[Bug c++/18934] New: Spurious Uninitialized Variable Warning

["llewins at raytheon dot com" <gcc-bugzilla at gcc dot gnu dot org>]

// Spurious Uninitialized Variable Warning (gcc 3.4.3)
// Lloyd Lewins
// Raytheon Co
// llewins@raytheon.com
//
// Using gcc 3.4.3, the following spurious warning regarding rFileName is 
generated:
/*
> g++-343 -v -c -Wno-deprecated -Wall -O2 test1.cc
Reading specs from /usr/local/lib/gcc/i686-pc-cygwin/3.4.3/specs
Configured with: /usr/local/src/gcc-3.4.3/configure --prefix=/usr/local --progra
m-suffix=-343 --enable-languages=c,c++ --with-gcc --with-gnu-ld --with-gnu-as --
enable-threads=posix --enable-nls --enable-shared
Thread model: posix
gcc version 3.4.3
 /usr/local/libexec/gcc/i686-pc-cygwin/3.4.3/cc1plus.exe -quiet -v -D__CYGWIN32_
_ -D__CYGWIN__ -Dunix -D__unix__ -D__unix -idirafter /usr/lib/../include/w32api
-idirafter /usr/local/lib/gcc/i686-pc-cygwin/3.4.3/../../../../../include/w32api
 test1.cc -quiet -dumpbase test1.cc -mtune=pentiumpro -auxbase test1 -O2 -Wno-de
precated -Wall -version -o /tmp/ccJ5ooP1.s
ignoring nonexistent directory "/usr/local/lib/gcc/i686-pc-cygwin/3.4.3/../../..
/../i686-pc-cygwin/include"
ignoring duplicate directory "/usr/local/lib/gcc/i686-pc-cygwin/3.4.3/../../../.
./../include/w32api"
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/lib/gcc/i686-pc-cygwin/3.4.3/../../../../include/c++/3.4.3
 /usr/local/lib/gcc/i686-pc-cygwin/3.4.3/../../../../include/c++/3.4.3/i686-pc-c
ygwin
 /usr/local/lib/gcc/i686-pc-cygwin/3.4.3/../../../../include/c++/3.4.3/backward
 /usr/local/include
 /usr/local/lib/gcc/i686-pc-cygwin/3.4.3/include
 /usr/include
 /usr/lib/../include/w32api
End of search list.
GNU C++ version 3.4.3 (i686-pc-cygwin)
        compiled by GNU C version 3.4.3.
GGC heuristics: --param ggc-min-expand=99 --param ggc-min-heapsize=130998
test1.cc: In function `int main()':
test1.cc:56: warning: unused variable 'c'
test1.cc:59: warning: 'rFileName' might be used uninitialized in this function
 as -o test1.o /tmp/ccJ5ooP1.s
*/

// Since rFileName is initialized at definition, it is hard to see how it is 
ever
// uninitialized!!

extern void foo();
extern void bar(char* );
extern char* foobar();

class C {public: ~C() {foo();}};

int main()
{
    C c;
        
    // Try to open the reserve file -- check for error
    char* rFileName = foobar();

    // Read the reserve file -- catch exceptions
    try {
        foo();
    }
    catch (...) {
        bar(rFileName);
    }
    
    foo();

}

-- 
           Summary: Spurious Uninitialized Variable Warning
           Product: gcc
           Version: 3.4.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: llewins at raytheon dot com
                CC: gcc-bugs at gcc dot gnu dot org,llewins at raytheon dot
                    com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18934