[Bug c++/21113] New: Jumps into VLA or VM scope not rejected for C++

[Bug c++/21113] New: Jumps into VLA or VM scope not rejected for C++

[jsm28 at gcc dot gnu dot org]

Jumps into the scope of an identifier with variably modified type (with goto or
switch) are not rejected by the C++ front end.  Bug 12913 describes this problem
for C, but there should be a separate bug for C++ since bug 16989 only depends
on the issue being fixed for C and not for C++.  The examples in bug 12913 apply:

void f(int l) { 
  goto label; 
  int a[l]; 
 label:; 
} 
    
void g (int l) {
  switch (l) {
  case 1:;
    int a[l];
  default:;
  }
}

(and note that if we follow the C99 rules, which I think is the sensible thing
for the C++ front end to do, the same applies for identifiers of variably
modified type, e.g. int (*a)[l], not just VLAs: cases where the temporary
variable with the array size might not get initialized are all covered, not just
cases where memory for a VLA might not be allocated).

-- 
           Summary: Jumps into VLA or VM scope not rejected for C++
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jsm28 at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21113

[Bug c++/21113] Jumps into VLA or VM scope not rejected for C++

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-04-19 21:56 -------
Confirmed.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
           Keywords|                            |accepts-invalid
   Last reconfirmed|0000-00-00 00:00:00         |2005-04-19 21:56:59
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21113

[Bug c++/21113] Jumps into VLA or VM scope not rejected for C++

[jsm28 at gcc dot gnu dot org]

------- Additional Comments From jsm28 at gcc dot gnu dot org  2005-05-01 11:32 -------
It should be possible to use the existing machinery in the C++ front end which
diagnoses jumps into the scope of initialized or non-POD variables to diagnose
jumps into VLA or VM scope (treating VLA or VM declarations as a special case of
being initialized; after all, the artificial variable with the array size is
initialized by the declaration).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21113

[Bug c++/21113] Jumps into VLA or VM scope not rejected for C++

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21113

--- Comment #3 from Jason Merrill <jason at gcc dot gnu.org> ---
Author: jason
Date: Fri Apr  4 19:35:54 2014
New Revision: 209124

URL: http://gcc.gnu.org/viewcvs?rev=209124&root=gcc&view=rev
Log:
    PR c++/21113
    * decl.c (decl_jump_unsafe): Consider variably-modified decls.

Added:
    trunk/gcc/testsuite/g++.dg/ext/vla14.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/decl.c