1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2004 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, 59 Temple Place - Suite 330, Boston, --
20 -- MA 02111-1307, 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 Nlists; use Nlists;
34 with Nmake; use Nmake;
36 with Restrict; use Restrict;
37 with Rident; use Rident;
38 with Rtsfind; use Rtsfind;
40 with Sem_Ch5; use Sem_Ch5;
41 with Sem_Ch8; use Sem_Ch8;
42 with Sem_Res; use Sem_Res;
43 with Sem_Util; use Sem_Util;
44 with Sinfo; use Sinfo;
45 with Stand; use Stand;
46 with Uintp; use Uintp;
48 package body Sem_Ch11 is
50 -----------------------------------
51 -- Analyze_Exception_Declaration --
52 -----------------------------------
54 procedure Analyze_Exception_Declaration (N : Node_Id) is
55 Id : constant Entity_Id := Defining_Identifier (N);
56 PF : constant Boolean := Is_Pure (Current_Scope);
59 Generate_Definition (Id);
61 Set_Ekind (Id, E_Exception);
62 Set_Exception_Code (Id, Uint_0);
63 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
185 -- a declarative part for it, so it constitutes a scope
186 -- for visibility purposes. We create an entity to denote
187 -- the whole exception part, and use it as the scope of all
188 -- the choices, which may even have the same name without
189 -- conflict. This scope plays no other role in expansion or
190 -- or code generation.
192 Choice := Choice_Parameter (Handler);
194 if Present (Choice) then
196 H_Scope := New_Internal_Entity
197 (E_Block, Current_Scope, Sloc (Choice), 'E');
201 Set_Etype (H_Scope, Standard_Void_Type);
203 -- Set the Finalization Chain entity to Error means that it
204 -- should not be used at that level but the parent one
205 -- should be used instead.
207 -- ??? this usage needs documenting in Einfo/Exp_Ch7 ???
208 -- ??? using Error for this non-error condition is nasty ???
210 Set_Finalization_Chain_Entity (H_Scope, Error);
213 Set_Ekind (Choice, E_Variable);
214 Set_Etype (Choice, RTE (RE_Exception_Occurrence));
215 Generate_Definition (Choice);
217 -- Set source assigned flag, since in effect this field
218 -- is always assigned an initial value by the exception.
220 Set_Never_Set_In_Source (Choice, False);
223 Id := First (Exception_Choices (Handler));
224 while Present (Id) loop
225 if Nkind (Id) = N_Others_Choice then
226 if Present (Next (Id))
227 or else Present (Next (Handler))
228 or else Present (Prev (Id))
230 Error_Msg_N ("OTHERS must appear alone and last", Id);
236 if not Is_Entity_Name (Id)
237 or else Ekind (Entity (Id)) /= E_Exception
239 Error_Msg_N ("exception name expected", Id);
242 if Present (Renamed_Entity (Entity (Id))) then
243 if Entity (Id) = Standard_Numeric_Error
244 and then Warn_On_Obsolescent_Feature
247 ("Numeric_Error is an " &
248 "obsolescent feature ('R'M 'J.6(1))?", Id);
250 ("|use Constraint_Error instead?", Id);
254 Check_Duplication (Id);
256 -- Check for exception declared within generic formal
257 -- package (which is illegal, see RM 11.2(8))
260 Ent : Entity_Id := Entity (Id);
264 if Present (Renamed_Entity (Ent)) then
265 Ent := Renamed_Entity (Ent);
269 while Scop /= Standard_Standard
270 and then Ekind (Scop) = E_Package
272 -- If the exception is declared in an inner
273 -- instance, nothing else to check.
275 if Is_Generic_Instance (Scop) then
278 elsif Nkind (Declaration_Node (Scop)) =
279 N_Package_Specification
281 Nkind (Original_Node (Parent
282 (Declaration_Node (Scop)))) =
283 N_Formal_Package_Declaration
286 ("exception& is declared in " &
287 "generic formal package", Id, Ent);
289 ("\and therefore cannot appear in " &
290 "handler ('R'M 11.2(8))", Id);
294 Scop := Scope (Scop);
303 -- Check for redundant handler (has only raise statement) and
304 -- is either an others handler, or is a specific handler when
305 -- no others handler is present.
307 if Warn_On_Redundant_Constructs
308 and then List_Length (Statements (Handler)) = 1
309 and then Nkind (First (Statements (Handler))) = N_Raise_Statement
310 and then No (Name (First (Statements (Handler))))
311 and then (not Others_Present
312 or else Nkind (First (Exception_Choices (Handler))) =
316 ("useless handler contains only a reraise statement?",
320 -- Now analyze the statements of this handler
322 Analyze_Statements (Statements (Handler));
324 -- If a choice was present, we created a special scope for it,
325 -- so this is where we pop that special scope to get rid of it.
327 if Present (Choice) then
334 end Analyze_Exception_Handlers;
336 --------------------------------
337 -- Analyze_Handled_Statements --
338 --------------------------------
340 procedure Analyze_Handled_Statements (N : Node_Id) is
341 Handlers : constant List_Id := Exception_Handlers (N);
344 if Present (Handlers) then
348 Analyze_Statements (Statements (N));
350 if Present (Handlers) then
351 Analyze_Exception_Handlers (Handlers);
353 elsif Present (At_End_Proc (N)) then
354 Analyze (At_End_Proc (N));
356 end Analyze_Handled_Statements;
358 -----------------------------
359 -- Analyze_Raise_Statement --
360 -----------------------------
362 procedure Analyze_Raise_Statement (N : Node_Id) is
363 Exception_Id : constant Node_Id := Name (N);
364 Exception_Name : Entity_Id := Empty;
369 Check_Unreachable_Code (N);
371 -- Check exception restrictions on the original source
373 if Comes_From_Source (N) then
374 Check_Restriction (No_Exceptions, N);
377 -- Check for useless assignment to OUT or IN OUT scalar
378 -- immediately preceding the raise. Right now we only look
379 -- at assignment statements, we could do more.
381 if Is_List_Member (N) then
390 and then Nkind (P) = N_Assignment_Statement
394 if Is_Scalar_Type (Etype (L))
395 and then Is_Entity_Name (L)
396 and then Is_Formal (Entity (L))
399 ("?assignment to pass-by-copy formal may have no effect",
402 ("\?RAISE statement is abnormal return" &
403 " ('R'M 6.4.1(17))", P);
411 if No (Exception_Id) then
414 Nkind_P := Nkind (P);
416 while Nkind_P /= N_Exception_Handler
417 and then Nkind_P /= N_Subprogram_Body
418 and then Nkind_P /= N_Package_Body
419 and then Nkind_P /= N_Task_Body
420 and then Nkind_P /= N_Entry_Body
423 Nkind_P := Nkind (P);
426 if Nkind (P) /= N_Exception_Handler then
428 ("reraise statement must appear directly in a handler", N);
431 -- Normal case with exception id present
434 Analyze (Exception_Id);
436 if Is_Entity_Name (Exception_Id) then
437 Exception_Name := Entity (Exception_Id);
440 if No (Exception_Name)
441 or else Ekind (Exception_Name) /= E_Exception
444 ("exception name expected in raise statement", Exception_Id);
447 end Analyze_Raise_Statement;
449 -----------------------------
450 -- Analyze_Raise_xxx_Error --
451 -----------------------------
453 -- Normally, the Etype is already set (when this node is used within
454 -- an expression, since it is copied from the node which it rewrites).
455 -- If this node is used in a statement context, then we set the type
456 -- Standard_Void_Type. This is used both by Gigi and by the front end
457 -- to distinguish the statement use and the subexpression use.
459 -- The only other required processing is to take care of the Condition
460 -- field if one is present.
462 procedure Analyze_Raise_xxx_Error (N : Node_Id) is
464 if No (Etype (N)) then
465 Set_Etype (N, Standard_Void_Type);
468 if Present (Condition (N)) then
469 Analyze_And_Resolve (Condition (N), Standard_Boolean);
472 -- Deal with static cases in obvious manner
474 if Nkind (Condition (N)) = N_Identifier then
475 if Entity (Condition (N)) = Standard_True then
476 Set_Condition (N, Empty);
478 elsif Entity (Condition (N)) = Standard_False then
479 Rewrite (N, Make_Null_Statement (Sloc (N)));
482 end Analyze_Raise_xxx_Error;
484 -----------------------------
485 -- Analyze_Subprogram_Info --
486 -----------------------------
488 procedure Analyze_Subprogram_Info (N : Node_Id) is
490 Set_Etype (N, RTE (RE_Code_Loc));
491 end Analyze_Subprogram_Info;