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.
170 (Decl : Node_Id := Empty;
171 Is_Loc : Source_Ptr := No_Location) return Boolean
173 Name_On_Separate_Line : Boolean;
174 -- Set True if the name on an END line is on a separate source line
175 -- from the END. This is highly suspicious, but is allowed. The point
176 -- is that we want to make sure that we don't just have a missing
177 -- semicolon misleading us into swallowing an identifier from the
180 Name_Scan_State : Saved_Scan_State;
181 -- Save state at start of name if Name_On_Separate_Line is TRUE
183 Span_Node : constant Node_Id := Scope.Table (Scope.Last).Node;
186 End_Labl_Present := False;
189 -- Our first task is to scan out the END sequence if one is present.
190 -- If none is present, signal by setting End_Type to E_Dummy.
192 if Token /= Tok_End then
196 Save_Scan_State (Scan_State); -- at END
197 End_Sloc := Token_Ptr;
198 End_Column := Start_Column;
202 -- Set End_Span if expected. note that this will be useless
203 -- if we do not have the right ending keyword, but in this
204 -- case we have a malformed program anyway, and the setting
205 -- of End_Span will simply be unreliable in this case anyway.
207 if Present (Span_Node) then
208 Set_End_Location (Span_Node, Token_Ptr);
211 -- Cases of keywords where no label is allowed
213 if Token = Tok_Case then
217 elsif Token = Tok_If then
221 elsif Token = Tok_Record then
222 End_Type := E_Record;
225 elsif Token = Tok_Return then
226 End_Type := E_Return;
229 elsif Token = Tok_Select then
230 End_Type := E_Select;
233 -- Cases which do allow labels
238 if Token = Tok_Loop then
242 -- FOR or WHILE allowed (signalling error) to substitute for LOOP
243 -- if on the same line as the END
245 elsif (Token = Tok_For or else Token = Tok_While)
246 and then not Token_Is_At_Start_Of_Line
248 Scan; -- past FOR or WHILE
252 -- Cases with no keyword
258 -- Now see if a name is present
260 if Token = Tok_Identifier or else
261 Token = Tok_String_Literal or else
262 Token = Tok_Operator_Symbol
264 if Token_Is_At_Start_Of_Line then
265 Name_On_Separate_Line := True;
266 Save_Scan_State (Name_Scan_State);
268 Name_On_Separate_Line := False;
271 End_Labl := P_Designator;
272 End_Labl_Present := True;
274 -- We have now scanned out a name. Here is where we do a check
275 -- to catch the cases like:
280 -- where the missing semicolon might make us swallow up the X
281 -- as a bogus end label. In a situation like this, where the
282 -- apparent name is on a separate line, we accept it only if
283 -- it matches the label and is followed by a semicolon.
285 if Name_On_Separate_Line then
286 if Token /= Tok_Semicolon or else
287 not Same_Label (End_Labl, Scope.Table (Scope.Last).Labl)
289 Restore_Scan_State (Name_Scan_State);
291 End_Labl_Present := False;
295 -- Here for case of name allowed, but no name present. We will
296 -- supply an implicit matching name, with source location set
297 -- to the scan location past the END token.
300 End_Labl := Scope.Table (Scope.Last).Labl;
302 if End_Labl > Empty_Or_Error then
304 -- The task here is to construct a designator from the
305 -- opening label, with the components all marked as not
306 -- from source, and Is_End_Label set in the identifier
307 -- or operator symbol. The location for all components
308 -- is the current token location.
310 -- Case of child unit name
312 if Nkind (End_Labl) = N_Defining_Program_Unit_Name then
314 Eref : constant Node_Id :=
315 Make_Identifier (Token_Ptr,
317 Chars (Defining_Identifier (End_Labl)));
319 function Copy_Name (N : Node_Id) return Node_Id;
320 -- Copies a selected component or identifier
326 function Copy_Name (N : Node_Id) return Node_Id is
330 if Nkind (N) = N_Selected_Component then
332 Make_Selected_Component (Token_Ptr,
334 Copy_Name (Prefix (N)),
336 Copy_Name (Selector_Name (N)));
339 R := Make_Identifier (Token_Ptr, Chars (N));
340 Set_Comes_From_Source (N, False);
345 -- Start of processing for Child_End
348 Set_Comes_From_Source (Eref, False);
351 Make_Designator (Token_Ptr,
352 Name => Copy_Name (Name (End_Labl)),
356 -- Simple identifier case
358 elsif Nkind (End_Labl) = N_Defining_Identifier
359 or else Nkind (End_Labl) = N_Identifier
361 End_Labl := Make_Identifier (Token_Ptr, Chars (End_Labl));
363 elsif Nkind (End_Labl) = N_Defining_Operator_Symbol
364 or else Nkind (End_Labl) = N_Operator_Symbol
366 Get_Decoded_Name_String (Chars (End_Labl));
369 Make_Operator_Symbol (Token_Ptr,
370 Chars => Chars (End_Labl),
371 Strval => String_From_Name_Buffer);
374 Set_Comes_From_Source (End_Labl, False);
375 End_Labl_Present := False;
377 -- Do style check for missing label
380 and then End_Type = E_Name
381 and then Explicit_Start_Label (Scope.Last)
383 Style.No_End_Name (Scope.Table (Scope.Last).Labl);
389 -- Deal with terminating aspect specifications and following semi-
390 -- colon. We skip this in the case of END RECORD, since in this
391 -- case the aspect specifications and semicolon are handled at
394 if End_Type /= E_Record then
396 -- Scan aspect specifications
398 if Aspect_Specifications_Present then
400 -- Aspect specifications not allowed
404 -- Package declaration case
406 if Is_Loc /= No_Location then
408 ("misplaced aspects for package declaration");
410 ("info: aspect specifications belong here", Is_Loc);
411 P_Aspect_Specifications (Empty);
413 -- Other cases where aspect specifications are not allowed
416 P_Aspect_Specifications (Error);
419 -- Aspect specifications allowed
422 P_Aspect_Specifications (Decl);
425 -- If no aspect specifications, must have a semicolon
427 elsif End_Type /= E_Record then
428 if Token = Tok_Semicolon then
431 -- Semicolon is missing. If the missing semicolon is at the end
432 -- of the line, i.e. we are at the start of the line now, then
433 -- a missing semicolon gets flagged, but is not serious enough
434 -- to consider the END statement to be bad in the sense that we
435 -- are dealing with (i.e. to be suspicious that this END is not
436 -- the END statement we are looking for).
438 -- Similarly, if we are at a colon, we flag it but a colon for
439 -- a semicolon is not serious enough to consider the END to be
440 -- incorrect. Same thing for a period in place of a semicolon.
442 elsif Token_Is_At_Start_Of_Line
443 or else Token = Tok_Colon
444 or else Token = Tok_Dot
448 -- If the missing semicolon is not at the start of the line,
449 -- then we consider the END line to be dubious in this sense.
458 -- Now we call the Pop_End_Context routine to get a recommendation
459 -- as to what should be done with the END sequence we have scanned.
463 -- Remaining action depends on End_Action set by Pop_End_Context
467 -- Accept_As_Scanned. In this case, Pop_End_Context left Token
468 -- pointing past the last token of a syntactically correct END
470 when Accept_As_Scanned =>
472 -- Syntactically correct included the possibility of a missing
473 -- semicolon. If we do have a missing semicolon, then we have
474 -- already given a message, but now we scan out possible rubbish
475 -- on the same line as the END
477 while not Token_Is_At_Start_Of_Line
478 and then Prev_Token /= Tok_Record
479 and then Prev_Token /= Tok_Semicolon
480 and then Token /= Tok_End
481 and then Token /= Tok_EOF
488 -- Insert_And_Accept. In this case, Pop_End_Context has reset Token
489 -- to point to the start of the END sequence, and recommends that it
490 -- be left in place to satisfy an outer scope level END. This means
491 -- that we proceed as though an END were present, and leave the scan
492 -- pointer unchanged.
494 when Insert_And_Accept =>
497 -- Skip_And_Accept. In this case, Pop_End_Context has reset Token
498 -- to point to the start of the END sequence. This END sequence is
499 -- syntactically incorrect, and an appropriate error message has
500 -- already been posted. Pop_End_Context recommends accepting the
501 -- END sequence as the one we want, so we skip past it and then
502 -- proceed as though an END were present.
504 when Skip_And_Accept =>
508 -- Skip_And_Reject. In this case, Pop_End_Context has reset Token
509 -- to point to the start of the END sequence. This END sequence is
510 -- syntactically incorrect, and an appropriate error message has
511 -- already been posted. Pop_End_Context recommends entirely ignoring
512 -- this END sequence, so we skip past it and then return False, since
513 -- as far as the caller is concerned, no END sequence is present.
515 when Skip_And_Reject =>
525 -- This procedure skips past an END sequence. On entry Token contains
526 -- Tok_End, and we know that the END sequence is syntactically incorrect,
527 -- and that an appropriate error message has already been posted. The
528 -- mission is simply to position the scan pointer to be the best guess of
529 -- the position after the END sequence. We do not issue any additional
530 -- error messages while carrying this out.
532 -- Error recovery: does not raise Error_Resync
534 procedure End_Skip is
538 -- If the scan past the END leaves us on the next line, that's probably
539 -- where we should quit the scan, since it is likely that what we have
540 -- is a missing semicolon. Consider the following:
545 -- This will have looked like a syntactically valid END sequence to the
546 -- initial scan of the END, but subsequent checking will have determined
547 -- that the label Process_Input is not an appropriate label. The real
548 -- error is a missing semicolon after the END, and by leaving the scan
549 -- pointer just past the END, we will improve the error recovery.
551 if Token_Is_At_Start_Of_Line then
555 -- If there is a semicolon after the END, scan it out and we are done
557 if Token = Tok_Semicolon then
562 -- Otherwise skip past a token after the END on the same line. Note
563 -- that we do not eat a token on the following line since it seems
564 -- very unlikely in any case that the END gets separated from its
565 -- token, and we do not want to swallow up a keyword that starts a
566 -- legitimate construct following the bad END.
568 if not Token_Is_At_Start_Of_Line
571 -- Cases of normal tokens following an END
573 (Token = Tok_Case or else
574 Token = Tok_For or else
575 Token = Tok_If or else
576 Token = Tok_Loop or else
577 Token = Tok_Record or else
578 Token = Tok_Select or else
580 -- Cases of bogus keywords ending loops
582 Token = Tok_For or else
583 Token = Tok_While or else
585 -- Cases of operator symbol names without quotes
587 Token = Tok_Abs or else
588 Token = Tok_And or else
589 Token = Tok_Mod or else
590 Token = Tok_Not or else
591 Token = Tok_Or or else
595 Scan; -- past token after END
597 -- If that leaves us on the next line, then we are done. This is the
598 -- same principle described above for the case of END at line end
600 if Token_Is_At_Start_Of_Line then
603 -- If we just scanned out record, then we are done, since the
604 -- semicolon after END RECORD is not part of the END sequence
606 elsif Prev_Token = Tok_Record then
609 -- If we have a semicolon, scan it out and we are done
611 elsif Token = Tok_Semicolon then
617 -- Check for a label present on the same line
620 if Token_Is_At_Start_Of_Line then
624 if Token /= Tok_Identifier
625 and then Token /= Tok_Operator_Symbol
626 and then Token /= Tok_String_Literal
631 Scan; -- past identifier, operator symbol or string literal
633 if Token_Is_At_Start_Of_Line then
635 elsif Token = Tok_Dot then
640 -- Skip final semicolon
642 if Token = Tok_Semicolon then
645 -- If we don't have a final semicolon, skip until we either encounter
646 -- an END token, or a semicolon or the start of the next line. This
647 -- allows general junk to follow the end line (normally it is hard to
648 -- think that anyone will put anything deliberate here, and remember
649 -- that we know there is a missing semicolon in any case). We also
650 -- quite on an EOF (or else we would get stuck in an infinite loop
651 -- if there is no line end at the end of the last line of the file)
654 while Token /= Tok_End
655 and then Token /= Tok_EOF
656 and then Token /= Tok_Semicolon
657 and then not Token_Is_At_Start_Of_Line
659 Scan; -- past junk token on same line
670 -- This procedure is called when END is required or expected to terminate
671 -- a sequence of statements. The caller has already made an appropriate
672 -- entry on the scope stack to describe the expected form of the END.
673 -- End_Statements should only be used in cases where the only appropriate
674 -- terminator is END.
676 -- Error recovery: cannot raise Error_Resync;
678 procedure End_Statements
679 (Parent : Node_Id := Empty;
680 Decl : Node_Id := Empty;
681 Is_Sloc : Source_Ptr := No_Location)
684 -- This loop runs more than once in the case where Check_End rejects
685 -- the END sequence, as indicated by Check_End returning False.
688 if Check_End (Decl, Is_Sloc) then
689 if Present (Parent) then
690 Set_End_Label (Parent, End_Labl);
696 -- Extra statements past the bogus END are discarded. This is not
697 -- ideal for maximum error recovery, but it's too much trouble to
698 -- find an appropriate place to put them!
700 Discard_Junk_List (P_Sequence_Of_Statements (SS_None));
704 ------------------------
705 -- Evaluate End Entry --
706 ------------------------
708 procedure Evaluate_End_Entry (SS_Index : Nat) is
710 Column_OK := (End_Column = Scope.Table (SS_Index).Ecol);
712 Token_OK := (End_Type = Scope.Table (SS_Index).Etyp or else
713 (End_Type = E_Name and then
714 Scope.Table (SS_Index).Etyp >= E_Name));
716 Label_OK := End_Labl_Present
718 (Same_Label (End_Labl, Scope.Table (SS_Index).Labl)
719 or else Scope.Table (SS_Index).Labl = Error);
721 -- Compute setting of Syntax_OK. We definitely have a syntax error
722 -- if the Token does not match properly or if P_End_Scan detected
723 -- a syntax error such as a missing semicolon.
725 if not Token_OK or not End_OK then
728 -- Final check is that label is OK. Certainly it is OK if there
729 -- was an exact match on the label (the END label = the stack label)
734 -- Case of label present
736 elsif End_Labl_Present then
738 -- If probably misspelling, then complain, and pretend it is OK
741 Nam : constant Node_Or_Entity_Id := Scope.Table (SS_Index).Labl;
744 if Nkind (End_Labl) in N_Has_Chars
745 and then Comes_From_Source (Nam)
746 and then Nkind (Nam) in N_Has_Chars
747 and then Chars (End_Labl) > Error_Name
748 and then Chars (Nam) > Error_Name
750 Error_Msg_Name_1 := Chars (Nam);
752 if Error_Msg_Name_1 > Error_Name then
753 if Is_Bad_Spelling_Of (Chars (Nam), Chars (End_Labl)) then
754 Error_Msg_Name_1 := Chars (Nam);
755 Error_Msg_N -- CODEFIX
756 ("misspelling of %", End_Labl);
766 -- Otherwise we have cases of no label on the END line. For the loop
767 -- case, this is acceptable only if the loop is unlabeled.
769 elsif End_Type = E_Loop then
770 Syntax_OK := not Explicit_Start_Label (SS_Index);
772 -- Cases where a label is definitely allowed on the END line
774 elsif End_Type = E_Name then
775 Syntax_OK := (not Explicit_Start_Label (SS_Index))
777 (not Scope.Table (SS_Index).Lreq);
779 -- Otherwise we have cases which don't allow labels anyway, so we
780 -- certainly accept an END which does not have a label.
785 end Evaluate_End_Entry;
787 --------------------------
788 -- Explicit_Start_Label --
789 --------------------------
791 function Explicit_Start_Label (SS_Index : Nat) return Boolean is
792 L : constant Node_Id := Scope.Table (SS_Index).Labl;
793 Etyp : constant SS_End_Type := Scope.Table (SS_Index).Etyp;
799 -- In the following test we protect the call to Comes_From_Source
800 -- against lines containing previously reported syntax errors.
803 or else Etyp = E_Name
804 or else Etyp = E_Suspicious_Is
805 or else Etyp = E_Bad_Is)
806 and then Comes_From_Source (L)
812 end Explicit_Start_Label;
814 ------------------------
815 -- Output End Deleted --
816 ------------------------
818 procedure Output_End_Deleted is
821 if End_Type = E_Loop then
822 Error_Msg_SC ("no LOOP for this `END LOOP`!");
824 elsif End_Type = E_Case then
825 Error_Msg_SC ("no CASE for this `END CASE`");
827 elsif End_Type = E_If then
828 Error_Msg_SC ("no IF for this `END IF`!");
830 elsif End_Type = E_Record then
831 Error_Msg_SC ("no RECORD for this `END RECORD`!");
833 elsif End_Type = E_Return then
834 Error_Msg_SC ("no RETURN for this `END RETURN`!");
836 elsif End_Type = E_Select then
837 Error_Msg_SC ("no SELECT for this `END SELECT`!");
840 Error_Msg_SC ("no BEGIN for this END!");
842 end Output_End_Deleted;
844 -------------------------
845 -- Output End Expected --
846 -------------------------
848 procedure Output_End_Expected (Ins : Boolean) is
849 End_Type : SS_End_Type;
852 -- Suppress message if this was a potentially junk entry (e.g. a
853 -- record entry where no record keyword was present.
855 if Scope.Table (Scope.Last).Junk then
859 End_Type := Scope.Table (Scope.Last).Etyp;
860 Error_Msg_Col := Scope.Table (Scope.Last).Ecol;
861 Error_Msg_Sloc := Scope.Table (Scope.Last).Sloc;
863 if Explicit_Start_Label (Scope.Last) then
864 Error_Msg_Node_1 := Scope.Table (Scope.Last).Labl;
866 Error_Msg_Node_1 := Empty;
869 -- Suppress message if error was posted on opening label
871 if Error_Msg_Node_1 > Empty_Or_Error
872 and then Error_Posted (Error_Msg_Node_1)
877 if End_Type = E_Case then
878 Error_Msg_SC -- CODEFIX
879 ("`END CASE;` expected@ for CASE#!");
881 elsif End_Type = E_If then
882 Error_Msg_SC -- CODEFIX
883 ("`END IF;` expected@ for IF#!");
885 elsif End_Type = E_Loop then
886 if Error_Msg_Node_1 = Empty then
887 Error_Msg_SC -- CODEFIX
888 ("`END LOOP;` expected@ for LOOP#!");
890 Error_Msg_SC -- CODEFIX
891 ("`END LOOP &;` expected@!");
894 elsif End_Type = E_Record then
895 Error_Msg_SC -- CODEFIX
896 ("`END RECORD;` expected@ for RECORD#!");
898 elsif End_Type = E_Return then
899 Error_Msg_SC -- CODEFIX
900 ("`END RETURN;` expected@ for RETURN#!");
902 elsif End_Type = E_Select then
903 Error_Msg_SC -- CODEFIX
904 ("`END SELECT;` expected@ for SELECT#!");
906 -- All remaining cases are cases with a name (we do not treat
907 -- the suspicious is cases specially for a replaced end, only
908 -- for an inserted end).
910 elsif End_Type = E_Name or else (not Ins) then
911 if Error_Msg_Node_1 = Empty then
912 Error_Msg_SC -- CODEFIX
913 ("`END;` expected@ for BEGIN#!");
915 Error_Msg_SC -- CODEFIX
916 ("`END &;` expected@!");
919 -- The other possibility is a missing END for a subprogram with a
920 -- suspicious IS (that probably should have been a semicolon). The
921 -- Missing IS confirms the suspicion!
923 else -- End_Type = E_Suspicious_Is or E_Bad_Is
924 Scope.Table (Scope.Last).Etyp := E_Bad_Is;
926 end Output_End_Expected;
928 ------------------------
929 -- Output End Missing --
930 ------------------------
932 procedure Output_End_Missing is
933 End_Type : SS_End_Type;
936 -- Suppress message if this was a potentially junk entry (e.g. a
937 -- record entry where no record keyword was present.
939 if Scope.Table (Scope.Last).Junk then
943 End_Type := Scope.Table (Scope.Last).Etyp;
944 Error_Msg_Sloc := Scope.Table (Scope.Last).Sloc;
946 if Explicit_Start_Label (Scope.Last) then
947 Error_Msg_Node_1 := Scope.Table (Scope.Last).Labl;
949 Error_Msg_Node_1 := Empty;
952 if End_Type = E_Case then
953 Error_Msg_BC ("missing `END CASE;` for CASE#!");
955 elsif End_Type = E_If then
956 Error_Msg_BC ("missing `END IF;` for IF#!");
958 elsif End_Type = E_Loop then
959 if Error_Msg_Node_1 = Empty then
960 Error_Msg_BC ("missing `END LOOP;` for LOOP#!");
962 Error_Msg_BC ("missing `END LOOP &;`!");
965 elsif End_Type = E_Record then
967 ("missing `END RECORD;` for RECORD#!");
969 elsif End_Type = E_Return then
971 ("missing `END RETURN;` for RETURN#!");
973 elsif End_Type = E_Select then
975 ("missing `END SELECT;` for SELECT#!");
977 elsif End_Type = E_Name then
978 if Error_Msg_Node_1 = Empty then
979 Error_Msg_BC ("missing `END;` for BEGIN#!");
981 Error_Msg_BC ("missing `END &;`!");
984 else -- End_Type = E_Suspicious_Is or E_Bad_Is
985 Scope.Table (Scope.Last).Etyp := E_Bad_Is;
987 end Output_End_Missing;
989 ---------------------
990 -- Pop End Context --
991 ---------------------
993 procedure Pop_End_Context is
995 Pretty_Good : Boolean;
996 -- This flag is set True if the END sequence is syntactically incorrect,
997 -- but is (from a heuristic point of view), pretty likely to be simply
998 -- a misspelling of the intended END.
1000 Outer_Match : Boolean;
1001 -- This flag is set True if we decide that the current END sequence
1002 -- belongs to some outer level entry in the scope stack, and thus
1003 -- we will NOT eat it up in matching the current expected END.
1006 -- If not at END, then output END expected message
1008 if End_Type = E_Dummy then
1011 End_Action := Insert_And_Accept;
1014 -- Otherwise we do have an END present
1017 -- A special check. If we have END; followed by an end of file,
1018 -- WITH or SEPARATE, then if we are not at the outer level, then
1019 -- we have a syntax error. Consider the example:
1031 -- Now the END; here is a syntactically correct closer for the
1032 -- declare block, but if we eat it up, then we obviously have
1033 -- a missing END for the outer context (since WITH can only appear
1034 -- at the outer level.
1036 -- In this situation, we always reserve the END; for the outer level,
1037 -- even if it is in the wrong column. This is because it's much more
1038 -- useful to have the error message point to the DECLARE than to the
1039 -- package header in this case.
1041 -- We also reserve an end with a name before the end of file if the
1042 -- name is the one we expect at the outer level.
1044 if (Token = Tok_EOF or else
1045 Token = Tok_With or else
1046 Token = Tok_Separate)
1047 and then End_Type >= E_Name
1048 and then (not End_Labl_Present
1049 or else Same_Label (End_Labl, Scope.Table (1).Labl))
1050 and then Scope.Last > 1
1052 Restore_Scan_State (Scan_State); -- to END
1053 Output_End_Expected (Ins => True);
1055 End_Action := Insert_And_Accept;
1059 -- Otherwise we go through the normal END evaluation procedure
1061 Evaluate_End_Entry (Scope.Last);
1063 -- If top entry in stack is syntactically correct, then we have
1064 -- scanned it out and everything is fine. This is the required
1065 -- action to properly process correct Ada programs.
1069 -- Complain if checking columns and END is not in right column.
1070 -- Right in this context means exactly right, or on the same
1071 -- line as the opener.
1073 if RM_Column_Check then
1074 if End_Column /= Scope.Table (Scope.Last).Ecol
1075 and then Current_Line_Start > Scope.Table (Scope.Last).Sloc
1077 -- A special case, for END RECORD, we are also allowed to
1078 -- line up with the TYPE keyword opening the declaration.
1080 and then (Scope.Table (Scope.Last).Etyp /= E_Record
1081 or else Get_Column_Number (End_Sloc) /=
1082 Get_Column_Number (Type_Token_Location))
1084 Error_Msg_Col := Scope.Table (Scope.Last).Ecol;
1086 ("(style) END in wrong column, should be@", End_Sloc);
1090 -- One final check. If the end had a label, check for an exact
1091 -- duplicate of this end sequence, and if so, skip it with an
1092 -- appropriate message.
1094 if End_Labl_Present and then Token = Tok_End then
1096 Scan_State : Saved_Scan_State;
1097 End_Loc : constant Source_Ptr := Token_Ptr;
1099 Dup_Found : Boolean := False;
1102 Save_Scan_State (Scan_State);
1106 if Token = Tok_Identifier
1107 or else Token = Tok_Operator_Symbol
1109 Nxt_Labl := P_Designator;
1111 -- We only consider it an error if the label is a match
1112 -- and would be wrong for the level one above us, and
1113 -- the indentation is the same.
1115 if Token = Tok_Semicolon
1116 and then Same_Label (End_Labl, Nxt_Labl)
1117 and then End_Column = Start_Column
1121 (not Explicit_Start_Label (Scope.Last - 1))
1125 Scope.Table (Scope.Last - 1).Labl)))
1128 Error_Msg ("duplicate end line ignored", End_Loc);
1133 if not Dup_Found then
1134 Restore_Scan_State (Scan_State);
1139 -- All OK, so return to caller indicating END is OK
1142 End_Action := Accept_As_Scanned;
1146 -- If that check failed, then we definitely have an error. The issue
1147 -- is how to choose among three possible courses of action:
1149 -- 1. Ignore the current END text completely, scanning past it,
1150 -- deciding that it belongs neither to the current context,
1151 -- nor to any outer context.
1153 -- 2. Accept the current END text, scanning past it, and issuing
1154 -- an error message that it does not have the right form.
1156 -- 3. Leave the current END text in place, NOT scanning past it,
1157 -- issuing an error message indicating the END expected for the
1158 -- current context. In this case, the END is available to match
1159 -- some outer END context.
1161 -- From a correct functioning point of view, it does not make any
1162 -- difference which of these three approaches we take, the program
1163 -- will work correctly in any case. However, making an accurate
1164 -- choice among these alternatives, i.e. choosing the one that
1165 -- corresponds to what the programmer had in mind, does make a
1166 -- significant difference in the quality of error recovery.
1168 Restore_Scan_State (Scan_State); -- to END
1170 -- First we see how good the current END entry is with respect to
1171 -- what we expect. It is considered pretty good if the token is OK,
1172 -- and either the label or the column matches. An END for RECORD is
1173 -- always considered to be pretty good in the record case. This is
1174 -- because not only does a record disallow a nested structure, but
1175 -- also it is unlikely that such nesting could occur by accident.
1177 Pretty_Good := (Token_OK and (Column_OK or Label_OK))
1178 or else Scope.Table (Scope.Last).Etyp = E_Record;
1180 -- Next check, if there is a deeper entry in the stack which
1181 -- has a very high probability of being acceptable, then insert
1182 -- the END entry we want, leaving the higher level entry for later
1184 for J in reverse 1 .. Scope.Last - 1 loop
1185 Evaluate_End_Entry (J);
1187 -- To even consider the deeper entry to be immediately acceptable,
1188 -- it must be syntactically correct. Furthermore it must either
1189 -- have a correct label, or the correct column. If the current
1190 -- entry was a close match (Pretty_Good set), then we are even
1191 -- more strict in accepting the outer level one: even if it has
1192 -- the right label, it must have the right column as well.
1196 Outer_Match := Label_OK and Column_OK;
1198 Outer_Match := Label_OK or Column_OK;
1201 Outer_Match := False;
1204 -- If the outer entry does convincingly match the END text, then
1205 -- back up the scan to the start of the END sequence, issue an
1206 -- error message indicating the END we expected, and return with
1207 -- Token pointing to the END (case 3 from above discussion).
1212 End_Action := Insert_And_Accept;
1217 -- Here we have a situation in which the current END entry is
1218 -- syntactically incorrect, but there is no deeper entry in the
1219 -- END stack which convincingly matches it.
1221 -- If the END text was judged to be a Pretty_Good match for the
1222 -- expected token or if it appears left of the expected column,
1223 -- then we will accept it as the one we want, scanning past it, even
1224 -- though it is not completely right (we issue a message showing what
1225 -- we expected it to be). This is action 2 from the discussion above.
1226 -- There is one other special case to consider: the LOOP case.
1227 -- Consider the example:
1233 -- Here the column lines up with Lbl, so END LOOP is to the right,
1234 -- but it is still acceptable. LOOP is the one case where alignment
1235 -- practices vary substantially in practice.
1238 or else End_Column <= Scope.Table (Scope.Last).Ecol
1239 or else (End_Type = Scope.Table (Scope.Last).Etyp
1240 and then End_Type = E_Loop)
1242 Output_End_Expected (Ins => False);
1244 End_Action := Skip_And_Accept;
1247 -- Here we have the case where the END is to the right of the
1248 -- expected column and does not have a correct label to convince
1249 -- us that it nevertheless belongs to the current scope. For this
1250 -- we consider that it probably belongs not to the current context,
1251 -- but to some inner context that was not properly recognized (due to
1252 -- other syntax errors), and for which no proper scope stack entry
1253 -- was made. The proper action in this case is to delete the END text
1254 -- and return False to the caller as a signal to keep on looking for
1255 -- an acceptable END. This is action 1 from the discussion above.
1259 End_Action := Skip_And_Reject;
1263 end Pop_End_Context;
1269 function Same_Label (Label1, Label2 : Node_Id) return Boolean is
1271 if Nkind (Label1) in N_Has_Chars
1272 and then Nkind (Label2) in N_Has_Chars
1274 return Chars (Label1) = Chars (Label2);
1276 elsif Nkind (Label1) = N_Selected_Component
1277 and then Nkind (Label2) = N_Selected_Component
1279 return Same_Label (Prefix (Label1), Prefix (Label2)) and then
1280 Same_Label (Selector_Name (Label1), Selector_Name (Label2));
1282 elsif Nkind (Label1) = N_Designator
1283 and then Nkind (Label2) = N_Defining_Program_Unit_Name
1285 return Same_Label (Name (Label1), Name (Label2)) and then
1286 Same_Label (Identifier (Label1), Defining_Identifier (Label2));