[Bug c++/16139] New: Wrong warnings (unused variable) reported for the code provided when -Wall is used

[Bug c++/16139] New: Wrong warnings (unused variable) reported for the code provided when -Wall is used

[kgardas at objectsecurity dot com]

Hello,

while developing MICO, I've found that gcc3.4.0 only reports some unused
variables, although the code contains much more. i.e. following code:

---code-----
#include <vector>
#include <string>

using namespace std;

void
foo()
{
    bool tcpip_initiator_used = false;
    string tcpip_initiator_options = "";
    bool tcpip_acceptor_used = false;
    string tcpip_acceptor_options = "";
    bool tls_initiator_used = false;
    string tls_initiator_options = "";
    bool tls_acceptor_used = false;
    string tls_acceptor_options = "";
    string tls_certs_initiator_options = "";
    string tls_certs_acceptor_options = "";
    vector<pair<string, string> > client_users;
    vector<pair<string, string> > server_users;
}

int
main(int argc, char* argv[])
{
  foo();
  return 0;
}

-----code-----

produces:

$ c++ -Wall -c w1.cc 
w1.cc: In function `void foo()':
w1.cc:9: warning: unused variable 'tcpip_initiator_used'
w1.cc:11: warning: unused variable 'tcpip_acceptor_used'
w1.cc:13: warning: unused variable 'tls_initiator_used'
w1.cc:15: warning: unused variable 'tls_acceptor_used'
$ 

Interesting is that it only reports bool variables as an unused. IMHO it should
report all variables in foo() function as unused.

Thanks,

Karel

-- 
           Summary: Wrong warnings (unused variable) reported for the code
                    provided when -Wall is used
           Product: gcc
           Version: 3.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: kgardas at objectsecurity dot com
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16139

[Bug c++/16139] Wrong warnings (unused variable) reported for the code provided when -Wall is used

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-06-22 15:30 -------
Invalid as they are not unused as the construtor gets called which might have side effects sorry.

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16139

[Bug c++/16139] Wrong warnings (unused variable) reported for the code provided when -Wall is used

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-06-22 17:24 -------
Well, I wouldn't call it "invalid", just "infeasible". Note that all the 
variables you don't get warnings about have non-trivial constructors that 
have side effects. Sometimes, as in some patterns, a con/destructor call is 
the only interesting effect of a class, the variable is actually not 
used otherwise. To prevent warnings in these cases, the compiler can't] 
warn you in the cases you show. 
 
W. 

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16139

[Bug c++/16139] Wrong warnings (unused variable) reported for the code provided when -Wall is used

[kgardas at objectsecurity dot com]

------- Additional Comments From kgardas at objectsecurity dot com  2004-06-22 18:16 -------
OK, you have convience me enough. :-) Anyway, I have tested it also with Intel
C++ 8.0 and Comeau C++ 4.3.3 and both emits the same warnings, so everything is
ok...
Thanks,
Karel

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16139