[Bug c/79152] -Wimplicit-fallthrough false positive triggered by goto statements

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79152

--- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
I think the problem is that

 1988   /* Don't warn for a non-case label followed by a statement:
 1989        case 0:
 1990          foo ();
 1991        label:
 1992          bar ();
 1993      as these are likely intentional.  */
 1994   if (!case_label_p (&gimplify_ctxp->case_labels, label))
 1995     {
 1996       gsi_next (&gsi);
 1997       if (gsi_end_p (gsi) || gimple_code (gsi_stmt (gsi)) !=
GIMPLE_LABEL)
 1998         return false;
 1999     }

doesn't handle consecutive non-case labels.