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template<typename T>            
  struct x                      
  {                             
  protected:
    typedef int type;
  };

template<typename T>
  struct y : public x<T>
  {
    typedef x<T> base_type;
    typedef typename base_type::type type;
  };

template<>
  struct y<void> : public x<void>
  {
    typedef x<void> base_type;
    typedef base_type::type type;
  };

template class y<int>;

int main()
{
  return 0;
}

$ g++4x spec.cc
spec.cc: In instantiation of ‘y<int>’:
spec.cc:22:   instantiated from here
spec.cc:5: error: ‘typedef int x<void>::type’ is protected
spec.cc:10: error: within this context
$ g++4x -v
Using built-in specs.
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-4.x/configure --prefix=/home/redi/gcc/4.x
--with-system-zlib --enable-__cxa_atexit --with-arch=k8
--enable-libstdcxx-debug --disable-libstdcxx-pch --enable-languages=c,c++
--enable-libstdcxx-time=yes --disable-bootstrap --enable-checking=release
Thread model: posix
gcc version 4.5.0 20090502 (experimental) (GCC)

If the base class is not a template there is no error, if the y<void>
specialisation is not defined there is no error.  As I'm not using the y<void>
specialisation, its contents should make no difference to the instantiation of
y<int>.

Looks like a regression since 4.3 as it works with gcc version 4.3.2 20081105
(Red Hat 4.3.2-7) (GCC) and Comeau's online compiler.

Only fails in trunk. I haven't checked, but could it be caused by the fix for
PR26693 ?

gcc-4.5-20090327 works, gcc-4.5-20090402 doesn't

Debugging cc1plus for this slightly reduced program:
template<typename T>
 struct x
 {
 protected:
   typedef int type;
 };

template<typename T>
 struct y : public x<T>
 {
   typename x<T>::type z;
 };

template<>
 struct y<void> : public x<void>
 {
   typedef x<void>::type z;
 };

template class y<int>;

shows the explicit instantiation of y<int> calls
perform_typedefs_access_check() which calls
enforce_access() with decl = x<void>::type.

That's wrong, it should be x<int>::type - somehow the wrong typedef is
added to the list of types to check for the y<int> specialisation.

(gdb) bt
#0  enforce_access (basetype_path=0x2aaaab643180, decl=0x2aaaab641cc0, 
    diag_decl=0x2aaaab641cc0) at ../../src/gcc/gcc/cp/call.c:4447      
#1  0x00000000004acabc in perform_typedefs_access_check (              
    tmpl=<value optimized out>, targs=0x2aaaab6429c0)
    at ../../src/gcc/gcc/cp/pt.c:6960
#2  0x00000000004b827b in instantiate_class_template (type=0x2aaaab644240)
    at ../../src/gcc/gcc/cp/pt.c:7443
#3  0x00000000004edf00 in complete_type (type=0x2aaaab644240)
    at ../../src/gcc/gcc/cp/typeck.c:130
#4  0x00000000004b062c in do_type_instantiation (t=0x2aaaab644240,
    storage=0x0, complain=1) at ../../src/gcc/gcc/cp/pt.c:15011
#5  0x00000000004e0f11 in cp_parser_explicit_instantiation (
    parser=0x2aaaab4b59b0) at ../../src/gcc/gcc/cp/parser.c:10812
#6  0x00000000004e6905 in cp_parser_declaration (parser=0x2aaaab4b59b0)
    at ../../src/gcc/gcc/cp/parser.c:8013
#7  0x00000000004e6caa in cp_parser_declaration_seq_opt (parser=0x2aaaab4b59b0)
    at ../../src/gcc/gcc/cp/parser.c:7927
#8  0x00000000004e7527 in c_parse_file () at ../../src/gcc/gcc/cp/parser.c:3029
#9  0x00000000005557fa in c_common_parse_file (
    set_yydebug=<value optimized out>) at ../../src/gcc/gcc/c-opts.c:1272
#10 0x00000000007519e2 in toplev_main (argc=13, argv=0x7fffffffe8a8)
    at ../../src/gcc/gcc/toplev.c:979
#11 0x00002aaaaace24ca in __libc_start_main () from /lib/libc.so.6
#12 0x000000000048216a in _start () at ../sysdeps/x86_64/elf/start.S:113
(gdb) n
4448      gcc_assert (TREE_CODE (basetype_path) == TREE_BINFO);
(gdb)
4450      if (!accessible_p (basetype_path, decl, true))
(gdb)
4452          if (TREE_PRIVATE (decl))
(gdb)
4454          else if (TREE_PROTECTED (decl))
(gdb)
4455            error ("%q+#D is protected", diag_decl);
(gdb)
pr40007.cc: In instantiation of ‘y<int>’:
pr40007.cc:20:   instantiated from here
pr40007.cc:5: error: ‘typedef int x<void>::type’ is protected
4458          error ("within this context");
(gdb)
pr40007.cc:10: error: within this context
4463    }

Created an attachment (id=17884) [edit]
A candidate patch

I am testing this patch at the moment.
Could you please test it in your environment and tell me if it helps at all ?

Thanks.

By the way, here what I think is happening.

During the parsing of 

template<>
 struct y<void> : public x<void>
 {
   typedef x<void>::type z;
 };

We detect that x<void>::type is a use of a typedef that is a member of the
class template x. We then wrongly append x<void>::type to the representation of
template<typename T> struct y so that we can perform access checks on the use
of x<void>::type once we instantiate y<void>. Later, during the instantiation
of template<typename T> struct y into y<int> we wrongly try to perform access
checks of x<void>::type even if x<void>::type has no business with the
instantiation of template<typename T> struct y;

In short, the typedef use x<void>::type should be added (for access checking
purposes) to the representation of the specialized template<> struct y<void>,
not to the representation of the most general template<typename T> struct y.

(In reply to comment #4)
> I am testing this patch at the moment.
> Could you please test it in your environment and tell me if it helps at all ?

Yes, that patch works for the code I was working on.

Subject: Bug 40007

Author: dodji
Date: Tue May 26 10:35:16 2009
New Revision: 147866

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=147866
Log:
Fix PR c++/40007

    gcc/cp/ChangeLog:
        PR c++/40007
        * cp-tree.h (MEMBER_TYPES_NEEDING_ACCESS_CHECK): Remove this accessor.
        (TI_TYPEDEFS_NEEDING_ACCESS_CHECKING): New accessor.
        (get_types_needing_access_check): Declare new entry point.
        * pt.c (append_type_to_template_for_access_check_1,
        get_types_needing_access_check): New functions.
        (perform_typedefs_access_check): Accept FUNCTION_DECLs and
        RECORD_TYPEs rather than TEMPLATE_DECLs. Use the new
        get_types_needing_access_check, no more
        MEMBER_TYPES_NEEDING_ACCESS_CHECK.
        (instantiate_class_template): Set input_location to the source
        location of the most specialized template definition.
        Perform access check using the RECORD_TYPE of the template, not its
        associated most generic TEMPLATE_DECL.
        (append_type_to_template_for_access_check): Augment function
        comments. Use the new get_types_needing_access_check, not
        MEMBER_TYPE_NEEDING_ACCESS_CHECK. Use the new
        append_type_to_template_for_access_check_1 subroutine.

    gcc/testsuite/ChangeLog:
        PR c++/40007
        * g++.dg/template/typedef18.C: New test.
        * g++.dg/template/typedef19.C: Likewise.
        * g++.dg/template/typedef20.C: Likewise.
        * g++.dg/template/access11.C: Adjust.


Added:
    trunk/gcc/testsuite/g++.dg/template/typedef18.C
    trunk/gcc/testsuite/g++.dg/template/typedef19.C
    trunk/gcc/testsuite/g++.dg/template/typedef20.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/cp-tree.h
    trunk/gcc/cp/pt.c
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/g++.dg/template/access11.C

Fixed in trunk.

Subject: Bug 40007

Author: hjl
Date: Sat May 30 13:49:33 2009
New Revision: 148004

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=148004
Log:
2009-05-30  H.J. Lu  <hongjiu.lu@intel.com>

        Backport from mainline:

        2009-05-28  Dodji Seketeli  <dodji@redhat.com>

        PR c++/39754
        * g++.dg/template/canon-type-1.C: New test.
        * g++.dg/template/canon-type-2.C: Likewise.
        * g++.dg/template/canon-type-3.C: Likewise.
        * g++.dg/template/canon-type-4.C: Likewise.
        * g++.dg/template/canon-type-5.C: Likewise.
        * g++.dg/template/canon-type-6.C: Likewise.
        * g++.dg/template/canon-type-7.C: Likewise.

        2009-05-28  Ira Rosen  <irar@il.ibm.com>

        PR tree-optimization/40254
        * gcc.dg/vect/pr40254.c: New test.

        2009-05-26  Richard Guenther  <rguenther@suse.de>

        PR middle-end/40252
        * gcc.c-torture/compile/pr40252.c: New testcase.

        2009-05-26  Dodji Seketeli  <dodji@redhat.com>

        PR c++/40007
        * g++.dg/template/typedef18.C: New test.
        * g++.dg/template/typedef19.C: Likewise.
        * g++.dg/template/typedef20.C: Likewise.

        2009-05-25  Ira Rosen  <irar@il.ibm.com>

        PR tree-optimization/40238
        * gcc.dg/vect/pr40238.c: New test.

        2009-05-24  Richard Guenther  <rguenther@suse.de>

        PR middle-end/40233
        * gcc.c-torture/compile/pr40233.c: New testcase.

Added:
    branches/gcc-4_4-branch/gcc/testsuite/g++.dg/template/canon-type-1.C
      - copied unchanged from r148002,
trunk/gcc/testsuite/g++.dg/template/canon-type-1.C
    branches/gcc-4_4-branch/gcc/testsuite/g++.dg/template/canon-type-2.C
      - copied unchanged from r148002,
trunk/gcc/testsuite/g++.dg/template/canon-type-2.C
    branches/gcc-4_4-branch/gcc/testsuite/g++.dg/template/canon-type-3.C
      - copied unchanged from r148002,
trunk/gcc/testsuite/g++.dg/template/canon-type-3.C
    branches/gcc-4_4-branch/gcc/testsuite/g++.dg/template/canon-type-4.C
      - copied unchanged from r148002,
trunk/gcc/testsuite/g++.dg/template/canon-type-4.C
    branches/gcc-4_4-branch/gcc/testsuite/g++.dg/template/canon-type-5.C
      - copied unchanged from r148002,
trunk/gcc/testsuite/g++.dg/template/canon-type-5.C
    branches/gcc-4_4-branch/gcc/testsuite/g++.dg/template/canon-type-6.C
      - copied unchanged from r148002,
trunk/gcc/testsuite/g++.dg/template/canon-type-6.C
    branches/gcc-4_4-branch/gcc/testsuite/g++.dg/template/canon-type-7.C
      - copied unchanged from r148002,
trunk/gcc/testsuite/g++.dg/template/canon-type-7.C
    branches/gcc-4_4-branch/gcc/testsuite/g++.dg/template/typedef18.C
      - copied unchanged from r148003,
trunk/gcc/testsuite/g++.dg/template/typedef18.C
    branches/gcc-4_4-branch/gcc/testsuite/g++.dg/template/typedef19.C
      - copied unchanged from r148003,
trunk/gcc/testsuite/g++.dg/template/typedef19.C
    branches/gcc-4_4-branch/gcc/testsuite/g++.dg/template/typedef20.C
      - copied unchanged from r148003,
trunk/gcc/testsuite/g++.dg/template/typedef20.C
    branches/gcc-4_4-branch/gcc/testsuite/gcc.c-torture/compile/pr40233.c
      - copied unchanged from r148003,
trunk/gcc/testsuite/gcc.c-torture/compile/pr40233.c
    branches/gcc-4_4-branch/gcc/testsuite/gcc.c-torture/compile/pr40252.c
      - copied unchanged from r148003,
trunk/gcc/testsuite/gcc.c-torture/compile/pr40252.c
    branches/gcc-4_4-branch/gcc/testsuite/gcc.dg/vect/pr40238.c
      - copied unchanged from r148003,
trunk/gcc/testsuite/gcc.dg/vect/pr40238.c
    branches/gcc-4_4-branch/gcc/testsuite/gcc.dg/vect/pr40254.c
      - copied unchanged from r148003,
trunk/gcc/testsuite/gcc.dg/vect/pr40254.c
Modified:
    branches/gcc-4_4-branch/gcc/testsuite/ChangeLog