re PR fortran/85520 (Out of memory when declaring a character with len << 0)

2018-04-24  Steven G. Kargl  <kargl@gcc.gnu.org>

	PR fortran/85520
	* decl.c (gfc_match_char_spec): Check for negative length and set to 0.

2018-04-24  Steven G. Kargl  <kargl@gcc.gnu.org>

	PR fortran/85520
	* gfortran.dg/pr85520.f90: New test.

From-SVN: r259623

gcc/fortran/ChangeLog

+2018-04-24  Steven G. Kargl  <kargl@gcc.gnu.org>
+
+	PR fortran/85520
+	* decl.c (gfc_match_char_spec): Check for negative length and set to 0.
+
 2018-04-14  Andre Vehreschild  <vehre@gcc.gnu.org>
 
 	PR fortran/81773

gcc/fortran/decl.c

@@ -3235,7 +3235,11 @@ done:
 	  e = gfc_copy_expr (len);
 	  gfc_reduce_init_expr (e);
 	  if (e->expr_type == EXPR_CONSTANT)
-	    gfc_replace_expr (len, e);
+	    {
+	      gfc_replace_expr (len, e);
+	      if (mpz_cmp_si (len->value.integer, 0) < 0)
+		mpz_set_ui (len->value.integer, 0);
+	    }
 	  else
 	    gfc_free_expr (e);
 	  cl->length = len;

gcc/testsuite/ChangeLog

+2018-04-24  Steven G. Kargl  <kargl@gcc.gnu.org>
+
+	PR fortran/85520
+	* gfortran.dg/pr85520.f90: New test.
+
 2018-04-24  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
 
 	PR target/85512

gcc/testsuite/gfortran.dg/pr85520.f90

+! { dg-do run }
+! PR fortran/85520
+! Original code from Gerhard Steinmetz <gscfq at t-online dot de>
+program p
+   character(-huge(1)) :: c = ' '
+    if (len(c) /= 0) stop 1
+end