[Bug c++/40695] New: bogus "may be used uninitialized in this function" warning

["shane dot beasley at aleri dot com" <gcc-bugzilla at gcc dot gnu dot org>]

Apologies if this is a duplicate, but I can't find another quite like this...

<blockquote>
struct Class
{
    // undefined
    void Method();
};

template < typename w_type >
struct NoPtr
{
    // inline
    NoPtr( bool = false ) : m_ptr( 0 ) { }

    // inline; calls a method
    ~NoPtr() { if ( m_ptr ) m_ptr->Method(); }

    // undefined
    w_type *Get();

    w_type *m_ptr;
};

void f()
{
    bool cond = true;

    // a named NoPtr< Class > initialized from a ternary expression
    // with an if-expr that refers to any named object,
    // plus a then-expr that contains an rvalue of type NoPtr< Class >
    NoPtr< Class > named(
        cond
        ? NoPtr< Class >().Get()
        : 0
    );
}
</blockquote>

$ /usr/bin/g++-4.2 -c -o/dev/null -xc++ -Wuninitialized -O file.cpp
$ /usr/bin/g++-4.2 -dumpversion
4.2.4

$ g++-4 -c -o/dev/null -xc++ -Wuninitialized -O file.cpp
file.cpp: In function 'void f()':
file.cpp:14: warning: 'named.NoPtr<Class>::m_ptr' may be used uninitialized in
this function
file.cpp:30: note: 'named.NoPtr<Class>::m_ptr' was declared here
$ g++-4 -dumpversion
4.3.2

$ /usr/bin/g++-4.3 -c -o/dev/null -xc++ -Wuninitialized -O file.cpp
file.cpp: In function 'void f()':
file.cpp:14: warning: 'named.NoPtr<Class>::m_ptr' may be used uninitialized in
this function
file.cpp:30: note: 'named.NoPtr<Class>::m_ptr' was declared here
$ /usr/bin/g++-4.3 -dumpversion
4.3.3

$ /usr/bin/g++-4.4 -c -o/dev/null -xc++ -Wuninitialized -O file.cpp
file.cpp: In function 'void f()':
file.cpp:14: warning: 'named.NoPtr<Class>::m_ptr' may be used uninitialized in
this function
file.cpp:30: note: 'named.NoPtr<Class>::m_ptr' was declared here
$ /usr/bin/g++-4.4 -dumpversion
4.4.0

If it helps, that's 4.2.4 on Debian; 4.3.2 on Cygwin; 4.3.3 and 4.4.0 on both
Solaris and Debian.


-- 
           Summary: bogus "may be used uninitialized in this function"
                    warning
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: shane dot beasley at aleri dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40695