1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2010, 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 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. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Namet.Sp; use Namet.Sp;
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 (Decl : Node_Id := Empty) 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 current 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 -- Scan aspect specifications if permitted here
392 if Aspect_Specifications_Present then
394 P_Aspect_Specifications (Error);
396 P_Aspect_Specifications (Decl);
399 -- Except in case of END RECORD, semicolon must follow. For END
400 -- RECORD, a semicolon does follow, but it is part of a higher level
401 -- construct. In any case, a missing semicolon is not serious enough
402 -- to consider the END statement to be bad in the sense that we
403 -- are dealing with (i.e. to be suspicious that it is not in fact
404 -- the END statement we are looking for!)
406 elsif End_Type /= E_Record then
407 if Token = Tok_Semicolon then
410 -- Semicolon is missing. If the missing semicolon is at the end
411 -- of the line, i.e. we are at the start of the line now, then
412 -- a missing semicolon gets flagged, but is not serious enough
413 -- to consider the END statement to be bad in the sense that we
414 -- are dealing with (i.e. to be suspicious that this END is not
415 -- the END statement we are looking for).
417 -- Similarly, if we are at a colon, we flag it but a colon for
418 -- a semicolon is not serious enough to consider the END to be
419 -- incorrect. Same thing for a period in place of a semicolon.
421 elsif Token_Is_At_Start_Of_Line
422 or else Token = Tok_Colon
423 or else Token = Tok_Dot
427 -- If the missing semicolon is not at the start of the line,
428 -- then we do consider the END line to be dubious in this sense.
436 -- Now we call the Pop_End_Context routine to get a recommendation
437 -- as to what should be done with the END sequence we have scanned.
441 -- Remaining action depends on End_Action set by Pop_End_Context
445 -- Accept_As_Scanned. In this case, Pop_End_Context left Token
446 -- pointing past the last token of a syntactically correct END
448 when Accept_As_Scanned =>
450 -- Syntactically correct included the possibility of a missing
451 -- semicolon. If we do have a missing semicolon, then we have
452 -- already given a message, but now we scan out possible rubbish
453 -- on the same line as the END
455 while not Token_Is_At_Start_Of_Line
456 and then Prev_Token /= Tok_Record
457 and then Prev_Token /= Tok_Semicolon
458 and then Token /= Tok_End
459 and then Token /= Tok_EOF
466 -- Insert_And_Accept. In this case, Pop_End_Context has reset Token
467 -- to point to the start of the END sequence, and recommends that it
468 -- be left in place to satisfy an outer scope level END. This means
469 -- that we proceed as though an END were present, and leave the scan
470 -- pointer unchanged.
472 when Insert_And_Accept =>
475 -- Skip_And_Accept. In this case, Pop_End_Context has reset Token
476 -- to point to the start of the END sequence. This END sequence is
477 -- syntactically incorrect, and an appropriate error message has
478 -- already been posted. Pop_End_Context recommends accepting the
479 -- END sequence as the one we want, so we skip past it and then
480 -- proceed as though an END were present.
482 when Skip_And_Accept =>
486 -- Skip_And_Reject. In this case, Pop_End_Context has reset Token
487 -- to point to the start of the END sequence. This END sequence is
488 -- syntactically incorrect, and an appropriate error message has
489 -- already been posted. Pop_End_Context recommends entirely ignoring
490 -- this END sequence, so we skip past it and then return False, since
491 -- as far as the caller is concerned, no END sequence is present.
493 when Skip_And_Reject =>
503 -- This procedure skips past an END sequence. On entry Token contains
504 -- Tok_End, and we know that the END sequence is syntactically incorrect,
505 -- and that an appropriate error message has already been posted. The
506 -- mission is simply to position the scan pointer to be the best guess of
507 -- the position after the END sequence. We do not issue any additional
508 -- error messages while carrying this out.
510 -- Error recovery: does not raise Error_Resync
512 procedure End_Skip is
516 -- If the scan past the END leaves us on the next line, that's probably
517 -- where we should quit the scan, since it is likely that what we have
518 -- is a missing semicolon. Consider the following:
523 -- This will have looked like a syntactically valid END sequence to the
524 -- initial scan of the END, but subsequent checking will have determined
525 -- that the label Process_Input is not an appropriate label. The real
526 -- error is a missing semicolon after the END, and by leaving the scan
527 -- pointer just past the END, we will improve the error recovery.
529 if Token_Is_At_Start_Of_Line then
533 -- If there is a semicolon after the END, scan it out and we are done
535 if Token = Tok_Semicolon then
540 -- Otherwise skip past a token after the END on the same line. Note
541 -- that we do not eat a token on the following line since it seems
542 -- very unlikely in any case that the END gets separated from its
543 -- token, and we do not want to swallow up a keyword that starts a
544 -- legitimate construct following the bad END.
546 if not Token_Is_At_Start_Of_Line
549 -- Cases of normal tokens following an END
551 (Token = Tok_Case or else
552 Token = Tok_For or else
553 Token = Tok_If or else
554 Token = Tok_Loop or else
555 Token = Tok_Record or else
556 Token = Tok_Select or else
558 -- Cases of bogus keywords ending loops
560 Token = Tok_For or else
561 Token = Tok_While or else
563 -- Cases of operator symbol names without quotes
565 Token = Tok_Abs or else
566 Token = Tok_And or else
567 Token = Tok_Mod or else
568 Token = Tok_Not or else
569 Token = Tok_Or or else
573 Scan; -- past token after END
575 -- If that leaves us on the next line, then we are done. This is the
576 -- same principle described above for the case of END at line end
578 if Token_Is_At_Start_Of_Line then
581 -- If we just scanned out record, then we are done, since the
582 -- semicolon after END RECORD is not part of the END sequence
584 elsif Prev_Token = Tok_Record then
587 -- If we have a semicolon, scan it out and we are done
589 elsif Token = Tok_Semicolon then
595 -- Check for a label present on the same line
598 if Token_Is_At_Start_Of_Line then
602 if Token /= Tok_Identifier
603 and then Token /= Tok_Operator_Symbol
604 and then Token /= Tok_String_Literal
609 Scan; -- past identifier, operator symbol or string literal
611 if Token_Is_At_Start_Of_Line then
613 elsif Token = Tok_Dot then
618 -- Skip final semicolon
620 if Token = Tok_Semicolon then
623 -- If we don't have a final semicolon, skip until we either encounter
624 -- an END token, or a semicolon or the start of the next line. This
625 -- allows general junk to follow the end line (normally it is hard to
626 -- think that anyone will put anything deliberate here, and remember
627 -- that we know there is a missing semicolon in any case). We also
628 -- quite on an EOF (or else we would get stuck in an infinite loop
629 -- if there is no line end at the end of the last line of the file)
632 while Token /= Tok_End
633 and then Token /= Tok_EOF
634 and then Token /= Tok_Semicolon
635 and then not Token_Is_At_Start_Of_Line
637 Scan; -- past junk token on same line
648 -- This procedure is called when END is required or expected to terminate
649 -- a sequence of statements. The caller has already made an appropriate
650 -- entry on the scope stack to describe the expected form of the END.
651 -- End_Statements should only be used in cases where the only appropriate
652 -- terminator is END.
654 -- Error recovery: cannot raise Error_Resync;
656 procedure End_Statements
657 (Parent : Node_Id := Empty;
658 Decl : Node_Id := Empty) is
660 -- This loop runs more than once in the case where Check_End rejects
661 -- the END sequence, as indicated by Check_End returning False.
664 if Check_End (Decl) then
665 if Present (Parent) then
666 Set_End_Label (Parent, End_Labl);
672 -- Extra statements past the bogus END are discarded. This is not
673 -- ideal for maximum error recovery, but it's too much trouble to
674 -- find an appropriate place to put them!
676 Discard_Junk_List (P_Sequence_Of_Statements (SS_None));
680 ------------------------
681 -- Evaluate End Entry --
682 ------------------------
684 procedure Evaluate_End_Entry (SS_Index : Nat) is
686 Column_OK := (End_Column = Scope.Table (SS_Index).Ecol);
688 Token_OK := (End_Type = Scope.Table (SS_Index).Etyp or else
689 (End_Type = E_Name and then
690 Scope.Table (SS_Index).Etyp >= E_Name));
692 Label_OK := End_Labl_Present
694 (Same_Label (End_Labl, Scope.Table (SS_Index).Labl)
695 or else Scope.Table (SS_Index).Labl = Error);
697 -- Compute setting of Syntax_OK. We definitely have a syntax error
698 -- if the Token does not match properly or if P_End_Scan detected
699 -- a syntax error such as a missing semicolon.
701 if not Token_OK or not End_OK then
704 -- Final check is that label is OK. Certainly it is OK if there
705 -- was an exact match on the label (the END label = the stack label)
710 -- Case of label present
712 elsif End_Labl_Present then
714 -- If probably misspelling, then complain, and pretend it is OK
717 Nam : constant Node_Or_Entity_Id := Scope.Table (SS_Index).Labl;
720 if Nkind (End_Labl) in N_Has_Chars
721 and then Comes_From_Source (Nam)
722 and then Nkind (Nam) in N_Has_Chars
723 and then Chars (End_Labl) > Error_Name
724 and then Chars (Nam) > Error_Name
726 Error_Msg_Name_1 := Chars (Nam);
728 if Error_Msg_Name_1 > Error_Name then
729 if Is_Bad_Spelling_Of (Chars (Nam), Chars (End_Labl)) then
730 Error_Msg_Name_1 := Chars (Nam);
731 Error_Msg_N -- CODEFIX
732 ("misspelling of %", End_Labl);
742 -- Otherwise we have cases of no label on the END line. For the loop
743 -- case, this is acceptable only if the loop is unlabeled.
745 elsif End_Type = E_Loop then
746 Syntax_OK := not Explicit_Start_Label (SS_Index);
748 -- Cases where a label is definitely allowed on the END line
750 elsif End_Type = E_Name then
751 Syntax_OK := (not Explicit_Start_Label (SS_Index))
753 (not Scope.Table (SS_Index).Lreq);
755 -- Otherwise we have cases which don't allow labels anyway, so we
756 -- certainly accept an END which does not have a label.
761 end Evaluate_End_Entry;
763 --------------------------
764 -- Explicit_Start_Label --
765 --------------------------
767 function Explicit_Start_Label (SS_Index : Nat) return Boolean is
768 L : constant Node_Id := Scope.Table (SS_Index).Labl;
769 Etyp : constant SS_End_Type := Scope.Table (SS_Index).Etyp;
775 -- In the following test we protect the call to Comes_From_Source
776 -- against lines containing previously reported syntax errors.
779 or else Etyp = E_Name
780 or else Etyp = E_Suspicious_Is
781 or else Etyp = E_Bad_Is)
782 and then Comes_From_Source (L)
788 end Explicit_Start_Label;
790 ------------------------
791 -- Output End Deleted --
792 ------------------------
794 procedure Output_End_Deleted is
797 if End_Type = E_Loop then
798 Error_Msg_SC ("no LOOP for this `END LOOP`!");
800 elsif End_Type = E_Case then
801 Error_Msg_SC ("no CASE for this `END CASE`");
803 elsif End_Type = E_If then
804 Error_Msg_SC ("no IF for this `END IF`!");
806 elsif End_Type = E_Record then
807 Error_Msg_SC ("no RECORD for this `END RECORD`!");
809 elsif End_Type = E_Return then
810 Error_Msg_SC ("no RETURN for this `END RETURN`!");
812 elsif End_Type = E_Select then
813 Error_Msg_SC ("no SELECT for this `END SELECT`!");
816 Error_Msg_SC ("no BEGIN for this END!");
818 end Output_End_Deleted;
820 -------------------------
821 -- Output End Expected --
822 -------------------------
824 procedure Output_End_Expected (Ins : Boolean) is
825 End_Type : SS_End_Type;
828 -- Suppress message if this was a potentially junk entry (e.g. a
829 -- record entry where no record keyword was present.
831 if Scope.Table (Scope.Last).Junk then
835 End_Type := Scope.Table (Scope.Last).Etyp;
836 Error_Msg_Col := Scope.Table (Scope.Last).Ecol;
837 Error_Msg_Sloc := Scope.Table (Scope.Last).Sloc;
839 if Explicit_Start_Label (Scope.Last) then
840 Error_Msg_Node_1 := Scope.Table (Scope.Last).Labl;
842 Error_Msg_Node_1 := Empty;
845 -- Suppress message if error was posted on opening label
847 if Error_Msg_Node_1 > Empty_Or_Error
848 and then Error_Posted (Error_Msg_Node_1)
853 if End_Type = E_Case then
854 Error_Msg_SC -- CODEFIX
855 ("`END CASE;` expected@ for CASE#!");
857 elsif End_Type = E_If then
858 Error_Msg_SC -- CODEFIX
859 ("`END IF;` expected@ for IF#!");
861 elsif End_Type = E_Loop then
862 if Error_Msg_Node_1 = Empty then
863 Error_Msg_SC -- CODEFIX
864 ("`END LOOP;` expected@ for LOOP#!");
866 Error_Msg_SC -- CODEFIX
867 ("`END LOOP &;` expected@!");
870 elsif End_Type = E_Record then
871 Error_Msg_SC -- CODEFIX
872 ("`END RECORD;` expected@ for RECORD#!");
874 elsif End_Type = E_Return then
875 Error_Msg_SC -- CODEFIX
876 ("`END RETURN;` expected@ for RETURN#!");
878 elsif End_Type = E_Select then
879 Error_Msg_SC -- CODEFIX
880 ("`END SELECT;` expected@ for SELECT#!");
882 -- All remaining cases are cases with a name (we do not treat
883 -- the suspicious is cases specially for a replaced end, only
884 -- for an inserted end).
886 elsif End_Type = E_Name or else (not Ins) then
887 if Error_Msg_Node_1 = Empty then
888 Error_Msg_SC -- CODEFIX
889 ("`END;` expected@ for BEGIN#!");
891 Error_Msg_SC -- CODEFIX
892 ("`END &;` expected@!");
895 -- The other possibility is a missing END for a subprogram with a
896 -- suspicious IS (that probably should have been a semicolon). The
897 -- Missing IS confirms the suspicion!
899 else -- End_Type = E_Suspicious_Is or E_Bad_Is
900 Scope.Table (Scope.Last).Etyp := E_Bad_Is;
902 end Output_End_Expected;
904 ------------------------
905 -- Output End Missing --
906 ------------------------
908 procedure Output_End_Missing is
909 End_Type : SS_End_Type;
912 -- Suppress message if this was a potentially junk entry (e.g. a
913 -- record entry where no record keyword was present.
915 if Scope.Table (Scope.Last).Junk then
919 End_Type := Scope.Table (Scope.Last).Etyp;
920 Error_Msg_Sloc := Scope.Table (Scope.Last).Sloc;
922 if Explicit_Start_Label (Scope.Last) then
923 Error_Msg_Node_1 := Scope.Table (Scope.Last).Labl;
925 Error_Msg_Node_1 := Empty;
928 if End_Type = E_Case then
929 Error_Msg_BC ("missing `END CASE;` for CASE#!");
931 elsif End_Type = E_If then
932 Error_Msg_BC ("missing `END IF;` for IF#!");
934 elsif End_Type = E_Loop then
935 if Error_Msg_Node_1 = Empty then
936 Error_Msg_BC ("missing `END LOOP;` for LOOP#!");
938 Error_Msg_BC ("missing `END LOOP &;`!");
941 elsif End_Type = E_Record then
943 ("missing `END RECORD;` for RECORD#!");
945 elsif End_Type = E_Return then
947 ("missing `END RETURN;` for RETURN#!");
949 elsif End_Type = E_Select then
951 ("missing `END SELECT;` for SELECT#!");
953 elsif End_Type = E_Name then
954 if Error_Msg_Node_1 = Empty then
955 Error_Msg_BC ("missing `END;` for BEGIN#!");
957 Error_Msg_BC ("missing `END &;`!");
960 else -- End_Type = E_Suspicious_Is or E_Bad_Is
961 Scope.Table (Scope.Last).Etyp := E_Bad_Is;
963 end Output_End_Missing;
965 ---------------------
966 -- Pop End Context --
967 ---------------------
969 procedure Pop_End_Context is
971 Pretty_Good : Boolean;
972 -- This flag is set True if the END sequence is syntactically incorrect,
973 -- but is (from a heuristic point of view), pretty likely to be simply
974 -- a misspelling of the intended END.
976 Outer_Match : Boolean;
977 -- This flag is set True if we decide that the current END sequence
978 -- belongs to some outer level entry in the scope stack, and thus
979 -- we will NOT eat it up in matching the current expected END.
982 -- If not at END, then output END expected message
984 if End_Type = E_Dummy then
987 End_Action := Insert_And_Accept;
990 -- Otherwise we do have an END present
993 -- A special check. If we have END; followed by an end of file,
994 -- WITH or SEPARATE, then if we are not at the outer level, then
995 -- we have a syntax error. Consider the example:
1007 -- Now the END; here is a syntactically correct closer for the
1008 -- declare block, but if we eat it up, then we obviously have
1009 -- a missing END for the outer context (since WITH can only appear
1010 -- at the outer level.
1012 -- In this situation, we always reserve the END; for the outer level,
1013 -- even if it is in the wrong column. This is because it's much more
1014 -- useful to have the error message point to the DECLARE than to the
1015 -- package header in this case.
1017 -- We also reserve an end with a name before the end of file if the
1018 -- name is the one we expect at the outer level.
1020 if (Token = Tok_EOF or else
1021 Token = Tok_With or else
1022 Token = Tok_Separate)
1023 and then End_Type >= E_Name
1024 and then (not End_Labl_Present
1025 or else Same_Label (End_Labl, Scope.Table (1).Labl))
1026 and then Scope.Last > 1
1028 Restore_Scan_State (Scan_State); -- to END
1029 Output_End_Expected (Ins => True);
1031 End_Action := Insert_And_Accept;
1035 -- Otherwise we go through the normal END evaluation procedure
1037 Evaluate_End_Entry (Scope.Last);
1039 -- If top entry in stack is syntactically correct, then we have
1040 -- scanned it out and everything is fine. This is the required
1041 -- action to properly process correct Ada programs.
1045 -- Complain if checking columns and END is not in right column.
1046 -- Right in this context means exactly right, or on the same
1047 -- line as the opener.
1049 if RM_Column_Check then
1050 if End_Column /= Scope.Table (Scope.Last).Ecol
1051 and then Current_Line_Start > Scope.Table (Scope.Last).Sloc
1053 -- A special case, for END RECORD, we are also allowed to
1054 -- line up with the TYPE keyword opening the declaration.
1056 and then (Scope.Table (Scope.Last).Etyp /= E_Record
1057 or else Get_Column_Number (End_Sloc) /=
1058 Get_Column_Number (Type_Token_Location))
1060 Error_Msg_Col := Scope.Table (Scope.Last).Ecol;
1062 ("(style) END in wrong column, should be@", End_Sloc);
1066 -- One final check. If the end had a label, check for an exact
1067 -- duplicate of this end sequence, and if so, skip it with an
1068 -- appropriate message.
1070 if End_Labl_Present and then Token = Tok_End then
1072 Scan_State : Saved_Scan_State;
1073 End_Loc : constant Source_Ptr := Token_Ptr;
1075 Dup_Found : Boolean := False;
1078 Save_Scan_State (Scan_State);
1082 if Token = Tok_Identifier
1083 or else Token = Tok_Operator_Symbol
1085 Nxt_Labl := P_Designator;
1087 -- We only consider it an error if the label is a match
1088 -- and would be wrong for the level one above us, and
1089 -- the indentation is the same.
1091 if Token = Tok_Semicolon
1092 and then Same_Label (End_Labl, Nxt_Labl)
1093 and then End_Column = Start_Column
1097 (not Explicit_Start_Label (Scope.Last - 1))
1101 Scope.Table (Scope.Last - 1).Labl)))
1104 Error_Msg ("duplicate end line ignored", End_Loc);
1109 if not Dup_Found then
1110 Restore_Scan_State (Scan_State);
1115 -- All OK, so return to caller indicating END is OK
1118 End_Action := Accept_As_Scanned;
1122 -- If that check failed, then we definitely have an error. The issue
1123 -- is how to choose among three possible courses of action:
1125 -- 1. Ignore the current END text completely, scanning past it,
1126 -- deciding that it belongs neither to the current context,
1127 -- nor to any outer context.
1129 -- 2. Accept the current END text, scanning past it, and issuing
1130 -- an error message that it does not have the right form.
1132 -- 3. Leave the current END text in place, NOT scanning past it,
1133 -- issuing an error message indicating the END expected for the
1134 -- current context. In this case, the END is available to match
1135 -- some outer END context.
1137 -- From a correct functioning point of view, it does not make any
1138 -- difference which of these three approaches we take, the program
1139 -- will work correctly in any case. However, making an accurate
1140 -- choice among these alternatives, i.e. choosing the one that
1141 -- corresponds to what the programmer had in mind, does make a
1142 -- significant difference in the quality of error recovery.
1144 Restore_Scan_State (Scan_State); -- to END
1146 -- First we see how good the current END entry is with respect to
1147 -- what we expect. It is considered pretty good if the token is OK,
1148 -- and either the label or the column matches. An END for RECORD is
1149 -- always considered to be pretty good in the record case. This is
1150 -- because not only does a record disallow a nested structure, but
1151 -- also it is unlikely that such nesting could occur by accident.
1153 Pretty_Good := (Token_OK and (Column_OK or Label_OK))
1154 or else Scope.Table (Scope.Last).Etyp = E_Record;
1156 -- Next check, if there is a deeper entry in the stack which
1157 -- has a very high probability of being acceptable, then insert
1158 -- the END entry we want, leaving the higher level entry for later
1160 for J in reverse 1 .. Scope.Last - 1 loop
1161 Evaluate_End_Entry (J);
1163 -- To even consider the deeper entry to be immediately acceptable,
1164 -- it must be syntactically correct. Furthermore it must either
1165 -- have a correct label, or the correct column. If the current
1166 -- entry was a close match (Pretty_Good set), then we are even
1167 -- more strict in accepting the outer level one: even if it has
1168 -- the right label, it must have the right column as well.
1172 Outer_Match := Label_OK and Column_OK;
1174 Outer_Match := Label_OK or Column_OK;
1177 Outer_Match := False;
1180 -- If the outer entry does convincingly match the END text, then
1181 -- back up the scan to the start of the END sequence, issue an
1182 -- error message indicating the END we expected, and return with
1183 -- Token pointing to the END (case 3 from above discussion).
1188 End_Action := Insert_And_Accept;
1193 -- Here we have a situation in which the current END entry is
1194 -- syntactically incorrect, but there is no deeper entry in the
1195 -- END stack which convincingly matches it.
1197 -- If the END text was judged to be a Pretty_Good match for the
1198 -- expected token or if it appears left of the expected column,
1199 -- then we will accept it as the one we want, scanning past it, even
1200 -- though it is not completely right (we issue a message showing what
1201 -- we expected it to be). This is action 2 from the discussion above.
1202 -- There is one other special case to consider: the LOOP case.
1203 -- Consider the example:
1209 -- Here the column lines up with Lbl, so END LOOP is to the right,
1210 -- but it is still acceptable. LOOP is the one case where alignment
1211 -- practices vary substantially in practice.
1214 or else End_Column <= Scope.Table (Scope.Last).Ecol
1215 or else (End_Type = Scope.Table (Scope.Last).Etyp
1216 and then End_Type = E_Loop)
1218 Output_End_Expected (Ins => False);
1220 End_Action := Skip_And_Accept;
1223 -- Here we have the case where the END is to the right of the
1224 -- expected column and does not have a correct label to convince
1225 -- us that it nevertheless belongs to the current scope. For this
1226 -- we consider that it probably belongs not to the current context,
1227 -- but to some inner context that was not properly recognized (due to
1228 -- other syntax errors), and for which no proper scope stack entry
1229 -- was made. The proper action in this case is to delete the END text
1230 -- and return False to the caller as a signal to keep on looking for
1231 -- an acceptable END. This is action 1 from the discussion above.
1235 End_Action := Skip_And_Reject;
1239 end Pop_End_Context;
1245 function Same_Label (Label1, Label2 : Node_Id) return Boolean is
1247 if Nkind (Label1) in N_Has_Chars
1248 and then Nkind (Label2) in N_Has_Chars
1250 return Chars (Label1) = Chars (Label2);
1252 elsif Nkind (Label1) = N_Selected_Component
1253 and then Nkind (Label2) = N_Selected_Component
1255 return Same_Label (Prefix (Label1), Prefix (Label2)) and then
1256 Same_Label (Selector_Name (Label1), Selector_Name (Label2));
1258 elsif Nkind (Label1) = N_Designator
1259 and then Nkind (Label2) = N_Defining_Program_Unit_Name
1261 return Same_Label (Name (Label1), Name (Label2)) and then
1262 Same_Label (Identifier (Label1), Defining_Identifier (Label2));