1 /* Help friends in C++.
2 Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
3 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
24 #include "coretypes.h"
34 /* Friend data structures are described in cp-tree.h. */
36 /* Returns nonzero if SUPPLICANT is a friend of TYPE. */
39 is_friend (tree type, tree supplicant)
45 if (supplicant == NULL_TREE || type == NULL_TREE)
48 declp = DECL_P (supplicant);
51 /* It's a function decl. */
53 tree list = DECL_FRIENDLIST (TYPE_MAIN_DECL (type));
54 tree name = DECL_NAME (supplicant);
56 for (; list ; list = TREE_CHAIN (list))
58 if (name == FRIEND_NAME (list))
60 tree friends = FRIEND_DECLS (list);
61 for (; friends ; friends = TREE_CHAIN (friends))
63 tree friend = TREE_VALUE (friends);
65 if (friend == NULL_TREE)
68 if (supplicant == friend)
71 if (is_specialization_of_friend (supplicant, friend))
81 /* Nested classes are implicitly friends of their enclosing types, as
82 per core issue 45 (this is a change from the standard). */
83 for (context = supplicant;
84 context && TYPE_P (context);
85 context = TYPE_CONTEXT (context))
89 list = CLASSTYPE_FRIEND_CLASSES (TREE_TYPE (TYPE_MAIN_DECL (type)));
90 for (; list ; list = TREE_CHAIN (list))
92 tree t = TREE_VALUE (list);
94 if (TREE_CODE (t) == TEMPLATE_DECL ?
95 is_specialization_of (TYPE_MAIN_DECL (supplicant), t) :
96 same_type_p (supplicant, t))
101 if (declp && DECL_FUNCTION_MEMBER_P (supplicant))
102 context = DECL_CONTEXT (supplicant);
104 /* Local classes have the same access as the enclosing function. */
105 context = decl_function_context (TYPE_MAIN_DECL (supplicant));
109 /* A namespace is not friend to anybody. */
110 if (context && TREE_CODE (context) == NAMESPACE_DECL)
114 return is_friend (type, context);
119 /* Add a new friend to the friends of the aggregate type TYPE.
120 DECL is the FUNCTION_DECL of the friend being added.
122 If COMPLAIN is true, warning about duplicate friend is issued.
123 We want to have this diagnostics during parsing but not
124 when a template is being instantiated. */
127 add_friend (tree type, tree decl, bool complain)
133 if (decl == error_mark_node)
136 typedecl = TYPE_MAIN_DECL (type);
137 list = DECL_FRIENDLIST (typedecl);
138 name = DECL_NAME (decl);
139 type = TREE_TYPE (typedecl);
143 if (name == FRIEND_NAME (list))
145 tree friends = FRIEND_DECLS (list);
146 for (; friends ; friends = TREE_CHAIN (friends))
148 if (decl == TREE_VALUE (friends))
151 warning ("`%D' is already a friend of class `%T'",
157 maybe_add_class_template_decl_list (type, decl, /*friend_p=*/1);
159 TREE_VALUE (list) = tree_cons (NULL_TREE, decl,
163 list = TREE_CHAIN (list);
166 if (DECL_CLASS_SCOPE_P (decl))
168 tree class_binfo = TYPE_BINFO (DECL_CONTEXT (decl));
169 if (!uses_template_parms (BINFO_TYPE (class_binfo)))
170 perform_or_defer_access_check (class_binfo, decl);
173 maybe_add_class_template_decl_list (type, decl, /*friend_p=*/1);
175 DECL_FRIENDLIST (typedecl)
176 = tree_cons (DECL_NAME (decl), build_tree_list (NULL_TREE, decl),
177 DECL_FRIENDLIST (typedecl));
178 if (!uses_template_parms (type))
179 DECL_BEFRIENDING_CLASSES (decl)
180 = tree_cons (NULL_TREE, type,
181 DECL_BEFRIENDING_CLASSES (decl));
184 /* Make FRIEND_TYPE a friend class to TYPE. If FRIEND_TYPE has already
185 been defined, we make all of its member functions friends of
186 TYPE. If not, we make it a pending friend, which can later be added
187 when its definition is seen. If a type is defined, then its TYPE_DECL's
188 DECL_UNDEFINED_FRIENDS contains a (possibly empty) list of friend
189 classes that are not defined. If a type has not yet been defined,
190 then the DECL_WAITING_FRIENDS contains a list of types
191 waiting to make it their friend. Note that these two can both
192 be in use at the same time!
194 If COMPLAIN is true, warning about duplicate friend is issued.
195 We want to have this diagnostics during parsing but not
196 when a template is being instantiated. */
199 make_friend_class (tree type, tree friend_type, bool complain)
202 int is_template_friend;
204 if (! IS_AGGR_TYPE (friend_type))
206 error ("invalid type `%T' declared `friend'", friend_type);
210 if (processing_template_decl > template_class_depth (type))
211 /* If the TYPE is a template then it makes sense for it to be
212 friends with itself; this means that each instantiation is
213 friends with all other instantiations. */
215 if (CLASS_TYPE_P (friend_type)
216 && CLASSTYPE_TEMPLATE_SPECIALIZATION (friend_type)
217 && uses_template_parms (friend_type))
220 Friend declarations shall not declare partial
222 error ("partial specialization `%T' declared `friend'",
227 is_template_friend = 1;
229 else if (same_type_p (type, friend_type))
232 pedwarn ("class `%T' is implicitly friends with itself",
237 is_template_friend = 0;
241 A friend of a class or class template can be a function or
242 class template, a specialization of a function template or
243 class template, or an ordinary (nontemplate) function or
245 if (!is_template_friend)
247 else if (TREE_CODE (friend_type) == TYPENAME_TYPE)
249 /* template <class T> friend typename S<T>::X; */
250 error ("typename type `%#T' declared `friend'", friend_type);
253 else if (TREE_CODE (friend_type) == TEMPLATE_TYPE_PARM)
255 /* template <class T> friend class T; */
256 error ("template parameter type `%T' declared `friend'", friend_type);
259 else if (!CLASSTYPE_TEMPLATE_INFO (friend_type))
261 /* template <class T> friend class A; where A is not a template */
262 error ("`%#T' is not a template", friend_type);
266 if (is_template_friend)
267 friend_type = CLASSTYPE_TI_TEMPLATE (friend_type);
269 /* See if it is already a friend. */
270 for (classes = CLASSTYPE_FRIEND_CLASSES (type);
272 classes = TREE_CHAIN (classes))
274 tree probe = TREE_VALUE (classes);
276 if (TREE_CODE (friend_type) == TEMPLATE_DECL)
278 if (friend_type == probe)
281 warning ("`%D' is already a friend of `%T'",
286 else if (TREE_CODE (probe) != TEMPLATE_DECL)
288 if (same_type_p (probe, friend_type))
291 warning ("`%T' is already a friend of `%T'",
300 maybe_add_class_template_decl_list (type, friend_type, /*friend_p=*/1);
302 CLASSTYPE_FRIEND_CLASSES (type)
303 = tree_cons (NULL_TREE, friend_type, CLASSTYPE_FRIEND_CLASSES (type));
304 if (is_template_friend)
305 friend_type = TREE_TYPE (friend_type);
306 if (!uses_template_parms (type))
307 CLASSTYPE_BEFRIENDING_CLASSES (friend_type)
308 = tree_cons (NULL_TREE, type,
309 CLASSTYPE_BEFRIENDING_CLASSES (friend_type));
313 /* Main friend processor.
315 CTYPE is the class this friend belongs to.
317 DECLARATOR is the name of the friend.
319 DECL is the FUNCTION_DECL that the friend is.
321 FLAGS is just used for `grokclassfn'.
323 QUALS say what special qualifies should apply to the object
324 pointed to by `this'. */
327 do_friend (tree ctype, tree declarator, tree decl,
328 tree attrlist, enum overload_flags flags, tree quals,
331 /* Every decl that gets here is a friend of something. */
332 DECL_FRIEND_P (decl) = 1;
334 if (TREE_CODE (declarator) == TEMPLATE_ID_EXPR)
336 declarator = TREE_OPERAND (declarator, 0);
337 if (is_overloaded_fn (declarator))
338 declarator = DECL_NAME (get_first_fn (declarator));
341 if (TREE_CODE (decl) != FUNCTION_DECL)
346 /* CLASS_TEMPLATE_DEPTH counts the number of template headers for
347 the enclosing class. FRIEND_DEPTH counts the number of template
348 headers used for this friend declaration. TEMPLATE_MEMBER_P is
349 true if a template header in FRIEND_DEPTH is intended for
350 DECLARATOR. For example, the code
352 template <class T> struct A {
353 template <class U> struct B {
354 template <class V> template <class W>
355 friend void C<V>::f(W);
359 will eventually give the following results
361 1. CLASS_TEMPLATE_DEPTH equals 2 (for `T' and `U').
362 2. FRIEND_DEPTH equals 2 (for `V' and `W').
363 3. TEMPLATE_MEMBER_P is true (for `W'). */
365 int class_template_depth = template_class_depth (current_class_type);
366 int friend_depth = processing_template_decl - class_template_depth;
367 /* We will figure this out later. */
368 bool template_member_p = false;
370 tree cname = TYPE_NAME (ctype);
371 if (TREE_CODE (cname) == TYPE_DECL)
372 cname = DECL_NAME (cname);
374 /* A method friend. */
375 if (flags == NO_SPECIAL && declarator == cname)
376 DECL_CONSTRUCTOR_P (decl) = 1;
378 /* This will set up DECL_ARGUMENTS for us. */
379 grokclassfn (ctype, decl, flags, quals);
383 if (!uses_template_parms_level (ctype, class_template_depth
385 template_member_p = true;
388 /* A nested class may declare a member of an enclosing class
389 to be a friend, so we do lookup here even if CTYPE is in
390 the process of being defined. */
391 if (class_template_depth
392 || COMPLETE_TYPE_P (ctype)
393 || TYPE_BEING_DEFINED (ctype))
395 if (DECL_TEMPLATE_INFO (decl))
396 /* DECL is a template specialization. No need to
397 build a new TEMPLATE_DECL. */
399 else if (class_template_depth)
400 /* We rely on tsubst_friend_function to check the
401 validity of the declaration later. */
402 decl = push_template_decl_real (decl, /*is_friend=*/1);
404 decl = check_classfn (ctype, decl,
406 ? current_template_parms
409 if (template_member_p && decl && TREE_CODE (decl) == FUNCTION_DECL)
410 decl = DECL_TI_TEMPLATE (decl);
413 add_friend (current_class_type, decl, /*complain=*/true);
416 error ("member `%D' declared as friend before type `%T' defined",
420 @@ or possibly a friend from a base class ?!? */
421 else if (TREE_CODE (decl) == FUNCTION_DECL)
423 int is_friend_template = PROCESSING_REAL_TEMPLATE_DECL_P ();
425 /* Friends must all go through the overload machinery,
426 even though they may not technically be overloaded.
428 Note that because classes all wind up being top-level
429 in their scope, their friend wind up in top-level scope as well. */
431 SET_DECL_FRIEND_CONTEXT (decl, current_class_type);
433 if (! DECL_USE_TEMPLATE (decl))
435 /* We must check whether the decl refers to template
436 arguments before push_template_decl_real adds a
437 reference to the containing template class. */
438 int warn = (warn_nontemplate_friend
439 && ! funcdef_flag && ! is_friend_template
440 && current_template_parms
441 && uses_template_parms (decl));
443 if (is_friend_template
444 || template_class_depth (current_class_type) != 0)
445 /* We can't call pushdecl for a template class, since in
446 general, such a declaration depends on template
447 parameters. Instead, we call pushdecl when the class
449 decl = push_template_decl_real (decl, /*is_friend=*/1);
450 else if (current_function_decl)
451 /* This must be a local class, so pushdecl will be ok, and
452 insert an unqualified friend into the local scope
453 (rather than the containing namespace scope, which the
454 next choice will do). */
455 decl = pushdecl (decl);
458 /* We can't use pushdecl, as we might be in a template
459 class specialization, and pushdecl will insert an
460 unqualified friend decl into the template parameter
461 scope, rather than the namespace containing it. */
462 tree ns = decl_namespace_context (decl);
464 push_nested_namespace (ns);
465 decl = pushdecl_namespace_level (decl);
466 pop_nested_namespace (ns);
471 static int explained;
472 warning ("friend declaration `%#D' declares a non-template function", decl);
475 warning ("(if this is not what you intended, make sure the function template has already been declared and add <> after the function name here) -Wno-non-template-friend disables this warning");
481 if (decl == error_mark_node)
482 return error_mark_node;
484 add_friend (current_class_type,
485 is_friend_template ? DECL_TI_TEMPLATE (decl) : decl,
487 DECL_FRIEND_P (decl) = 1;
490 /* Unfortunately, we have to handle attributes here. Normally we would
491 handle them in start_decl_1, but since this is a friend decl start_decl_1
492 never gets to see it. */
494 /* Set attributes here so if duplicate decl, will have proper attributes. */
495 cplus_decl_attributes (&decl, attrlist, 0);