[Bug c++/37854] New: No error when creating a variable from itself

[Bug c++/37854] New: No error when creating a variable from itself

[julien dot sagnard at gmail dot com]

If I try to compile this code:

class X {};

int main {
  int i = i;
  X x = x;
  X y(y);
  return 0;
}

With:
gcc -Wall main.cpp

There is no error and no warning.


INFOS:

OS:
Ubuntu Hardy

gcc -v
Using built-in specs.
Target: i486-linux-gnu
Configured with: ../src/configure -v
--enable-languages=c,c++,fortran,objc,obj-c++,treelang --prefix=/usr
--enable-shared --with-system-zlib --libexecdir=/usr/lib
--without-included-gettext --enable-threads=posix --enable-nls
--with-gxx-include-dir=/usr/include/c++/4.2 --program-suffix=-4.2
--enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --enable-mpfr
--enable-targets=all --enable-checking=release --build=i486-linux-gnu
--host=i486-linux-gnu --target=i486-linux-gnu
Thread model: posix
gcc version 4.2.3 (Ubuntu 4.2.3-2ubuntu7)

uname -a
Linux VmWare-Ubuntu 2.6.24-19-generic #1 SMP Fri Jul 11 23:41:49 UTC 2008 i686
GNU/Linux


-- 
           Summary: No error when creating a variable from itself
           Product: gcc
           Version: 4.2.3
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: julien dot sagnard at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37854

[Bug c++/37854] No error when creating a variable from itself

[paolo dot carlini at oracle dot com]

------- Comment #1 from paolo dot carlini at oracle dot com  2008-10-16 16:16 -------


*** This bug has been marked as a duplicate of 34772 ***


-- 

paolo dot carlini at oracle dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |DUPLICATE


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37854

[Bug c++/37854] No error when creating a variable from itself

[paolo dot carlini at oracle dot com]

------- Comment #2 from paolo dot carlini at oracle dot com  2008-10-16 16:18 -------
Oops, sorry.


-- 

paolo dot carlini at oracle dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |UNCONFIRMED
         Resolution|DUPLICATE                   |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37854

[Bug c++/37854] No error when creating a variable from itself

[paolo dot carlini at oracle dot com]

------- Comment #3 from paolo dot carlini at oracle dot com  2008-10-16 16:22 -------
In mainline (would be 4.4.0), with -Winit-self a warning is emitted for line 4
only. EDG-based compilers apparently do the same...


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37854

[Bug c++/37854] No error when creating a variable from itself

[pinskia at gcc dot gnu dot org]

------- Comment #4 from pinskia at gcc dot gnu dot org  2008-10-16 19:08 -------
In this case since x and y are empty structs there are no real uses of them.
If I change the code to:
struct X {int i;};

int main()
{
  int i = i;
  X x = x;
  X y(y);
  return i+x.i+y.i;
}
--- CUT ---
And turn on optimization, I get the following warnings:
t.c: In function 'int main()':
t.c:5: warning: 'i' is used uninitialized in this function
t.c:8: warning: 'x.X::i' is used uninitialized in this function
t.c:8: warning: 'y.X::i' is used uninitialized in this function


Note all of the above warnings should only happen with -Winit-self (which works
correctly with the C front-end and is PR 34772 ).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37854

[Bug c++/37854] No error when creating a variable from itself

[manu at gcc dot gnu dot org]

------- Comment #5 from manu at gcc dot gnu dot org  2008-10-21 20:58 -------
Given Andrew's comments, this is not a bug. Thanks for the report nonetheless.


-- 

manu at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37854