[Bug c/81049] New: no warning for simple uninitialized variables

[luc.vanoostenryck at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81049

            Bug ID: 81049
           Summary: no warning for simple uninitialized variables
           Product: gcc
           Version: 7.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: luc.vanoostenryck at gmail dot com
  Target Milestone: ---

gcc doesn't issue a warning for very simple cases of uninitialized variable.
The options used are '-Wuninitialized -O2' or '-Wmaybe-uninitialized -O2'. It
can be reproduced with gcc 5.4, 6.3 and gcc 7.1 (I didn't tried older
versions).

One example of code to show this is:

        int g;
        int foo(void)
        {
                int r = 0;
                int u;

                if (g)
                        r = u;
                return r;
        }