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------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- P A R . E N D H -- -- -- -- B o d y -- -- -- -- Copyright (C) 1992-2009, Free Software Foundation, Inc. -- -- -- -- GNAT is free software; you can redistribute it and/or modify it under -- -- terms of the GNU General Public License as published by the Free Soft- -- -- ware Foundation; either version 3, or (at your option) any later ver- -- -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- -- for more details. You should have received a copy of the GNU General -- -- Public License distributed with GNAT; see file COPYING3. If not, go to -- -- http://www.gnu.org/licenses for a complete copy of the license. -- -- -- -- GNAT was originally developed by the GNAT team at New York University. -- -- Extensive contributions were provided by Ada Core Technologies Inc. -- -- -- ------------------------------------------------------------------------------ with Namet.Sp; use Namet.Sp; with Stringt; use Stringt; with Uintp; use Uintp; with GNAT.Spelling_Checker; use GNAT.Spelling_Checker; separate (Par) package body Endh is ---------------- -- Local Data -- ---------------- type End_Action_Type is ( -- Type used to describe the result of the Pop_End_Context call Accept_As_Scanned, -- Current end sequence is entirely c correct. In this case Token and -- the scan pointer are left pointing past the end sequence (i.e. they -- are unchanged from the values set on entry to Pop_End_Context). Insert_And_Accept, -- Current end sequence is to be left in place to satisfy some outer -- scope. Token and the scan pointer are set to point to the end -- token, and should be left there. A message has been generated -- indicating a missing end sequence. This status is also used for -- the case when no end token is present. Skip_And_Accept, -- The end sequence is incorrect (and an error message has been -- posted), but it will still be accepted. In this case Token and -- the scan pointer point back to the end token, and the caller -- should skip past the end sequence before proceeding. Skip_And_Reject); -- The end sequence is judged to belong to an unrecognized inner -- scope. An appropriate message has been issued and the caller -- should skip past the end sequence and then proceed as though -- no end sequence had been encountered. End_Action : End_Action_Type; -- The variable set by Pop_End_Context call showing which of the four -- decisions described above is judged the best. End_Sloc : Source_Ptr; -- Source location of END token End_OK : Boolean; -- Set False if error is found in END line End_Column : Column_Number; -- Column of END line End_Type : SS_End_Type; -- Type of END expected. The special value E_Dummy is set to indicate that -- no END token was present (so a missing END inserted message is needed) End_Labl : Node_Id; -- Node_Id value for explicit name on END line, or for compiler supplied -- name in the case where an optional name is not given. Empty if no name -- appears. If non-empty, then it is either an N_Designator node for a -- child unit or a node with a Chars field identifying the actual label. End_Labl_Present : Boolean; -- Indicates that the value in End_Labl was for an explicit label Syntax_OK : Boolean; -- Set True if the entry is syntactically correct Token_OK : Boolean; -- Set True if the keyword in the END sequence matches, or if neither -- the END sequence nor the END stack entry has a keyword. Label_OK : Boolean; -- Set True if both the END sequence and the END stack entry contained -- labels (other than No_Name or Error_Name) and the labels matched. -- This is a stronger condition than SYNTAX_OK, since it means that a -- label was present, even in a case where it was optional. Note that -- the case of no label required, and no label present does NOT set -- Label_OK to True, it is True only if a positive label match is found. Column_OK : Boolean; -- Column_OK is set True if the END sequence appears in the expected column Scan_State : Saved_Scan_State; -- Save state at start of END sequence, in case we decide not to eat it up ----------------------- -- Local Subprograms -- ----------------------- procedure Evaluate_End_Entry (SS_Index : Nat); -- Compare scanned END entry (as recorded by a prior call to P_End_Scan) -- with a specified entry in the scope stack (the single parameter is the -- entry index in the scope stack). Note that Scan is not called. The above -- variables xxx_OK are set to indicate the result of the evaluation. function Explicit_Start_Label (SS_Index : Nat) return Boolean; -- Determines whether the specified entry in the scope stack has an -- explicit start label (i.e. one other than one that was created by -- the parser when no explicit label was present) procedure Output_End_Deleted; -- Output a message complaining that the current END structure does not -- match anything and is being deleted. procedure Output_End_Expected (Ins : Boolean); -- Output a message at the start of the current token which is always an -- END, complaining that the END is not of the right form. The message -- indicates the expected form. The information for the message is taken -- from the top entry in the scope stack. The Ins parameter is True if -- an end is being inserted, and false if an existing end is being -- replaced. Note that in the case of a suspicious IS for the Ins case, -- we do not output the message, but instead simply mark the scope stack -- entry as being a case of a bad IS. procedure Output_End_Missing; -- Output a message just before the current token, complaining that the -- END is not of the right form. The message indicates the expected form. -- The information for the message is taken from the top entry in the -- scope stack. Note that in the case of a suspicious IS, we do not output -- the message, but instead simply mark the scope stack entry as a bad IS. procedure Pop_End_Context; -- Pop_End_Context is called after processing a construct, to pop the -- top entry off the end stack. It decides on the appropriate action to -- to take, signalling the result by setting End_Action as described in -- the global variable section. function Same_Label (Label1, Label2 : Node_Id) return Boolean; -- This function compares the two names associated with the given nodes. -- If they are both simple (i.e. have Chars fields), then they have to -- be the same name. Otherwise they must both be N_Selected_Component -- nodes, referring to the same set of names, or Label1 is an N_Designator -- referring to the same set of names as the N_Defining_Program_Unit_Name -- in Label2. Any other combination returns False. This routine is used -- to compare the End_Labl scanned from the End line with the saved label -- value in the scope stack. --------------- -- Check_End -- --------------- function Check_End return Boolean is Name_On_Separate_Line : Boolean; -- Set True if the name on an END line is on a separate source line -- from the END. This is highly suspicious, but is allowed. The point -- is that we want to make sure that we don't just have a missing -- semicolon misleading us into swallowing an identifier from the -- following line. Name_Scan_State : Saved_Scan_State; -- Save state at start of name if Name_On_Separate_Line is TRUE Span_Node : constant Node_Id := Scope.Table (Scope.Last).Node; begin End_Labl_Present := False; End_Labl := Empty; -- Our first task is to scan out the END sequence if one is present. -- If none is present, signal by setting End_Type to E_Dummy. if Token /= Tok_End then End_Type := E_Dummy; else Save_Scan_State (Scan_State); -- at END End_Sloc := Token_Ptr; End_Column := Start_Column; End_OK := True; Scan; -- past END -- Set End_Span if expected. note that this will be useless -- if we do not have the right ending keyword, but in this -- case we have a malformed program anyway, and the setting -- of End_Span will simply be unreliable in this case anyway. if Present (Span_Node) then Set_End_Location (Span_Node, Token_Ptr); end if; -- Cases of keywords where no label is allowed if Token = Tok_Case then End_Type := E_Case; Scan; -- past CASE elsif Token = Tok_If then End_Type := E_If; Scan; -- past IF elsif Token = Tok_Record then End_Type := E_Record; Scan; -- past RECORD elsif Token = Tok_Return then End_Type := E_Return; Scan; -- past RETURN elsif Token = Tok_Select then End_Type := E_Select; Scan; -- past SELECT -- Cases which do allow labels else -- LOOP if Token = Tok_Loop then Scan; -- past LOOP End_Type := E_Loop; -- FOR or WHILE allowed (signalling error) to substitute for LOOP -- if on the same line as the END elsif (Token = Tok_For or else Token = Tok_While) and then not Token_Is_At_Start_Of_Line then Scan; -- past FOR or WHILE End_Type := E_Loop; End_OK := False; -- Cases with no keyword else End_Type := E_Name; end if; -- Now see if a name is present if Token = Tok_Identifier or else Token = Tok_String_Literal or else Token = Tok_Operator_Symbol then if Token_Is_At_Start_Of_Line then Name_On_Separate_Line := True; Save_Scan_State (Name_Scan_State); else Name_On_Separate_Line := False; end if; End_Labl := P_Designator; End_Labl_Present := True; -- We have now scanned out a name. Here is where we do a check -- to catch the cases like: -- -- end loop -- X := 3; -- -- where the missing semicolon might make us swallow up the X -- as a bogus end label. In a situation like this, where the -- apparent name is on a separate line, we accept it only if -- it matches the label and is followed by a semicolon. if Name_On_Separate_Line then if Token /= Tok_Semicolon or else not Same_Label (End_Labl, Scope.Table (Scope.Last).Labl) then Restore_Scan_State (Name_Scan_State); End_Labl := Empty; End_Labl_Present := False; end if; end if; -- Here for case of name allowed, but no name present. We will -- supply an implicit matching name, with source location set -- to the scan location past the END token. else End_Labl := Scope.Table (Scope.Last).Labl; if End_Labl > Empty_Or_Error then -- The task here is to construct a designator from the -- opening label, with the components all marked as not -- from source, and Is_End_Label set in the identifier -- or operator symbol. The location for all components -- is the current token location. -- Case of child unit name if Nkind (End_Labl) = N_Defining_Program_Unit_Name then Child_End : declare Eref : constant Node_Id := Make_Identifier (Token_Ptr, Chars => Chars (Defining_Identifier (End_Labl))); function Copy_Name (N : Node_Id) return Node_Id; -- Copies a selected component or identifier --------------- -- Copy_Name -- --------------- function Copy_Name (N : Node_Id) return Node_Id is R : Node_Id; begin if Nkind (N) = N_Selected_Component then return Make_Selected_Component (Token_Ptr, Prefix => Copy_Name (Prefix (N)), Selector_Name => Copy_Name (Selector_Name (N))); else R := Make_Identifier (Token_Ptr, Chars => Chars (N)); Set_Comes_From_Source (N, False); return R; end if; end Copy_Name; -- Start of processing for Child_End begin Set_Comes_From_Source (Eref, False); End_Labl := Make_Designator (Token_Ptr, Name => Copy_Name (Name (End_Labl)), Identifier => Eref); end Child_End; -- Simple identifier case elsif Nkind (End_Labl) = N_Defining_Identifier or else Nkind (End_Labl) = N_Identifier then End_Labl := Make_Identifier (Token_Ptr, Chars => Chars (End_Labl)); elsif Nkind (End_Labl) = N_Defining_Operator_Symbol or else Nkind (End_Labl) = N_Operator_Symbol then Get_Decoded_Name_String (Chars (End_Labl)); End_Labl := Make_Operator_Symbol (Token_Ptr, Chars => Chars (End_Labl), Strval => String_From_Name_Buffer); end if; Set_Comes_From_Source (End_Labl, False); End_Labl_Present := False; -- Do style check for missing label if Style_Check and then End_Type = E_Name and then Explicit_Start_Label (Scope.Last) then Style.No_End_Name (Scope.Table (Scope.Last).Labl); end if; end if; end if; end if; -- Except in case of END RECORD, semicolon must follow. For END -- RECORD, a semicolon does follow, but it is part of a higher level -- construct. In any case, a missing semicolon is not serious enough -- to consider the END statement to be bad in the sense that we -- are dealing with (i.e. to be suspicious that it is not in fact -- the END statement we are looking for!) if End_Type /= E_Record then if Token = Tok_Semicolon then T_Semicolon; -- Semicolon is missing. If the missing semicolon is at the end -- of the line, i.e. we are at the start of the line now, then -- a missing semicolon gets flagged, but is not serious enough -- to consider the END statement to be bad in the sense that we -- are dealing with (i.e. to be suspicious that this END is not -- the END statement we are looking for). -- Similarly, if we are at a colon, we flag it but a colon for -- a semicolon is not serious enough to consider the END to be -- incorrect. Same thing for a period in place of a semicolon. elsif Token_Is_At_Start_Of_Line or else Token = Tok_Colon or else Token = Tok_Dot then T_Semicolon; -- If the missing semicolon is not at the start of the line, -- then we do consider the END line to be dubious in this sense. else End_OK := False; end if; end if; end if; -- Now we call the Pop_End_Context routine to get a recommendation -- as to what should be done with the END sequence we have scanned. Pop_End_Context; -- Remaining action depends on End_Action set by Pop_End_Context case End_Action is -- Accept_As_Scanned. In this case, Pop_End_Context left Token -- pointing past the last token of a syntactically correct END when Accept_As_Scanned => -- Syntactically correct included the possibility of a missing -- semicolon. If we do have a missing semicolon, then we have -- already given a message, but now we scan out possible rubbish -- on the same line as the END while not Token_Is_At_Start_Of_Line and then Prev_Token /= Tok_Record and then Prev_Token /= Tok_Semicolon and then Token /= Tok_End and then Token /= Tok_EOF loop Scan; -- past junk end loop; return True; -- Insert_And_Accept. In this case, Pop_End_Context has reset Token -- to point to the start of the END sequence, and recommends that it -- be left in place to satisfy an outer scope level END. This means -- that we proceed as though an END were present, and leave the scan -- pointer unchanged. when Insert_And_Accept => return True; -- Skip_And_Accept. In this case, Pop_End_Context has reset Token -- to point to the start of the END sequence. This END sequence is -- syntactically incorrect, and an appropriate error message has -- already been posted. Pop_End_Context recommends accepting the -- END sequence as the one we want, so we skip past it and then -- proceed as though an END were present. when Skip_And_Accept => End_Skip; return True; -- Skip_And_Reject. In this case, Pop_End_Context has reset Token -- to point to the start of the END sequence. This END sequence is -- syntactically incorrect, and an appropriate error message has -- already been posted. Pop_End_Context recommends entirely ignoring -- this END sequence, so we skip past it and then return False, since -- as far as the caller is concerned, no END sequence is present. when Skip_And_Reject => End_Skip; return False; end case; end Check_End; -------------- -- End Skip -- -------------- -- This procedure skips past an END sequence. On entry Token contains -- Tok_End, and we know that the END sequence is syntactically incorrect, -- and that an appropriate error message has already been posted. The -- mission is simply to position the scan pointer to be the best guess of -- the position after the END sequence. We do not issue any additional -- error messages while carrying this out. -- Error recovery: does not raise Error_Resync procedure End_Skip is begin Scan; -- past END -- If the scan past the END leaves us on the next line, that's probably -- where we should quit the scan, since it is likely that what we have -- is a missing semicolon. Consider the following: -- END -- Process_Input; -- This will have looked like a syntactically valid END sequence to the -- initial scan of the END, but subsequent checking will have determined -- that the label Process_Input is not an appropriate label. The real -- error is a missing semicolon after the END, and by leaving the scan -- pointer just past the END, we will improve the error recovery. if Token_Is_At_Start_Of_Line then return; end if; -- If there is a semicolon after the END, scan it out and we are done if Token = Tok_Semicolon then T_Semicolon; return; end if; -- Otherwise skip past a token after the END on the same line. Note -- that we do not eat a token on the following line since it seems -- very unlikely in any case that the END gets separated from its -- token, and we do not want to swallow up a keyword that starts a -- legitimate construct following the bad END. if not Token_Is_At_Start_Of_Line and then -- Cases of normal tokens following an END (Token = Tok_Case or else Token = Tok_For or else Token = Tok_If or else Token = Tok_Loop or else Token = Tok_Record or else Token = Tok_Select or else -- Cases of bogus keywords ending loops Token = Tok_For or else Token = Tok_While or else -- Cases of operator symbol names without quotes Token = Tok_Abs or else Token = Tok_And or else Token = Tok_Mod or else Token = Tok_Not or else Token = Tok_Or or else Token = Tok_Xor) then Scan; -- past token after END -- If that leaves us on the next line, then we are done. This is the -- same principle described above for the case of END at line end if Token_Is_At_Start_Of_Line then return; -- If we just scanned out record, then we are done, since the -- semicolon after END RECORD is not part of the END sequence elsif Prev_Token = Tok_Record then return; -- If we have a semicolon, scan it out and we are done elsif Token = Tok_Semicolon then T_Semicolon; return; end if; end if; -- Check for a label present on the same line loop if Token_Is_At_Start_Of_Line then return; end if; if Token /= Tok_Identifier and then Token /= Tok_Operator_Symbol and then Token /= Tok_String_Literal then exit; end if; Scan; -- past identifier, operator symbol or string literal if Token_Is_At_Start_Of_Line then return; elsif Token = Tok_Dot then Scan; -- past dot end if; end loop; -- Skip final semicolon if Token = Tok_Semicolon then T_Semicolon; -- If we don't have a final semicolon, skip until we either encounter -- an END token, or a semicolon or the start of the next line. This -- allows general junk to follow the end line (normally it is hard to -- think that anyone will put anything deliberate here, and remember -- that we know there is a missing semicolon in any case). We also -- quite on an EOF (or else we would get stuck in an infinite loop -- if there is no line end at the end of the last line of the file) else while Token /= Tok_End and then Token /= Tok_EOF and then Token /= Tok_Semicolon and then not Token_Is_At_Start_Of_Line loop Scan; -- past junk token on same line end loop; end if; return; end End_Skip; -------------------- -- End Statements -- -------------------- -- This procedure is called when END is required or expected to terminate -- a sequence of statements. The caller has already made an appropriate -- entry on the scope stack to describe the expected form of the END. -- End_Statements should only be used in cases where the only appropriate -- terminator is END. -- Error recovery: cannot raise Error_Resync; procedure End_Statements (Parent : Node_Id := Empty) is begin -- This loop runs more than once in the case where Check_End rejects -- the END sequence, as indicated by Check_End returning False. loop if Check_End then if Present (Parent) then Set_End_Label (Parent, End_Labl); end if; return; end if; -- Extra statements past the bogus END are discarded. This is not -- ideal for maximum error recovery, but it's too much trouble to -- find an appropriate place to put them! Discard_Junk_List (P_Sequence_Of_Statements (SS_None)); end loop; end End_Statements; ------------------------ -- Evaluate End Entry -- ------------------------ procedure Evaluate_End_Entry (SS_Index : Nat) is begin Column_OK := (End_Column = Scope.Table (SS_Index).Ecol); Token_OK := (End_Type = Scope.Table (SS_Index).Etyp or else (End_Type = E_Name and then Scope.Table (SS_Index).Etyp >= E_Name)); Label_OK := End_Labl_Present and then (Same_Label (End_Labl, Scope.Table (SS_Index).Labl) or else Scope.Table (SS_Index).Labl = Error); -- Compute setting of Syntax_OK. We definitely have a syntax error -- if the Token does not match properly or if P_End_Scan detected -- a syntax error such as a missing semicolon. if not Token_OK or not End_OK then Syntax_OK := False; -- Final check is that label is OK. Certainly it is OK if there -- was an exact match on the label (the END label = the stack label) elsif Label_OK then Syntax_OK := True; -- Case of label present elsif End_Labl_Present then -- If probably misspelling, then complain, and pretend it is OK declare Nam : constant Node_Or_Entity_Id := Scope.Table (SS_Index).Labl; begin if Nkind (End_Labl) in N_Has_Chars and then Comes_From_Source (Nam) and then Nkind (Nam) in N_Has_Chars and then Chars (End_Labl) > Error_Name and then Chars (Nam) > Error_Name then Error_Msg_Name_1 := Chars (Nam); if Error_Msg_Name_1 > Error_Name then if Is_Bad_Spelling_Of (Chars (Nam), Chars (End_Labl)) then Error_Msg_Name_1 := Chars (Nam); Error_Msg_N -- CODEFIX ("misspelling of %", End_Labl); Syntax_OK := True; return; end if; end if; end if; end; Syntax_OK := False; -- Otherwise we have cases of no label on the END line. For the loop -- case, this is acceptable only if the loop is unlabeled. elsif End_Type = E_Loop then Syntax_OK := not Explicit_Start_Label (SS_Index); -- Cases where a label is definitely allowed on the END line elsif End_Type = E_Name then Syntax_OK := (not Explicit_Start_Label (SS_Index)) or else (not Scope.Table (SS_Index).Lreq); -- Otherwise we have cases which don't allow labels anyway, so we -- certainly accept an END which does not have a label. else Syntax_OK := True; end if; end Evaluate_End_Entry; -------------------------- -- Explicit_Start_Label -- -------------------------- function Explicit_Start_Label (SS_Index : Nat) return Boolean is L : constant Node_Id := Scope.Table (SS_Index).Labl; Etyp : constant SS_End_Type := Scope.Table (SS_Index).Etyp; begin if No (L) then return False; -- In the following test we protect the call to Comes_From_Source -- against lines containing previously reported syntax errors. elsif (Etyp = E_Loop or else Etyp = E_Name or else Etyp = E_Suspicious_Is or else Etyp = E_Bad_Is) and then Comes_From_Source (L) then return True; else return False; end if; end Explicit_Start_Label; ------------------------ -- Output End Deleted -- ------------------------ procedure Output_End_Deleted is begin if End_Type = E_Loop then Error_Msg_SC ("no LOOP for this `END LOOP`!"); elsif End_Type = E_Case then Error_Msg_SC ("no CASE for this `END CASE`"); elsif End_Type = E_If then Error_Msg_SC ("no IF for this `END IF`!"); elsif End_Type = E_Record then Error_Msg_SC ("no RECORD for this `END RECORD`!"); elsif End_Type = E_Return then Error_Msg_SC ("no RETURN for this `END RETURN`!"); elsif End_Type = E_Select then Error_Msg_SC ("no SELECT for this `END SELECT`!"); else Error_Msg_SC ("no BEGIN for this END!"); end if; end Output_End_Deleted; ------------------------- -- Output End Expected -- ------------------------- procedure Output_End_Expected (Ins : Boolean) is End_Type : SS_End_Type; begin -- Suppress message if this was a potentially junk entry (e.g. a -- record entry where no record keyword was present. if Scope.Table (Scope.Last).Junk then return; end if; End_Type := Scope.Table (Scope.Last).Etyp; Error_Msg_Col := Scope.Table (Scope.Last).Ecol; Error_Msg_Sloc := Scope.Table (Scope.Last).Sloc; if Explicit_Start_Label (Scope.Last) then Error_Msg_Node_1 := Scope.Table (Scope.Last).Labl; else Error_Msg_Node_1 := Empty; end if; -- Suppress message if error was posted on opening label if Error_Msg_Node_1 > Empty_Or_Error and then Error_Posted (Error_Msg_Node_1) then return; end if; if End_Type = E_Case then Error_Msg_SC -- CODEFIX ("`END CASE;` expected@ for CASE#!"); elsif End_Type = E_If then Error_Msg_SC -- CODEFIX ("`END IF;` expected@ for IF#!"); elsif End_Type = E_Loop then if Error_Msg_Node_1 = Empty then Error_Msg_SC -- CODEFIX ("`END LOOP;` expected@ for LOOP#!"); else Error_Msg_SC -- CODEFIX ("`END LOOP &;` expected@!"); end if; elsif End_Type = E_Record then Error_Msg_SC -- CODEFIX ("`END RECORD;` expected@ for RECORD#!"); elsif End_Type = E_Return then Error_Msg_SC -- CODEFIX ("`END RETURN;` expected@ for RETURN#!"); elsif End_Type = E_Select then Error_Msg_SC -- CODEFIX ("`END SELECT;` expected@ for SELECT#!"); -- All remaining cases are cases with a name (we do not treat -- the suspicious is cases specially for a replaced end, only -- for an inserted end). elsif End_Type = E_Name or else (not Ins) then if Error_Msg_Node_1 = Empty then Error_Msg_SC -- CODEFIX ("`END;` expected@ for BEGIN#!"); else Error_Msg_SC -- CODEFIX ("`END &;` expected@!"); end if; -- The other possibility is a missing END for a subprogram with a -- suspicious IS (that probably should have been a semicolon). The -- Missing IS confirms the suspicion! else -- End_Type = E_Suspicious_Is or E_Bad_Is Scope.Table (Scope.Last).Etyp := E_Bad_Is; end if; end Output_End_Expected; ------------------------ -- Output End Missing -- ------------------------ procedure Output_End_Missing is End_Type : SS_End_Type; begin -- Suppress message if this was a potentially junk entry (e.g. a -- record entry where no record keyword was present. if Scope.Table (Scope.Last).Junk then return; end if; End_Type := Scope.Table (Scope.Last).Etyp; Error_Msg_Sloc := Scope.Table (Scope.Last).Sloc; if Explicit_Start_Label (Scope.Last) then Error_Msg_Node_1 := Scope.Table (Scope.Last).Labl; else Error_Msg_Node_1 := Empty; end if; if End_Type = E_Case then Error_Msg_BC ("missing `END CASE;` for CASE#!"); elsif End_Type = E_If then Error_Msg_BC ("missing `END IF;` for IF#!"); elsif End_Type = E_Loop then if Error_Msg_Node_1 = Empty then Error_Msg_BC ("missing `END LOOP;` for LOOP#!"); else Error_Msg_BC ("missing `END LOOP &;`!"); end if; elsif End_Type = E_Record then Error_Msg_SC ("missing `END RECORD;` for RECORD#!"); elsif End_Type = E_Return then Error_Msg_SC ("missing `END RETURN;` for RETURN#!"); elsif End_Type = E_Select then Error_Msg_BC ("missing `END SELECT;` for SELECT#!"); elsif End_Type = E_Name then if Error_Msg_Node_1 = Empty then Error_Msg_BC ("missing `END;` for BEGIN#!"); else Error_Msg_BC ("missing `END &;`!"); end if; else -- End_Type = E_Suspicious_Is or E_Bad_Is Scope.Table (Scope.Last).Etyp := E_Bad_Is; end if; end Output_End_Missing; --------------------- -- Pop End Context -- --------------------- procedure Pop_End_Context is Pretty_Good : Boolean; -- This flag is set True if the END sequence is syntactically incorrect, -- but is (from a heuristic point of view), pretty likely to be simply -- a misspelling of the intended END. Outer_Match : Boolean; -- This flag is set True if we decide that the current END sequence -- belongs to some outer level entry in the scope stack, and thus -- we will NOT eat it up in matching the current expected END. begin -- If not at END, then output END expected message if End_Type = E_Dummy then Output_End_Missing; Pop_Scope_Stack; End_Action := Insert_And_Accept; return; -- Otherwise we do have an END present else -- A special check. If we have END; followed by an end of file, -- WITH or SEPARATE, then if we are not at the outer level, then -- we have a syntax error. Consider the example: -- ... -- declare -- X : Integer; -- begin -- X := Father (A); -- Process (X, X); -- end; -- with Package1; -- ... -- Now the END; here is a syntactically correct closer for the -- declare block, but if we eat it up, then we obviously have -- a missing END for the outer context (since WITH can only appear -- at the outer level. -- In this situation, we always reserve the END; for the outer level, -- even if it is in the wrong column. This is because it's much more -- useful to have the error message point to the DECLARE than to the -- package header in this case. -- We also reserve an end with a name before the end of file if the -- name is the one we expect at the outer level. if (Token = Tok_EOF or else Token = Tok_With or else Token = Tok_Separate) and then End_Type >= E_Name and then (not End_Labl_Present or else Same_Label (End_Labl, Scope.Table (1).Labl)) and then Scope.Last > 1 then Restore_Scan_State (Scan_State); -- to END Output_End_Expected (Ins => True); Pop_Scope_Stack; End_Action := Insert_And_Accept; return; end if; -- Otherwise we go through the normal END evaluation procedure Evaluate_End_Entry (Scope.Last); -- If top entry in stack is syntactically correct, then we have -- scanned it out and everything is fine. This is the required -- action to properly process correct Ada programs. if Syntax_OK then -- Complain if checking columns and END is not in right column. -- Right in this context means exactly right, or on the same -- line as the opener. if RM_Column_Check then if End_Column /= Scope.Table (Scope.Last).Ecol and then Current_Line_Start > Scope.Table (Scope.Last).Sloc -- A special case, for END RECORD, we are also allowed to -- line up with the TYPE keyword opening the declaration. and then (Scope.Table (Scope.Last).Etyp /= E_Record or else Get_Column_Number (End_Sloc) /= Get_Column_Number (Type_Token_Location)) then Error_Msg_Col := Scope.Table (Scope.Last).Ecol; Error_Msg ("(style) END in wrong column, should be@", End_Sloc); end if; end if; -- One final check. If the end had a label, check for an exact -- duplicate of this end sequence, and if so, skip it with an -- appropriate message. if End_Labl_Present and then Token = Tok_End then declare Scan_State : Saved_Scan_State; End_Loc : constant Source_Ptr := Token_Ptr; Nxt_Labl : Node_Id; Dup_Found : Boolean := False; begin Save_Scan_State (Scan_State); Scan; -- past END if Token = Tok_Identifier or else Token = Tok_Operator_Symbol then Nxt_Labl := P_Designator; -- We only consider it an error if the label is a match -- and would be wrong for the level one above us, and -- the indentation is the same. if Token = Tok_Semicolon and then Same_Label (End_Labl, Nxt_Labl) and then End_Column = Start_Column and then (Scope.Last = 1 or else (not Explicit_Start_Label (Scope.Last - 1)) or else (not Same_Label (End_Labl, Scope.Table (Scope.Last - 1).Labl))) then T_Semicolon; Error_Msg ("duplicate end line ignored", End_Loc); Dup_Found := True; end if; end if; if not Dup_Found then Restore_Scan_State (Scan_State); end if; end; end if; -- All OK, so return to caller indicating END is OK Pop_Scope_Stack; End_Action := Accept_As_Scanned; return; end if; -- If that check failed, then we definitely have an error. The issue -- is how to choose among three possible courses of action: -- 1. Ignore the current END text completely, scanning past it, -- deciding that it belongs neither to the current context, -- nor to any outer context. -- 2. Accept the current END text, scanning past it, and issuing -- an error message that it does not have the right form. -- 3. Leave the current END text in place, NOT scanning past it, -- issuing an error message indicating the END expected for the -- current context. In this case, the END is available to match -- some outer END context. -- From a correct functioning point of view, it does not make any -- difference which of these three approaches we take, the program -- will work correctly in any case. However, making an accurate -- choice among these alternatives, i.e. choosing the one that -- corresponds to what the programmer had in mind, does make a -- significant difference in the quality of error recovery. Restore_Scan_State (Scan_State); -- to END -- First we see how good the current END entry is with respect to -- what we expect. It is considered pretty good if the token is OK, -- and either the label or the column matches. An END for RECORD is -- always considered to be pretty good in the record case. This is -- because not only does a record disallow a nested structure, but -- also it is unlikely that such nesting could occur by accident. Pretty_Good := (Token_OK and (Column_OK or Label_OK)) or else Scope.Table (Scope.Last).Etyp = E_Record; -- Next check, if there is a deeper entry in the stack which -- has a very high probability of being acceptable, then insert -- the END entry we want, leaving the higher level entry for later for J in reverse 1 .. Scope.Last - 1 loop Evaluate_End_Entry (J); -- To even consider the deeper entry to be immediately acceptable, -- it must be syntactically correct. Furthermore it must either -- have a correct label, or the correct column. If the current -- entry was a close match (Pretty_Good set), then we are even -- more strict in accepting the outer level one: even if it has -- the right label, it must have the right column as well. if Syntax_OK then if Pretty_Good then Outer_Match := Label_OK and Column_OK; else Outer_Match := Label_OK or Column_OK; end if; else Outer_Match := False; end if; -- If the outer entry does convincingly match the END text, then -- back up the scan to the start of the END sequence, issue an -- error message indicating the END we expected, and return with -- Token pointing to the END (case 3 from above discussion). if Outer_Match then Output_End_Missing; Pop_Scope_Stack; End_Action := Insert_And_Accept; return; end if; end loop; -- Here we have a situation in which the current END entry is -- syntactically incorrect, but there is no deeper entry in the -- END stack which convincingly matches it. -- If the END text was judged to be a Pretty_Good match for the -- expected token or if it appears left of the expected column, -- then we will accept it as the one we want, scanning past it, even -- though it is not completely right (we issue a message showing what -- we expected it to be). This is action 2 from the discussion above. -- There is one other special case to consider: the LOOP case. -- Consider the example: -- Lbl: loop -- null; -- end loop; -- Here the column lines up with Lbl, so END LOOP is to the right, -- but it is still acceptable. LOOP is the one case where alignment -- practices vary substantially in practice. if Pretty_Good or else End_Column <= Scope.Table (Scope.Last).Ecol or else (End_Type = Scope.Table (Scope.Last).Etyp and then End_Type = E_Loop) then Output_End_Expected (Ins => False); Pop_Scope_Stack; End_Action := Skip_And_Accept; return; -- Here we have the case where the END is to the right of the -- expected column and does not have a correct label to convince -- us that it nevertheless belongs to the current scope. For this -- we consider that it probably belongs not to the current context, -- but to some inner context that was not properly recognized (due to -- other syntax errors), and for which no proper scope stack entry -- was made. The proper action in this case is to delete the END text -- and return False to the caller as a signal to keep on looking for -- an acceptable END. This is action 1 from the discussion above. else Output_End_Deleted; End_Action := Skip_And_Reject; return; end if; end if; end Pop_End_Context; ---------------- -- Same_Label -- ---------------- function Same_Label (Label1, Label2 : Node_Id) return Boolean is begin if Nkind (Label1) in N_Has_Chars and then Nkind (Label2) in N_Has_Chars then return Chars (Label1) = Chars (Label2); elsif Nkind (Label1) = N_Selected_Component and then Nkind (Label2) = N_Selected_Component then return Same_Label (Prefix (Label1), Prefix (Label2)) and then Same_Label (Selector_Name (Label1), Selector_Name (Label2)); elsif Nkind (Label1) = N_Designator and then Nkind (Label2) = N_Defining_Program_Unit_Name then return Same_Label (Name (Label1), Name (Label2)) and then Same_Label (Identifier (Label1), Defining_Identifier (Label2)); else return False; end if; end Same_Label; end Endh;
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