[Bug c++/44277] [C++0x] Add warning to facilitate nullptr conversion.

[Bug c++/44277] [C++0x] Add warning to facilitate nullptr conversion.

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44277

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|gcc-bugs at gcc dot gnu.org |jason at gcc dot gnu.org

--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-10-17 18:12:49 UTC ---
Jason, what do you think about this?

[Bug c++/44277] [C++0x] Add warning to facilitate nullptr conversion.

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44277

--- Comment #2 from Jason Merrill <jason at gcc dot gnu.org> 2011-10-17 18:53:07 UTC ---
That seems reasonable, though I wouldn't have it enabled by default or -Wall. 
Could start with replacing convert_and_check with a cp_convert_and_check that
also performs this check.

[Bug c++/44277] [C++0x] Add warning to facilitate nullptr conversion.

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44277

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED

[Bug c++/44277] [C++0x] Add warning to facilitate nullptr conversion.

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44277

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011-10-17
         AssignedTo|unassigned at gcc dot       |paolo.carlini at oracle dot
                   |gnu.org                     |com
     Ever Confirmed|0                           |1

--- Comment #3 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-10-17 18:55:05 UTC ---
Thanks a lot for the tip.

[Bug c++/44277] [C++0x] Add warning to facilitate nullptr conversion.

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44277

--- Comment #4 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-10-17 23:12:58 UTC ---
Jason, would it make sense to produce the warning in cp_convert_to_pointer? I
see the function does *not* have a complain argument (which would be used in
the existing error calls), and that is good because it means we should be safe
wrt undesired warnings in sfinae. Then, about the below, I guess we have also
to decide what to do wrt pointers to members: the same? Then, we'll have also
to decide the exact *name* of the  warning... So many questions ;)

////////////

--- cvt.c       (revision 180110)
+++ cvt.c       (working copy)
@@ -209,7 +209,11 @@ cp_convert_to_pointer (tree type, tree expr)
          expr = build_int_cst_type (type, -1);
        }
       else
-       expr = build_int_cst (type, 0);
+       {
+         if (!NULLPTR_TYPE_P (TREE_TYPE (expr)))
+           warning (0, "zero as null pointer constant");
+         expr = build_int_cst (type, 0);
+       }

       return expr;
     }

[Bug c++/44277] [C++0x] Add warning to facilitate nullptr conversion.

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44277

--- Comment #5 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-10-17 23:29:00 UTC ---
Humm, I already see something wrong in my wild idea: the patchlet triggers also
in conditionals, eg 'if (!p)'...

[Bug c++/44277] [C++0x] Add warning to facilitate nullptr conversion.

[paolo at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44277

--- Comment #6 from paolo at gcc dot gnu.org <paolo at gcc dot gnu.org> 2011-11-01 23:28:23 UTC ---
Author: paolo
Date: Tue Nov  1 23:28:19 2011
New Revision: 180750

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=180750
Log:
/cp
2011-11-01  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/44277
    * cvt.c (cp_convert_to_pointer): Warn for zero as null pointer
    constant.
    * typeck.c (cp_truthvalue_conversion): Handle pointers and member
    function pointers under c_inhibit_evaluation_warnings; use
    nullptr_node for data member pointers.
    (cp_build_binary_op): Tweak, just forward to cp_convert op1,
    either a nullptr_node or an integer_zero_node.
    (build_ptrmemfunc): Use nullptr_node.
    * init.c (build_zero_init_1): Likewise.

/c-family
2011-11-01  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/44277
    * c.opt: Add Wzero-as-null-pointer-constant.

/gcc
2011-11-01  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/44277
    * doc/invoke.texi: Document -Wzero-as-null-pointer-constant.

/testsuite
2011-11-01  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/44277
    * g++.dg/warn/Wzero-as-null-pointer-constant-1.C: New.
    * g++.dg/cpp0x/Wzero-as-null-pointer-constant-1.C: Likewise.

Added:
    trunk/gcc/testsuite/g++.dg/cpp0x/Wzero-as-null-pointer-constant-1.C
    trunk/gcc/testsuite/g++.dg/warn/Wzero-as-null-pointer-constant-1.C
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/c-family/ChangeLog
    trunk/gcc/c-family/c.opt
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/cvt.c
    trunk/gcc/cp/init.c
    trunk/gcc/cp/typeck.c
    trunk/gcc/doc/invoke.texi
    trunk/gcc/testsuite/ChangeLog

[Bug c++/44277] [C++0x] Add warning to facilitate nullptr conversion.

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44277

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |4.7.0

--- Comment #7 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-11-01 23:30:08 UTC ---
Done for 4.7.0.