[Bug fortran/56594] Invalid read of size 1 for gfortran.dg/realloc_on_assign_5.f03

[tilo@tilo-schwarz.de]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56594

Tilo Schwarz <tilo@tilo-schwarz.de> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tilo@tilo-schwarz.de

--- Comment #1 from Tilo Schwarz <tilo@tilo-schwarz.de> 2013-03-17 19:56:11 UTC ---
I think the problem is, that for the line 

a = a(2:2)

1st, a is realloced to length one and
2nd, a(2) is memmoved to a(1), but at that time a(2) is already invalid.

Using -fdump-tree-original:

On line 42 the realloc happens to length 1.
On line 50 the memmove happens from &(*a)[2], which is not valid anymore
because of the realloc on line 42.

 42         a = (character(kind=1)[1:.a] *) __builtin_realloc ((void *) a, 1);
 43         L.4:;
 44         .a = 1;
 45         D.1827 = .a;
 46         if (D.1827 != 0)
 47           {
 48             if ((character(kind=4)) D.1827 <= 1)
 49               {
 50                 __builtin_memmove ((void *) a, (void *) &(*a)[2]{lb: 1 sz:
1}, (character(kind=4)) D.1827);
 51               }