1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2006, 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, 51 Franklin Street, Fifth Floor, --
20 -- Boston, MA 02110-1301, 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_Return then
223 End_Type := E_Return;
226 elsif Token = Tok_Select then
227 End_Type := E_Select;
230 -- Cases which do allow labels
235 if Token = Tok_Loop then
239 -- FOR or WHILE allowed (signalling error) to substitute for LOOP
240 -- if on the same line as the END
242 elsif (Token = Tok_For or else Token = Tok_While)
243 and then not Token_Is_At_Start_Of_Line
245 Scan; -- past FOR or WHILE
249 -- Cases with no keyword
255 -- Now see if a name is present
257 if Token = Tok_Identifier or else
258 Token = Tok_String_Literal or else
259 Token = Tok_Operator_Symbol
261 if Token_Is_At_Start_Of_Line then
262 Name_On_Separate_Line := True;
263 Save_Scan_State (Name_Scan_State);
265 Name_On_Separate_Line := False;
268 End_Labl := P_Designator;
269 End_Labl_Present := True;
271 -- We have now scanned out a name. Here is where we do a check
272 -- to catch the cases like:
277 -- where the missing semicolon might make us swallow up the X
278 -- as a bogus end label. In a situation like this, where the
279 -- apparent name is on a separate line, we accept it only if
280 -- it matches the label and is followed by a semicolon.
282 if Name_On_Separate_Line then
283 if Token /= Tok_Semicolon or else
284 not Same_Label (End_Labl, Scope.Table (Scope.Last).Labl)
286 Restore_Scan_State (Name_Scan_State);
288 End_Labl_Present := False;
292 -- Here for case of name allowed, but no name present. We will
293 -- supply an implicit matching name, with source location set
294 -- to the scan location past the END token.
297 End_Labl := Scope.Table (Scope.Last).Labl;
299 if End_Labl > Empty_Or_Error then
301 -- The task here is to construct a designator from the
302 -- opening label, with the components all marked as not
303 -- from source, and Is_End_Label set in the identifier
304 -- or operator symbol. The location for all components
305 -- is the curent token location.
307 -- Case of child unit name
309 if Nkind (End_Labl) = N_Defining_Program_Unit_Name then
311 Eref : constant Node_Id :=
312 Make_Identifier (Token_Ptr,
314 Chars (Defining_Identifier (End_Labl)));
316 function Copy_Name (N : Node_Id) return Node_Id;
317 -- Copies a selected component or identifier
323 function Copy_Name (N : Node_Id) return Node_Id is
327 if Nkind (N) = N_Selected_Component then
329 Make_Selected_Component (Token_Ptr,
331 Copy_Name (Prefix (N)),
333 Copy_Name (Selector_Name (N)));
337 Make_Identifier (Token_Ptr,
339 Set_Comes_From_Source (N, False);
344 -- Start of processing for Child_End
347 Set_Comes_From_Source (Eref, False);
350 Make_Designator (Token_Ptr,
351 Name => Copy_Name (Name (End_Labl)),
355 -- Simple identifier case
357 elsif Nkind (End_Labl) = N_Defining_Identifier
358 or else Nkind (End_Labl) = N_Identifier
361 Make_Identifier (Token_Ptr,
362 Chars => Chars (End_Labl));
364 elsif Nkind (End_Labl) = N_Defining_Operator_Symbol
365 or else Nkind (End_Labl) = N_Operator_Symbol
367 Get_Decoded_Name_String (Chars (End_Labl));
370 Make_Operator_Symbol (Token_Ptr,
371 Chars => Chars (End_Labl),
372 Strval => String_From_Name_Buffer);
375 Set_Comes_From_Source (End_Labl, False);
376 End_Labl_Present := False;
378 -- Do style check for missing label
381 and then End_Type = E_Name
382 and then Explicit_Start_Label (Scope.Last)
384 Style.No_End_Name (Scope.Table (Scope.Last).Labl);
390 -- Except in case of END RECORD, semicolon must follow. For END
391 -- RECORD, a semicolon does follow, but it is part of a higher level
392 -- construct. In any case, a missing semicolon is not serious enough
393 -- to consider the END statement to be bad in the sense that we
394 -- are dealing with (i.e. to be suspicious that it is not in fact
395 -- the END statement we are looking for!)
397 if End_Type /= E_Record then
398 if Token = Tok_Semicolon then
401 -- Semicolon is missing. If the missing semicolon is at the end
402 -- of the line, i.e. we are at the start of the line now, then
403 -- a missing semicolon gets flagged, but is not serious enough
404 -- to consider the END statement to be bad in the sense that we
405 -- are dealing with (i.e. to be suspicious that this END is not
406 -- the END statement we are looking for).
408 -- Similarly, if we are at a colon, we flag it but a colon for
409 -- a semicolon is not serious enough to consider the END to be
410 -- incorrect. Same thing for a period in place of a semicolon.
412 elsif Token_Is_At_Start_Of_Line
413 or else Token = Tok_Colon
414 or else Token = Tok_Dot
418 -- If the missing semicolon is not at the start of the line,
419 -- then we do consider the END line to be dubious in this sense.
427 -- Now we call the Pop_End_Context routine to get a recommendation
428 -- as to what should be done with the END sequence we have scanned.
432 -- Remaining action depends on End_Action set by Pop_End_Context
436 -- Accept_As_Scanned. In this case, Pop_End_Context left Token
437 -- pointing past the last token of a syntactically correct END
439 when Accept_As_Scanned =>
441 -- Syntactically correct included the possibility of a missing
442 -- semicolon. If we do have a missing semicolon, then we have
443 -- already given a message, but now we scan out possible rubbish
444 -- on the same line as the END
446 while not Token_Is_At_Start_Of_Line
447 and then Prev_Token /= Tok_Record
448 and then Prev_Token /= Tok_Semicolon
449 and then Token /= Tok_End
450 and then Token /= Tok_EOF
457 -- Insert_And_Accept. In this case, Pop_End_Context has reset Token
458 -- to point to the start of the END sequence, and recommends that it
459 -- be left in place to satisfy an outer scope level END. This means
460 -- that we proceed as though an END were present, and leave the scan
461 -- pointer unchanged.
463 when Insert_And_Accept =>
466 -- Skip_And_Accept. In this case, Pop_End_Context has reset Token
467 -- to point to the start of the END sequence. This END sequence is
468 -- syntactically incorrect, and an appropriate error message has
469 -- already been posted. Pop_End_Context recommends accepting the
470 -- END sequence as the one we want, so we skip past it and then
471 -- proceed as though an END were present.
473 when Skip_And_Accept =>
477 -- Skip_And_Reject. In this case, Pop_End_Context has reset Token
478 -- to point to the start of the END sequence. This END sequence is
479 -- syntactically incorrect, and an appropriate error message has
480 -- already been posted. Pop_End_Context recommends entirely ignoring
481 -- this END sequence, so we skip past it and then return False, since
482 -- as far as the caller is concerned, no END sequence is present.
484 when Skip_And_Reject =>
494 -- This procedure skips past an END sequence. On entry Token contains
495 -- Tok_End, and we know that the END sequence is syntactically incorrect,
496 -- and that an appropriate error message has already been posted. The
497 -- mission is simply to position the scan pointer to be the best guess of
498 -- the position after the END sequence. We do not issue any additional
499 -- error messages while carrying this out.
501 -- Error recovery: does not raise Error_Resync
503 procedure End_Skip is
507 -- If the scan past the END leaves us on the next line, that's probably
508 -- where we should quit the scan, since it is likely that what we have
509 -- is a missing semicolon. Consider the following:
514 -- This will have looked like a syntactically valid END sequence to the
515 -- initial scan of the END, but subsequent checking will have determined
516 -- that the label Process_Input is not an appropriate label. The real
517 -- error is a missing semicolon after the END, and by leaving the scan
518 -- pointer just past the END, we will improve the error recovery.
520 if Token_Is_At_Start_Of_Line then
524 -- If there is a semicolon after the END, scan it out and we are done
526 if Token = Tok_Semicolon then
531 -- Otherwise skip past a token after the END on the same line. Note
532 -- that we do not eat a token on the following line since it seems
533 -- very unlikely in any case that the END gets separated from its
534 -- token, and we do not want to swallow up a keyword that starts a
535 -- legitimate construct following the bad END.
537 if not Token_Is_At_Start_Of_Line
540 -- Cases of normal tokens following an END
542 (Token = Tok_Case or else
543 Token = Tok_For or else
544 Token = Tok_If or else
545 Token = Tok_Loop or else
546 Token = Tok_Record or else
547 Token = Tok_Select or else
549 -- Cases of bogus keywords ending loops
551 Token = Tok_For or else
552 Token = Tok_While or else
554 -- Cases of operator symbol names without quotes
556 Token = Tok_Abs or else
557 Token = Tok_And or else
558 Token = Tok_Mod or else
559 Token = Tok_Not or else
560 Token = Tok_Or or else
564 Scan; -- past token after END
566 -- If that leaves us on the next line, then we are done. This is the
567 -- same principle described above for the case of END at line end
569 if Token_Is_At_Start_Of_Line then
572 -- If we just scanned out record, then we are done, since the
573 -- semicolon after END RECORD is not part of the END sequence
575 elsif Prev_Token = Tok_Record then
578 -- If we have a semicolon, scan it out and we are done
580 elsif Token = Tok_Semicolon then
586 -- Check for a label present on the same line
589 if Token_Is_At_Start_Of_Line then
593 if Token /= Tok_Identifier
594 and then Token /= Tok_Operator_Symbol
595 and then Token /= Tok_String_Literal
600 Scan; -- past identifier, operator symbol or string literal
602 if Token_Is_At_Start_Of_Line then
604 elsif Token = Tok_Dot then
609 -- Skip final semicolon
611 if Token = Tok_Semicolon then
614 -- If we don't have a final semicolon, skip until we either encounter
615 -- an END token, or a semicolon or the start of the next line. This
616 -- allows general junk to follow the end line (normally it is hard to
617 -- think that anyone will put anything deliberate here, and remember
618 -- that we know there is a missing semicolon in any case). We also
619 -- quite on an EOF (or else we would get stuck in an infinite loop
620 -- if there is no line end at the end of the last line of the file)
623 while Token /= Tok_End
624 and then Token /= Tok_EOF
625 and then Token /= Tok_Semicolon
626 and then not Token_Is_At_Start_Of_Line
628 Scan; -- past junk token on same line
639 -- This procedure is called when END is required or expected to terminate
640 -- a sequence of statements. The caller has already made an appropriate
641 -- entry on the scope stack to describe the expected form of the END.
642 -- End_Statements should only be used in cases where the only appropriate
643 -- terminator is END.
645 -- Error recovery: cannot raise Error_Resync;
647 procedure End_Statements (Parent : Node_Id := Empty) is
649 -- This loop runs more than once in the case where Check_End rejects
650 -- the END sequence, as indicated by Check_End returning False.
654 if Present (Parent) then
655 Set_End_Label (Parent, End_Labl);
661 -- Extra statements past the bogus END are discarded. This is not
662 -- ideal for maximum error recovery, but it's too much trouble to
663 -- find an appropriate place to put them!
665 Discard_Junk_List (P_Sequence_Of_Statements (SS_None));
669 ------------------------
670 -- Evaluate End Entry --
671 ------------------------
673 procedure Evaluate_End_Entry (SS_Index : Nat) is
675 Column_OK := (End_Column = Scope.Table (SS_Index).Ecol);
677 Token_OK := (End_Type = Scope.Table (SS_Index).Etyp or else
678 (End_Type = E_Name and then
679 Scope.Table (SS_Index).Etyp >= E_Name));
681 Label_OK := End_Labl_Present
683 (Same_Label (End_Labl, Scope.Table (SS_Index).Labl)
684 or else Scope.Table (SS_Index).Labl = Error);
686 -- Compute setting of Syntax_OK. We definitely have a syntax error
687 -- if the Token does not match properly or if P_End_Scan detected
688 -- a syntax error such as a missing semicolon.
690 if not Token_OK or not End_OK then
693 -- Final check is that label is OK. Certainly it is OK if there
694 -- was an exact match on the label (the END label = the stack label)
699 -- Case of label present
701 elsif End_Labl_Present then
703 -- If probably misspelling, then complain, and pretend it is OK
706 Nam : constant Node_Or_Entity_Id := Scope.Table (SS_Index).Labl;
709 if Nkind (End_Labl) in N_Has_Chars
710 and then Comes_From_Source (Nam)
711 and then Nkind (Nam) in N_Has_Chars
712 and then Chars (End_Labl) > Error_Name
713 and then Chars (Nam) > Error_Name
715 Get_Name_String (Chars (End_Labl));
716 Error_Msg_Name_1 := Chars (Nam);
718 if Error_Msg_Name_1 > Error_Name then
720 S : constant String (1 .. Name_Len) :=
721 Name_Buffer (1 .. Name_Len);
724 Get_Name_String (Error_Msg_Name_1);
726 if Is_Bad_Spelling_Of
727 (Name_Buffer (1 .. Name_Len), S)
729 Error_Msg_N ("misspelling of %", End_Labl);
740 -- Otherwise we have cases of no label on the END line. For the loop
741 -- case, this is acceptable only if the loop is unlabeled.
743 elsif End_Type = E_Loop then
744 Syntax_OK := not Explicit_Start_Label (SS_Index);
746 -- Cases where a label is definitely allowed on the END line
748 elsif End_Type = E_Name then
749 Syntax_OK := (not Explicit_Start_Label (SS_Index))
751 (not Scope.Table (SS_Index).Lreq);
753 -- Otherwise we have cases which don't allow labels anyway, so we
754 -- certainly accept an END which does not have a label.
759 end Evaluate_End_Entry;
761 --------------------------
762 -- Explicit_Start_Label --
763 --------------------------
765 function Explicit_Start_Label (SS_Index : Nat) return Boolean is
766 L : constant Node_Id := Scope.Table (SS_Index).Labl;
767 Etyp : constant SS_End_Type := Scope.Table (SS_Index).Etyp;
773 -- In the following test we protect the call to Comes_From_Source
774 -- against lines containing previously reported syntax errors.
777 or else Etyp = E_Name
778 or else Etyp = E_Suspicious_Is
779 or else Etyp = E_Bad_Is)
780 and then Comes_From_Source (L)
786 end Explicit_Start_Label;
788 ------------------------
789 -- Output End Deleted --
790 ------------------------
792 procedure Output_End_Deleted is
795 if End_Type = E_Loop then
796 Error_Msg_SC ("no LOOP for this `END LOOP`!");
798 elsif End_Type = E_Case then
799 Error_Msg_SC ("no CASE for this `END CASE`");
801 elsif End_Type = E_If then
802 Error_Msg_SC ("no IF for this `END IF`!");
804 elsif End_Type = E_Record then
805 Error_Msg_SC ("no RECORD for this `END RECORD`!");
807 elsif End_Type = E_Return then
808 Error_Msg_SC ("no RETURN for this `END RETURN`!");
810 elsif End_Type = E_Select then
811 Error_Msg_SC ("no SELECT for this `END SELECT`!");
814 Error_Msg_SC ("no BEGIN for this END!");
816 end Output_End_Deleted;
818 -------------------------
819 -- Output End Expected --
820 -------------------------
822 procedure Output_End_Expected (Ins : Boolean) is
823 End_Type : SS_End_Type;
826 -- Suppress message if this was a potentially junk entry (e.g. a
827 -- record entry where no record keyword was present.
829 if Scope.Table (Scope.Last).Junk then
833 End_Type := Scope.Table (Scope.Last).Etyp;
834 Error_Msg_Col := Scope.Table (Scope.Last).Ecol;
835 Error_Msg_Sloc := Scope.Table (Scope.Last).Sloc;
837 if Explicit_Start_Label (Scope.Last) then
838 Error_Msg_Node_1 := Scope.Table (Scope.Last).Labl;
840 Error_Msg_Node_1 := Empty;
843 -- Suppress message if error was posted on opening label
845 if Error_Msg_Node_1 > Empty_Or_Error
846 and then Error_Posted (Error_Msg_Node_1)
851 if End_Type = E_Case then
852 Error_Msg_SC ("`END CASE;` expected@ for CASE#!");
854 elsif End_Type = E_If then
855 Error_Msg_SC ("`END IF;` expected@ for IF#!");
857 elsif End_Type = E_Loop then
858 if Error_Msg_Node_1 = Empty then
860 ("`END LOOP;` expected@ for LOOP#!");
862 Error_Msg_SC ("`END LOOP &;` expected@!");
865 elsif End_Type = E_Record then
867 ("`END RECORD;` expected@ for RECORD#!");
869 elsif End_Type = E_Return then
871 ("`END RETURN;` expected@ for RETURN#!");
873 elsif End_Type = E_Select then
875 ("`END SELECT;` expected@ for SELECT#!");
877 -- All remaining cases are cases with a name (we do not treat
878 -- the suspicious is cases specially for a replaced end, only
879 -- for an inserted end).
881 elsif End_Type = E_Name or else (not Ins) then
882 if Error_Msg_Node_1 = Empty then
883 Error_Msg_SC ("`END;` expected@ for BEGIN#!");
885 Error_Msg_SC ("`END &;` expected@!");
888 -- The other possibility is a missing END for a subprogram with a
889 -- suspicious IS (that probably should have been a semicolon). The
890 -- Missing IS confirms the suspicion!
892 else -- End_Type = E_Suspicious_Is or E_Bad_Is
893 Scope.Table (Scope.Last).Etyp := E_Bad_Is;
895 end Output_End_Expected;
897 ------------------------
898 -- Output End Missing --
899 ------------------------
901 procedure Output_End_Missing is
902 End_Type : SS_End_Type;
905 -- Suppress message if this was a potentially junk entry (e.g. a
906 -- record entry where no record keyword was present.
908 if Scope.Table (Scope.Last).Junk then
912 End_Type := Scope.Table (Scope.Last).Etyp;
913 Error_Msg_Sloc := Scope.Table (Scope.Last).Sloc;
915 if Explicit_Start_Label (Scope.Last) then
916 Error_Msg_Node_1 := Scope.Table (Scope.Last).Labl;
918 Error_Msg_Node_1 := Empty;
921 if End_Type = E_Case then
922 Error_Msg_BC ("missing `END CASE;` for CASE#!");
924 elsif End_Type = E_If then
925 Error_Msg_BC ("missing `END IF;` for IF#!");
927 elsif End_Type = E_Loop then
928 if Error_Msg_Node_1 = Empty then
929 Error_Msg_BC ("missing `END LOOP;` for LOOP#!");
931 Error_Msg_BC ("missing `END LOOP &;`!");
934 elsif End_Type = E_Record then
936 ("missing `END RECORD;` for RECORD#!");
938 elsif End_Type = E_Return then
940 ("missing `END RETURN;` for RETURN#!");
942 elsif End_Type = E_Select then
944 ("missing `END SELECT;` for SELECT#!");
946 elsif End_Type = E_Name then
947 if Error_Msg_Node_1 = Empty then
948 Error_Msg_BC ("missing `END;` for BEGIN#!");
950 Error_Msg_BC ("missing `END &;`!");
953 else -- End_Type = E_Suspicious_Is or E_Bad_Is
954 Scope.Table (Scope.Last).Etyp := E_Bad_Is;
956 end Output_End_Missing;
958 ---------------------
959 -- Pop End Context --
960 ---------------------
962 procedure Pop_End_Context is
964 Pretty_Good : Boolean;
965 -- This flag is set True if the END sequence is syntactically incorrect,
966 -- but is (from a heuristic point of view), pretty likely to be simply
967 -- a misspelling of the intended END.
969 Outer_Match : Boolean;
970 -- This flag is set True if we decide that the current END sequence
971 -- belongs to some outer level entry in the scope stack, and thus
972 -- we will NOT eat it up in matching the current expected END.
975 -- If not at END, then output END expected message
977 if End_Type = E_Dummy then
980 End_Action := Insert_And_Accept;
983 -- Otherwise we do have an END present
986 -- A special check. If we have END; followed by an end of file,
987 -- WITH or SEPARATE, then if we are not at the outer level, then
988 -- we have a sytax error. Consider the example:
1000 -- Now the END; here is a syntactically correct closer for the
1001 -- declare block, but if we eat it up, then we obviously have
1002 -- a missing END for the outer context (since WITH can only appear
1003 -- at the outer level.
1005 -- In this situation, we always reserve the END; for the outer level,
1006 -- even if it is in the wrong column. This is because it's much more
1007 -- useful to have the error message point to the DECLARE than to the
1008 -- package header in this case.
1010 -- We also reserve an end with a name before the end of file if the
1011 -- name is the one we expect at the outer level.
1013 if (Token = Tok_EOF or else
1014 Token = Tok_With or else
1015 Token = Tok_Separate)
1016 and then End_Type >= E_Name
1017 and then (not End_Labl_Present
1018 or else Same_Label (End_Labl, Scope.Table (1).Labl))
1019 and then Scope.Last > 1
1021 Restore_Scan_State (Scan_State); -- to END
1022 Output_End_Expected (Ins => True);
1024 End_Action := Insert_And_Accept;
1028 -- Otherwise we go through the normal END evaluation procedure
1030 Evaluate_End_Entry (Scope.Last);
1032 -- If top entry in stack is syntactically correct, then we have
1033 -- scanned it out and everything is fine. This is the required
1034 -- action to properly process correct Ada programs.
1038 -- Complain if checking columns and END is not in right column.
1039 -- Right in this context means exactly right, or on the same
1040 -- line as the opener.
1042 if Style.RM_Column_Check then
1043 if End_Column /= Scope.Table (Scope.Last).Ecol
1044 and then Current_Line_Start > Scope.Table (Scope.Last).Sloc
1046 -- A special case, for END RECORD, we are also allowed to
1047 -- line up with the TYPE keyword opening the declaration.
1049 and then (Scope.Table (Scope.Last).Etyp /= E_Record
1050 or else Get_Column_Number (End_Sloc) /=
1051 Get_Column_Number (Type_Token_Location))
1053 Error_Msg_Col := Scope.Table (Scope.Last).Ecol;
1055 ("(style) END in wrong column, should be@", End_Sloc);
1059 -- One final check. If the end had a label, check for an exact
1060 -- duplicate of this end sequence, and if so, skip it with an
1061 -- appropriate message.
1063 if End_Labl_Present and then Token = Tok_End then
1065 Scan_State : Saved_Scan_State;
1066 End_Loc : constant Source_Ptr := Token_Ptr;
1068 Dup_Found : Boolean := False;
1071 Save_Scan_State (Scan_State);
1075 if Token = Tok_Identifier
1076 or else Token = Tok_Operator_Symbol
1078 Nxt_Labl := P_Designator;
1080 -- We only consider it an error if the label is a match
1081 -- and would be wrong for the level one above us, and
1082 -- the indentation is the same.
1084 if Token = Tok_Semicolon
1085 and then Same_Label (End_Labl, Nxt_Labl)
1086 and then End_Column = Start_Column
1090 (not Explicit_Start_Label (Scope.Last - 1))
1094 Scope.Table (Scope.Last - 1).Labl)))
1097 Error_Msg ("duplicate end line ignored", End_Loc);
1102 if not Dup_Found then
1103 Restore_Scan_State (Scan_State);
1108 -- All OK, so return to caller indicating END is OK
1111 End_Action := Accept_As_Scanned;
1115 -- If that check failed, then we definitely have an error. The issue
1116 -- is how to choose among three possible courses of action:
1118 -- 1. Ignore the current END text completely, scanning past it,
1119 -- deciding that it belongs neither to the current context,
1120 -- nor to any outer context.
1122 -- 2. Accept the current END text, scanning past it, and issuing
1123 -- an error message that it does not have the right form.
1125 -- 3. Leave the current END text in place, NOT scanning past it,
1126 -- issuing an error message indicating the END expected for the
1127 -- current context. In this case, the END is available to match
1128 -- some outer END context.
1130 -- From a correct functioning point of view, it does not make any
1131 -- difference which of these three approaches we take, the program
1132 -- will work correctly in any case. However, making an accurate
1133 -- choice among these alternatives, i.e. choosing the one that
1134 -- corresponds to what the programmer had in mind, does make a
1135 -- significant difference in the quality of error recovery.
1137 Restore_Scan_State (Scan_State); -- to END
1139 -- First we see how good the current END entry is with respect to
1140 -- what we expect. It is considered pretty good if the token is OK,
1141 -- and either the label or the column matches. an END for RECORD is
1142 -- always considered to be pretty good in the record case. This is
1143 -- because not only does a record disallow a nested structure, but
1144 -- also it is unlikely that such nesting could occur by accident.
1146 Pretty_Good := (Token_OK and (Column_OK or Label_OK))
1147 or else Scope.Table (Scope.Last).Etyp = E_Record;
1149 -- Next check, if there is a deeper entry in the stack which
1150 -- has a very high probability of being acceptable, then insert
1151 -- the END entry we want, leaving the higher level entry for later
1153 for J in reverse 1 .. Scope.Last - 1 loop
1154 Evaluate_End_Entry (J);
1156 -- To even consider the deeper entry to be immediately acceptable,
1157 -- it must be syntactically correct. Furthermore it must either
1158 -- have a correct label, or the correct column. If the current
1159 -- entry was a close match (Pretty_Good set), then we are even
1160 -- more strict in accepting the outer level one: even if it has
1161 -- the right label, it must have the right column as well.
1165 Outer_Match := Label_OK and Column_OK;
1167 Outer_Match := Label_OK or Column_OK;
1170 Outer_Match := False;
1173 -- If the outer entry does convincingly match the END text, then
1174 -- back up the scan to the start of the END sequence, issue an
1175 -- error message indicating the END we expected, and return with
1176 -- Token pointing to the END (case 3 from above discussion).
1181 End_Action := Insert_And_Accept;
1186 -- Here we have a situation in which the current END entry is
1187 -- syntactically incorrect, but there is no deeper entry in the
1188 -- END stack which convincingly matches it.
1190 -- If the END text was judged to be a Pretty_Good match for the
1191 -- expected token or if it appears left of the expected column,
1192 -- then we will accept it as the one we want, scanning past it, even
1193 -- though it is not completely right (we issue a message showing what
1194 -- we expected it to be). This is action 2 from the discussion above.
1195 -- There is one other special case to consider: the LOOP case.
1196 -- Consider the example:
1202 -- Here the column lines up with Lbl, so END LOOP is to the right,
1203 -- but it is still acceptable. LOOP is the one case where alignment
1204 -- practices vary substantially in practice.
1207 or else End_Column <= Scope.Table (Scope.Last).Ecol
1208 or else (End_Type = Scope.Table (Scope.Last).Etyp
1209 and then End_Type = E_Loop)
1211 Output_End_Expected (Ins => False);
1213 End_Action := Skip_And_Accept;
1216 -- Here we have the case where the END is to the right of the
1217 -- expected column and does not have a correct label to convince
1218 -- us that it nevertheless belongs to the current scope. For this
1219 -- we consider that it probably belongs not to the current context,
1220 -- but to some inner context that was not properly recognized (due to
1221 -- other syntax errors), and for which no proper scope stack entry
1222 -- was made. The proper action in this case is to delete the END text
1223 -- and return False to the caller as a signal to keep on looking for
1224 -- an acceptable END. This is action 1 from the discussion above.
1228 End_Action := Skip_And_Reject;
1232 end Pop_End_Context;
1238 function Same_Label (Label1, Label2 : Node_Id) return Boolean is
1240 if Nkind (Label1) in N_Has_Chars
1241 and then Nkind (Label2) in N_Has_Chars
1243 return Chars (Label1) = Chars (Label2);
1245 elsif Nkind (Label1) = N_Selected_Component
1246 and then Nkind (Label2) = N_Selected_Component
1248 return Same_Label (Prefix (Label1), Prefix (Label2)) and then
1249 Same_Label (Selector_Name (Label1), Selector_Name (Label2));
1251 elsif Nkind (Label1) = N_Designator
1252 and then Nkind (Label2) = N_Defining_Program_Unit_Name
1254 return Same_Label (Name (Label1), Name (Label2)) and then
1255 Same_Label (Identifier (Label1), Defining_Identifier (Label2));