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 -- Deal with terminating aspect specifications and following semi-
391 -- colon. We skip this in the case of END RECORD, since in this
392 -- case the aspect specifications and semicolon are handled at
395 if End_Type /= E_Record then
397 -- Scan aspect specifications if permitted here
399 if Aspect_Specifications_Present then
401 P_Aspect_Specifications (Error);
403 P_Aspect_Specifications (Decl);
406 -- If no aspect specifications, must have a semicolon
408 elsif End_Type /= E_Record then
409 if Token = Tok_Semicolon then
412 -- Semicolon is missing. If the missing semicolon is at the end
413 -- of the line, i.e. we are at the start of the line now, then
414 -- a missing semicolon gets flagged, but is not serious enough
415 -- to consider the END statement to be bad in the sense that we
416 -- are dealing with (i.e. to be suspicious that this END is not
417 -- the END statement we are looking for).
419 -- Similarly, if we are at a colon, we flag it but a colon for
420 -- a semicolon is not serious enough to consider the END to be
421 -- incorrect. Same thing for a period in place of a semicolon.
423 elsif Token_Is_At_Start_Of_Line
424 or else Token = Tok_Colon
425 or else Token = Tok_Dot
429 -- If the missing semicolon is not at the start of the line,
430 -- then we consider the END line to be dubious in this sense.
439 -- Now we call the Pop_End_Context routine to get a recommendation
440 -- as to what should be done with the END sequence we have scanned.
444 -- Remaining action depends on End_Action set by Pop_End_Context
448 -- Accept_As_Scanned. In this case, Pop_End_Context left Token
449 -- pointing past the last token of a syntactically correct END
451 when Accept_As_Scanned =>
453 -- Syntactically correct included the possibility of a missing
454 -- semicolon. If we do have a missing semicolon, then we have
455 -- already given a message, but now we scan out possible rubbish
456 -- on the same line as the END
458 while not Token_Is_At_Start_Of_Line
459 and then Prev_Token /= Tok_Record
460 and then Prev_Token /= Tok_Semicolon
461 and then Token /= Tok_End
462 and then Token /= Tok_EOF
469 -- Insert_And_Accept. In this case, Pop_End_Context has reset Token
470 -- to point to the start of the END sequence, and recommends that it
471 -- be left in place to satisfy an outer scope level END. This means
472 -- that we proceed as though an END were present, and leave the scan
473 -- pointer unchanged.
475 when Insert_And_Accept =>
478 -- Skip_And_Accept. In this case, Pop_End_Context has reset Token
479 -- to point to the start of the END sequence. This END sequence is
480 -- syntactically incorrect, and an appropriate error message has
481 -- already been posted. Pop_End_Context recommends accepting the
482 -- END sequence as the one we want, so we skip past it and then
483 -- proceed as though an END were present.
485 when Skip_And_Accept =>
489 -- Skip_And_Reject. In this case, Pop_End_Context has reset Token
490 -- to point to the start of the END sequence. This END sequence is
491 -- syntactically incorrect, and an appropriate error message has
492 -- already been posted. Pop_End_Context recommends entirely ignoring
493 -- this END sequence, so we skip past it and then return False, since
494 -- as far as the caller is concerned, no END sequence is present.
496 when Skip_And_Reject =>
506 -- This procedure skips past an END sequence. On entry Token contains
507 -- Tok_End, and we know that the END sequence is syntactically incorrect,
508 -- and that an appropriate error message has already been posted. The
509 -- mission is simply to position the scan pointer to be the best guess of
510 -- the position after the END sequence. We do not issue any additional
511 -- error messages while carrying this out.
513 -- Error recovery: does not raise Error_Resync
515 procedure End_Skip is
519 -- If the scan past the END leaves us on the next line, that's probably
520 -- where we should quit the scan, since it is likely that what we have
521 -- is a missing semicolon. Consider the following:
526 -- This will have looked like a syntactically valid END sequence to the
527 -- initial scan of the END, but subsequent checking will have determined
528 -- that the label Process_Input is not an appropriate label. The real
529 -- error is a missing semicolon after the END, and by leaving the scan
530 -- pointer just past the END, we will improve the error recovery.
532 if Token_Is_At_Start_Of_Line then
536 -- If there is a semicolon after the END, scan it out and we are done
538 if Token = Tok_Semicolon then
543 -- Otherwise skip past a token after the END on the same line. Note
544 -- that we do not eat a token on the following line since it seems
545 -- very unlikely in any case that the END gets separated from its
546 -- token, and we do not want to swallow up a keyword that starts a
547 -- legitimate construct following the bad END.
549 if not Token_Is_At_Start_Of_Line
552 -- Cases of normal tokens following an END
554 (Token = Tok_Case or else
555 Token = Tok_For or else
556 Token = Tok_If or else
557 Token = Tok_Loop or else
558 Token = Tok_Record or else
559 Token = Tok_Select or else
561 -- Cases of bogus keywords ending loops
563 Token = Tok_For or else
564 Token = Tok_While or else
566 -- Cases of operator symbol names without quotes
568 Token = Tok_Abs or else
569 Token = Tok_And or else
570 Token = Tok_Mod or else
571 Token = Tok_Not or else
572 Token = Tok_Or or else
576 Scan; -- past token after END
578 -- If that leaves us on the next line, then we are done. This is the
579 -- same principle described above for the case of END at line end
581 if Token_Is_At_Start_Of_Line then
584 -- If we just scanned out record, then we are done, since the
585 -- semicolon after END RECORD is not part of the END sequence
587 elsif Prev_Token = Tok_Record then
590 -- If we have a semicolon, scan it out and we are done
592 elsif Token = Tok_Semicolon then
598 -- Check for a label present on the same line
601 if Token_Is_At_Start_Of_Line then
605 if Token /= Tok_Identifier
606 and then Token /= Tok_Operator_Symbol
607 and then Token /= Tok_String_Literal
612 Scan; -- past identifier, operator symbol or string literal
614 if Token_Is_At_Start_Of_Line then
616 elsif Token = Tok_Dot then
621 -- Skip final semicolon
623 if Token = Tok_Semicolon then
626 -- If we don't have a final semicolon, skip until we either encounter
627 -- an END token, or a semicolon or the start of the next line. This
628 -- allows general junk to follow the end line (normally it is hard to
629 -- think that anyone will put anything deliberate here, and remember
630 -- that we know there is a missing semicolon in any case). We also
631 -- quite on an EOF (or else we would get stuck in an infinite loop
632 -- if there is no line end at the end of the last line of the file)
635 while Token /= Tok_End
636 and then Token /= Tok_EOF
637 and then Token /= Tok_Semicolon
638 and then not Token_Is_At_Start_Of_Line
640 Scan; -- past junk token on same line
651 -- This procedure is called when END is required or expected to terminate
652 -- a sequence of statements. The caller has already made an appropriate
653 -- entry on the scope stack to describe the expected form of the END.
654 -- End_Statements should only be used in cases where the only appropriate
655 -- terminator is END.
657 -- Error recovery: cannot raise Error_Resync;
659 procedure End_Statements
660 (Parent : Node_Id := Empty;
661 Decl : Node_Id := Empty) is
663 -- This loop runs more than once in the case where Check_End rejects
664 -- the END sequence, as indicated by Check_End returning False.
667 if Check_End (Decl) then
668 if Present (Parent) then
669 Set_End_Label (Parent, End_Labl);
675 -- Extra statements past the bogus END are discarded. This is not
676 -- ideal for maximum error recovery, but it's too much trouble to
677 -- find an appropriate place to put them!
679 Discard_Junk_List (P_Sequence_Of_Statements (SS_None));
683 ------------------------
684 -- Evaluate End Entry --
685 ------------------------
687 procedure Evaluate_End_Entry (SS_Index : Nat) is
689 Column_OK := (End_Column = Scope.Table (SS_Index).Ecol);
691 Token_OK := (End_Type = Scope.Table (SS_Index).Etyp or else
692 (End_Type = E_Name and then
693 Scope.Table (SS_Index).Etyp >= E_Name));
695 Label_OK := End_Labl_Present
697 (Same_Label (End_Labl, Scope.Table (SS_Index).Labl)
698 or else Scope.Table (SS_Index).Labl = Error);
700 -- Compute setting of Syntax_OK. We definitely have a syntax error
701 -- if the Token does not match properly or if P_End_Scan detected
702 -- a syntax error such as a missing semicolon.
704 if not Token_OK or not End_OK then
707 -- Final check is that label is OK. Certainly it is OK if there
708 -- was an exact match on the label (the END label = the stack label)
713 -- Case of label present
715 elsif End_Labl_Present then
717 -- If probably misspelling, then complain, and pretend it is OK
720 Nam : constant Node_Or_Entity_Id := Scope.Table (SS_Index).Labl;
723 if Nkind (End_Labl) in N_Has_Chars
724 and then Comes_From_Source (Nam)
725 and then Nkind (Nam) in N_Has_Chars
726 and then Chars (End_Labl) > Error_Name
727 and then Chars (Nam) > Error_Name
729 Error_Msg_Name_1 := Chars (Nam);
731 if Error_Msg_Name_1 > Error_Name then
732 if Is_Bad_Spelling_Of (Chars (Nam), Chars (End_Labl)) then
733 Error_Msg_Name_1 := Chars (Nam);
734 Error_Msg_N -- CODEFIX
735 ("misspelling of %", End_Labl);
745 -- Otherwise we have cases of no label on the END line. For the loop
746 -- case, this is acceptable only if the loop is unlabeled.
748 elsif End_Type = E_Loop then
749 Syntax_OK := not Explicit_Start_Label (SS_Index);
751 -- Cases where a label is definitely allowed on the END line
753 elsif End_Type = E_Name then
754 Syntax_OK := (not Explicit_Start_Label (SS_Index))
756 (not Scope.Table (SS_Index).Lreq);
758 -- Otherwise we have cases which don't allow labels anyway, so we
759 -- certainly accept an END which does not have a label.
764 end Evaluate_End_Entry;
766 --------------------------
767 -- Explicit_Start_Label --
768 --------------------------
770 function Explicit_Start_Label (SS_Index : Nat) return Boolean is
771 L : constant Node_Id := Scope.Table (SS_Index).Labl;
772 Etyp : constant SS_End_Type := Scope.Table (SS_Index).Etyp;
778 -- In the following test we protect the call to Comes_From_Source
779 -- against lines containing previously reported syntax errors.
782 or else Etyp = E_Name
783 or else Etyp = E_Suspicious_Is
784 or else Etyp = E_Bad_Is)
785 and then Comes_From_Source (L)
791 end Explicit_Start_Label;
793 ------------------------
794 -- Output End Deleted --
795 ------------------------
797 procedure Output_End_Deleted is
800 if End_Type = E_Loop then
801 Error_Msg_SC ("no LOOP for this `END LOOP`!");
803 elsif End_Type = E_Case then
804 Error_Msg_SC ("no CASE for this `END CASE`");
806 elsif End_Type = E_If then
807 Error_Msg_SC ("no IF for this `END IF`!");
809 elsif End_Type = E_Record then
810 Error_Msg_SC ("no RECORD for this `END RECORD`!");
812 elsif End_Type = E_Return then
813 Error_Msg_SC ("no RETURN for this `END RETURN`!");
815 elsif End_Type = E_Select then
816 Error_Msg_SC ("no SELECT for this `END SELECT`!");
819 Error_Msg_SC ("no BEGIN for this END!");
821 end Output_End_Deleted;
823 -------------------------
824 -- Output End Expected --
825 -------------------------
827 procedure Output_End_Expected (Ins : Boolean) is
828 End_Type : SS_End_Type;
831 -- Suppress message if this was a potentially junk entry (e.g. a
832 -- record entry where no record keyword was present.
834 if Scope.Table (Scope.Last).Junk then
838 End_Type := Scope.Table (Scope.Last).Etyp;
839 Error_Msg_Col := Scope.Table (Scope.Last).Ecol;
840 Error_Msg_Sloc := Scope.Table (Scope.Last).Sloc;
842 if Explicit_Start_Label (Scope.Last) then
843 Error_Msg_Node_1 := Scope.Table (Scope.Last).Labl;
845 Error_Msg_Node_1 := Empty;
848 -- Suppress message if error was posted on opening label
850 if Error_Msg_Node_1 > Empty_Or_Error
851 and then Error_Posted (Error_Msg_Node_1)
856 if End_Type = E_Case then
857 Error_Msg_SC -- CODEFIX
858 ("`END CASE;` expected@ for CASE#!");
860 elsif End_Type = E_If then
861 Error_Msg_SC -- CODEFIX
862 ("`END IF;` expected@ for IF#!");
864 elsif End_Type = E_Loop then
865 if Error_Msg_Node_1 = Empty then
866 Error_Msg_SC -- CODEFIX
867 ("`END LOOP;` expected@ for LOOP#!");
869 Error_Msg_SC -- CODEFIX
870 ("`END LOOP &;` expected@!");
873 elsif End_Type = E_Record then
874 Error_Msg_SC -- CODEFIX
875 ("`END RECORD;` expected@ for RECORD#!");
877 elsif End_Type = E_Return then
878 Error_Msg_SC -- CODEFIX
879 ("`END RETURN;` expected@ for RETURN#!");
881 elsif End_Type = E_Select then
882 Error_Msg_SC -- CODEFIX
883 ("`END SELECT;` expected@ for SELECT#!");
885 -- All remaining cases are cases with a name (we do not treat
886 -- the suspicious is cases specially for a replaced end, only
887 -- for an inserted end).
889 elsif End_Type = E_Name or else (not Ins) then
890 if Error_Msg_Node_1 = Empty then
891 Error_Msg_SC -- CODEFIX
892 ("`END;` expected@ for BEGIN#!");
894 Error_Msg_SC -- CODEFIX
895 ("`END &;` expected@!");
898 -- The other possibility is a missing END for a subprogram with a
899 -- suspicious IS (that probably should have been a semicolon). The
900 -- Missing IS confirms the suspicion!
902 else -- End_Type = E_Suspicious_Is or E_Bad_Is
903 Scope.Table (Scope.Last).Etyp := E_Bad_Is;
905 end Output_End_Expected;
907 ------------------------
908 -- Output End Missing --
909 ------------------------
911 procedure Output_End_Missing is
912 End_Type : SS_End_Type;
915 -- Suppress message if this was a potentially junk entry (e.g. a
916 -- record entry where no record keyword was present.
918 if Scope.Table (Scope.Last).Junk then
922 End_Type := Scope.Table (Scope.Last).Etyp;
923 Error_Msg_Sloc := Scope.Table (Scope.Last).Sloc;
925 if Explicit_Start_Label (Scope.Last) then
926 Error_Msg_Node_1 := Scope.Table (Scope.Last).Labl;
928 Error_Msg_Node_1 := Empty;
931 if End_Type = E_Case then
932 Error_Msg_BC ("missing `END CASE;` for CASE#!");
934 elsif End_Type = E_If then
935 Error_Msg_BC ("missing `END IF;` for IF#!");
937 elsif End_Type = E_Loop then
938 if Error_Msg_Node_1 = Empty then
939 Error_Msg_BC ("missing `END LOOP;` for LOOP#!");
941 Error_Msg_BC ("missing `END LOOP &;`!");
944 elsif End_Type = E_Record then
946 ("missing `END RECORD;` for RECORD#!");
948 elsif End_Type = E_Return then
950 ("missing `END RETURN;` for RETURN#!");
952 elsif End_Type = E_Select then
954 ("missing `END SELECT;` for SELECT#!");
956 elsif End_Type = E_Name then
957 if Error_Msg_Node_1 = Empty then
958 Error_Msg_BC ("missing `END;` for BEGIN#!");
960 Error_Msg_BC ("missing `END &;`!");
963 else -- End_Type = E_Suspicious_Is or E_Bad_Is
964 Scope.Table (Scope.Last).Etyp := E_Bad_Is;
966 end Output_End_Missing;
968 ---------------------
969 -- Pop End Context --
970 ---------------------
972 procedure Pop_End_Context is
974 Pretty_Good : Boolean;
975 -- This flag is set True if the END sequence is syntactically incorrect,
976 -- but is (from a heuristic point of view), pretty likely to be simply
977 -- a misspelling of the intended END.
979 Outer_Match : Boolean;
980 -- This flag is set True if we decide that the current END sequence
981 -- belongs to some outer level entry in the scope stack, and thus
982 -- we will NOT eat it up in matching the current expected END.
985 -- If not at END, then output END expected message
987 if End_Type = E_Dummy then
990 End_Action := Insert_And_Accept;
993 -- Otherwise we do have an END present
996 -- A special check. If we have END; followed by an end of file,
997 -- WITH or SEPARATE, then if we are not at the outer level, then
998 -- we have a syntax error. Consider the example:
1010 -- Now the END; here is a syntactically correct closer for the
1011 -- declare block, but if we eat it up, then we obviously have
1012 -- a missing END for the outer context (since WITH can only appear
1013 -- at the outer level.
1015 -- In this situation, we always reserve the END; for the outer level,
1016 -- even if it is in the wrong column. This is because it's much more
1017 -- useful to have the error message point to the DECLARE than to the
1018 -- package header in this case.
1020 -- We also reserve an end with a name before the end of file if the
1021 -- name is the one we expect at the outer level.
1023 if (Token = Tok_EOF or else
1024 Token = Tok_With or else
1025 Token = Tok_Separate)
1026 and then End_Type >= E_Name
1027 and then (not End_Labl_Present
1028 or else Same_Label (End_Labl, Scope.Table (1).Labl))
1029 and then Scope.Last > 1
1031 Restore_Scan_State (Scan_State); -- to END
1032 Output_End_Expected (Ins => True);
1034 End_Action := Insert_And_Accept;
1038 -- Otherwise we go through the normal END evaluation procedure
1040 Evaluate_End_Entry (Scope.Last);
1042 -- If top entry in stack is syntactically correct, then we have
1043 -- scanned it out and everything is fine. This is the required
1044 -- action to properly process correct Ada programs.
1048 -- Complain if checking columns and END is not in right column.
1049 -- Right in this context means exactly right, or on the same
1050 -- line as the opener.
1052 if RM_Column_Check then
1053 if End_Column /= Scope.Table (Scope.Last).Ecol
1054 and then Current_Line_Start > Scope.Table (Scope.Last).Sloc
1056 -- A special case, for END RECORD, we are also allowed to
1057 -- line up with the TYPE keyword opening the declaration.
1059 and then (Scope.Table (Scope.Last).Etyp /= E_Record
1060 or else Get_Column_Number (End_Sloc) /=
1061 Get_Column_Number (Type_Token_Location))
1063 Error_Msg_Col := Scope.Table (Scope.Last).Ecol;
1065 ("(style) END in wrong column, should be@", End_Sloc);
1069 -- One final check. If the end had a label, check for an exact
1070 -- duplicate of this end sequence, and if so, skip it with an
1071 -- appropriate message.
1073 if End_Labl_Present and then Token = Tok_End then
1075 Scan_State : Saved_Scan_State;
1076 End_Loc : constant Source_Ptr := Token_Ptr;
1078 Dup_Found : Boolean := False;
1081 Save_Scan_State (Scan_State);
1085 if Token = Tok_Identifier
1086 or else Token = Tok_Operator_Symbol
1088 Nxt_Labl := P_Designator;
1090 -- We only consider it an error if the label is a match
1091 -- and would be wrong for the level one above us, and
1092 -- the indentation is the same.
1094 if Token = Tok_Semicolon
1095 and then Same_Label (End_Labl, Nxt_Labl)
1096 and then End_Column = Start_Column
1100 (not Explicit_Start_Label (Scope.Last - 1))
1104 Scope.Table (Scope.Last - 1).Labl)))
1107 Error_Msg ("duplicate end line ignored", End_Loc);
1112 if not Dup_Found then
1113 Restore_Scan_State (Scan_State);
1118 -- All OK, so return to caller indicating END is OK
1121 End_Action := Accept_As_Scanned;
1125 -- If that check failed, then we definitely have an error. The issue
1126 -- is how to choose among three possible courses of action:
1128 -- 1. Ignore the current END text completely, scanning past it,
1129 -- deciding that it belongs neither to the current context,
1130 -- nor to any outer context.
1132 -- 2. Accept the current END text, scanning past it, and issuing
1133 -- an error message that it does not have the right form.
1135 -- 3. Leave the current END text in place, NOT scanning past it,
1136 -- issuing an error message indicating the END expected for the
1137 -- current context. In this case, the END is available to match
1138 -- some outer END context.
1140 -- From a correct functioning point of view, it does not make any
1141 -- difference which of these three approaches we take, the program
1142 -- will work correctly in any case. However, making an accurate
1143 -- choice among these alternatives, i.e. choosing the one that
1144 -- corresponds to what the programmer had in mind, does make a
1145 -- significant difference in the quality of error recovery.
1147 Restore_Scan_State (Scan_State); -- to END
1149 -- First we see how good the current END entry is with respect to
1150 -- what we expect. It is considered pretty good if the token is OK,
1151 -- and either the label or the column matches. An END for RECORD is
1152 -- always considered to be pretty good in the record case. This is
1153 -- because not only does a record disallow a nested structure, but
1154 -- also it is unlikely that such nesting could occur by accident.
1156 Pretty_Good := (Token_OK and (Column_OK or Label_OK))
1157 or else Scope.Table (Scope.Last).Etyp = E_Record;
1159 -- Next check, if there is a deeper entry in the stack which
1160 -- has a very high probability of being acceptable, then insert
1161 -- the END entry we want, leaving the higher level entry for later
1163 for J in reverse 1 .. Scope.Last - 1 loop
1164 Evaluate_End_Entry (J);
1166 -- To even consider the deeper entry to be immediately acceptable,
1167 -- it must be syntactically correct. Furthermore it must either
1168 -- have a correct label, or the correct column. If the current
1169 -- entry was a close match (Pretty_Good set), then we are even
1170 -- more strict in accepting the outer level one: even if it has
1171 -- the right label, it must have the right column as well.
1175 Outer_Match := Label_OK and Column_OK;
1177 Outer_Match := Label_OK or Column_OK;
1180 Outer_Match := False;
1183 -- If the outer entry does convincingly match the END text, then
1184 -- back up the scan to the start of the END sequence, issue an
1185 -- error message indicating the END we expected, and return with
1186 -- Token pointing to the END (case 3 from above discussion).
1191 End_Action := Insert_And_Accept;
1196 -- Here we have a situation in which the current END entry is
1197 -- syntactically incorrect, but there is no deeper entry in the
1198 -- END stack which convincingly matches it.
1200 -- If the END text was judged to be a Pretty_Good match for the
1201 -- expected token or if it appears left of the expected column,
1202 -- then we will accept it as the one we want, scanning past it, even
1203 -- though it is not completely right (we issue a message showing what
1204 -- we expected it to be). This is action 2 from the discussion above.
1205 -- There is one other special case to consider: the LOOP case.
1206 -- Consider the example:
1212 -- Here the column lines up with Lbl, so END LOOP is to the right,
1213 -- but it is still acceptable. LOOP is the one case where alignment
1214 -- practices vary substantially in practice.
1217 or else End_Column <= Scope.Table (Scope.Last).Ecol
1218 or else (End_Type = Scope.Table (Scope.Last).Etyp
1219 and then End_Type = E_Loop)
1221 Output_End_Expected (Ins => False);
1223 End_Action := Skip_And_Accept;
1226 -- Here we have the case where the END is to the right of the
1227 -- expected column and does not have a correct label to convince
1228 -- us that it nevertheless belongs to the current scope. For this
1229 -- we consider that it probably belongs not to the current context,
1230 -- but to some inner context that was not properly recognized (due to
1231 -- other syntax errors), and for which no proper scope stack entry
1232 -- was made. The proper action in this case is to delete the END text
1233 -- and return False to the caller as a signal to keep on looking for
1234 -- an acceptable END. This is action 1 from the discussion above.
1238 End_Action := Skip_And_Reject;
1242 end Pop_End_Context;
1248 function Same_Label (Label1, Label2 : Node_Id) return Boolean is
1250 if Nkind (Label1) in N_Has_Chars
1251 and then Nkind (Label2) in N_Has_Chars
1253 return Chars (Label1) = Chars (Label2);
1255 elsif Nkind (Label1) = N_Selected_Component
1256 and then Nkind (Label2) = N_Selected_Component
1258 return Same_Label (Prefix (Label1), Prefix (Label2)) and then
1259 Same_Label (Selector_Name (Label1), Selector_Name (Label2));
1261 elsif Nkind (Label1) = N_Designator
1262 and then Nkind (Label2) = N_Defining_Program_Unit_Name
1264 return Same_Label (Name (Label1), Name (Label2)) and then
1265 Same_Label (Identifier (Label1), Defining_Identifier (Label2));