aboutsummaryrefslogtreecommitdiffstats
path: root/gcc-4.9/gcc/cp/except.c
blob: 3a66c678b6ba2a04f45534905f17ced6eef49799 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
/* Handle exceptional things in C++.
   Copyright (C) 1989-2014 Free Software Foundation, Inc.
   Contributed by Michael Tiemann <tiemann@cygnus.com>
   Rewritten by Mike Stump <mrs@cygnus.com>, based upon an
   initial re-implementation courtesy Tad Hunt.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.

GCC is distributed in the hope that it will be useful,
but WITHOUT 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
along with GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */


#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
#include "stringpool.h"
#include "trans-mem.h"
#include "attribs.h"
#include "cp-tree.h"
#include "flags.h"
#include "tree-inline.h"
#include "tree-iterator.h"
#include "target.h"

static void push_eh_cleanup (tree);
static tree prepare_eh_type (tree);
static tree do_begin_catch (void);
static int dtor_nothrow (tree);
static tree do_end_catch (tree);
static bool decl_is_java_type (tree decl, int err);
static void initialize_handler_parm (tree, tree);
static tree do_allocate_exception (tree);
static tree wrap_cleanups_r (tree *, int *, void *);
static int complete_ptr_ref_or_void_ptr_p (tree, tree);
static bool is_admissible_throw_operand_or_catch_parameter (tree, bool);
static int can_convert_eh (tree, tree);

/* Sets up all the global eh stuff that needs to be initialized at the
   start of compilation.  */

void
init_exception_processing (void)
{
  tree tmp;

  /* void std::terminate (); */
  push_namespace (std_identifier);
  tmp = build_function_type_list (void_type_node, NULL_TREE);
  terminate_node = build_cp_library_fn_ptr ("terminate", tmp,
					   ECF_NOTHROW | ECF_NORETURN);
  TREE_THIS_VOLATILE (terminate_node) = 1;
  TREE_NOTHROW (terminate_node) = 1;
  pop_namespace ();

  /* void __cxa_call_unexpected(void *); */
  tmp = build_function_type_list (void_type_node, ptr_type_node, NULL_TREE);
  call_unexpected_node
    = push_throw_library_fn (get_identifier ("__cxa_call_unexpected"), tmp);
}

/* Returns an expression to be executed if an unhandled exception is
   propagated out of a cleanup region.  */

tree
cp_protect_cleanup_actions (void)
{
  /* [except.terminate]

     When the destruction of an object during stack unwinding exits
     using an exception ... void terminate(); is called.  */
  return terminate_node;
}

static tree
prepare_eh_type (tree type)
{
  if (type == NULL_TREE)
    return type;
  if (type == error_mark_node)
    return error_mark_node;

  /* peel back references, so they match.  */
  type = non_reference (type);

  /* Peel off cv qualifiers.  */
  type = TYPE_MAIN_VARIANT (type);

  /* Functions and arrays decay to pointers.  */
  type = type_decays_to (type);

  return type;
}

/* Return the type info for TYPE as used by EH machinery.  */
tree
eh_type_info (tree type)
{
  tree exp;

  if (type == NULL_TREE || type == error_mark_node)
    return type;

  if (decl_is_java_type (type, 0))
    exp = build_java_class_ref (TREE_TYPE (type));
  else
    exp = get_tinfo_decl (type);

  return exp;
}

/* Build the address of a typeinfo decl for use in the runtime
   matching field of the exception model.  */

tree
build_eh_type_type (tree type)
{
  tree exp = eh_type_info (type);

  if (!exp)
    return NULL;

  mark_used (exp);

  return convert (ptr_type_node, build_address (exp));
}

tree
build_exc_ptr (void)
{
  return build_call_n (builtin_decl_explicit (BUILT_IN_EH_POINTER),
		       1, integer_zero_node);
}

/* Declare a function NAME, returning RETURN_TYPE, taking a single
   parameter PARM_TYPE, with an empty exception specification.

   Note that the C++ ABI document does not have a throw-specifier on
   the routines declared below via this function.  The declarations
   are consistent with the actual implementations in libsupc++.  */

static tree
declare_library_fn (tree name, tree return_type, tree parm_type, int ecf_flags)
{
  return push_library_fn (name, build_function_type_list (return_type,
							  parm_type,
							  NULL_TREE),
			  empty_except_spec,
			  ecf_flags);
}

/* Build up a call to __cxa_get_exception_ptr so that we can build a
   copy constructor for the thrown object.  */

static tree
do_get_exception_ptr (void)
{
  tree fn;

  fn = get_identifier ("__cxa_get_exception_ptr");
  if (!get_global_value_if_present (fn, &fn))
    {
      /* Declare void* __cxa_get_exception_ptr (void *) throw().  */
      fn = declare_library_fn (fn, ptr_type_node, ptr_type_node,
			       ECF_NOTHROW | ECF_PURE | ECF_LEAF | ECF_TM_PURE);
    }

  return cp_build_function_call_nary (fn, tf_warning_or_error,
				      build_exc_ptr (), NULL_TREE);
}

/* Build up a call to __cxa_begin_catch, to tell the runtime that the
   exception has been handled.  */

static tree
do_begin_catch (void)
{
  tree fn;

  fn = get_identifier ("__cxa_begin_catch");
  if (!get_global_value_if_present (fn, &fn))
    {
      /* Declare void* __cxa_begin_catch (void *) throw().  */
      fn = declare_library_fn (fn, ptr_type_node, ptr_type_node, ECF_NOTHROW);

      /* Create its transactional-memory equivalent.  */
      if (flag_tm)
	{
	  tree fn2 = get_identifier ("_ITM_cxa_begin_catch");
	  if (!get_global_value_if_present (fn2, &fn2))
	    fn2 = declare_library_fn (fn2, ptr_type_node,
				      ptr_type_node, ECF_NOTHROW | ECF_TM_PURE);
	  record_tm_replacement (fn, fn2);
	}
    }

  return cp_build_function_call_nary (fn, tf_warning_or_error,
				      build_exc_ptr (), NULL_TREE);
}

/* Returns nonzero if cleaning up an exception of type TYPE (which can be
   NULL_TREE for a ... handler) will not throw an exception.  */

static int
dtor_nothrow (tree type)
{
  if (type == NULL_TREE || type == error_mark_node)
    return 0;

  if (TYPE_HAS_TRIVIAL_DESTRUCTOR (type))
    return 1;

  if (CLASSTYPE_LAZY_DESTRUCTOR (type))
    lazily_declare_fn (sfk_destructor, type);

  return TREE_NOTHROW (CLASSTYPE_DESTRUCTORS (type));
}

/* Build up a call to __cxa_end_catch, to destroy the exception object
   for the current catch block if no others are currently using it.  */

static tree
do_end_catch (tree type)
{
  tree fn, cleanup;

  fn = get_identifier ("__cxa_end_catch");
  if (!get_global_value_if_present (fn, &fn))
    {
      /* Declare void __cxa_end_catch ().
         This can throw if the destructor for the exception throws.  */
      fn = push_void_library_fn (fn, void_list_node, 0);

      /* Create its transactional-memory equivalent.  */
      if (flag_tm)
	{
	  tree fn2 = get_identifier ("_ITM_cxa_end_catch");
	  if (!get_global_value_if_present (fn2, &fn2))
	    fn2 = push_void_library_fn (fn2, void_list_node, ECF_TM_PURE);
	  record_tm_replacement (fn, fn2);
	}
    }

  cleanup = cp_build_function_call_vec (fn, NULL, tf_warning_or_error);
  TREE_NOTHROW (cleanup) = dtor_nothrow (type);

  return cleanup;
}

/* This routine creates the cleanup for the current exception.  */

static void
push_eh_cleanup (tree type)
{
  finish_decl_cleanup (NULL_TREE, do_end_catch (type));
}

/* Return nonzero value if DECL is a Java type suitable for catch or
   throw.  */

static bool
decl_is_java_type (tree decl, int err)
{
  bool r = (TYPE_PTR_P (decl)
	    && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
	    && TYPE_FOR_JAVA (TREE_TYPE (decl)));

  if (err)
    {
      if (TREE_CODE (decl) == REFERENCE_TYPE
	  && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
	  && TYPE_FOR_JAVA (TREE_TYPE (decl)))
	{
	  /* Can't throw a reference.  */
	  error ("type %qT is disallowed in Java %<throw%> or %<catch%>",
		 decl);
	}

      if (r)
	{
	  tree jthrow_node
	    = IDENTIFIER_GLOBAL_VALUE (get_identifier ("jthrowable"));

	  if (jthrow_node == NULL_TREE)
	    fatal_error
	      ("call to Java %<catch%> or %<throw%> with %<jthrowable%> undefined");

	  jthrow_node = TREE_TYPE (TREE_TYPE (jthrow_node));

	  if (! DERIVED_FROM_P (jthrow_node, TREE_TYPE (decl)))
	    {
	      /* Thrown object must be a Throwable.  */
	      error ("type %qT is not derived from %<java::lang::Throwable%>",
		     TREE_TYPE (decl));
	    }
	}
    }

  return r;
}

/* Select the personality routine to be used for exception handling,
   or issue an error if we need two different ones in the same
   translation unit.
   ??? At present DECL_FUNCTION_PERSONALITY is set via
   LANG_HOOKS_EH_PERSONALITY.  Should it be done here instead?  */
void
choose_personality_routine (enum languages lang)
{
  static enum {
    chose_none,
    chose_cpp,
    chose_java,
    gave_error
  } state;

  switch (state)
    {
    case gave_error:
      return;

    case chose_cpp:
      if (lang != lang_cplusplus)
	goto give_error;
      return;

    case chose_java:
      if (lang != lang_java)
	goto give_error;
      return;

    case chose_none:
      ; /* Proceed to language selection.  */
    }

  switch (lang)
    {
    case lang_cplusplus:
      state = chose_cpp;
      break;

    case lang_java:
      state = chose_java;
      terminate_node = builtin_decl_explicit (BUILT_IN_ABORT);
      pragma_java_exceptions = true;
      break;

    default:
      gcc_unreachable ();
    }
  return;

 give_error:
  error ("mixing C++ and Java catches in a single translation unit");
  state = gave_error;
}

/* Wrap EXPR in a MUST_NOT_THROW_EXPR expressing that EXPR must
   not throw any exceptions if COND is true.  A condition of
   NULL_TREE is treated as 'true'.  */

tree
build_must_not_throw_expr (tree body, tree cond)
{
  tree type = body ? TREE_TYPE (body) : void_type_node;

  if (!flag_exceptions)
    return body;

  if (cond && !value_dependent_expression_p (cond))
    {
      cond = cxx_constant_value (cond);
      if (integer_zerop (cond))
	return body;
      else if (integer_onep (cond))
	cond = NULL_TREE;
    }

  return build2 (MUST_NOT_THROW_EXPR, type, body, cond);
}


/* Initialize the catch parameter DECL.  */

static void
initialize_handler_parm (tree decl, tree exp)
{
  tree init;
  tree init_type;

  /* Make sure we mark the catch param as used, otherwise we'll get a
     warning about an unused ((anonymous)).  */
  TREE_USED (decl) = 1;
  DECL_READ_P (decl) = 1;

  /* Figure out the type that the initializer is.  Pointers are returned
     adjusted by value from __cxa_begin_catch.  Others are returned by
     reference.  */
  init_type = TREE_TYPE (decl);
  if (!POINTER_TYPE_P (init_type))
    init_type = build_reference_type (init_type);

  choose_personality_routine (decl_is_java_type (init_type, 0)
			      ? lang_java : lang_cplusplus);

  /* Since pointers are passed by value, initialize a reference to
     pointer catch parm with the address of the temporary.  */
  if (TREE_CODE (init_type) == REFERENCE_TYPE
      && TYPE_PTR_P (TREE_TYPE (init_type)))
    exp = cp_build_addr_expr (exp, tf_warning_or_error);

  exp = ocp_convert (init_type, exp, CONV_IMPLICIT|CONV_FORCE_TEMP, 0,
		     tf_warning_or_error);

  init = convert_from_reference (exp);

  /* If the constructor for the catch parm exits via an exception, we
     must call terminate.  See eh23.C.  */
  if (TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl)))
    {
      /* Generate the copy constructor call directly so we can wrap it.
	 See also expand_default_init.  */
      init = ocp_convert (TREE_TYPE (decl), init,
			  CONV_IMPLICIT|CONV_FORCE_TEMP, 0,
			  tf_warning_or_error);
      /* Force cleanups now to avoid nesting problems with the
	 MUST_NOT_THROW_EXPR.  */
      init = fold_build_cleanup_point_expr (TREE_TYPE (init), init);
      init = build_must_not_throw_expr (init, NULL_TREE);
    }

  decl = pushdecl (decl);

  start_decl_1 (decl, true);
  cp_finish_decl (decl, init, /*init_const_expr_p=*/false, NULL_TREE,
		  LOOKUP_ONLYCONVERTING|DIRECT_BIND);
}


/* Routine to see if exception handling is turned on.
   DO_WARN is nonzero if we want to inform the user that exception
   handling is turned off.

   This is used to ensure that -fexceptions has been specified if the
   compiler tries to use any exception-specific functions.  */

static inline int
doing_eh (void)
{
  if (! flag_exceptions)
    {
      static int warned = 0;
      if (! warned)
	{
	  error ("exception handling disabled, use -fexceptions to enable");
	  warned = 1;
	}
      return 0;
    }
  return 1;
}

/* Call this to start a catch block.  DECL is the catch parameter.  */

tree
expand_start_catch_block (tree decl)
{
  tree exp;
  tree type, init;

  if (! doing_eh ())
    return NULL_TREE;

  if (decl)
    {
      if (!is_admissible_throw_operand_or_catch_parameter (decl, false))
	decl = error_mark_node;

      type = prepare_eh_type (TREE_TYPE (decl));
      mark_used (eh_type_info (type));
    }
  else
    type = NULL_TREE;

  if (decl && decl_is_java_type (type, 1))
    {
      /* Java only passes object via pointer and doesn't require
	 adjusting.  The java object is immediately before the
	 generic exception header.  */
      exp = build_exc_ptr ();
      exp = build1 (NOP_EXPR, build_pointer_type (type), exp);
      exp = fold_build_pointer_plus (exp,
		    fold_build1_loc (input_location,
				     NEGATE_EXPR, sizetype,
				     TYPE_SIZE_UNIT (TREE_TYPE (exp))));
      exp = cp_build_indirect_ref (exp, RO_NULL, tf_warning_or_error);
      initialize_handler_parm (decl, exp);
      return type;
    }

  /* Call __cxa_end_catch at the end of processing the exception.  */
  push_eh_cleanup (type);

  init = do_begin_catch ();

  /* If there's no decl at all, then all we need to do is make sure
     to tell the runtime that we've begun handling the exception.  */
  if (decl == NULL || decl == error_mark_node || init == error_mark_node)
    finish_expr_stmt (init);

  /* If the C++ object needs constructing, we need to do that before
     calling __cxa_begin_catch, so that std::uncaught_exception gets
     the right value during the copy constructor.  */
  else if (flag_use_cxa_get_exception_ptr
	   && TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl)))
    {
      exp = do_get_exception_ptr ();
      initialize_handler_parm (decl, exp);
      finish_expr_stmt (init);
    }

  /* Otherwise the type uses a bitwise copy, and we don't have to worry
     about the value of std::uncaught_exception and therefore can do the
     copy with the return value of __cxa_end_catch instead.  */
  else
    {
      tree init_type = type;

      /* Pointers are passed by values, everything else by reference.  */
      if (!TYPE_PTR_P (type))
	init_type = build_pointer_type (type);
      if (init_type != TREE_TYPE (init))
	init = build1 (NOP_EXPR, init_type, init);
      exp = create_temporary_var (init_type);
      DECL_REGISTER (exp) = 1;
      cp_finish_decl (exp, init, /*init_const_expr=*/false,
		      NULL_TREE, LOOKUP_ONLYCONVERTING);
      initialize_handler_parm (decl, exp);
    }

  return type;
}


/* Call this to end a catch block.  Its responsible for emitting the
   code to handle jumping back to the correct place, and for emitting
   the label to jump to if this catch block didn't match.  */

void
expand_end_catch_block (void)
{
  if (! doing_eh ())
    return;

  /* The exception being handled is rethrown if control reaches the end of
     a handler of the function-try-block of a constructor or destructor.  */
  if (in_function_try_handler
      && (DECL_CONSTRUCTOR_P (current_function_decl)
	  || DECL_DESTRUCTOR_P (current_function_decl)))
    finish_expr_stmt (build_throw (NULL_TREE));
}

tree
begin_eh_spec_block (void)
{
  tree r;
  location_t spec_location = DECL_SOURCE_LOCATION (current_function_decl);

  /* A noexcept specification (or throw() with -fnothrow-opt) is a
     MUST_NOT_THROW_EXPR.  */
  if (TYPE_NOEXCEPT_P (TREE_TYPE (current_function_decl)))
    {
      r = build_stmt (spec_location, MUST_NOT_THROW_EXPR,
		      NULL_TREE, NULL_TREE);
      TREE_SIDE_EFFECTS (r) = 1;
    }
  else
    r = build_stmt (spec_location, EH_SPEC_BLOCK, NULL_TREE, NULL_TREE);
  add_stmt (r);
  TREE_OPERAND (r, 0) = push_stmt_list ();
  return r;
}

void
finish_eh_spec_block (tree raw_raises, tree eh_spec_block)
{
  tree raises;

  TREE_OPERAND (eh_spec_block, 0)
    = pop_stmt_list (TREE_OPERAND (eh_spec_block, 0));

  if (TREE_CODE (eh_spec_block) == MUST_NOT_THROW_EXPR)
    return;

  /* Strip cv quals, etc, from the specification types.  */
  for (raises = NULL_TREE;
       raw_raises && TREE_VALUE (raw_raises);
       raw_raises = TREE_CHAIN (raw_raises))
    {
      tree type = prepare_eh_type (TREE_VALUE (raw_raises));
      tree tinfo = eh_type_info (type);

      mark_used (tinfo);
      raises = tree_cons (NULL_TREE, type, raises);
    }

  EH_SPEC_RAISES (eh_spec_block) = raises;
}

/* Return a pointer to a buffer for an exception object of type TYPE.  */

static tree
do_allocate_exception (tree type)
{
  tree fn;

  fn = get_identifier ("__cxa_allocate_exception");
  if (!get_global_value_if_present (fn, &fn))
    {
      /* Declare void *__cxa_allocate_exception(size_t) throw().  */
      fn = declare_library_fn (fn, ptr_type_node, size_type_node,
			        ECF_NOTHROW | ECF_MALLOC);

      if (flag_tm)
	{
	  tree fn2 = get_identifier ("_ITM_cxa_allocate_exception");
	  if (!get_global_value_if_present (fn2, &fn2))
	    fn2 = declare_library_fn (fn2, ptr_type_node,
				      size_type_node, 
				      ECF_NOTHROW | ECF_MALLOC | ECF_TM_PURE);
	  record_tm_replacement (fn, fn2);
	}
    }

  return cp_build_function_call_nary (fn, tf_warning_or_error,
				      size_in_bytes (type), NULL_TREE);
}

/* Call __cxa_free_exception from a cleanup.  This is never invoked
   directly, but see the comment for stabilize_throw_expr.  */

static tree
do_free_exception (tree ptr)
{
  tree fn;

  fn = get_identifier ("__cxa_free_exception");
  if (!get_global_value_if_present (fn, &fn))
    {
      /* Declare void __cxa_free_exception (void *) throw().  */
      fn = declare_library_fn (fn, void_type_node, ptr_type_node,
			       ECF_NOTHROW | ECF_LEAF);
    }

  return cp_build_function_call_nary (fn, tf_warning_or_error, ptr, NULL_TREE);
}

/* Wrap all cleanups for TARGET_EXPRs in MUST_NOT_THROW_EXPR.
   Called from build_throw via walk_tree_without_duplicates.  */

static tree
wrap_cleanups_r (tree *tp, int *walk_subtrees, void * /*data*/)
{
  tree exp = *tp;
  tree cleanup;

  /* Don't walk into types.  */
  if (TYPE_P (exp))
    {
      *walk_subtrees = 0;
      return NULL_TREE;
    }
  if (TREE_CODE (exp) != TARGET_EXPR)
    return NULL_TREE;

  cleanup = TARGET_EXPR_CLEANUP (exp);
  if (cleanup)
    {
      cleanup = build2 (MUST_NOT_THROW_EXPR, void_type_node, cleanup,
			NULL_TREE);
      TARGET_EXPR_CLEANUP (exp) = cleanup;
    }

  /* Keep iterating.  */
  return NULL_TREE;
}

/* Build a throw expression.  */

tree
build_throw (tree exp)
{
  tree fn;

  if (exp == error_mark_node)
    return exp;

  if (processing_template_decl)
    {
      if (cfun)
	current_function_returns_abnormally = 1;
      exp = build_min (THROW_EXPR, void_type_node, exp);
      SET_EXPR_LOCATION (exp, input_location);
      return exp;
    }

  if (exp == null_node)
    warning (0, "throwing NULL, which has integral, not pointer type");

  if (exp != NULL_TREE)
    {
      if (!is_admissible_throw_operand_or_catch_parameter (exp, true))
	return error_mark_node;
    }

  if (! doing_eh ())
    return error_mark_node;

  if (exp && decl_is_java_type (TREE_TYPE (exp), 1))
    {
      tree fn = get_identifier ("_Jv_Throw");
      if (!get_global_value_if_present (fn, &fn))
	{
	  /* Declare void _Jv_Throw (void *).  */
	  tree tmp;
	  tmp = build_function_type_list (ptr_type_node,
					  ptr_type_node, NULL_TREE);
	  fn = push_throw_library_fn (fn, tmp);
	}
      else if (really_overloaded_fn (fn))
	{
	  error ("%qD should never be overloaded", fn);
	  return error_mark_node;
	}
      fn = OVL_CURRENT (fn);
      exp = cp_build_function_call_nary (fn, tf_warning_or_error,
					 exp, NULL_TREE);
    }
  else if (exp)
    {
      tree throw_type;
      tree temp_type;
      tree cleanup;
      tree object, ptr;
      tree tmp;
      tree allocate_expr;

      /* The CLEANUP_TYPE is the internal type of a destructor.  */
      if (!cleanup_type)
	{
	  tmp = build_function_type_list (void_type_node,
					  ptr_type_node, NULL_TREE);
	  cleanup_type = build_pointer_type (tmp);
	}

      fn = get_identifier ("__cxa_throw");
      if (!get_global_value_if_present (fn, &fn))
	{
	  /* Declare void __cxa_throw (void*, void*, void (*)(void*)).  */
	  /* ??? Second argument is supposed to be "std::type_info*".  */
	  tmp = build_function_type_list (void_type_node,
					  ptr_type_node, ptr_type_node,
					  cleanup_type, NULL_TREE);
	  fn = push_throw_library_fn (fn, tmp);

	  if (flag_tm)
	    {
	      tree fn2 = get_identifier ("_ITM_cxa_throw");
	      if (!get_global_value_if_present (fn2, &fn2))
		fn2 = push_throw_library_fn (fn2, tmp);
	      apply_tm_attr (fn2, get_identifier ("transaction_pure"));
	      record_tm_replacement (fn, fn2);
	    }
	}

      /* [except.throw]

	 A throw-expression initializes a temporary object, the type
	 of which is determined by removing any top-level
	 cv-qualifiers from the static type of the operand of throw
	 and adjusting the type from "array of T" or "function return
	 T" to "pointer to T" or "pointer to function returning T"
	 respectively.  */
      temp_type = is_bitfield_expr_with_lowered_type (exp);
      if (!temp_type)
	temp_type = cv_unqualified (type_decays_to (TREE_TYPE (exp)));

      /* OK, this is kind of wacky.  The standard says that we call
	 terminate when the exception handling mechanism, after
	 completing evaluation of the expression to be thrown but
	 before the exception is caught (_except.throw_), calls a
	 user function that exits via an uncaught exception.

	 So we have to protect the actual initialization of the
	 exception object with terminate(), but evaluate the
	 expression first.  Since there could be temps in the
	 expression, we need to handle that, too.  We also expand
	 the call to __cxa_allocate_exception first (which doesn't
	 matter, since it can't throw).  */

      /* Allocate the space for the exception.  */
      allocate_expr = do_allocate_exception (temp_type);
      allocate_expr = get_target_expr (allocate_expr);
      ptr = TARGET_EXPR_SLOT (allocate_expr);
      TARGET_EXPR_CLEANUP (allocate_expr) = do_free_exception (ptr);
      CLEANUP_EH_ONLY (allocate_expr) = 1;

      object = build_nop (build_pointer_type (temp_type), ptr);
      object = cp_build_indirect_ref (object, RO_NULL, tf_warning_or_error);

      /* And initialize the exception object.  */
      if (CLASS_TYPE_P (temp_type))
	{
	  int flags = LOOKUP_NORMAL | LOOKUP_ONLYCONVERTING;
	  vec<tree, va_gc> *exp_vec;

	  /* Under C++0x [12.8/16 class.copy], a thrown lvalue is sometimes
	     treated as an rvalue for the purposes of overload resolution
	     to favor move constructors over copy constructors.  */
	  if (/* Must be a local, automatic variable.  */
	      VAR_P (exp)
	      && DECL_CONTEXT (exp) == current_function_decl
	      && ! TREE_STATIC (exp)
	      /* The variable must not have the `volatile' qualifier.  */
	      && !(cp_type_quals (TREE_TYPE (exp)) & TYPE_QUAL_VOLATILE))
	    flags = flags | LOOKUP_PREFER_RVALUE;

	  /* Call the copy constructor.  */
	  exp_vec = make_tree_vector_single (exp);
	  exp = (build_special_member_call
		 (object, complete_ctor_identifier, &exp_vec,
		  TREE_TYPE (object), flags, tf_warning_or_error));
	  release_tree_vector (exp_vec);
	  if (exp == error_mark_node)
	    {
	      error ("  in thrown expression");
	      return error_mark_node;
	    }
	}
      else
	{
	  tmp = decay_conversion (exp, tf_warning_or_error);
	  if (tmp == error_mark_node)
	    return error_mark_node;
	  exp = build2 (INIT_EXPR, temp_type, object, tmp);
	}

      /* Mark any cleanups from the initialization as MUST_NOT_THROW, since
	 they are run after the exception object is initialized.  */
      cp_walk_tree_without_duplicates (&exp, wrap_cleanups_r, 0);

      /* Prepend the allocation.  */
      exp = build2 (COMPOUND_EXPR, TREE_TYPE (exp), allocate_expr, exp);

      /* Force all the cleanups to be evaluated here so that we don't have
	 to do them during unwinding.  */
      exp = build1 (CLEANUP_POINT_EXPR, void_type_node, exp);

      throw_type = build_eh_type_type (prepare_eh_type (TREE_TYPE (object)));

      cleanup = NULL_TREE;
      if (type_build_dtor_call (TREE_TYPE (object)))
	{
	  tree fn = lookup_fnfields (TYPE_BINFO (TREE_TYPE (object)),
				     complete_dtor_identifier, 0);
	  fn = BASELINK_FUNCTIONS (fn);
	  mark_used (fn);
	  if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TREE_TYPE (object)))
	    {
	      cxx_mark_addressable (fn);
	      /* Pretend it's a normal function.  */
	      cleanup = build1 (ADDR_EXPR, cleanup_type, fn);
	    }
	}
      if (cleanup == NULL_TREE)
	cleanup = build_int_cst (cleanup_type, 0);

      /* ??? Indicate that this function call throws throw_type.  */
      tmp = cp_build_function_call_nary (fn, tf_warning_or_error,
					 ptr, throw_type, cleanup, NULL_TREE);

      /* Tack on the initialization stuff.  */
      exp = build2 (COMPOUND_EXPR, TREE_TYPE (tmp), exp, tmp);
    }
  else
    {
      /* Rethrow current exception.  */

      tree fn = get_identifier ("__cxa_rethrow");
      if (!get_global_value_if_present (fn, &fn))
	{
	  /* Declare void __cxa_rethrow (void).  */
	  fn = push_throw_library_fn
	    (fn, build_function_type_list (void_type_node, NULL_TREE));
	}

      if (flag_tm)
	apply_tm_attr (fn, get_identifier ("transaction_pure"));

      /* ??? Indicate that this function call allows exceptions of the type
	 of the enclosing catch block (if known).  */
      exp = cp_build_function_call_vec (fn, NULL, tf_warning_or_error);
    }

  exp = build1 (THROW_EXPR, void_type_node, exp);
  SET_EXPR_LOCATION (exp, input_location);

  return exp;
}

/* Make sure TYPE is complete, pointer to complete, reference to
   complete, or pointer to cv void. Issue diagnostic on failure.
   Return the zero on failure and nonzero on success. FROM can be
   the expr or decl from whence TYPE came, if available.  */

static int
complete_ptr_ref_or_void_ptr_p (tree type, tree from)
{
  int is_ptr;

  /* Check complete.  */
  type = complete_type_or_else (type, from);
  if (!type)
    return 0;

  /* Or a pointer or ref to one, or cv void *.  */
  is_ptr = TYPE_PTR_P (type);
  if (is_ptr || TREE_CODE (type) == REFERENCE_TYPE)
    {
      tree core = TREE_TYPE (type);

      if (is_ptr && VOID_TYPE_P (core))
	/* OK */;
      else if (!complete_type_or_else (core, from))
	return 0;
    }
  return 1;
}

/* If IS_THROW is true return truth-value if T is an expression admissible
   in throw-expression, i.e. if it is not of incomplete type or a pointer/
   reference to such a type or of an abstract class type.
   If IS_THROW is false, likewise for a catch parameter, same requirements
   for its type plus rvalue reference type is also not admissible.  */

static bool
is_admissible_throw_operand_or_catch_parameter (tree t, bool is_throw)
{
  tree expr = is_throw ? t : NULL_TREE;
  tree type = TREE_TYPE (t);

  /* C++11 [except.handle] The exception-declaration shall not denote
     an incomplete type, an abstract class type, or an rvalue reference 
     type.  */

  /* 15.1/4 [...] The type of the throw-expression shall not be an
	    incomplete type, or a pointer or a reference to an incomplete
	    type, other than void*, const void*, volatile void*, or
	    const volatile void*.  Except for these restriction and the
	    restrictions on type matching mentioned in 15.3, the operand
	    of throw is treated exactly as a function argument in a call
	    (5.2.2) or the operand of a return statement.  */
  if (!complete_ptr_ref_or_void_ptr_p (type, expr))
    return false;

  /* 10.4/3 An abstract class shall not be used as a parameter type,
	    as a function return type or as type of an explicit
	    conversion.  */
  else if (abstract_virtuals_error (is_throw ? ACU_THROW : ACU_CATCH, type))
    return false;
  else if (!is_throw
	   && TREE_CODE (type) == REFERENCE_TYPE
	   && TYPE_REF_IS_RVALUE (type))
    {
      error ("cannot declare catch parameter to be of rvalue "
	     "reference type %qT", type);
      return false;
    }
  else if (variably_modified_type_p (type, NULL_TREE))
    {
      if (is_throw)
	error ("cannot throw expression of type %qT because it involves "
	       "types of variable size", type);
      else
	error ("cannot catch type %qT because it involves types of "
	       "variable size", type);
      return false;
    }

  return true;
}

/* Returns nonzero if FN is a declaration of a standard C library
   function which is known not to throw.

   [lib.res.on.exception.handling]: None of the functions from the
   Standard C library shall report an error by throwing an
   exception, unless it calls a program-supplied function that
   throws an exception.  */

#include "cfns.h"

int
nothrow_libfn_p (const_tree fn)
{
  tree id;

  if (TREE_PUBLIC (fn)
      && DECL_EXTERNAL (fn)
      && DECL_NAMESPACE_SCOPE_P (fn)
      && DECL_EXTERN_C_P (fn))
    /* OK */;
  else
    /* Can't be a C library function.  */
    return 0;

  /* Being a C library function, DECL_ASSEMBLER_NAME == DECL_NAME
     unless the system headers are playing rename tricks, and if
     they are, we don't want to be confused by them.  */
  id = DECL_NAME (fn);
  return !!libc_name_p (IDENTIFIER_POINTER (id), IDENTIFIER_LENGTH (id));
}

/* Returns nonzero if an exception of type FROM will be caught by a
   handler for type TO, as per [except.handle].  */

static int
can_convert_eh (tree to, tree from)
{
  to = non_reference (to);
  from = non_reference (from);

  if (TYPE_PTR_P (to) && TYPE_PTR_P (from))
    {
      to = TREE_TYPE (to);
      from = TREE_TYPE (from);

      if (! at_least_as_qualified_p (to, from))
	return 0;

      if (VOID_TYPE_P (to))
	return 1;

      /* Else fall through.  */
    }

  if (CLASS_TYPE_P (to) && CLASS_TYPE_P (from)
      && publicly_uniquely_derived_p (to, from))
    return 1;

  return 0;
}

/* Check whether any of the handlers in I are shadowed by another handler
   accepting TYPE.  Note that the shadowing may not be complete; even if
   an exception of type B would be caught by a handler for A, there could
   be a derived class C for which A is an ambiguous base but B is not, so
   the handler for B would catch an exception of type C.  */

static void
check_handlers_1 (tree master, tree_stmt_iterator i)
{
  tree type = TREE_TYPE (master);

  for (; !tsi_end_p (i); tsi_next (&i))
    {
      tree handler = tsi_stmt (i);
      if (TREE_TYPE (handler) && can_convert_eh (type, TREE_TYPE (handler)))
	{
	  warning_at (EXPR_LOCATION (handler), 0,
		      "exception of type %qT will be caught",
		      TREE_TYPE (handler));
	  warning_at (EXPR_LOCATION (master), 0,
		      "   by earlier handler for %qT", type);
	  break;
	}
    }
}

/* Given a STATEMENT_LIST of HANDLERs, make sure that they're OK.  */

void
check_handlers (tree handlers)
{
  tree_stmt_iterator i;

  /* If we don't have a STATEMENT_LIST, then we've just got one
     handler, and thus nothing to warn about.  */
  if (TREE_CODE (handlers) != STATEMENT_LIST)
    return;

  i = tsi_start (handlers);
  if (!tsi_end_p (i))
    while (1)
      {
	tree handler = tsi_stmt (i);
	tsi_next (&i);

	/* No more handlers; nothing to shadow.  */
	if (tsi_end_p (i))
	  break;
	if (TREE_TYPE (handler) == NULL_TREE)
	  permerror (EXPR_LOCATION (handler), "%<...%>"
		     " handler must be the last handler for its try block");
	else
	  check_handlers_1 (handler, i);
      }
}

/* walk_tree helper for finish_noexcept_expr.  Returns non-null if the
   expression *TP causes the noexcept operator to evaluate to false.

   5.3.7 [expr.noexcept]: The result of the noexcept operator is false if
   in a potentially-evaluated context the expression would contain
   * a potentially evaluated call to a function, member function,
     function pointer, or member function pointer that does not have a
     non-throwing exception-specification (15.4),
   * a potentially evaluated throw-expression (15.1),
   * a potentially evaluated dynamic_cast expression dynamic_cast<T>(v),
     where T is a reference type, that requires a run-time check (5.2.7), or
   * a potentially evaluated typeid expression (5.2.8) applied to a glvalue
     expression whose type is a polymorphic class type (10.3).  */

static tree
check_noexcept_r (tree *tp, int * /*walk_subtrees*/, void * /*data*/)
{
  tree t = *tp;
  enum tree_code code = TREE_CODE (t);
  if (code == CALL_EXPR
      || code == AGGR_INIT_EXPR)
    {
      /* We can only use the exception specification of the called function
	 for determining the value of a noexcept expression; we can't use
	 TREE_NOTHROW, as it might have a different value in another
	 translation unit, creating ODR problems.

         We could use TREE_NOTHROW (t) for !TREE_PUBLIC fns, though... */
      tree fn = (code == AGGR_INIT_EXPR
		 ? AGGR_INIT_EXPR_FN (t) : CALL_EXPR_FN (t));
      tree type = TREE_TYPE (TREE_TYPE (fn));

      STRIP_NOPS (fn);
      if (TREE_CODE (fn) == ADDR_EXPR)
	fn = TREE_OPERAND (fn, 0);
      if (TREE_CODE (fn) == FUNCTION_DECL)
	{
	  /* We do use TREE_NOTHROW for ABI internals like __dynamic_cast,
	     and for C library functions known not to throw.  */
	  if (DECL_EXTERN_C_P (fn)
	      && (DECL_ARTIFICIAL (fn)
		  || nothrow_libfn_p (fn)))
	    return TREE_NOTHROW (fn) ? NULL_TREE : fn;
	  /* A call to a constexpr function is noexcept if the call
	     is a constant expression.  */
	  if (DECL_DECLARED_CONSTEXPR_P (fn)
	      && is_sub_constant_expr (t))
	    return NULL_TREE;
	}
      if (!TYPE_NOTHROW_P (type))
	return fn;
    }

  return NULL_TREE;
}

/* If a function that causes a noexcept-expression to be false isn't
   defined yet, remember it and check it for TREE_NOTHROW again at EOF.  */

typedef struct GTY(()) pending_noexcept {
  tree fn;
  location_t loc;
} pending_noexcept;
static GTY(()) vec<pending_noexcept, va_gc> *pending_noexcept_checks;

/* FN is a FUNCTION_DECL that caused a noexcept-expr to be false.  Warn if
   it can't throw.  */

static void
maybe_noexcept_warning (tree fn)
{
  if (TREE_NOTHROW (fn))
    {
      warning (OPT_Wnoexcept, "noexcept-expression evaluates to %<false%> "
	       "because of a call to %qD", fn);
      warning (OPT_Wnoexcept, "but %q+D does not throw; perhaps "
	       "it should be declared %<noexcept%>", fn);
    }
}

/* Check any functions that weren't defined earlier when they caused a
   noexcept expression to evaluate to false.  */

void
perform_deferred_noexcept_checks (void)
{
  int i;
  pending_noexcept *p;
  location_t saved_loc = input_location;
  FOR_EACH_VEC_SAFE_ELT (pending_noexcept_checks, i, p)
    {
      input_location = p->loc;
      maybe_noexcept_warning (p->fn);
    }
  input_location = saved_loc;
}

/* Evaluate noexcept ( EXPR ).  */

tree
finish_noexcept_expr (tree expr, tsubst_flags_t complain)
{
  if (expr == error_mark_node)
    return error_mark_node;

  if (processing_template_decl)
    return build_min (NOEXCEPT_EXPR, boolean_type_node, expr);

  return (expr_noexcept_p (expr, complain)
	  ? boolean_true_node : boolean_false_node);
}

/* Returns whether EXPR is noexcept, possibly warning if allowed by
   COMPLAIN.  */

bool
expr_noexcept_p (tree expr, tsubst_flags_t complain)
{
  tree fn;

  if (expr == error_mark_node)
    return false;

  fn = cp_walk_tree_without_duplicates (&expr, check_noexcept_r, 0);
  if (fn)
    {
      if ((complain & tf_warning) && warn_noexcept
	  && TREE_CODE (fn) == FUNCTION_DECL)
	{
	  if (!DECL_INITIAL (fn))
	    {
	      /* Not defined yet; check again at EOF.  */
	      pending_noexcept p = {fn, input_location};
	      vec_safe_push (pending_noexcept_checks, p);
	    }
	  else
	    maybe_noexcept_warning (fn);
	}
      return false;
    }
  else
    return true;
}

/* Return true iff SPEC is throw() or noexcept(true).  */

bool
nothrow_spec_p (const_tree spec)
{
  gcc_assert (!DEFERRED_NOEXCEPT_SPEC_P (spec));
  if (spec == NULL_TREE && flag_default_noexcept)
    return true;
  if (spec == NULL_TREE
      || TREE_VALUE (spec) != NULL_TREE
      || spec == noexcept_false_spec)
    return false;
  if (TREE_PURPOSE (spec) == NULL_TREE
      || spec == noexcept_true_spec)
    return true;
  gcc_assert (processing_template_decl
	      || TREE_PURPOSE (spec) == error_mark_node);
  return false;
}

/* For FUNCTION_TYPE or METHOD_TYPE, true if NODE is noexcept.  This is the
   case for things declared noexcept(true) and, with -fnothrow-opt, for
   throw() functions.  */

bool
type_noexcept_p (const_tree type)
{
  tree spec = TYPE_RAISES_EXCEPTIONS (type);
  gcc_assert (!DEFERRED_NOEXCEPT_SPEC_P (spec));
  if (flag_nothrow_opt || flag_default_noexcept)
    return nothrow_spec_p (spec);
  else
    return spec == noexcept_true_spec;
}

/* For FUNCTION_TYPE or METHOD_TYPE, true if NODE can throw any type,
   i.e. no exception-specification or noexcept(false).  */

bool
type_throw_all_p (const_tree type)
{
  tree spec = TYPE_RAISES_EXCEPTIONS (type);
  gcc_assert (!DEFERRED_NOEXCEPT_SPEC_P (spec));
  return spec == NULL_TREE || spec == noexcept_false_spec;
}

/* Create a representation of the noexcept-specification with
   constant-expression of EXPR.  COMPLAIN is as for tsubst.  */

tree
build_noexcept_spec (tree expr, int complain)
{
  /* This isn't part of the signature, so don't bother trying to evaluate
     it until instantiation.  */
  if (!processing_template_decl && TREE_CODE (expr) != DEFERRED_NOEXCEPT)
    {
      expr = perform_implicit_conversion_flags (boolean_type_node, expr,
						complain,
						LOOKUP_NORMAL);
      expr = cxx_constant_value (expr);
    }
  if (TREE_CODE (expr) == INTEGER_CST)
    {
      if (operand_equal_p (expr, boolean_true_node, 0))
	return noexcept_true_spec;
      else
	{
	  gcc_checking_assert (operand_equal_p (expr, boolean_false_node, 0));
	  return noexcept_false_spec;
	}
    }
  else if (expr == error_mark_node)
    return error_mark_node;
  else
    {
      gcc_assert (processing_template_decl
		  || TREE_CODE (expr) == DEFERRED_NOEXCEPT);
      return build_tree_list (expr, NULL_TREE);
    }
}

/* Returns a TRY_CATCH_EXPR that will put TRY_LIST and CATCH_LIST in the
   TRY and CATCH locations.  CATCH_LIST must be a STATEMENT_LIST */

tree
create_try_catch_expr (tree try_expr, tree catch_list)
{
  location_t loc = EXPR_LOCATION (try_expr);
 
  append_to_statement_list (do_begin_catch (), &catch_list);
  append_to_statement_list (build_throw (NULL_TREE), &catch_list);
  tree catch_tf_expr = build_stmt (loc, TRY_FINALLY_EXPR, catch_list, 
				   do_end_catch (NULL_TREE));
  catch_list = build2 (CATCH_EXPR, void_type_node, NULL_TREE,
		       catch_tf_expr);
  tree try_catch_expr = build_stmt (loc, TRY_CATCH_EXPR, try_expr, catch_list);
  return try_catch_expr;
}

#include "gt-cp-except.h"