1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2007, 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 2, 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 COPYING. If not, write --
19 -- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
20 -- Boston, MA 02110-1301, USA. --
22 -- GNAT was originally developed by the GNAT team at New York University. --
23 -- Extensive contributions were provided by Ada Core Technologies Inc. --
25 ------------------------------------------------------------------------------
27 with Atree; use Atree;
28 with Checks; use Checks;
29 with Einfo; use Einfo;
30 with Errout; use Errout;
32 with Lib.Xref; use Lib.Xref;
33 with Namet; use Namet;
34 with Nlists; use Nlists;
35 with Nmake; use Nmake;
37 with Restrict; use Restrict;
38 with Rident; use Rident;
39 with Rtsfind; use Rtsfind;
41 with Sem_Ch5; use Sem_Ch5;
42 with Sem_Ch8; use Sem_Ch8;
43 with Sem_Res; use Sem_Res;
44 with Sem_Util; use Sem_Util;
45 with Sem_Warn; use Sem_Warn;
46 with Sinfo; use Sinfo;
47 with Stand; use Stand;
48 with Uintp; use Uintp;
50 package body Sem_Ch11 is
52 -----------------------------------
53 -- Analyze_Exception_Declaration --
54 -----------------------------------
56 procedure Analyze_Exception_Declaration (N : Node_Id) is
57 Id : constant Entity_Id := Defining_Identifier (N);
58 PF : constant Boolean := Is_Pure (Current_Scope);
60 Generate_Definition (Id);
62 Set_Ekind (Id, E_Exception);
63 Set_Exception_Code (Id, Uint_0);
64 Set_Etype (Id, Standard_Exception_Type);
65 Set_Is_Statically_Allocated (Id);
67 end Analyze_Exception_Declaration;
69 --------------------------------
70 -- Analyze_Exception_Handlers --
71 --------------------------------
73 procedure Analyze_Exception_Handlers (L : List_Id) is
77 H_Scope : Entity_Id := Empty;
79 procedure Check_Duplication (Id : Node_Id);
80 -- Iterate through the identifiers in each handler to find duplicates
82 function Others_Present return Boolean;
83 -- Returns True if others handler is present
85 -----------------------
86 -- Check_Duplication --
87 -----------------------
89 procedure Check_Duplication (Id : Node_Id) is
92 Id_Entity : Entity_Id := Entity (Id);
95 if Present (Renamed_Entity (Id_Entity)) then
96 Id_Entity := Renamed_Entity (Id_Entity);
99 Handler := First_Non_Pragma (L);
100 while Present (Handler) loop
101 Id1 := First (Exception_Choices (Handler));
102 while Present (Id1) loop
104 -- Only check against the exception choices which precede
105 -- Id in the handler, since the ones that follow Id have not
106 -- been analyzed yet and will be checked in a subsequent call.
111 elsif Nkind (Id1) /= N_Others_Choice
113 (Id_Entity = Entity (Id1)
114 or else (Id_Entity = Renamed_Entity (Entity (Id1))))
116 if Handler /= Parent (Id) then
117 Error_Msg_Sloc := Sloc (Id1);
119 ("exception choice duplicates &#", Id, Id1);
122 if Ada_Version = Ada_83
123 and then Comes_From_Source (Id)
126 ("(Ada 83): duplicate exception choice&", Id);
131 Next_Non_Pragma (Id1);
136 end Check_Duplication;
142 function Others_Present return Boolean is
147 while Present (H) loop
148 if Nkind (H) /= N_Pragma
149 and then Nkind (First (Exception_Choices (H))) = N_Others_Choice
160 -- Start processing for Analyze_Exception_Handlers
163 Handler := First (L);
164 Check_Restriction (No_Exceptions, Handler);
165 Check_Restriction (No_Exception_Handlers, Handler);
167 -- Kill current remembered values, since we don't know where we were
168 -- when the exception was raised.
172 -- Loop through handlers (which can include pragmas)
174 while Present (Handler) loop
176 -- If pragma just analyze it
178 if Nkind (Handler) = N_Pragma then
181 -- Otherwise we have a real exception handler
184 -- Deal with choice parameter. The exception handler is a
185 -- declarative part for the choice parameter, so it constitutes a
186 -- scope for visibility purposes. We create an entity to denote
187 -- the whole exception part, and use it as the scope of all the
188 -- choices, which may even have the same name without conflict.
189 -- This scope plays no other role in expansion or or code
192 Choice := Choice_Parameter (Handler);
194 if Present (Choice) then
195 Set_Local_Raise_Not_OK (Handler);
197 if Comes_From_Source (Choice) then
198 Check_Restriction (No_Exception_Propagation, Choice);
204 (E_Block, Current_Scope, Sloc (Choice), 'E');
207 Push_Scope (H_Scope);
208 Set_Etype (H_Scope, Standard_Void_Type);
210 -- Set the Finalization Chain entity to Error means that it
211 -- should not be used at that level but the parent one should
214 -- ??? this usage needs documenting in Einfo/Exp_Ch7 ???
215 -- ??? using Error for this non-error condition is nasty ???
217 Set_Finalization_Chain_Entity (H_Scope, Error);
220 Set_Ekind (Choice, E_Variable);
222 if RTE_Available (RE_Exception_Occurrence) then
223 Set_Etype (Choice, RTE (RE_Exception_Occurrence));
226 Generate_Definition (Choice);
228 -- Set source assigned flag, since in effect this field is
229 -- always assigned an initial value by the exception.
231 Set_Never_Set_In_Source (Choice, False);
234 Id := First (Exception_Choices (Handler));
235 while Present (Id) loop
236 if Nkind (Id) = N_Others_Choice then
237 if Present (Next (Id))
238 or else Present (Next (Handler))
239 or else Present (Prev (Id))
241 Error_Msg_N ("OTHERS must appear alone and last", Id);
247 -- In most cases the choice has already been analyzed in
248 -- Analyze_Handled_Statement_Sequence, in order to expand
249 -- local handlers. This advance analysis does not take into
250 -- account the case in which a choice has the same name as
251 -- the choice parameter of the handler, which may hide an
252 -- outer exception. This pathological case appears in ACATS
253 -- B80001_3.adb, and requires an explicit check to verify
254 -- that the id is not hidden.
256 if not Is_Entity_Name (Id)
257 or else Ekind (Entity (Id)) /= E_Exception
259 (Nkind (Id) = N_Identifier
260 and then Chars (Id) = Chars (Choice))
262 Error_Msg_N ("exception name expected", Id);
265 if Present (Renamed_Entity (Entity (Id))) then
266 if Entity (Id) = Standard_Numeric_Error then
267 Check_Restriction (No_Obsolescent_Features, Id);
269 if Warn_On_Obsolescent_Feature then
271 ("Numeric_Error is an " &
272 "obsolescent feature ('R'M 'J.6(1))?", Id);
274 ("\use Constraint_Error instead?", Id);
279 Check_Duplication (Id);
281 -- Check for exception declared within generic formal
282 -- package (which is illegal, see RM 11.2(8))
285 Ent : Entity_Id := Entity (Id);
289 if Present (Renamed_Entity (Ent)) then
290 Ent := Renamed_Entity (Ent);
294 while Scop /= Standard_Standard
295 and then Ekind (Scop) = E_Package
297 if Nkind (Declaration_Node (Scop)) =
298 N_Package_Specification
300 Nkind (Original_Node (Parent
301 (Declaration_Node (Scop)))) =
302 N_Formal_Package_Declaration
305 ("exception& is declared in " &
306 "generic formal package", Id, Ent);
308 ("\and therefore cannot appear in " &
309 "handler ('R'M 11.2(8))", Id);
312 -- If the exception is declared in an inner
313 -- instance, nothing else to check.
315 elsif Is_Generic_Instance (Scop) then
319 Scop := Scope (Scop);
328 -- Check for redundant handler (has only raise statement) and is
329 -- either an others handler, or is a specific handler when no
330 -- others handler is present.
332 if Warn_On_Redundant_Constructs
333 and then List_Length (Statements (Handler)) = 1
334 and then Nkind (First (Statements (Handler))) = N_Raise_Statement
335 and then No (Name (First (Statements (Handler))))
336 and then (not Others_Present
337 or else Nkind (First (Exception_Choices (Handler))) =
341 ("useless handler contains only a reraise statement?",
345 -- Now analyze the statements of this handler
347 Analyze_Statements (Statements (Handler));
349 -- If a choice was present, we created a special scope for it,
350 -- so this is where we pop that special scope to get rid of it.
352 if Present (Choice) then
359 end Analyze_Exception_Handlers;
361 --------------------------------
362 -- Analyze_Handled_Statements --
363 --------------------------------
365 procedure Analyze_Handled_Statements (N : Node_Id) is
366 Handlers : constant List_Id := Exception_Handlers (N);
371 if Present (Handlers) then
375 -- We are now going to analyze the statements and then the exception
376 -- handlers. We certainly need to do things in this order to get the
377 -- proper sequential semantics for various warnings.
379 -- However, there is a glitch. When we process raise statements, an
380 -- optimization is to look for local handlers and specialize the code
383 -- In order to detect if a handler is matching, we must have at least
384 -- analyzed the choices in the proper scope so that proper visibility
385 -- analysis is performed. Hence we analyze just the choices first,
386 -- before we analyze the statement sequence.
388 Handler := First_Non_Pragma (Handlers);
389 while Present (Handler) loop
390 Choice := First_Non_Pragma (Exception_Choices (Handler));
391 while Present (Choice) loop
393 Next_Non_Pragma (Choice);
396 Next_Non_Pragma (Handler);
399 -- Analyze statements in sequence
401 Analyze_Statements (Statements (N));
403 -- If the current scope is a subprogram, then this is the right place to
404 -- check for hanging useless assignments from the statement sequence of
405 -- the subprogram body.
407 if Is_Subprogram (Current_Scope) then
408 Warn_On_Useless_Assignments (Current_Scope);
411 -- Deal with handlers or AT END proc
413 if Present (Handlers) then
414 Analyze_Exception_Handlers (Handlers);
415 elsif Present (At_End_Proc (N)) then
416 Analyze (At_End_Proc (N));
418 end Analyze_Handled_Statements;
420 -----------------------------
421 -- Analyze_Raise_Statement --
422 -----------------------------
424 procedure Analyze_Raise_Statement (N : Node_Id) is
425 Exception_Id : constant Node_Id := Name (N);
426 Exception_Name : Entity_Id := Empty;
431 Check_Unreachable_Code (N);
433 -- Check exception restrictions on the original source
435 if Comes_From_Source (N) then
436 Check_Restriction (No_Exceptions, N);
439 -- Check for useless assignment to OUT or IN OUT scalar immediately
440 -- preceding the raise. Right now we only look at assignment statements,
443 if Is_List_Member (N) then
452 and then Nkind (P) = N_Assignment_Statement
456 if Is_Scalar_Type (Etype (L))
457 and then Is_Entity_Name (L)
458 and then Is_Formal (Entity (L))
461 ("?assignment to pass-by-copy formal may have no effect",
464 ("\?RAISE statement may result in abnormal return" &
465 " ('R'M 6.4.1(17))", P);
473 if No (Exception_Id) then
475 Nkind_P := Nkind (P);
477 while Nkind_P /= N_Exception_Handler
478 and then Nkind_P /= N_Subprogram_Body
479 and then Nkind_P /= N_Package_Body
480 and then Nkind_P /= N_Task_Body
481 and then Nkind_P /= N_Entry_Body
484 Nkind_P := Nkind (P);
487 if Nkind (P) /= N_Exception_Handler then
489 ("reraise statement must appear directly in a handler", N);
491 -- If a handler has a reraise, it cannot be the target of a local
492 -- raise (goto optimization is impossible), and if the no exception
493 -- propagation restriction is set, this is a violation.
496 Set_Local_Raise_Not_OK (P);
497 Check_Restriction (No_Exception_Propagation, N);
500 -- Normal case with exception id present
503 Analyze (Exception_Id);
505 if Is_Entity_Name (Exception_Id) then
506 Exception_Name := Entity (Exception_Id);
509 if No (Exception_Name)
510 or else Ekind (Exception_Name) /= E_Exception
513 ("exception name expected in raise statement", Exception_Id);
516 if Present (Expression (N)) then
517 Analyze_And_Resolve (Expression (N), Standard_String);
520 end Analyze_Raise_Statement;
522 -----------------------------
523 -- Analyze_Raise_xxx_Error --
524 -----------------------------
526 -- Normally, the Etype is already set (when this node is used within
527 -- an expression, since it is copied from the node which it rewrites).
528 -- If this node is used in a statement context, then we set the type
529 -- Standard_Void_Type. This is used both by Gigi and by the front end
530 -- to distinguish the statement use and the subexpression use.
532 -- The only other required processing is to take care of the Condition
533 -- field if one is present.
535 procedure Analyze_Raise_xxx_Error (N : Node_Id) is
537 if No (Etype (N)) then
538 Set_Etype (N, Standard_Void_Type);
541 if Present (Condition (N)) then
542 Analyze_And_Resolve (Condition (N), Standard_Boolean);
545 -- Deal with static cases in obvious manner
547 if Nkind (Condition (N)) = N_Identifier then
548 if Entity (Condition (N)) = Standard_True then
549 Set_Condition (N, Empty);
551 elsif Entity (Condition (N)) = Standard_False then
552 Rewrite (N, Make_Null_Statement (Sloc (N)));
555 end Analyze_Raise_xxx_Error;
557 -----------------------------
558 -- Analyze_Subprogram_Info --
559 -----------------------------
561 procedure Analyze_Subprogram_Info (N : Node_Id) is
563 Set_Etype (N, RTE (RE_Code_Loc));
564 end Analyze_Subprogram_Info;