Hello world,

the attached patch fixes the PR by adding a dependency check
for the case of concatenation operators.

Regression-tested.  OK for trunk?

Regards

	Thomas

2017-08-07  Thomas Koenig  <tkoenig@gcc.gnu.org>

         PR fortran/81116
         * frontend-passes.c (realloc_string_callback): If expression is
	a concatenation, also check for dependency.
         (constant_string_length): Check for presence of symtree.

2017-08-07  Thomas Koenig  <tkoenig@gcc.gnu.org>

         PR fortran/81116
         * gfortran.dg/realloc_on_assignment_29.f90:  New test.