1 files changed, 49 insertions, 0 deletions
diff --git a/gcc/testsuite/gfortran.dg/missing_optional_dummy_1.f90 b/gcc/testsuite/gfortran.dg/missing_optional_dummy_1.f90
new file mode 100644
index 00000000000..29f08f9e0e8
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/missing_optional_dummy_1.f90
@@ -0,0 +1,49 @@
+! { dg-do run }
+! Test the fix for PR26891, in which an optional argument, whose actual
+! is a missing dummy argument would cause a segfault.
+!
+! Contributed by Paul Thomas  <pault@gcc.gnu.org>
+!
+  logical :: back =.false.
+
+! This was the case that would fail - PR case was an intrinsic call.
+  if (scan ("A quick brown fox jumps over the lazy dog", "lazy", back) &
+      .ne. myscan ("A quick brown fox jumps over the lazy dog", "lazy")) &
+    call abort ()
+
+! Check that the patch works with non-intrinsic functions.
+  if (myscan ("A quick brown fox jumps over the lazy dog", "fox", back) &
+      .ne. thyscan ("A quick brown fox jumps over the lazy dog", "fox")) &
+    call abort ()
+
+! Check that missing, optional character actual arguments are OK.
+  if (scan ("A quick brown fox jumps over the lazy dog", "over", back) &
+      .ne. thyscan ("A quick brown fox jumps over the lazy dog")) &
+    call abort ()
+
+contains
+  integer function myscan (str, substr, back)
+    character(*), intent(in) :: str, substr
+    logical, optional, intent(in) :: back
+    myscan = scan (str, substr, back)
+  end function myscan
+
+  integer function thyscan (str, substr, back)
+    character(*), intent(in) :: str
+    character(*), optional, intent(in) :: substr
+    logical, optional, intent(in) :: back
+    thyscan = isscan (str, substr, back)
+  end function thyscan
+
+  integer function isscan (str, substr, back)
+    character(*), intent(in) :: str
+    character(*), optional :: substr
+    logical, optional, intent(in) :: back
+    if (.not.present(substr)) then
+      isscan = myscan (str, "over", back)
+    else
+      isscan = myscan (str, substr, back)
+    end if
+  end function isscan
+
+end