[Bug c/39113] New: no warning that a variable may be used uninitialized

[dhill at clusterresources dot com]

$gcc -O -Wextra -save-temps um3.c
$

um3.c

#include 

main()
{
char *J;

if (rand())
  J = NULL;

printf("\ntest %s\n",J);
}


In this example, J could be used uninitialized but the compiler is not giving
that warning.


-- 
   Summary: no warning that a variable may be used uninitialized
   Product: gcc
   Version: 4.3.2
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: dhill at clusterresources dot com
 GCC build triplet: --build=x86_64-linux-gnu
  GCC host triplet: --host=x86_64-linux-gnu
GCC target triplet: --target=x86_64-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39113

[Bug c/39113] no warning that a variable may be used uninitialized

[dhill at clusterresources dot com]

--- Comment #1 from dhill at clusterresources dot com  2009-02-05 20:51 
---
Created an attachment (id=17252)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17252&action=view)
.i file


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39113

[Bug c/39113] no warning that a variable may be used uninitialized

[dhill at clusterresources dot com]

--- Comment #2 from dhill at clusterresources dot com  2009-02-05 21:04 
---
Here is the gcc -v output if that is helpful

$ gcc -v
Using built-in specs.
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.3.2-1ubuntu12'
--with-bugurl=file:///usr/share/doc/gcc-4.3/README.Bugs
--enable-languages=c,c++,fortran,objc,obj-c++ --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++/4.3
--program-suffix=-4.3 --enable-clocale=gnu --enable-libstdcxx-debug
--enable-objc-gc --enable-mpfr --enable-checking=release
--build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.3.2 (Ubuntu 4.3.2-1ubuntu12) 


-- 

dhill at clusterresources dot com changed:

   What|Removed |Added

 CC|        |dhill at clusterresources
   |            |dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39113

[Bug c/39113] no warning that a variable may be used uninitialized

[dhill at clusterresources dot com]

--- Comment #3 from dhill at clusterresources dot com  2009-02-05 21:48 
---
Note that the warning is correctly reported in older versions of the compiler.

The following example is from gcc 3.2.3


$ gcc -O -W um3.c
um3.c: In function `main':
um3.c:5: warning: `J' might be used uninitialized in this function


$ gcc -v
Reading specs from /usr/lib/gcc-lib/i386-redhat-linux/3.2.3/specs
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
--infodir=/usr/share/info --enable-shared --enable-threads=posix
--disable-checking --with-system-zlib --enable-__cxa_atexit
--host=i386-redhat-linux
Thread model: posix
gcc version 3.2.3 20030502 (Red Hat Linux 3.2.3-59)

$ cat um3.c
#include 

main()
{
char *J;

if (rand())
  J = NULL;

printf("\ntest %s\n",J);
}


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39113

[Bug tree-optimization/18501] [4.2/4.3/4.4 Regression] Missing 'used uninitialized' warning (CCP)

[dhill at clusterresources dot com]

--- Comment #23 from dhill at clusterresources dot com  2009-02-05 22:44 
---
note that gcc version 3.2.3 correctly reports this warning


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18501