--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/gfortran.dg/optional_absent_2.f90	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,53 @@
+! { dg-do run }
+!
+! PR fortran/51758
+!
+! Contributed by Mikael Morin
+!
+! Check whether passing NULL() to an elemental procedure works,
+! where NULL() denotes an absent optional argument.
+!
+program p
+
+  integer :: a(2)
+  integer :: b
+
+  a = 0
+  a = foo((/ 1, 1 /), null())
+!  print *, a
+  if (any(a /= 2)) call abort
+
+  a = 0
+  a = bar((/ 1, 1 /), null())
+!  print *, a
+  if (any(a /= 2)) call abort
+
+  b = 0
+  b = bar(1, null())
+!  print *, b
+  if (b /= 2) call abort
+
+contains
+
+  function foo(a, b)
+    integer           :: a(:)
+    integer, optional :: b(:)
+    integer           :: foo(size(a))
+
+    if (present(b)) call abort
+
+    foo = 2
+  end function foo
+
+  elemental function bar(a, b)
+    integer, intent(in)           :: a
+    integer, intent(in), optional :: b
+    integer                       :: bar
+
+    bar = 2
+
+    if (present(b)) bar = 1
+
+  end function bar
+
+end program p