2006-06-08  Francois-Xavier Coudert  <coudert@clipper.ens.fr>

	PR fortran/27958
	* trans-expr.c (gfc_conv_substring): If the substring start is
	greater than its end, the length of the substring is zero, and
	not negative.
	(gfc_trans_string_copy): Don't generate a call to
	_gfortran_copy_string when destination length is zero.


2006-06-08  Francois-Xavier Coudert  <coudert@clipper.ens.fr>

	PR fortran/27958
	* gcc/testsuite/gfortran.dg/substr_2.f: New test.