[patch, fortran] Don't initialize components of pointers to derived compounds (PR30793)

[Tobias Burnus <burnus at net-b dot de>]

:ADDPATCH fortran:

If a function returns a variable of a derived type, its components are
initialized. (So far so good.) Unfortunally, gfortran also initializes
the components if the variable is only a pointer to a derived compound.

This yields to code like the following:

get_scalar_field_msh (fld)
{
  struct mesh * __result_get_scalar_field_msh;
  __result_get_scalar_field_msh->area.data = 0B; /* SIC! */
  __result_get_scalar_field_msh->dist.data = 0B; /* SIC! */
  __result_get_scalar_field_msh->interp.data = 0B; /* SIC! */
  __result_get_scalar_field_msh = msh_ (&fld->base);
  return __result_get_scalar_field_msh;
}


Solution: Well, simply don't initialize the components, if we have a
function which returns a pointer.

The following patch has been build and regression tested on
x86_64-unknown-linux-gnu.
Thanks for Salvatore Filippone for sending in the test case.

Ok for the trunk and after a week or so for 4.2 and 4.1?

Tobias

2007-02-15  Tobias Burnus  <burnus@net-b.de>

	PR fortran/30793
	* trans-decl.c (): Do not initialize pointers to
	  derived components.

2007-02-15  Tobias Burnus  <burnus@net-b.de>

	PR fortran/30793
	* gfortran.dg/func_derived_4.f90: New test.


Index: gcc/fortran/trans-decl.c
===================================================================
--- gcc/fortran/trans-decl.c	(Revision 121986)
+++ gcc/fortran/trans-decl.c	(Arbeitskopie)
@@ -3257,7 +3257,8 @@
 
       if (result != NULL_TREE && sym->attr.function
 	    && sym->ts.type == BT_DERIVED
-	    && sym->ts.derived->attr.alloc_comp)
+	    && sym->ts.derived->attr.alloc_comp
+	    && !sym->attr.pointer)
 	{
 	  rank = sym->as ? sym->as->rank : 0;
 	  tmp2 = gfc_nullify_alloc_comp (sym->ts.derived, result, rank);
Index: gcc/testsuite/gfortran.dg/func_derived_4.f90
===================================================================
--- gcc/testsuite/gfortran.dg/func_derived_4.f90	(Revision 0)
+++ gcc/testsuite/gfortran.dg/func_derived_4.f90	(Revision 0)
@@ -0,0 +1,105 @@
+! { dg-do run }
+! PR fortran/30793
+! Check that pointer-returing functions
+! work derived types.
+!
+! Contributed by Salvatore Filippone.
+!
+module class_mesh
+  type mesh
+    real(kind(1.d0)), allocatable :: area(:) 
+  end type mesh
+contains 
+  subroutine create_mesh(msh)
+    type(mesh), intent(out) :: msh
+    allocate(msh%area(10))
+    return
+  end subroutine create_mesh
+end module class_mesh
+
+module class_field
+  use class_mesh
+  implicit none
+  private ! Default
+  public :: create_field, field
+  public :: msh_
+
+  type field
+     private
+     type(mesh),     pointer :: msh   => null()
+     integer                 :: isize(2)
+  end type field
+
+  interface msh_
+    module procedure msh_
+  end interface
+  interface create_field
+    module procedure create_field
+  end interface
+contains
+  subroutine create_field(fld,msh)
+    type(field),      intent(out)        :: fld
+    type(mesh),       intent(in), target :: msh
+    fld%msh => msh
+    fld%isize = 1
+  end subroutine create_field
+
+  function msh_(fld)
+    type(mesh), pointer :: msh_
+    type(field), intent(in) :: fld
+    msh_ => fld%msh
+  end function msh_
+end module class_field
+
+module class_scalar_field
+  use class_field
+  implicit none
+  private
+  public :: create_field, scalar_field
+  public :: msh_
+
+  type scalar_field
+    private
+    type(field) :: base
+    real(kind(1.d0)), allocatable :: x(:)  
+    real(kind(1.d0)), allocatable :: bx(:) 
+    real(kind(1.d0)), allocatable :: x_old(:) 
+  end type scalar_field
+
+  interface create_field
+    module procedure create_scalar_field
+  end interface
+  interface msh_
+    module procedure get_scalar_field_msh
+  end interface
+contains
+  subroutine create_scalar_field(fld,msh)
+    use class_mesh
+    type(scalar_field), intent(out)          :: fld
+    type(mesh),         intent(in), target   :: msh
+    call create_field(fld%base,msh)
+    allocate(fld%x(10),fld%bx(20))
+  end subroutine create_scalar_field
+
+  function get_scalar_field_msh(fld)
+    use class_mesh
+    type(mesh), pointer :: get_scalar_field_msh
+    type(scalar_field), intent(in), target  :: fld
+
+    get_scalar_field_msh => msh_(fld%base)
+  end function get_scalar_field_msh
+end module class_scalar_field
+
+program test_pnt
+  use class_mesh
+  use class_scalar_field
+  implicit none
+  type(mesh) :: msh
+  type(mesh), pointer  :: mshp
+  type(scalar_field) :: quality
+  call create_mesh(msh)
+  call create_field(quality,msh)
+  mshp => msh_(quality)
+end program test_pnt
+
+! { dg-final { cleanup-modules "class_mesh class_scalar_field class_mesh" } }