blob: 15b21cdddcfcf3e5b590750b816cc74ec780082b [file] [log] [blame]
------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- P A R . E N D H --
-- --
-- B o d y --
-- --
-- Copyright (C) 1992-2022, 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
(Decl : Node_Id := Empty;
Is_Loc : Source_Ptr := No_Location) 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 := Scopes (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 in Tok_For | 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, Scopes (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 := Scopes (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 (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 (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 label permitted but not present. Note:
-- for the case of a block statement, the label is required
-- to be repeated, and this legality rule is enforced
-- independently.
if Style_Check
and then End_Type = E_Name
and then Explicit_Start_Label (Scope.Last)
and then Nkind (Parent (Scopes (Scope.Last).Labl))
/= N_Block_Statement
then
Style.No_End_Name (Scopes (Scope.Last).Labl);
end if;
end if;
end if;
end if;
-- Deal with terminating aspect specifications and following semi-
-- colon. We skip this in the case of END RECORD, since in this
-- case the aspect specifications and semicolon are handled at
-- a higher level.
if End_Type /= E_Record then
-- Scan aspect specifications
if Aspect_Specifications_Present then
-- Aspect specifications not allowed
if No (Decl) then
-- Package declaration case
if Is_Loc /= No_Location then
Error_Msg_SC
("misplaced aspects for package declaration");
Error_Msg
("info: aspect specifications belong here??", Is_Loc);
P_Aspect_Specifications (Empty);
-- Other cases where aspect specifications are not allowed
else
P_Aspect_Specifications (Error);
end if;
-- Aspect specifications allowed
else
P_Aspect_Specifications (Decl);
end if;
-- If no aspect specifications, must have a semicolon
elsif 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 in Tok_Colon | Tok_Dot
then
T_Semicolon;
-- If the missing semicolon is not at the start of the line,
-- then we consider the END line to be dubious in this sense.
else
End_OK := False;
end if;
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 not in Tok_Record | Tok_Semicolon
and then Token not in Tok_End | 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_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 not in
Tok_Identifier | Tok_Operator_Symbol | 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 not in Tok_End | Tok_EOF | 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;
Decl : Node_Id := Empty;
Is_Sloc : Source_Ptr := No_Location)
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 (Decl, Is_Sloc) 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
STE : Scope_Table_Entry renames Scopes (SS_Index).all;
begin
Column_OK := (End_Column = STE.Ecol);
Token_OK := (End_Type = STE.Etyp
or else (End_Type = E_Name and then STE.Etyp >= E_Name));
Label_OK := End_Labl_Present
and then (Same_Label (End_Labl, STE.Labl)
or else STE.Labl = Error);
-- Special case to consider. Suppose we have the suspicious label case,
-- e.g. a situation like:
-- My_Label;
-- declare
-- ...
-- begin
-- ...
-- end My_Label;
-- This is the case where we want to use the entry in the suspicious
-- label table to flag the semicolon saying it should be a colon.
-- Label_OK will be false because the label does not match (we have
-- My_Label on the end line, and the generated name for the scope). Also
-- End_Labl_Present will be True.
if not Label_OK
and then End_Labl_Present
and then not Comes_From_Source (Scopes (SS_Index).Labl)
then
-- Here is where we will search the suspicious labels table
for J in 1 .. Suspicious_Labels.Last loop
declare
SLE : Suspicious_Label_Entry renames
Suspicious_Labels.Table (J);
begin
-- See if character name of label matches
if Chars (Name (SLE.Proc_Call)) = Chars (End_Labl)
-- And first token of loop/block identifies this entry
and then SLE.Start_Token = STE.Sloc
then
-- We have the special case, issue the error message
Error_Msg -- CODEFIX
(""";"" should be "":""", SLE.Semicolon_Loc);
-- And indicate we consider the Label OK after all
Label_OK := True;
exit;
end if;
end;
end loop;
end if;
-- 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 := Scopes (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 Scopes (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 := Scopes (SS_Index).Labl;
Etyp : constant SS_End_Type := Scopes (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 Scopes (Scope.Last).Junk then
return;
end if;
End_Type := Scopes (Scope.Last).Etyp;
Error_Msg_Col := Scopes (Scope.Last).Ecol;
Error_Msg_Sloc := Scopes (Scope.Last).Sloc;
if Explicit_Start_Label (Scope.Last) then
Error_Msg_Node_1 := Scopes (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
Scopes (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 Scopes (Scope.Last).Junk then
return;
end if;
End_Type := Scopes (Scope.Last).Etyp;
Error_Msg_Sloc := Scopes (Scope.Last).Sloc;
if Explicit_Start_Label (Scope.Last) then
Error_Msg_Node_1 := Scopes (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
Scopes (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, Scopes (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 /= Scopes (Scope.Last).Ecol
and then Current_Line_Start > Scopes (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 (Scopes (Scope.Last).Etyp /= E_Record
or else Get_Column_Number (End_Sloc) /=
Get_Column_Number (Type_Token_Location))
then
Error_Msg_Col := Scopes (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 in Tok_Identifier | 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,
Scopes (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 Scopes (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 <= Scopes (Scope.Last).Ecol
or else (End_Type = Scopes (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;