_Labl_Present := False;
374 -- Do style check for missing label
377 and then End_Type = E_Name
378 and then Explicit_Start_Label (Scope.Last)
380 Style.No_End_Name (Scope.Table (Scope.Last).Labl);
386 -- Except in case of END RECORD, semicolon must follow. For END
387 -- RECORD, a semicolon does follow, but it is part of a higher level
388 -- construct. In any case, a missing semicolon is not serious enough
389 -- to consider the END statement to be bad in the sense that we
390 -- are dealing with (i.e. to be suspicious that it is not in fact
391 -- the END statement we are looking for!)
393 if End_Type /= E_Record then
394 if Token = Tok_Semicolon then
397 -- Semicolon is missing. If the missing semicolon is at the end
398 -- of the line, i.e. we are at the start of the line now, then
399 -- a missing semicolon gets flagged, but is not serious enough
400 -- to consider the END statement to be bad in the sense that we
401 -- are dealing with (i.e. to be suspicious that this END is not
402 -- the END statement we are looking for).
404 -- Similarly, if we are at a colon, we flag it but a colon for
405 -- a semicolon is not serious enough to consider the END to be
406 -- incorrect. Same thing for a period in place of a semicolon.
408 elsif Token_Is_At_Start_Of_Line
409 or else Token = Tok_Colon
410 or else Token = Tok_Dot
414 -- If the missing semicolon is not at the start of the line,
415 -- then we do consider the END line to be dubious in this sense.
423 -- Now we call the Pop_End_Context routine to get a recommendation
424 -- as to what should be done with the END sequence we have scanned.
428 -- Remaining action depends on End_Action set by Pop_End_Context
432 -- Accept_As_Scanned. In this case, Pop_End_Context left Token
433 -- pointing past the last token of a syntactically correct END
435 when Accept_As_Scanned =>
437 -- Syntactically correct included the possibility of a missing
438 -- semicolon. If we do have a missing semicolon, then we have
439 -- already given a message, but now we scan out possible rubbish
440 -- on the same line as the END
442 while not Token_Is_At_Start_Of_Line
443 and then Prev_Token /= Tok_Record
444 and then Prev_Token /= Tok_Semicolon
445 and then Token /= Tok_End
446 and then Token /= Tok_EOF
453 -- Insert_And_Accept. In this case, Pop_End_Context has reset Token
454 -- to point to the start of the END sequence, and recommends that it
455 -- be left in place to satisfy an outer scope level END. This means
456 -- that we proceed as though an END were present, and leave the scan
457 -- pointer unchanged.
459 when Insert_And_Accept =>
462 -- Skip_And_Accept. In this case, Pop_End_Context has reset Token
463 -- to point to the start of the END sequence. This END sequence is
464 -- syntactically incorrect, and an appropriate error message has
465 -- already been posted. Pop_End_Context recommends accepting the
466 -- END sequence as the one we want, so we skip past it and then
467 -- proceed as though an END were present.
469 when Skip_And_Accept =>
473 -- Skip_And_Reject. In this case, Pop_End_Context has reset Token
474 -- to point to the start of the END sequence. This END sequence is
475 -- syntactically incorrect, and an appropriate error message has
476 -- already been posted. Pop_End_Context recommends entirely ignoring
477 -- this END sequence, so we skip past it and then return False, since
478 -- as far as the caller is concerned, no END sequence is present.
480 when Skip_And_Reject =>
490 -- This procedure skips past an END sequence. On entry Token contains
491 -- Tok_End, and we know that the END sequence is syntactically incorrect,
492 -- and that an appropriate error message has already been posted. The
493 -- mission is simply to position the scan pointer to be the best guess of
494 -- the position after the END sequence. We do not issue any additional
495 -- error messages while carrying this out.
497 -- Error recovery: does not raise Error_Resync
499 procedure End_Skip is
503 -- If the scan past the END leaves us on the next line, that's probably
504 -- where we should quit the scan, since it is likely that what we have
505 -- is a missing semicolon. Consider the following:
510 -- This will have looked like a syntactically valid END sequence to the
511 -- initial scan of the END, but subsequent checking will have determined
512 -- that the label Process_Input is not an appropriate label. The real
513 -- error is a missing semicolon after the END, and by leaving the scan
514 -- pointer just past the END, we will improve the error recovery.
516 if Token_Is_At_Start_Of_Line then
520 -- If there is a semicolon after the END, scan it out and we are done
522 if Token = Tok_Semicolon then
527 -- Otherwise skip past a token after the END on the same line. Note
528 -- that we do not eat a token on the following line since it seems
529 -- very unlikely in any case that the END gets separated from its
530 -- token, and we do not want to swallow up a keyword that starts a
531 -- legitimate construct following the bad END.
533 if not Token_Is_At_Start_Of_Line
536 -- Cases of normal tokens following an END
538 (Token = Tok_Case or else
539 Token = Tok_For or else
540 Token = Tok_If or else
541 Token = Tok_Loop or else
542 Token = Tok_Record or else
543 Token = Tok_Select or else
545 -- Cases of bogus keywords ending loops
547 Token = Tok_For or else
548 Token = Tok_While or else
550 -- Cases of operator symbol names without quotes
552 Token = Tok_Abs or else
553 Token = Tok_And or else
554 Token = Tok_Mod or else
555 Token = Tok_Not or else
556 Token = Tok_Or or else
560 Scan; -- past token after END
562 -- If that leaves us on the next line, then we are done. This is the
563 -- same principle described above for the case of END at line end
565 if Token_Is_At_Start_Of_Line then
568 -- If we just scanned out record, then we are done, since the
569 -- semicolon after END RECORD is not part of the END sequence
571 elsif Prev_Token = Tok_Record then
574 -- If we have a semicolon, scan it out and we are done
576 elsif Token = Tok_Semicolon then
582 -- Check for a label present on the same line
585 if Token_Is_At_Start_Of_Line then
589 if Token /= Tok_Identifier
590 and then Token /= Tok_Operator_Symbol
591 and then Token /= Tok_String_Literal
596 Scan; -- past identifier, operator symbol or string literal
598 if Token_Is_At_Start_Of_Line then
600 elsif Token = Tok_Dot then
605 -- Skip final semicolon
607 if Token = Tok_Semicolon then
610 -- If we don't have a final semicolon, skip until we either encounter
611 -- an END token, or a semicolon or the start of the next line. This
612 -- allows general junk to follow the end line (normally it is hard to
613 -- think that anyone will put anything deliberate here, and remember
614 -- that we know there is a missing semicolon in any case). We also
615 -- quite on an EOF (or else we would get stuck in an infinite loop
616 -- if there is no line end at the end of the last line of the file)
619 while Token /= Tok_End
620 and then Token /= Tok_EOF
621 and then Token /= Tok_Semicolon
622 and then not Token_Is_At_Start_Of_Line
624 Scan; -- past junk token on same line
635 -- This procedure is called when END is required or expected to terminate
636 -- a sequence of statements. The caller has already made an appropriate
637 -- entry on the scope stack to describe the expected form of the END.
638 -- End_Statements should only be used in cases where the only appropriate
639 -- terminator is END.
641 -- Error recovery: cannot raise Error_Resync;
643 procedure End_Statements (Parent : Node_Id := Empty) is
645 -- This loop runs more than once in the case where Check_End rejects
646 -- the END sequence, as indicated by Check_End returning False.
650 if Present (Parent) then
651 Set_End_Label (Parent, End_Labl);
657 -- Extra statements past the bogus END are discarded. This is not
658 -- ideal for maximum error recovery, but it's too much trouble to
659 -- find an appropriate place to put them!
661 Discard_Junk_List (P_Sequence_Of_Statements (SS_None));
665 ------------------------
666 -- Evaluate End Entry --
667 ------------------------
669 procedure Evaluate_End_Entry (SS_Index : Nat) is
671 Column_OK := (End_Column = Scope.Table (SS_Index).Ecol);
673 Token_OK := (End_Type = Scope.Table (SS_Index).Etyp or else
674 (End_Type = E_Name and then
675 Scope.Table (SS_Index).Etyp >= E_Name));
677 Label_OK := End_Labl_Present
679 (Same_Label (End_Labl, Scope.Table (SS_Index).Labl)
680 or else Scope.Table (SS_Index).Labl = Error);
682 -- Compute setting of Syntax_OK. We definitely have a syntax error
683 -- if the Token does not match properly or if P_End_Scan detected
684 -- a syntax error such as a missing semicolon.
686 if not Token_OK or not End_OK then
689 -- Final check is that label is OK. Certainly it is OK if there
690 -- was an exact match on the label (the END label = the stack label)
695 -- Case of label present
697 elsif End_Labl_Present then
699 -- If probably misspelling, then complain, and pretend it is OK
702 Nam : constant Node_Or_Entity_Id := Scope.Table (SS_Index).Labl;
705 if Nkind (End_Labl) in N_Has_Chars
706 and then Comes_From_Source (Nam)
707 and then Nkind (Nam) in N_Has_Chars
708 and then Chars (End_Labl) > Error_Name
709 and then Chars (Nam) > Error_Name
711 Get_Name_String (Chars (End_Labl));
712 Error_Msg_Name_1 := Chars (Nam);
714 if Error_Msg_Name_1 > Error_Name then
716 S : constant String (1 .. Name_Len) :=
717 Name_Buffer (1 .. Name_Len);
720 Get_Name_String (Error_Msg_Name_1);
722 if Is_Bad_Spelling_Of
723 (Name_Buffer (1 .. Name_Len), S)
725 Error_Msg_N ("misspelling of %", End_Labl);
736 -- Otherwise we have cases of no label on the END line. For the loop
737 -- case, this is acceptable only if the loop is unlabeled.
739 elsif End_Type = E_Loop then
740 Syntax_OK := not Explicit_Start_Label (SS_Index);
742 -- Cases where a label is definitely allowed on the END line
744 elsif End_Type = E_Name then
745 Syntax_OK := (not Explicit_Start_Label (SS_Index))
747 (not Scope.Table (SS_Index).Lreq);
749 -- Otherwise we have cases which don't allow labels anyway, so we
750 -- certainly accept an END which does not have a label.
755 end Evaluate_End_Entry;
757 --------------------------
758 -- Explicit_Start_Label --
759 --------------------------
761 function Explicit_Start_Label (SS_Index : Nat) return Boolean is
762 L : constant Node_Id := Scope.Table (SS_Index).Labl;
767 elsif Comes_From_Source (L) then
772 end Explicit_Start_Label;
774 ------------------------
775 -- Output End Deleted --
776 ------------------------
778 procedure Output_End_Deleted is
781 if End_Type = E_Loop then
782 Error_Msg_SC ("no LOOP for this `END LOOP`!");
784 elsif End_Type = E_Case then
785 Error_Msg_SC ("no CASE for this `END CASE`");
787 elsif End_Type = E_If then
788 Error_Msg_SC ("no IF for this `END IF`!");
790 elsif End_Type = E_Record then
791 Error_Msg_SC ("no RECORD for this `END RECORD`!");
793 elsif End_Type = E_Select then
794 Error_Msg_SC ("no SELECT for this `END SELECT`!");
797 Error_Msg_SC ("no BEGIN for this END!");
799 end Output_End_Deleted;
801 -------------------------
802 -- Output End Expected --
803 -------------------------
805 procedure Output_End_Expected (Ins : Boolean) is
806 End_Type : SS_End_Type;
809 -- Suppress message if this was a potentially junk entry (e.g. a
810 -- record entry where no record keyword was present.
812 if Scope.Table (Scope.Last).Junk then
816 End_Type := Scope.Table (Scope.Last).Etyp;
817 Error_Msg_Col := Scope.Table (Scope.Last).Ecol;
818 Error_Msg_Sloc := Scope.Table (Scope.Last).Sloc;
820 if Explicit_Start_Label (Scope.Last) then
821 Error_Msg_Node_1 := Scope.Table (Scope.Last).Labl;
823 Error_Msg_Node_1 := Empty;
826 -- Suppress message if error was posted on opening label
828 if Error_Msg_Node_1 > Empty_Or_Error
829 and then Error_Posted (Error_Msg_Node_1)
834 if End_Type = E_Case then
835 Error_Msg_SC ("`END CASE;` expected@ for CASE#!");
837 elsif End_Type = E_If then
838 Error_Msg_SC ("`END IF;` expected@ for IF#!");
840 elsif End_Type = E_Loop then
841 if Error_Msg_Node_1 = Empty then
843 ("`END LOOP;` expected@ for LOOP#!");
845 Error_Msg_SC ("`END LOOP &;` expected@!");
848 elsif End_Type = E_Record then
850 ("`END RECORD;` expected@ for RECORD#!");
852 elsif End_Type = E_Select then
854 ("`END SELECT;` expected@ for SELECT#!");
856 -- All remaining cases are cases with a name (we do not treat
857 -- the suspicious is cases specially for a replaced end, only
858 -- for an inserted end).
860 elsif End_Type = E_Name or else (not Ins) then
861 if Error_Msg_Node_1 = Empty then
862 Error_Msg_SC ("`END;` expected@ for BEGIN#!");
864 Error_Msg_SC ("`END &;` expected@!");
867 -- The other possibility is a missing END for a subprogram with a
868 -- suspicious IS (that probably should have been a semicolon). The
869 -- Missing IS confirms the suspicion!
871 else -- End_Type = E_Suspicious_Is or E_Bad_Is
872 Scope.Table (Scope.Last).Etyp := E_Bad_Is;
874 end Output_End_Expected;
876 ------------------------
877 -- Output End Missing --
878 ------------------------
880 procedure Output_End_Missing is
881 End_Type : SS_End_Type;
884 -- Suppress message if this was a potentially junk entry (e.g. a
885 -- record entry where no record keyword was present.
887 if Scope.Table (Scope.Last).Junk then
891 End_Type := Scope.Table (Scope.Last).Etyp;
892 Error_Msg_Sloc := Scope.Table (Scope.Last).Sloc;
894 if Explicit_Start_Label (Scope.Last) then
895 Error_Msg_Node_1 := Scope.Table (Scope.Last).Labl;
897 Error_Msg_Node_1 := Empty;
900 if End_Type = E_Case then
901 Error_Msg_BC ("missing `END CASE;` for CASE#!");
903 elsif End_Type = E_If then
904 Error_Msg_BC ("missing `END IF;` for IF#!");
906 elsif End_Type = E_Loop then
907 if Error_Msg_Node_1 = Empty then
908 Error_Msg_BC ("missing `END LOOP;` for LOOP#!");
910 Error_Msg_BC ("missing `END LOOP &;`!");
913 elsif End_Type = E_Record then
915 ("missing `END RECORD;` for RECORD#!");
917 elsif End_Type = E_Select then
919 ("missing `END SELECT;` for SELECT#!");
921 elsif End_Type = E_Name then
922 if Error_Msg_Node_1 = Empty then
923 Error_Msg_BC ("missing `END;` for BEGIN#!");
925 Error_Msg_BC ("missing `END &;`!");
928 else -- End_Type = E_Suspicious_Is or E_Bad_Is
929 Scope.Table (Scope.Last).Etyp := E_Bad_Is;
931 end Output_End_Missing;
933 ---------------------
934 -- Pop End Context --
935 ---------------------
937 procedure Pop_End_Context is
939 Pretty_Good : Boolean;
940 -- This flag is set True if the END sequence is syntactically incorrect,
941 -- but is (from a heuristic point of view), pretty likely to be simply
942 -- a misspelling of the intended END.
944 Outer_Match : Boolean;
945 -- This flag is set True if we decide that the current END sequence
946 -- belongs to some outer level entry in the scope stack, and thus
947 -- we will NOT eat it up in matching the current expected END.
950 -- If not at END, then output END expected message
952 if End_Type = E_Dummy then
955 End_Action := Insert_And_Accept;
958 -- Otherwise we do have an END present
961 -- A special check. If we have END; followed by an end of file,
962 -- WITH or SEPARATE, then if we are not at the outer level, then
963 -- we have a sytax error. Consider the example:
975 -- Now the END; here is a syntactically correct closer for the
976 -- declare block, but if we eat it up, then we obviously have
977 -- a missing END for the outer context (since WITH can only appear
978 -- at the outer level.
980 -- In this situation, we always reserve the END; for the outer level,
981 -- even if it is in the wrong column. This is because it's much more
982 -- useful to have the error message point to the DECLARE than to the
983 -- package header in this case.
985 -- We also reserve an end with a name before the end of file if the
986 -- name is the one we expect at the outer level.
988 if (Token = Tok_EOF or else
989 Token = Tok_With or else
990 Token = Tok_Separate)
991 and then End_Type >= E_Name
992 and then (not End_Labl_Present
993 or else Same_Label (End_Labl, Scope.Table (1).Labl))
994 and then Scope.Last > 1
996 Restore_Scan_State (Scan_State); -- to END
997 Output_End_Expected (Ins => True);
999 End_Action := Insert_And_Accept;
1003 -- Otherwise we go through the normal END evaluation procedure
1005 Evaluate_End_Entry (Scope.Last);
1007 -- If top entry in stack is syntactically correct, then we have
1008 -- scanned it out and everything is fine. This is the required
1009 -- action to properly process correct Ada programs.
1013 -- Complain if checking columns and END is not in right column.
1014 -- Right in this context means exactly right, or on the same
1015 -- line as the opener.
1017 if Style.RM_Column_Check then
1018 if End_Column /= Scope.Table (Scope.Last).Ecol
1019 and then Current_Line_Start > Scope.Table (Scope.Last).Sloc
1021 Error_Msg_Col := Scope.Table (Scope.Last).Ecol;
1023 ("(style) END in wrong column, should be@", End_Sloc);
1027 -- One final check. If the end had a label, check for an exact
1028 -- duplicate of this end sequence, and if so, skip it with an
1029 -- appropriate message.
1031 if End_Labl_Present and then Token = Tok_End then
1033 Scan_State : Saved_Scan_State;
1034 End_Loc : constant Source_Ptr := Token_Ptr;
1036 Dup_Found : Boolean := False;
1039 Save_Scan_State (Scan_State);
1043 if Token = Tok_Identifier
1044 or else Token = Tok_Operator_Symbol
1046 Nxt_Labl := P_Designator;
1048 -- We only consider it an error if the label is a match
1049 -- and would be wrong for the level one above us, and
1050 -- the indentation is the same.
1052 if Token = Tok_Semicolon
1053 and then Same_Label (End_Labl, Nxt_Labl)
1054 and then End_Column = Start_Column
1058 (not Explicit_Start_Label (Scope.Last - 1))
1062 Scope.Table (Scope.Last - 1).Labl)))
1065 Error_Msg ("duplicate end line ignored", End_Loc);
1070 if not Dup_Found then
1071 Restore_Scan_State (Scan_State);
1076 -- All OK, so return to caller indicating END is OK
1079 End_Action := Accept_As_Scanned;
1083 -- If that check failed, then we definitely have an error. The issue
1084 -- is how to choose among three possible courses of action:
1086 -- 1. Ignore the current END text completely, scanning past it,
1087 -- deciding that it belongs neither to the current context,
1088 -- nor to any outer context.
1090 -- 2. Accept the current END text, scanning past it, and issuing
1091 -- an error message that it does not have the right form.
1093 -- 3. Leave the current END text in place, NOT scanning past it,
1094 -- issuing an error message indicating the END expected for the
1095 -- current context. In this case, the END is available to match
1096 -- some outer END context.
1098 -- From a correct functioning point of view, it does not make any
1099 -- difference which of these three approaches we take, the program
1100 -- will work correctly in any case. However, making an accurate
1101 -- choice among these alternatives, i.e. choosing the one that
1102 -- corresponds to what the programmer had in mind, does make a
1103 -- significant difference in the quality of error recovery.
1105 Restore_Scan_State (Scan_State); -- to END
1107 -- First we see how good the current END entry is with respect to
1108 -- what we expect. It is considered pretty good if the token is OK,
1109 -- and either the label or the column matches. an END for RECORD is
1110 -- always considered to be pretty good in the record case. This is
1111 -- because not only does a record disallow a nested structure, but
1112 -- also it is unlikely that such nesting could occur by accident.
1114 Pretty_Good := (Token_OK and (Column_OK or Label_OK))
1115 or else Scope.Table (Scope.Last).Etyp = E_Record;
1117 -- Next check, if there is a deeper entry in the stack which
1118 -- has a very high probability of being acceptable, then insert
1119 -- the END entry we want, leaving the higher level entry for later
1121 for J in reverse 1 .. Scope.Last - 1 loop
1122 Evaluate_End_Entry (J);
1124 -- To even consider the deeper entry to be immediately acceptable,
1125 -- it must be syntactically correct. Furthermore it must either
1126 -- have a correct label, or the correct column. If the current
1127 -- entry was a close match (Pretty_Good set), then we are even
1128 -- more strict in accepting the outer level one: even if it has
1129 -- the right label, it must have the right column as well.
1133 Outer_Match := Label_OK and Column_OK;
1135 Outer_Match := Label_OK or Column_OK;
1138 Outer_Match := False;
1141 -- If the outer entry does convincingly match the END text, then
1142 -- back up the scan to the start of the END sequence, issue an
1143 -- error message indicating the END we expected, and return with
1144 -- Token pointing to the END (case 3 from above discussion).
1149 End_Action := Insert_And_Accept;
1154 -- Here we have a situation in which the current END entry is
1155 -- syntactically incorrect, but there is no deeper entry in the
1156 -- END stack which convincingly matches it.
1158 -- If the END text was judged to be a Pretty_Good match for the
1159 -- expected token or if it appears left of the expected column,
1160 -- then we will accept it as the one we want, scanning past it, even
1161 -- though it is not completely right (we issue a message showing what
1162 -- we expected it to be). This is action 2 from the discussion above.
1163 -- There is one other special case to consider: the LOOP case.
1164 -- Consider the example:
1170 -- Here the column lines up with Lbl, so END LOOP is to the right,
1171 -- but it is still acceptable. LOOP is the one case where alignment
1172 -- practices vary substantially in practice.
1175 or else End_Column <= Scope.Table (Scope.Last).Ecol
1176 or else (End_Type = Scope.Table (Scope.Last).Etyp
1177 and then End_Type = E_Loop)
1179 Output_End_Expected (Ins => False);
1181 End_Action := Skip_And_Accept;
1184 -- Here we have the case where the END is to the right of the
1185 -- expected column and does not have a correct label to convince
1186 -- us that it nevertheless belongs to the current scope. For this
1187 -- we consider that it probably belongs not to the current context,
1188 -- but to some inner context that was not properly recognized (due to
1189 -- other syntax errors), and for which no proper scope stack entry
1190 -- was made. The proper action in this case is to delete the END text
1191 -- and return False to the caller as a signal to keep on looking for
1192 -- an acceptable END. This is action 1 from the discussion above.
1196 End_Action := Skip_And_Reject;
1200 end Pop_End_Context;
1206 function Same_Label (Label1, Label2 : Node_Id) return Boolean is
1208 if Nkind (Label1) in N_Has_Chars
1209 and then Nkind (Label2) in N_Has_Chars
1211 return Chars (Label1) = Chars (Label2);
1213 elsif Nkind (Label1) = N_Selected_Component
1214 and then Nkind (Label2) = N_Selected_Component
1216 return Same_Label (Prefix (Label1), Prefix (Label2)) and then
1217 Same_Label (Selector_Name (Label1), Selector_Name (Label2));
1219 elsif Nkind (Label1) = N_Designator
1220 and then Nkind (Label2) = N_Defining_Program_Unit_Name
1222 return Same_Label (Name (Label1), Name (Label2)) and then
1223 Same_Label (Identifier (Label1), Defining_Identifier (Label2));