[Patch, fortran] PR65792 - allocation of scalar elemental function with structure constructor fails

[Paul Richard Thomas <paul.richard.thomas@gmail.com>]

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Dear All,

This patch exploits Mikael's identification of the location of the
problem and his testcase. It requires Andre's patch for PR59678 as a
prerequisite. It is almost certainly a bit over-conservative but it
seems to be free of any memory leakage. The ChangeLog and the comments
describe it sufficiently for review.

OK for trunk and 5.x?

Paul

2015-04-26  Mikael Morin  <mikael@gcc.gnu.org
        Paul Thomas  <pault@gcc.gnu.org>

    PR fortran/65792
    * trans-expr.c (gfc_trans_subcomponent_assign): Always assign
    the expression component to the destination. In addition, if
    the component has allocatable components, copy them and
    deallocate those of the expression, if it is not a variable.
    The expression is fixed if not a variable to prevent multiple
    evaluations.

2015-04-26  Mikael Morin  <mikael@gcc.gnu.org>

    PR fortran/65792
    * gfortran.dg/derived_constructor_components_5: New test

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Index: gcc/fortran/trans-expr.c
===================================================================
*** gcc/fortran/trans-expr.c	(revision 222439)
--- gcc/fortran/trans-expr.c	(working copy)
*************** gfc_trans_subcomponent_assign (tree dest
*** 7062,7080 ****
      {
        if (expr->expr_type != EXPR_STRUCTURE)
  	{
  	  gfc_init_se (&se, NULL);
  	  gfc_conv_expr (&se, expr);
  	  gfc_add_block_to_block (&block, &se.pre);
  	  if (cm->ts.u.derived->attr.alloc_comp
! 	      && expr->expr_type == EXPR_VARIABLE)
  	    {
  	      tmp = gfc_copy_alloc_comp (cm->ts.u.derived, se.expr,
  					 dest, expr->rank);
  	      gfc_add_expr_to_block (&block, tmp);
  	    }
- 	  else
- 	    gfc_add_modify (&block, dest,
- 			    fold_convert (TREE_TYPE (dest), se.expr));
  	  gfc_add_block_to_block (&block, &se.post);
  	}
        else
--- 7062,7091 ----
      {
        if (expr->expr_type != EXPR_STRUCTURE)
  	{
+ 	  tree dealloc = NULL_TREE;
  	  gfc_init_se (&se, NULL);
  	  gfc_conv_expr (&se, expr);
  	  gfc_add_block_to_block (&block, &se.pre);
+ 	  /* Prevent repeat evaluations in gfc_copy_alloc_comp by fixing the
+ 	     expression in  a temporary variable and deallocate is allocatable
+ 	     components the copy to the result.  */
  	  if (cm->ts.u.derived->attr.alloc_comp
! 	      && expr->expr_type != EXPR_VARIABLE)
! 	    {
! 	      se.expr = gfc_evaluate_now (se.expr, &block);
! 	      dealloc = gfc_deallocate_alloc_comp (cm->ts.u.derived, se.expr,
! 						   expr->rank);
! 	    }
! 	  gfc_add_modify (&block, dest,
! 			  fold_convert (TREE_TYPE (dest), se.expr));
! 	  if (cm->ts.u.derived->attr.alloc_comp)
  	    {
  	      tmp = gfc_copy_alloc_comp (cm->ts.u.derived, se.expr,
  					 dest, expr->rank);
  	      gfc_add_expr_to_block (&block, tmp);
+ 	      if (dealloc != NULL_TREE)
+ 		gfc_add_expr_to_block (&block, dealloc);
  	    }
  	  gfc_add_block_to_block (&block, &se.post);
  	}
        else

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! { dg-do run }
!
! PR fortran/65792
! The evaluation of the argument in the call to new_prt_spec2
! failed to properly initialize the comp component.
! While the array contents were properly copied, the array bounds remained
! uninitialized.
!
! Contributed by Dominique D'Humieres <dominiq@lps.ens.fr>

program main
  implicit none

  integer, parameter :: n = 2

  type :: string_t
     character(LEN=1), dimension(:), allocatable :: chars
  end type string_t

  type :: string_container_t
     type(string_t) :: comp
  end type string_container_t

  type(string_t) :: prt_in, tmp, tmpa(n)
  type(string_container_t) :: tmpc, tmpca(n)
  integer :: i, j, k

  do i=1,2

! scalar elemental function with structure constructor
     prt_in = string_t(["D"])
     tmpc = new_prt_spec2 (string_container_t(prt_in))
     if (any(tmpc%comp%chars .ne. ["D"])) call abort
     deallocate (prt_in%chars)
     deallocate(tmpc%comp%chars)
! Check that function arguments are OK too
     tmpc = new_prt_spec2 (string_container_t(new_str_t(["h","e","l","l","o"])))
     if (any(tmpc%comp%chars .ne. ["h","e","l","l","o"])) call abort
     deallocate(tmpc%comp%chars)

  end do

contains

  impure elemental function new_prt_spec2 (name) result (prt_spec)
    type(string_container_t), intent(in) :: name
    type(string_container_t) :: prt_spec
    prt_spec = name
  end function new_prt_spec2


  function new_str_t (name) result (prt_spec)
    character (*), intent(in), dimension (:) :: name
    type(string_t) :: prt_spec
    prt_spec = string_t(name)
  end function new_str_t

end program main