summaryrefslogtreecommitdiff
path: root/gcc/cp/friend.c
blob: 083372849b93d3896e3da67e1cb541bcce8c0c68 (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
/* Help friends in C++.
   Copyright (C) 1997-2013 Free Software Foundation, Inc.

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 "cp-tree.h"
#include "flags.h"

/* Friend data structures are described in cp-tree.h.  */

/* Returns nonzero if SUPPLICANT is a friend of TYPE.  */

int
is_friend (tree type, tree supplicant)
{
  int declp;
  tree list;
  tree context;

  if (supplicant == NULL_TREE || type == NULL_TREE)
    return 0;

  declp = DECL_P (supplicant);

  if (declp)
    /* It's a function decl.  */
    {
      tree list = DECL_FRIENDLIST (TYPE_MAIN_DECL (type));
      tree name = DECL_NAME (supplicant);

      for (; list ; list = TREE_CHAIN (list))
	{
	  if (name == FRIEND_NAME (list))
	    {
	      tree friends = FRIEND_DECLS (list);
	      for (; friends ; friends = TREE_CHAIN (friends))
		{
		  tree this_friend = TREE_VALUE (friends);

		  if (this_friend == NULL_TREE)
		    continue;

		  if (supplicant == this_friend)
		    return 1;

		  if (is_specialization_of_friend (supplicant, this_friend))
		    return 1;
		}
	      break;
	    }
	}
    }
  else
    /* It's a type.  */
    {
      if (same_type_p (supplicant, type))
	return 1;

      list = CLASSTYPE_FRIEND_CLASSES (TREE_TYPE (TYPE_MAIN_DECL (type)));
      for (; list ; list = TREE_CHAIN (list))
	{
	  tree t = TREE_VALUE (list);

	  if (TREE_CODE (t) == TEMPLATE_DECL ?
	      is_specialization_of_friend (TYPE_MAIN_DECL (supplicant), t) :
	      same_type_p (supplicant, t))
	    return 1;
	}
    }

  if (declp)
    {
      if (DECL_FUNCTION_MEMBER_P (supplicant))
	context = DECL_CONTEXT (supplicant);
      else
	context = NULL_TREE;
    }
  else
    {
      if (TYPE_CLASS_SCOPE_P (supplicant))
	/* Nested classes get the same access as their enclosing types, as
	   per DR 45 (this is a change from the standard).  */
	context = TYPE_CONTEXT (supplicant);
      else
	/* Local classes have the same access as the enclosing function.  */
	context = decl_function_context (TYPE_MAIN_DECL (supplicant));
    }

  /* A namespace is not friend to anybody.  */
  if (context && TREE_CODE (context) == NAMESPACE_DECL)
    context = NULL_TREE;

  if (context)
    return is_friend (type, context);

  return 0;
}

/* Add a new friend to the friends of the aggregate type TYPE.
   DECL is the FUNCTION_DECL of the friend being added.

   If COMPLAIN is true, warning about duplicate friend is issued.
   We want to have this diagnostics during parsing but not
   when a template is being instantiated.  */

void
add_friend (tree type, tree decl, bool complain)
{
  tree typedecl;
  tree list;
  tree name;
  tree ctx;

  if (decl == error_mark_node)
    return;

  typedecl = TYPE_MAIN_DECL (type);
  list = DECL_FRIENDLIST (typedecl);
  name = DECL_NAME (decl);
  type = TREE_TYPE (typedecl);

  while (list)
    {
      if (name == FRIEND_NAME (list))
	{
	  tree friends = FRIEND_DECLS (list);
	  for (; friends ; friends = TREE_CHAIN (friends))
	    {
	      if (decl == TREE_VALUE (friends))
		{
		  if (complain)
		    warning (0, "%qD is already a friend of class %qT",
			     decl, type);
		  return;
		}
	    }

	  maybe_add_class_template_decl_list (type, decl, /*friend_p=*/1);

	  TREE_VALUE (list) = tree_cons (NULL_TREE, decl,
					 TREE_VALUE (list));
	  return;
	}
      list = TREE_CHAIN (list);
    }

  ctx = DECL_CONTEXT (decl);
  if (ctx && CLASS_TYPE_P (ctx) && !uses_template_parms (ctx))
    perform_or_defer_access_check (TYPE_BINFO (ctx), decl, decl,
				   tf_warning_or_error);

  maybe_add_class_template_decl_list (type, decl, /*friend_p=*/1);

  DECL_FRIENDLIST (typedecl)
    = tree_cons (DECL_NAME (decl), build_tree_list (NULL_TREE, decl),
		 DECL_FRIENDLIST (typedecl));
  if (!uses_template_parms (type))
    DECL_BEFRIENDING_CLASSES (decl)
      = tree_cons (NULL_TREE, type,
		   DECL_BEFRIENDING_CLASSES (decl));
}

/* Make FRIEND_TYPE a friend class to TYPE.  If FRIEND_TYPE has already
   been defined, we make all of its member functions friends of
   TYPE.  If not, we make it a pending friend, which can later be added
   when its definition is seen.  If a type is defined, then its TYPE_DECL's
   DECL_UNDEFINED_FRIENDS contains a (possibly empty) list of friend
   classes that are not defined.  If a type has not yet been defined,
   then the DECL_WAITING_FRIENDS contains a list of types
   waiting to make it their friend.  Note that these two can both
   be in use at the same time!

   If COMPLAIN is true, warning about duplicate friend is issued.
   We want to have this diagnostics during parsing but not
   when a template is being instantiated.  */

void
make_friend_class (tree type, tree friend_type, bool complain)
{
  tree classes;

  /* CLASS_TEMPLATE_DEPTH counts the number of template headers for
     the enclosing class.  FRIEND_DEPTH counts the number of template
     headers used for this friend declaration.  TEMPLATE_MEMBER_P,
     defined inside the `if' block for TYPENAME_TYPE case, is true if
     a template header in FRIEND_DEPTH is intended for DECLARATOR.
     For example, the code

       template <class T> struct A {
	 template <class U> struct B {
	   template <class V> template <class W>
	     friend class C<V>::D;
	 };
       };

     will eventually give the following results

     1. CLASS_TEMPLATE_DEPTH equals 2 (for `T' and `U').
     2. FRIEND_DEPTH equals 2 (for `V' and `W').
     3. TEMPLATE_MEMBER_P is true (for `W').

     The friend is a template friend iff FRIEND_DEPTH is nonzero.  */

  int class_template_depth = template_class_depth (type);
  int friend_depth = processing_template_decl - class_template_depth;

  if (! MAYBE_CLASS_TYPE_P (friend_type)
      && TREE_CODE (friend_type) != TEMPLATE_TEMPLATE_PARM)
    {
      /* N1791: If the type specifier in a friend declaration designates a
	 (possibly cv-qualified) class type, that class is declared as a
	 friend; otherwise, the friend declaration is ignored.

         So don't complain in C++0x mode.  */
      if (cxx_dialect < cxx0x)
	pedwarn (input_location, complain ? 0 : OPT_Wpedantic,
		 "invalid type %qT declared %<friend%>", friend_type);
      return;
    }

  friend_type = cv_unqualified (friend_type);

  if (check_for_bare_parameter_packs (friend_type))
    return;

  if (friend_depth)
    /* If the TYPE is a template then it makes sense for it to be
       friends with itself; this means that each instantiation is
       friends with all other instantiations.  */
    {
      if (CLASS_TYPE_P (friend_type)
	  && CLASSTYPE_TEMPLATE_SPECIALIZATION (friend_type)
	  && uses_template_parms (friend_type))
	{
	  /* [temp.friend]
	     Friend declarations shall not declare partial
	     specializations.  */
	  error ("partial specialization %qT declared %<friend%>",
		 friend_type);
	  return;
	}
    }
  else if (same_type_p (type, friend_type))
    {
      if (complain)
	warning (0, "class %qT is implicitly friends with itself",
		 type);
      return;
    }

  /* [temp.friend]

     A friend of a class or class template can be a function or
     class template, a specialization of a function template or
     class template, or an ordinary (nontemplate) function or
     class.  */
  if (!friend_depth)
    ;/* ok */
  else if (TREE_CODE (friend_type) == TYPENAME_TYPE)
    {
      if (TREE_CODE (TYPENAME_TYPE_FULLNAME (friend_type))
	  == TEMPLATE_ID_EXPR)
	{
	  /* template <class U> friend class T::X<U>; */
	  /* [temp.friend]
	     Friend declarations shall not declare partial
	     specializations.  */
	  error ("partial specialization %qT declared %<friend%>",
		 friend_type);
	  return;
	}
      else
	{
	  /* We will figure this out later.  */
	  bool template_member_p = false;

	  tree ctype = TYPE_CONTEXT (friend_type);
	  tree name = TYPE_IDENTIFIER (friend_type);
	  tree decl;

	  if (!uses_template_parms_level (ctype, class_template_depth
						 + friend_depth))
	    template_member_p = true;

	  if (class_template_depth)
	    {
	      /* We rely on tsubst_friend_class to check the
		 validity of the declaration later.  */
	      if (template_member_p)
		friend_type
		  = make_unbound_class_template (ctype,
						 name,
						 current_template_parms,
						 tf_error);
	      else
		friend_type
		  = make_typename_type (ctype, name, class_type, tf_error);
	    }
	  else
	    {
	      decl = lookup_member (ctype, name, 0, true, tf_warning_or_error);
	      if (!decl)
		{
		  error ("%qT is not a member of %qT", name, ctype);
		  return;
		}
	      if (template_member_p && !DECL_CLASS_TEMPLATE_P (decl))
		{
		  error ("%qT is not a member class template of %qT",
			 name, ctype);
		  error ("%q+D declared here", decl);
		  return;
		}
	      if (!template_member_p && (TREE_CODE (decl) != TYPE_DECL
					 || !CLASS_TYPE_P (TREE_TYPE (decl))))
		{
		  error ("%qT is not a nested class of %qT",
			 name, ctype);
		  error ("%q+D declared here", decl);
		  return;
		}

	      friend_type = CLASSTYPE_TI_TEMPLATE (TREE_TYPE (decl));
	    }
	}
    }
  else if (TREE_CODE (friend_type) == TEMPLATE_TYPE_PARM)
    {
      /* template <class T> friend class T; */
      error ("template parameter type %qT declared %<friend%>", friend_type);
      return;
    }
  else if (TREE_CODE (friend_type) == TEMPLATE_TEMPLATE_PARM)
    friend_type = TYPE_NAME (friend_type);
  else if (!CLASSTYPE_TEMPLATE_INFO (friend_type))
    {
      /* template <class T> friend class A; where A is not a template */
      error ("%q#T is not a template", friend_type);
      return;
    }
  else
    /* template <class T> friend class A; where A is a template */
    friend_type = CLASSTYPE_TI_TEMPLATE (friend_type);

  if (friend_type == error_mark_node)
    return;

  /* See if it is already a friend.  */
  for (classes = CLASSTYPE_FRIEND_CLASSES (type);
       classes;
       classes = TREE_CHAIN (classes))
    {
      tree probe = TREE_VALUE (classes);

      if (TREE_CODE (friend_type) == TEMPLATE_DECL)
	{
	  if (friend_type == probe)
	    {
	      if (complain)
		warning (0, "%qD is already a friend of %qT", probe, type);
	      break;
	    }
	}
      else if (TREE_CODE (probe) != TEMPLATE_DECL)
	{
	  if (same_type_p (probe, friend_type))
	    {
	      if (complain)
		warning (0, "%qT is already a friend of %qT", probe, type);
	      break;
	    }
	}
    }

  if (!classes)
    {
      maybe_add_class_template_decl_list (type, friend_type, /*friend_p=*/1);

      CLASSTYPE_FRIEND_CLASSES (type)
	= tree_cons (NULL_TREE, friend_type, CLASSTYPE_FRIEND_CLASSES (type));
      if (TREE_CODE (friend_type) == TEMPLATE_DECL)
	friend_type = TREE_TYPE (friend_type);
      if (!uses_template_parms (type))
	CLASSTYPE_BEFRIENDING_CLASSES (friend_type)
	  = tree_cons (NULL_TREE, type,
		       CLASSTYPE_BEFRIENDING_CLASSES (friend_type));
    }
}

/* Record DECL (a FUNCTION_DECL) as a friend of the
   CURRENT_CLASS_TYPE.  If DECL is a member function, CTYPE is the
   class of which it is a member, as named in the friend declaration.
   DECLARATOR is the name of the friend.  FUNCDEF_FLAG is true if the
   friend declaration is a definition of the function.  FLAGS is as
   for grokclass fn.  */

tree
do_friend (tree ctype, tree declarator, tree decl,
	   tree attrlist, enum overload_flags flags,
	   bool funcdef_flag)
{
  gcc_assert (TREE_CODE (decl) == FUNCTION_DECL);
  gcc_assert (!ctype || MAYBE_CLASS_TYPE_P (ctype));

  /* Every decl that gets here is a friend of something.  */
  DECL_FRIEND_P (decl) = 1;

  /* Unfortunately, we have to handle attributes here.  Normally we would
     handle them in start_decl_1, but since this is a friend decl start_decl_1
     never gets to see it.  */

  /* Set attributes here so if duplicate decl, will have proper attributes.  */
  cplus_decl_attributes (&decl, attrlist, 0);

  if (TREE_CODE (declarator) == TEMPLATE_ID_EXPR)
    {
      declarator = TREE_OPERAND (declarator, 0);
      if (is_overloaded_fn (declarator))
	declarator = DECL_NAME (get_first_fn (declarator));
    }

  if (ctype)
    {
      /* CLASS_TEMPLATE_DEPTH counts the number of template headers for
	 the enclosing class.  FRIEND_DEPTH counts the number of template
	 headers used for this friend declaration.  TEMPLATE_MEMBER_P is
	 true if a template header in FRIEND_DEPTH is intended for
	 DECLARATOR.  For example, the code

	   template <class T> struct A {
	     template <class U> struct B {
	       template <class V> template <class W>
		 friend void C<V>::f(W);
	     };
	   };

	 will eventually give the following results

	 1. CLASS_TEMPLATE_DEPTH equals 2 (for `T' and `U').
	 2. FRIEND_DEPTH equals 2 (for `V' and `W').
	 3. TEMPLATE_MEMBER_P is true (for `W').  */

      int class_template_depth = template_class_depth (current_class_type);
      int friend_depth = processing_template_decl - class_template_depth;
      /* We will figure this out later.  */
      bool template_member_p = false;

      tree cname = TYPE_NAME (ctype);
      if (TREE_CODE (cname) == TYPE_DECL)
	cname = DECL_NAME (cname);

      /* A method friend.  */
      if (flags == NO_SPECIAL && declarator == cname)
	DECL_CONSTRUCTOR_P (decl) = 1;

      grokclassfn (ctype, decl, flags);

      if (friend_depth)
	{
	  if (!uses_template_parms_level (ctype, class_template_depth
						 + friend_depth))
	    template_member_p = true;
	}

      /* A nested class may declare a member of an enclosing class
	 to be a friend, so we do lookup here even if CTYPE is in
	 the process of being defined.  */
      if (class_template_depth
	  || COMPLETE_TYPE_P (ctype)
	  || (CLASS_TYPE_P (ctype) && TYPE_BEING_DEFINED (ctype)))
	{
	  if (DECL_TEMPLATE_INFO (decl))
	    /* DECL is a template specialization.  No need to
	       build a new TEMPLATE_DECL.  */
	    ;
	  else if (class_template_depth)
	    /* We rely on tsubst_friend_function to check the
	       validity of the declaration later.  */
	    decl = push_template_decl_real (decl, /*is_friend=*/true);
	  else
	    decl = check_classfn (ctype, decl,
				  template_member_p
				  ? current_template_parms
				  : NULL_TREE);

	  if (template_member_p && decl && TREE_CODE (decl) == FUNCTION_DECL)
	    decl = DECL_TI_TEMPLATE (decl);

	  if (decl)
	    add_friend (current_class_type, decl, /*complain=*/true);
	}
      else
	error ("member %qD declared as friend before type %qT defined",
		  decl, ctype);
    }
  /* A global friend.
     @@ or possibly a friend from a base class ?!?  */
  else if (TREE_CODE (decl) == FUNCTION_DECL)
    {
      int is_friend_template = PROCESSING_REAL_TEMPLATE_DECL_P ();

      /* Friends must all go through the overload machinery,
	 even though they may not technically be overloaded.

	 Note that because classes all wind up being top-level
	 in their scope, their friend wind up in top-level scope as well.  */
      if (funcdef_flag)
	SET_DECL_FRIEND_CONTEXT (decl, current_class_type);

      if (! DECL_USE_TEMPLATE (decl))
	{
	  /* We must check whether the decl refers to template
	     arguments before push_template_decl_real adds a
	     reference to the containing template class.  */
	  int warn = (warn_nontemplate_friend
		      && ! funcdef_flag && ! is_friend_template
		      && current_template_parms
		      && uses_template_parms (decl));

	  if (is_friend_template
	      || template_class_depth (current_class_type) != 0)
	    /* We can't call pushdecl for a template class, since in
	       general, such a declaration depends on template
	       parameters.  Instead, we call pushdecl when the class
	       is instantiated.  */
	    decl = push_template_decl_real (decl, /*is_friend=*/true);
	  else if (current_function_decl)
	    {
	      /* This must be a local class.  11.5p11:

		 If a friend declaration appears in a local class (9.8) and
		 the name specified is an unqualified name, a prior
		 declaration is looked up without considering scopes that
		 are outside the innermost enclosing non-class scope. For a
		 friend function declaration, if there is no prior
		 declaration, the program is ill-formed.  */
	      tree t = lookup_name_innermost_nonclass_level (DECL_NAME (decl));
	      if (t)
		decl = pushdecl_maybe_friend (decl, /*is_friend=*/true);
	      else
		{
		  error ("friend declaration %qD in local class without "
			 "prior declaration", decl);
		  return error_mark_node;
		}
	    }
	  else
	    {
	      /* We can't use pushdecl, as we might be in a template
		 class specialization, and pushdecl will insert an
		 unqualified friend decl into the template parameter
		 scope, rather than the namespace containing it.  */
	      tree ns = decl_namespace_context (decl);

	      push_nested_namespace (ns);
	      decl = pushdecl_namespace_level (decl, /*is_friend=*/true);
	      pop_nested_namespace (ns);
	    }

	  if (warn)
	    {
	      static int explained;
	      bool warned;

	      warned = warning (OPT_Wnon_template_friend, "friend declaration "
				"%q#D declares a non-template function", decl);
	      if (! explained && warned)
		{
		  inform (input_location, "(if this is not what you intended, make sure "
			  "the function template has already been declared "
			  "and add <> after the function name here) ");
		  explained = 1;
		}
	    }
	}

      if (decl == error_mark_node)
	return error_mark_node;

      add_friend (current_class_type,
		  is_friend_template ? DECL_TI_TEMPLATE (decl) : decl,
		  /*complain=*/true);
      DECL_FRIEND_P (decl) = 1;
    }

  return decl;
}