http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59482
--- Comment #1 from Ville Voutilainen <ville.voutilainen at gmail dot com> ---
A friend function can access the private class, thus
void f();
struct B {
friend void f();
private:
struct C {};};
void f() {
struct D : B::C{};
}
Some analysis follows:
I investigated this a bit. The right place seemed to be enforce_access
in search.c, and that then ends up in accessible_p. From there we go
to friend_accessible_p, which returns false. The problem is that
the current_scope() in accessible_p is NAMESPACE_DECL,
and we should perhaps already be in a class scope, since we're dealing
with the base-clause. Now that we get NAMESPACE_DECL, there
are no befriended_classes for it.
Then again, it's probably not that simple. I guess we shouldn't
willy-nilly make the compiler think it's in a class scope when
dealing with a base-clause, so that lookup doesn't look into the class yet.
Any guidance as to "what now?" would be appreciated.
I'll dump the backtrace how we get to current_scope, hope that helps.
(I must admit I stand at least _some chance_ of figuring things out
with a debugger with my puny gcc skills, but not much of a chance...)
If you need any trees to be printed, I can certainly provide them.
#0 current_scope () at ../../gcc/cp/search.c:526
#1 0x00000000006be0c5 in accessible_p (type=0x7ffff1af64e0,
decl=0x7ffff1ae8b80, consider_local_p=<optimized out>) at
../../gcc/cp/search.c:873
#2 0x0000000000540e0d in enforce_access (basetype_path=<optimized
out>, decl=0x7ffff1ae8b80, diag_decl=0x7ffff1ae8b80, complain=3) at
../../gcc/cp/call.c:5753
#3 0x00000000006c72a0 in perform_or_defer_access_check
(binfo=0x7ffff1ae8b80, decl=0x7ffff1ae8b80, diag_decl=0x7ffff19b5000,
complain=0) at ../../gcc/cp/semantics.c:340
#4 0x0000000000641b2f in cp_parser_lookup_name
(parser=parser@entry=0x7ffff1afb000, name=name@entry=0x7ffff1afad68,
tag_type=tag_type@entry=typename_type,
is_template=is_template@entry=false,
is_namespace=is_namespace@entry=false, check_dependency=<optimized
out>, ambiguous_decls=ambiguous_decls@entry=0x7fffffffd708,
name_location=91) at ../../gcc/cp/parser.c:22155
#5 0x00000000006626d9 in cp_parser_class_name
(parser=parser@entry=0x7ffff1afb000, typename_keyword_p=<optimized
out>, template_keyword_p=<optimized out>,
tag_type=tag_type@entry=typename_type,
check_dependency_p=check_dependency_p@entry=true,
class_head_p=class_head_p@entry=false,
is_declaration=is_declaration@entry=true) at
../../gcc/cp/parser.c:19023
#6 0x000000000064b89d in cp_parser_base_specifier
(parser=0x7ffff1afb000) at ../../gcc/cp/parser.c:20747
#7 cp_parser_base_clause (parser=0x7ffff1afb000) at
../../gcc/cp/parser.c:20577
#8 cp_parser_class_head (nested_name_specifier_p=<synthetic pointer>,
parser=0x7ffff1afb000) at ../../gcc/cp/parser.c:19824
#9 cp_parser_class_specifier_1 (parser=0x7ffff1afb000) at
../../gcc/cp/parser.c:19119
#10 cp_parser_class_specifier (parser=0x7ffff1afb000) at
../../gcc/cp/parser.c:19401
#11 cp_parser_type_specifier (parser=parser@entry=0x7ffff1afb000,
flags=flags@entry=1, decl_specs=decl_specs@entry=0x7fffffffd8e0,
is_declaration=is_declaration@entry=true,
declares_class_or_enum=declares_class_or_enum@entry=0x7fffffffd85c,
is_cv_qualifier=is_cv_qualifier@entry=0x7fffffffd85b) at
../../gcc/cp/parser.c:14292
#12 0x0000000000662ba0 in cp_parser_decl_specifier_seq
(parser=parser@entry=0x7ffff1afb000, flags=flags@entry=1,
decl_specs=decl_specs@entry=0x7fffffffd8e0,
declares_class_or_enum=declares_class_or_enum@entry=0x7fffffffd8dc) at
../../gcc/cp/parser.c:11537
#13 0x000000000066972a in cp_parser_simple_declaration
(parser=parser@entry=0x7ffff1afb000,
function_definition_allowed_p=function_definition_allowed_p@entry=true,
maybe_range_for_decl=maybe_range_for_decl@entry=0x0) at
../../gcc/cp/parser.c:11127
#14 0x000000000064d2a4 in cp_parser_block_declaration
(parser=0x7ffff1afb000, statement_p=<optimized out>) at
../../gcc/cp/parser.c:11076
#15 0x0000000000673fa4 in cp_parser_declaration
(parser=parser@entry=0x7ffff1afb000) at ../../gcc/cp/parser.c:10973
#16 0x0000000000672c99 in cp_parser_declaration_seq_opt
(parser=parser@entry=0x7ffff1afb000) at ../../gcc/cp/parser.c:10859
#17 0x000000000067458b in cp_parser_translation_unit
(parser=0x7ffff1afb000) at ../../gcc/cp/parser.c:4018
#18 c_parse_file () at ../../gcc/cp/parser.c:31322
#19 0x0000000000796444 in c_common_parse_file () at
../../gcc/c-family/c-opts.c:1056
#20 0x0000000000b46fd6 in compile_file () at ../../gcc/toplev.c:547
#21 0x0000000000b48f98 in do_compile () at ../../gcc/toplev.c:1887
#22 toplev_main (argc=31, argv=0x7fffffffdc18) at ../../gcc/toplev.c:1963
#23 0x00000030a0421735 in __libc_start_main (main=0x53d970 <main(int,
char**)>, argc=31, ubp_av=0x7fffffffdc18, init=<optimized out>,
fini=<optimized out>, rtld_fini=<optimized out>,
stack_end=0x7fffffffdc08) at libc-start.c:226
#24 0x000000000053d9f1 in _start ()
(gdb)
