[patch, fortran] PR69110 ICE with NEWUNIT

[Jerry DeLisle]

This patch from Steve on c.l.f

Fixes the segfault from attempting a string compare where there is no string 
yet.

Regression tested on x86-64.  New test case.

OK for trunk.

Regards,

Jerry

2016-02-24  Jerry DeLisle  <jvdeli...@gcc.gnu.org>
            Steven G. Kargl  <ka...@gcc.gnu.org>

        PR fortran/69110
        * io.c (gfc_match_open): Check that open status is an expression
        constant before comparing string to 'scratch' with NEWUNIT.

diff --git a/gcc/fortran/io.c b/gcc/fortran/io.c
index fddd36b..da0e1c5 100644
--- a/gcc/fortran/io.c
+++ b/gcc/fortran/io.c
@@ -1890,13 +1890,16 @@ gfc_match_open (void)
 	  goto cleanup;
 	}
 
-      if (!(open->file || (open->status
-          && gfc_wide_strncasecmp (open->status->value.character.string,
-				   "scratch", 7) == 0)))
-	{
-	  gfc_error ("NEWUNIT specifier must have FILE= "
-		     "or STATUS='scratch' at %C");
-	  goto cleanup;
+      if (!open->file && open->status)
+        {
+	  if (open->status->expr_type == EXPR_CONSTANT
+	     && gfc_wide_strncasecmp (open->status->value.character.string,
+				       "scratch", 7) != 0)
+	   {
+	     gfc_error ("NEWUNIT specifier must have FILE= "
+			"or STATUS='scratch' at %C");
+	     goto cleanup;
+	   }
 	}
     }
   else if (!open->unit)
diff --git a/gcc/testsuite/gfortran.dg/newunit_4.f90 b/gcc/testsuite/gfortran.dg/newunit_4.f90
new file mode 100644
index 0000000..4d7d738
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/newunit_4.f90
@@ -0,0 +1,7 @@
+! { dg-do compile }
+! PR69110 ICE with NEWUNIT 
+subroutine open_file_safe(fname, fstatus, faction, fposition, funit)
+  character(*), intent(in)  :: fname, fstatus, faction, fposition
+  integer, intent(out)      :: funit
+  open(newunit=funit, status=fstatus)
+end subroutine open_file_safe