1 files changed, 61 insertions, 0 deletions
diff --git a/gcc/testsuite/gfortran.dg/alloc_comp_assign_10.f90 b/gcc/testsuite/gfortran.dg/alloc_comp_assign_10.f90
new file mode 100644
index 000000000..c85edea62
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/alloc_comp_assign_10.f90
@@ -0,0 +1,61 @@
+! { dg-do run }
+!
+! Test the fix for PR39879, in which gfc gagged on the double
+! defined assignment where the rhs had a default initialiser.
+!
+! Contributed by David Sagan <david.sagan@gmail.com>
+!
+module test_struct
+  interface assignment (=)
+    module procedure tao_lat_equal_tao_lat
+  end interface
+  type bunch_params_struct
+    integer n_live_particle          
+  end type
+  type tao_lattice_struct
+    type (bunch_params_struct), allocatable :: bunch_params(:)
+    type (bunch_params_struct), allocatable :: bunch_params2(:)
+  end type
+  type tao_universe_struct
+    type (tao_lattice_struct), pointer :: model, design
+    character(200), pointer :: descrip => NULL()
+  end type
+  type tao_super_universe_struct
+    type (tao_universe_struct), allocatable :: u(:)          
+  end type
+  type (tao_super_universe_struct), save, target :: s
+  contains
+    subroutine tao_lat_equal_tao_lat (lat1, lat2)
+      implicit none
+      type (tao_lattice_struct), intent(inout) :: lat1
+      type (tao_lattice_struct), intent(in) :: lat2
+      if (allocated(lat2%bunch_params)) then
+        lat1%bunch_params = lat2%bunch_params
+      end if 
+      if (allocated(lat2%bunch_params2)) then
+        lat1%bunch_params2 = lat2%bunch_params2
+      end if 
+    end subroutine
+end module
+
+program tao_program
+  use test_struct
+  implicit none
+  type (tao_universe_struct), pointer :: u
+  integer n, i
+  allocate (s%u(1))
+  u => s%u(1)
+  allocate (u%design, u%model)
+  n = 112
+  allocate (u%model%bunch_params(0:n), u%design%bunch_params(0:n))
+  u%design%bunch_params%n_live_particle = [(i, i = 0, n)]
+  u%model = u%design
+  u%model = u%design ! The double assignment was the cause of the ICE
+  if (.not. allocated (u%model%bunch_params)) call abort
+  if (any (u%model%bunch_params%n_live_particle .ne. [(i, i = 0, n)])) call abort
+  Deallocate (u%model%bunch_params, u%design%bunch_params)
+  deallocate (u%design, u%model)
+  deallocate (s%u)
+end program
+
+! { dg-final { cleanup-modules "test_struct" } }