[Bug c/45821] no warning when returning a local variable address within a statement expression

[manu at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=45821

Manuel López-Ibáñez <manu at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2015-09-18
                 CC|                            |manu at gcc dot gnu.org
         Depends on|                            |60517
     Ever confirmed|0                           |1

--- Comment #4 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
(In reply to Andrew Gaul from comment #3)
> int *function_return_local(void)
> {
>     int x = 0;
>     return &x;
> }
> 
> int *statement_expression_return_local(void)
> {
>     int *y = ({
>         int x = 0;
>         &x;
>     });
>     return y;
> }

We now warn at -O2:

test.c:14:10: warning: function returns address of local variable
[-Wreturn-local-addr]
   return y;
          ^
test.c:11:11: note: declared here
       int x = 0;
           ^

but only because we return y. For this testcase,

int statement_expression_return_local(void)
{
    int *y = ({
        int x = 0;
        &x;
    });
    return *y;
}

we get: 

test.c:14:10: warning: ‘x’ is used uninitialized in this function
[-Wuninitialized]
   return *y;
          ^

which is a bit confusing (and not the same warning).

Possibly related to 60517.
it would be good to add the testcase


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60517
[Bug 60517] warning/error for taking address of member of a temporary object