[Bug c++/31952] New: parameters may be redeclared in a function try-block

[Bug c++/31952] New: parameters may be redeclared in a function try-block

[andrew dot stubbs at st dot com]

According to the C++ standard, clause 3.3.2, paragraph 2, sentence 3, the
following program should be invalid:

int
foo (int bar)
try
{
  return 0;
}
catch (...)
{
  int bar = 0; // invalid
  return 1;
}

Specifically, `bar' may not be redeclared in the outermost block of a handler
in a function try-block.

GCC 4.1.1 gives no errors or warnings (other than unused parameters and
variables).


-- 
           Summary: parameters may be redeclared in a function try-block
           Product: gcc
           Version: 4.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: andrew dot stubbs at st dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31952

[Bug c++/31952] parameters may be redeclared in a function try-block

[fang at csl dot cornell dot edu]

------- Comment #1 from fang at csl dot cornell dot edu  2007-05-16 20:46 -------
Poor man's workaround: -Wshadow -Werror


-- 

fang at csl dot cornell dot edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fang at csl dot cornell dot
                   |                            |edu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31952

[Bug c++/31952] parameters may be redeclared in a function try-block

[andrew dot stubbs at st dot com]

------- Comment #2 from andrew dot stubbs at st dot com  2007-05-17 15:34 -------
Another example perhaps?

void
foo()
{
  try
    {
    }
  catch (void *e)
    {
      void *e; // invalid
    }
}

The C++ standard, clause 3.3.2 paragraph 3, states that catch
exception-declarations may not be redeclared in the outermost block of the
catch block.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31952

[Bug c++/31952] parameters may be redeclared in a function try-block

[bangerth at dealii dot org]

------- Comment #3 from bangerth at dealii dot org  2007-05-17 15:51 -------
Confirmed.


-- 

bangerth at dealii dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bangerth at dealii dot org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
           Keywords|                            |accepts-invalid, diagnostic
   Last reconfirmed|0000-00-00 00:00:00         |2007-05-17 15:51:41
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31952

[Bug c++/31952] parameters may be redeclared in a function try-block

[andrew dot stubbs at st dot com]

------- Comment #4 from andrew dot stubbs at st dot com  2007-11-01 18:15 -------
It gets worse :(

The following example used to be detected by GCC 4.1.1, but is now permitted by
GCC 4.1.2, 4.2.1, 4.2.2, and 4.3-20071026, and hence is a regression.

int
foo (int bar)
try
{
  return 0;
}
catch (int bar)  // invalid
{
  return 1;
}


-Wshadow still detects it, but it is no longer an error.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31952

[Bug c++/31952] parameters may be redeclared in a function try-block

[pi3orama at gmail dot com]

------- Comment #5 from pi3orama at gmail dot com  2009-11-06 06:58 -------
still not solved at 4.3.4


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31952

[Bug c++/31952] parameters may be redeclared in a function try-block

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31952

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

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

--- Comment #6 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-08-20 10:29:11 UTC ---
Comment #2 is PR5605.

Comparing to Janis' fix for PR2288
(http://gcc.gnu.org/ml/gcc-patches/2010-03/msg00838.html) looks like the
pushdecl_maybe_friend_1 checks must be beefed up, maybe we need an additional
sk_* for Comment #2. Seems doable.

Adding Janis in CC in case she wants to beat me (or somebody else) on this.

[Bug c++/31952] parameters may be redeclared in a function try-block

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31952

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |cs at plesk dot com

--- Comment #7 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-08-20 10:40:59 UTC ---
*** Bug 5605 has been marked as a duplicate of this bug. ***

[Bug c++/31952] parameters may be redeclared in a function try-block

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31952

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

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

--- Comment #9 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Jason, I'm on this issue but I'm not sure how we want to resolve it.

After Janis' patch (see Comment #6) in pushdecl_maybe_friend_1 we issue hard
errors for some kinds of shadowings but not for others. For comparison, clang
issues hard errors for all three testcases here, ICC warnings (like current
GCC). If we wanted, I could tweak the parser to carefully do_pushlevel
(sk_catch) and therefore change to errors only the specific shadowings at issue
in this PR, but I'm also aiming for some consistency.

[Bug c++/31952] parameters may be redeclared in a function try-block

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31952

--- Comment #10 from Jason Merrill <jason at gcc dot gnu.org> ---
(In reply to Paolo Carlini from comment #9)
> After Janis' patch (see Comment #6) in pushdecl_maybe_friend_1 we issue hard
> errors for some kinds of shadowings but not for others. For comparison,
> clang issues hard errors for all three testcases here, ICC warnings (like
> current GCC). If we wanted, I could tweak the parser to carefully
> do_pushlevel (sk_catch) and therefore change to errors only the specific
> shadowings at issue in this PR, but I'm also aiming for some consistency.

Well, the language requires diagnostics for some shadowings and not others, so
it makes sense for us to mirror that.  But we probably want permerror rather
than error.

[Bug c++/31952] parameters may be redeclared in a function try-block

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31952

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
                 CC|jason at gcc dot gnu.org           |
         Resolution|---                         |FIXED
   Target Milestone|---                         |4.9.0

--- Comment #11 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Fixed for 4.9.0.