[Bug 41437] (c++) No access control for classes in template functions

[Bug 41437] (c++) No access control for classes in template functions

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41437

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |liranuna at gmail dot com

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> 2010-09-24 09:35:15 UTC ---
*** Bug 45775 has been marked as a duplicate of this bug. ***

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Configure bugmail: http://gcc.gnu.org/bugzilla/userprefs.cgi?tab=email
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[Bug c++/41437] No access control for classes in template functions

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41437

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |sylvestre at debian dot org

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-02-24 16:50:25 UTC ---
*** Bug 52373 has been marked as a duplicate of this bug. ***

[Bug c++/41437] No access control for classes in template functions

[w.shane.grant at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41437

Shane <w.shane.grant at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |w.shane.grant at gmail dot com

--- Comment #5 from Shane <w.shane.grant at gmail dot com> ---
This bug still exists for g++ 4.8.1.  Crops up regardless of where the template
function is that tries to access the protected/private member:

class Base { void snarf() {} };

struct Derived : public Base
{
  template <class T>
  void bar( T & t )
  {
    snarf(); // this is incorrectly marked ok
  }
};

[Bug c++/41437] No access control for classes in template functions

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41437

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |yyc1992 at gmail dot com

--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
*** Bug 64216 has been marked as a duplicate of this bug. ***

[Bug c++/41437] No access control for classes in template functions

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41437

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |wrong-code
   Last reconfirmed|2010-09-20 15:53:01         |2020-3-12

--- Comment #10 from Jonathan Wakely <redi at gcc dot gnu.org> ---
As Bug 94003 shows, this is also a wrong-code bug.

[Bug c++/41437] No access control for classes in template functions

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41437

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|                            |ppalka at gcc dot gnu.org
           Assignee|unassigned at gcc dot gnu.org      |ppalka at gcc dot gnu.org

[Bug c++/41437] No access control for classes in template functions

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41437

--- Comment #11 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Patrick Palka <ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:92bed036098928cd4659c8990e14cf7ad040e0c2

commit r11-1350-g92bed036098928cd4659c8990e14cf7ad040e0c2
Author: Patrick Palka <ppalka@redhat.com>
Date:   Tue Jun 16 08:21:33 2020 -0400

    c++: Improve access checking inside templates [PR41437]

    This patch generalizes our existing functionality for deferring access
    checking of typedefs when parsing a function or class template to now
    defer all kinds of access checks until template instantiation time,
    including member function and member object accesses.

    Since all access checks eventually go through enforce_access, the main
    component of this patch is new handling inside enforce_access to defer
    the current access check if we're inside a template.  The bulk of the
    rest of the patch consists of removing now-unneeded code pertaining to
    suppressing access checks inside templates or pertaining to
    typedef-specific access handling.  Renamings and other changes with no
    functional impact have been split off into the followup patch.

    gcc/cp/ChangeLog:

            PR c++/41437
            PR c++/47346
            * call.c (enforce_access): Move to semantics.c.
            * cp-tree.h (enforce_access): Delete.
            (get_types_needing_access_check): Delete.
            (add_typedef_to_current_template_for_access_check): Delete.
            * decl.c (make_typename_type): Adjust accordingly.  Use
            check_accessibility_of_qualified_id instead of directly using
            perform_or_defer_access_check.
            * parser.c (cp_parser_template_declaration_after_parameters):
            Don't push a dk_no_check access state when parsing a template.
            * pt.c (get_types_needing_access_check): Delete.
            (append_type_to_template_for_access_check_1): Delete.
            (perform_typedefs_access_check): Adjust.  If type_decl is a
            FIELD_DECL, also check its DECL_CONTEXT for dependence. Use
            tsubst_copy instead of tsubst to substitute into type_decl so
            that we substitute into the DECL_CONTEXT of a FIELD_DECL.
            (append_type_to_template_for_access_check): Delete.
            * search.c (accessible_p): Remove the processing_template_decl
            early exit.
            * semantics.c (enforce_access): Moved from call.c.  If we're
            parsing a template and the access check failed, add the check to
            TI_TYPEDEFS_NEEDING_ACCESS_CHECKING.
            (perform_or_defer_access_check): Adjust comment.
            (add_typedef_to_current_template_for_access_check): Delete.
            (check_accessibility_of_qualified_id):  Adjust accordingly.
            Exit early if the scope is dependent.

    gcc/testsuite/ChangeLog:

            PR c++/41437
            PR c++/47346
            * g++.dg/cpp2a/concepts-using2.C: Adjust.
            * g++.dg/lto/20081219_1.C: Adjust.
            * g++.dg/lto/20091002-1_0.C: Adjust.
            * g++.dg/lto/pr65475c_0.C: Adjust.
            * g++.dg/opt/dump1.C: Adjust.
            * g++.dg/other/pr53574.C: Adjust.
            * g++.dg/template/access30.C: New test.
            * g++.dg/template/access31.C: New test.
            * g++.dg/wrappers/wrapper-around-type-pack-expansion.C: Adjust.

    libstdc++-v3/ChangeLog:

            PR libstdc++/94003
            * testsuite/20_util/is_constructible/94003.cc: New test.

[Bug c++/41437] No access control for classes in template functions

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41437

--- Comment #12 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Patrick Palka <ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:668ef28fbb44c1e51d9c5a35b421903c98d87b03

commit r11-1351-g668ef28fbb44c1e51d9c5a35b421903c98d87b03
Author: Patrick Palka <ppalka@redhat.com>
Date:   Tue Jun 16 08:21:36 2020 -0400

    c++: Clean up previous change [PR41437]

    The previous patch mostly avoided making any changes that had no
    functional impact, such as adjusting now-outdated comments and
    performing renamings.  Such changes have been consolidated to this
    followup patch for easier review.

    The main change here is that we now reuse struct deferred_access_check
    as the element type of the vector TI_TYPEDEFS_NEEDING_ACCESS_CHECKING
    (now renamed to TI_DEFERRED_ACCESS_CHECKS, since it may contain any kind
    of access check).

    gcc/cp/ChangeLog:

            PR c++/41437
            PR c++/47346
            * cp-tree.h (qualified_typedef_usage_s): Delete.
            (qualified_typedef_usage_t): Delete.
            (deferred_access_check): Move up in file.
            (tree_template_info::typedefs_needing_access_checking): Delete.
            (tree_template_info::deferred_access_checks): New field.
            (TI_TYPEDEFS_NEEDING_ACCESS_CHECKING): Rename to ...
            (TI_DEFERRED_ACCESS_CHECKS): ... this, and adjust accordingly.
            * pt.c (perform_typedefs_access_check): Rename to ...
            (perform_instantiation_time_access_checks): ... this, and adjust
            accordingly.  Remove unnecessary tree tests.
            (instantiate_class_template_1): Adjust accordingly.
            (instantiate_decl): Likewise.
            * semantics.c (enforce_access): Likewise.

[Bug c++/41437] No access control for classes in template functions

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41437

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED

--- Comment #13 from Patrick Palka <ppalka at gcc dot gnu.org> ---
This should be fixed for GCC 11 now.

[Bug c++/41437] No access control for classes in template functions

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41437

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |11.0

[Bug c++/41437] No access control for classes in template functions

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41437

--- Comment #14 from Jonathan Wakely <redi at gcc dot gnu.org> ---
*** Bug 94644 has been marked as a duplicate of this bug. ***

[Bug c++/41437] No access control for classes in template functions

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41437

--- Comment #15 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Patrick Palka <ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:29853c653245c37ed31b6abcc9799b534372e938

commit r11-6800-g29853c653245c37ed31b6abcc9799b534372e938
Author: Patrick Palka <ppalka@redhat.com>
Date:   Tue Jan 19 16:20:00 2021 -0500

    c++: Always check access during late-parsing of members [PR58993]

    This patch removes a vestigial use of dk_no_check from
    cp_parser_late_parsing_for_member, which ideally should have been
    removed as part of the PR41437 patch that improved access checking
    inside templates.  This allows us to correctly reject f1 and f2 in
    the testcase access34.C below (whereas before we'd only reject f3).

    Additional testing revealed a new access issue when late-parsing a hidden
    friend within a class template.  In the testcase friend68.C below, we're
    tripping over the checking assert from friend_accessible_p(f, S::j, S, S)
    during lookup of j in x.j (for which type_dependent_object_expression_p
    returns false, which is why we're doing the lookup at parse time).  The
    reason for the assert failure is that DECL_FRIENDLIST(S) contains f but
    DECL_BEFRIENDING_CLASSES(f) is empty, and so friend_accessible_p (which
    looks at DECL_BEFRIENDING_CLASSES) wants to return false, but is_friend
    (which looks at DECL_FRIENDLIST) returns true.

    For sake of symmetry one would expect that DECL_BEFRIENDING_CLASSES(f)
    contains S, but add_friend avoids updating DECL_BEFRIENDING_CLASSES when
    the class type (S in this case) is dependent, for some reason.

    This patch works around this issue by making friend_accessible_p
    consider the DECL_FRIEND_CONTEXT of the access scope.  Thus we sidestep
    the DECL_BEFRIENDING_CLASSES / DECL_FRIENDLIST asymmetry issue while
    correctly validating the x.j access at parse time.

    A earlier version of this patch checked friend_accessible_p instead of
    protected_accessible_p in the DECL_FRIEND_CONTEXT hunk below, but this
    had the side effect of making us accept the ill-formed testcase friend69.C
    below (ill-formed because the hidden friend g is not actually a member
    of A, so g doesn't have access to B's members despite B befriending A).

    gcc/cp/ChangeLog:

            PR c++/41437
            PR c++/58993
            * search.c (friend_accessible_p): If scope is a hidden friend
            defined inside a dependent class, consider access from the
            class.
            * parser.c (cp_parser_late_parsing_for_member): Don't push a
            dk_no_check access state.

    gcc/testsuite/ChangeLog:

            PR c++/41437
            PR c++/58993
            * g++.dg/opt/pr87974.C: Adjust.
            * g++.dg/template/access34.C: New test.
            * g++.dg/template/friend68.C: New test.
            * g++.dg/template/friend69.C: New test.

[Bug c++/41437] No access control for classes in template functions

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41437

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |cgd at google dot com

--- Comment #16 from Jonathan Wakely <redi at gcc dot gnu.org> ---
*** Bug 48078 has been marked as a duplicate of this bug. ***

[Bug c++/41437] No access control for classes in template functions

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41437

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |lhyatt at gmail dot com

--- Comment #17 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 58740 has been marked as a duplicate of this bug. ***

[Bug c++/41437] No access control for classes in template functions

[timturnerc at yahoo dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41437

Tim Turner <timturnerc at yahoo dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |timturnerc at yahoo dot com

--- Comment #18 from Tim Turner <timturnerc at yahoo dot com> ---
------8<-------
 1 size_t fwrite(const void * __restrict ptr, size_t size,
http://www-look-4.com/category/travel/
 2               size_t nmemb, register FILE * __restrict stream)
 3 {
 4     size_t retval; https://komiya-dental.com/category/technology/
 5     __STDIO_AUTO_THREADLOCK_VAR;
 6  http://www.iu-bloomington.com/category/technology/
 7 >   __STDIO_AUTO_THREADLOCK(stream);
 8 
 9     retval = fwrite_unlocked(ptr, size, nmemb, stream);
10  https://waytowhatsnext.com/category/technology/
11     __STDIO_AUTO_THREADUNLOCK(stream);
12  http://www.wearelondonmade.com/category/travel/
13     return retval;
14 }
------>8-------
 http://www.jopspeech.com/category/travel/
Here, we are at line 7. Using the "next" command leads no where. However,
setting a breakpoint on line 9 and issuing "continue" works.
http://joerg.li/category/travel/
Looking at the assembly instructions reveals that we're dealing with the
critical section entry code http://the-hunters.org/technology/meta-symbol/ [1]
that should never be interrupted, in this
case by the debugger's implicit breakpoints:
http://connstr.net/category/travel/

------8<-------
  ... http://embermanchester.uk/category/travel/
1 add_s   r0,r13,0x38
2 mov_s   r3,1
3 llock   r2,[r0]        <-.
4 brne.nt r2,0,14     --.  | http://www.slipstone.co.uk/category/travel/
5 scond   r3,[r0]       |  |
6 bne     -10         --|--'
7 brne_s  r2,0,84     <-' http://www.logoarts.co.uk/category/travel/
  ...
------>8-------
 http://www.acpirateradio.co.uk/category/travel/
Lines 3 until 5 (inclusive) are supposed to be executed atomically. Therefore,
http://fishingnewsletters.co.uk/crypto/kelleci-bay/
GDB should never (implicitly) insert a breakpoint on lines 4 and 5, else the
http://www.compilatori.com/category/travel/ 
program will try to acquire the lock again by jumping back to line 3 and
gets stuck in an infinite loop. https://www.webb-dev.co.uk/category/technology/

The solution is to make GDB aware of these patterns so it inserts breakpoints
after the sequence -- line 6 in this example. The solution is to make GDB aware
of these patterns so it inserts breakpoints
http://www.go-mk-websites.co.uk/services/kyoto/
after the sequence -- line 6 in this example.
 The solution is to make GDB aware of these patterns so it inserts breakpoints
after the sequence -- line 6 in this example.
http://www.mconstantine.co.uk/services/new-zealand/
The solution is to make GDB aware of these patterns so it inserts breakpoints
after the sequence -- line 6 in this example.