[Bug libstdc++/39310] New: T const assumed to be compatible with int (A::*) (void) const

[Bug libstdc++/39310] New: T const assumed to be compatible with int (A::*) (void) const

[dodji at gcc dot gnu dot org]

In the test file
libstdc++-v3/testsuite/tr1/4_metaprogramming/is_member_function_pointer/value.cc,
the test
VERIFY( (test_category<is_member_function_pointer, int (ClassType::*) (int)
const>(true)) );
should not PASS IMO.

It passes today because of a bug in gcc. More on this in some comments to come
below.

Why shouldn't it PASS ?

Consider:
struct remove_const<T> {};
struct remove_const<T const> 
{
  typedef T type;
};


The  is_member_function_pointer template in the value.cc is written based on
the assumption that the T in the template parameter of

struct remove_const<T const> 
{
  typedef T type;
};

Should deduce to int (A::*) (void), when we try to instantiate 
remove_const<int (A::*) (void) const>; Hence, the current implementation of
is_member_function_pointer assumes that 
struct remove_const<T const> 
{
  typedef T type;
};
should be intantiated.

Actually T const is not compatible with int (A::*) (void) vonst; So it's the
template struct remove_const<T> {}; that should be instantiated. Not its
specialization.

So the test VERIFY( (test_category<is_member_function_pointer,
int (ClassType::*) (int) const>(true)) ); should not PASS.

I will paste in the comments a patch to apply to GCC so that it doesn't compile
that test.


-- 
           Summary: T const assumed to be compatible with int (A::*) (void)
                    const
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: dodji at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39310

[Bug libstdc++/39310] T const assumed to be compatible with int (A::*) (void) const

[jason at gcc dot gnu dot org]

------- Comment #1 from jason at gcc dot gnu dot org  2009-02-26 16:56 -------
Created an attachment (id=17367)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17367&action=view)
Fix for is_member_function_pointer and GCC

Rather, the test should pass, but we need to fix is_member_function_pointer so
it will still pass without the GCC bug.  Patch attached.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39310

[Bug libstdc++/39310] T const assumed to be compatible with int (A::*) (void) const

[dodji at gcc dot gnu dot org]

------- Comment #2 from dodji at gcc dot gnu dot org  2009-02-27 20:08 -------
I have filed bug http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39321 that
describes the gcc bug. It also has a patch that should fix it.


-- 

dodji at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c++                         |libstdc++


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39310

[Bug libstdc++/39310] T const assumed to be compatible with int (A::*) (void) const

[jason at gcc dot gnu dot org]

------- Comment #3 from jason at gcc dot gnu dot org  2009-03-02 01:47 -------
The discussion of Core issue 547
(http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#547) suggests that
we ought to be able to write partial specializations of is_function that can
deal with function cv-quals.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39310

[Bug libstdc++/39310] T const assumed to be compatible with int (A::*) (void) const

[jason at gcc dot gnu dot org]

------- Comment #4 from jason at gcc dot gnu dot org  2009-03-02 20:09 -------
Created an attachment (id=17389)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17389&action=view)
New fix that adds function cv-qual handling to is_function, and fixes compiler
to allow that

Here's a fix along those lines.


-- 

jason at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #17367|0                           |1
        is obsolete|                            |
         AssignedTo|unassigned at gcc dot gnu   |jason at gcc dot gnu dot org
                   |dot org                     |
             Status|UNCONFIRMED                 |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39310

[Bug libstdc++/39310] T const assumed to be compatible with int (A::*) (void) const

[paolo dot carlini at oracle dot com]

------- Comment #5 from paolo dot carlini at oracle dot com  2009-03-03 08:02 -------
Hi. I'll try to catch up as soon as possible on the details of (the v3 bits of)
this issue, but first blush it seems real strange to me that we cannot
implement anymore the is_member_pointer trait as an OR of the
is_member_object_pointer and the is_member_function_pointer traits. Can I have
a quick "executive report" about the rationale of this part of the proposed
fix?


-- 

paolo dot carlini at oracle dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |paolo at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39310

[Bug libstdc++/39310] T const assumed to be compatible with int (A::*) (void) const

[jason at redhat dot com]

------- Comment #6 from jason at redhat dot com  2009-03-03 13:08 -------
Subject: Re:  T const assumed to be compatible with int
 (A::*) (void) const

paolo dot carlini at oracle dot com wrote:
> it seems real strange to me that we cannot
> implement anymore the is_member_pointer trait as an OR of the
> is_member_object_pointer and the is_member_function_pointer traits.

We can still implement it that way; that part of the patch is just an 
optimization.  I'm can drop it if you prefer.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39310

[Bug libstdc++/39310] T const assumed to be compatible with int (A::*) (void) const

[paolo dot carlini at oracle dot com]

------- Comment #7 from paolo dot carlini at oracle dot com  2009-03-03 15:46 -------
Thanks, Jason, now I see it. Then I'm Ok with the patch as-is.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39310

[Bug libstdc++/39310] T const assumed to be compatible with int (A::*) (void) const

[paolo dot carlini at oracle dot com]

------- Comment #8 from paolo dot carlini at oracle dot com  2009-03-13 17:39 -------
Jason, are you going to commit the is_member-2.patch?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39310

[Bug libstdc++/39310] T const assumed to be compatible with int (A::*) (void) const

[jason at gcc dot gnu dot org]

------- Comment #9 from jason at gcc dot gnu dot org  2009-03-15 01:45 -------
I was planning to wait until 4.4 branches.  If you'd rather have it in 4.4, I
can commit it now.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39310

[Bug libstdc++/39310] T const assumed to be compatible with int (A::*) (void) const

[paolo dot carlini at oracle dot com]

------- Comment #10 from paolo dot carlini at oracle dot com  2009-03-15 02:07 -------
(In reply to comment #9)
> I was planning to wait until 4.4 branches.  If you'd rather have it in 4.4, I
> can commit it now.

Well, if you ask me, yes, I would like to see it in 4.4. Thanks in advance. 


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39310

[Bug libstdc++/39310] T const assumed to be compatible with int (A::*) (void) const

[jason at gcc dot gnu dot org]

------- Comment #11 from jason at gcc dot gnu dot org  2009-03-31 18:31 -------
Subject: Bug 39310

Author: jason
Date: Tue Mar 31 18:31:17 2009
New Revision: 145365

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=145365
Log:
        PR c++/37806
        * typeck.c (cp_apply_type_quals_to_decl): Don't apply any quals
        to a typedef.
        * tree.c (cp_build_qualified_type_real): Don't apply restrict to a
        function type.
        * decl.h (enum decl_context): Add TEMPLATE_TYPE_ARG.
        * decl.c (groktypename): Add is_template_arg parameter.
        (grokdeclarator): Allow function cv-quals on a template type arg.
        * parser.c (cp_parser_new_type_id, cp_parser_type_id): Add
        is_template_arg argument in calls to groktypename.
        * cp-tree.h: Adjust prototype.
        * error.c (dump_type_prefix, dump_type_suffix): Fix plain
        FUNCTION_TYPE printing.

        PR libstdc++/39310
        * include/tr1_impl/type_traits (is_function): Add partial
        specializations with function cv-quals.
        (__is_function_helper): Remove.
        (is_member_pointer): Don't define in terms of is_member_*_pointer.

Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/cp-tree.h
    trunk/gcc/cp/decl.c
    trunk/gcc/cp/decl.h
    trunk/gcc/cp/error.c
    trunk/gcc/cp/parser.c
    trunk/gcc/cp/tree.c
    trunk/gcc/cp/typeck.c
    trunk/gcc/testsuite/g++.dg/template/qualttp20.C
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/tr1_impl/type_traits


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39310

[Bug libstdc++/39310] T const assumed to be compatible with int (A::*) (void) const

[dodji at gcc dot gnu dot org]

------- Comment #12 from dodji at gcc dot gnu dot org  2009-04-02 14:19 -------
Fixed in trunk (gcc 4.5).


-- 

dodji at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39310

[Bug libstdc++/39310] T const assumed to be compatible with int (A::*) (void) const

[jason at gcc dot gnu dot org]

------- Comment #13 from jason at gcc dot gnu dot org  2009-04-07 04:38 -------
Subject: Bug 39310

Author: jason
Date: Tue Apr  7 04:38:10 2009
New Revision: 145648

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=145648
Log:
        * decl.c (grokdeclarator): Reject pointer to qualified function
        type.

        PR c++/37806, core issue 547
        * typeck.c (cp_apply_type_quals_to_decl): Don't apply any quals
        to a typedef.
        * tree.c (cp_build_qualified_type_real): Don't apply restrict to a
        function type.
        * decl.h (enum decl_context): Add TEMPLATE_TYPE_ARG.
        * decl.c (groktypename): Add is_template_arg parameter.
        (grokdeclarator): Allow function cv-quals on a template type arg.
        * parser.c (cp_parser_new_type_id, cp_parser_type_id): Add
        is_template_arg argument in calls to groktypename.
        * cp-tree.h: Adjust prototype.
        * error.c (dump_type_prefix, dump_type_suffix): Fix plain
        FUNCTION_TYPE printing.

        PR libstdc++/39310
        * include/tr1_impl/type_traits (is_function): Add partial
        specializations with function cv-quals.
        (__is_function_helper): Remove.
        (is_member_pointer): Don't define in terms of is_member_*_pointer.

Added:
    branches/gcc-4_4-branch/gcc/testsuite/g++.dg/other/typedef2.C
      - copied unchanged from r145367,
trunk/gcc/testsuite/g++.dg/other/typedef2.C
    branches/gcc-4_4-branch/gcc/testsuite/g++.dg/template/typedef17.C
      - copied unchanged from r145367,
trunk/gcc/testsuite/g++.dg/template/typedef17.C
Modified:
    branches/gcc-4_4-branch/gcc/cp/ChangeLog
    branches/gcc-4_4-branch/gcc/cp/cp-tree.h
    branches/gcc-4_4-branch/gcc/cp/decl.c
    branches/gcc-4_4-branch/gcc/cp/decl.h
    branches/gcc-4_4-branch/gcc/cp/error.c
    branches/gcc-4_4-branch/gcc/cp/parser.c
    branches/gcc-4_4-branch/gcc/cp/tree.c
    branches/gcc-4_4-branch/gcc/cp/typeck.c
    branches/gcc-4_4-branch/gcc/testsuite/ChangeLog
    branches/gcc-4_4-branch/gcc/testsuite/g++.dg/template/qualttp20.C
    branches/gcc-4_4-branch/libstdc++-v3/ChangeLog
    branches/gcc-4_4-branch/libstdc++-v3/include/tr1_impl/type_traits


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39310

[Bug libstdc++/39310] T const assumed to be compatible with int (A::*) (void) const

[paolo dot carlini at oracle dot com]

------- Comment #14 from paolo dot carlini at oracle dot com  2009-04-07 08:51 -------
Fixed for 4.4.0 too. Thanks Jason.


-- 

paolo dot carlini at oracle dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.4.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39310