[Bug c++/31449] New: static_cast can remove const-ness

[Bug c++/31449] New: static_cast can remove const-ness

[simon_baldwin at yahoo dot com]

The following const-incorrect program compiles without error on gcc 4.1.0, and
4.3.0 20070323:

class Foo {};
class Bar : public Foo {};
static const Foo *foo = 0;

static Bar *bar = static_cast<const Bar*>(foo);  // Error, casts away const

void func(const Foo *foo) {
  Bar *bar = static_cast<const Bar*>(foo);  // Error, casts away const
}

gcc 2.95.3, 3.4.5, and 4.0.2 report errors on the commented lines above, so it
looks like a compiler regression in 4.1.0.

I looked hard through existing PRs, and couldn't find this reported elsewhere
(the closest is PR 20475, but it's concerned with 3.4.4 and the const-ness, or
otherwise, of string literals, so not the same).  I'd be a little surprised if
I'm the first to see it, but it's possible...


-- 
           Summary: static_cast can remove const-ness
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: simon_baldwin at yahoo dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31449

[Bug c++/31449] [4.1/4.2/4.3 regression] static_cast can remove const-ness

[reichelt at gcc dot gnu dot org]

------- Comment #1 from reichelt at gcc dot gnu dot org  2007-04-04 00:06 -------
Confirmed.
The regression was introduced between GCC 4.0.2 and 4.0.3.

Mark, it looks like the following patch of yours is responsible for the
regression:

2006-01-21  Mark Mitchell  <mark@codesourcery.com>

        PR c++/25895
        * class.c (build_base_path): Generate a NOP_EXPR instead of a
        COMPONENT_REF if the base and derived classes are at the same
        address.


-- 

reichelt at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mark at codesourcery dot
                   |                            |com, reichelt at gcc dot gnu
                   |                            |dot org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
           Keywords|                            |accepts-invalid, monitored
      Known to fail|                            |4.0.3
      Known to work|                            |4.0.2
   Last reconfirmed|0000-00-00 00:00:00         |2007-04-04 00:06:46
               date|                            |
            Summary|static_cast can remove      |[4.1/4.2/4.3 regression]
                   |const-ness                  |static_cast can remove
                   |                            |const-ness
   Target Milestone|---                         |4.1.3


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31449

[Bug c++/31449] [4.1/4.2/4.3 regression] static_cast can remove const-ness

[mmitchel at gcc dot gnu dot org]

-- 

mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |mark at codesourcery dot com
                   |dot org                     |
             Status|NEW                         |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31449

[Bug c++/31449] [4.1/4.2/4.3 regression] static_cast can remove const-ness

[mmitchel at gcc dot gnu dot org]

------- Comment #2 from mmitchel at gcc dot gnu dot org  2007-04-09 20:46 -------
Subject: Bug 31449

Author: mmitchel
Date: Mon Apr  9 20:45:53 2007
New Revision: 123679

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=123679
Log:
        PR c++/31449
        * class.c (build_base_path): Ensure that the converted pointer has
        the same cv-qualification as the input.
        PR c++/31449
        * g++.dg/init/const5.C: New test.

Added:
    trunk/gcc/testsuite/g++.dg/init/const5.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/class.c
    trunk/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31449

[Bug c++/31449] [4.1/4.2] static_cast can remove const-ness

[mmitchel at gcc dot gnu dot org]

------- Comment #3 from mmitchel at gcc dot gnu dot org  2007-04-09 20:51 -------
Fixed in 4.3.0.


-- 

mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[4.1/4.2/4.3 regression]    |[4.1/4.2] static_cast can
                   |static_cast can remove      |remove const-ness
                   |const-ness                  |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31449

[Bug c++/31449] [4.1] static_cast can remove const-ness

[mmitchel at gcc dot gnu dot org]

------- Comment #5 from mmitchel at gcc dot gnu dot org  2007-04-10 04:01 -------
Fixed in 4.2.0.


-- 

mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[4.1/4.2] static_cast can   |[4.1] static_cast can remove
                   |remove const-ness           |const-ness


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31449

[Bug c++/31449] [4.1/4.2] static_cast can remove const-ness

[mmitchel at gcc dot gnu dot org]

------- Comment #4 from mmitchel at gcc dot gnu dot org  2007-04-10 04:01 -------
Subject: Bug 31449

Author: mmitchel
Date: Tue Apr 10 04:01:08 2007
New Revision: 123690

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=123690
Log:
        PR c++/31449
        * class.c (build_base_path): Ensure that the converted pointer has
        the same cv-qualification as the input.
        PR c++/31449
        * g++.dg/init/const5.C: New test.

Added:
    branches/gcc-4_2-branch/gcc/testsuite/g++.dg/init/const5.C
Modified:
    branches/gcc-4_2-branch/gcc/cp/ChangeLog
    branches/gcc-4_2-branch/gcc/cp/class.c
    branches/gcc-4_2-branch/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31449

[Bug c++/31449] [4.1] static_cast can remove const-ness

[mmitchel at gcc dot gnu dot org]

------- Comment #6 from mmitchel at gcc dot gnu dot org  2007-04-10 06:07 -------
Subject: Bug 31449

Author: mmitchel
Date: Tue Apr 10 06:07:41 2007
New Revision: 123691

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=123691
Log:
        PR c++/31449
        * class.c (build_base_path): Ensure that the converted pointer has
        the same cv-qualification as the input.
        PR c++/31449
        * g++.dg/init/const5.C: New test.

Added:
    branches/gcc-4_1-branch/gcc/testsuite/g++.dg/init/const5.C
Modified:
    branches/gcc-4_1-branch/gcc/cp/ChangeLog
    branches/gcc-4_1-branch/gcc/cp/class.c
    branches/gcc-4_1-branch/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31449

[Bug c++/31449] [4.1] static_cast can remove const-ness

[mmitchel at gcc dot gnu dot org]

------- Comment #7 from mmitchel at gcc dot gnu dot org  2007-04-10 06:07 -------
Fixed in 4.1.3.


-- 

mmitchel at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31449