[Patch, fortran] PR79434 - [submodules] separate module procedure breaks encapsulation

[Paul Richard Thomas]

Dear All,

Another straightforward patch, although it took some head scratching
to realize how simple the fix could be :-)

Bootstraps and regtests on FC23/x_86_64 - OK for trunk and 6-branch?

Cheers

Paul

2017-02-15  Paul Thomas  <pault@gcc.gnu.org>

    PR fortran/79434
    * parse.c (check_component, parse_union): Whitespace.
    (set_syms_host_assoc): For a derived type, check if the module
    in which it was declared is one of the submodule ancestors. If
    it is, make the components public. Otherwise, reset attribute
    'host_assoc' and set 'use-assoc' so that encapsulation is
    preserved.

2017-02-15  Paul Thomas  <pault@gcc.gnu.org>

    PR fortran/79434
    * gfortran.dg/submodule_25.f08 : New test.
-------------- next part --------------
Index: gcc/fortran/parse.c
===================================================================
*** gcc/fortran/parse.c	(revision 245196)
--- gcc/fortran/parse.c	(working copy)
*************** check_component (gfc_symbol *sym, gfc_co
*** 2917,2923 ****
        coarray = true;
        sym->attr.coarray_comp = 1;
      }
!  
    if (c->ts.type == BT_DERIVED && c->ts.u.derived->attr.coarray_comp
        && !c->attr.pointer)
      {
--- 2917,2923 ----
        coarray = true;
        sym->attr.coarray_comp = 1;
      }
! 
    if (c->ts.type == BT_DERIVED && c->ts.u.derived->attr.coarray_comp
        && !c->attr.pointer)
      {
*************** parse_union (void)
*** 3081,3087 ****
            /* Add a component to the union for each map. */
            if (!gfc_add_component (un, gfc_new_block->name, &c))
              {
!               gfc_internal_error ("failed to create map component '%s'", 
                    gfc_new_block->name);
                reject_statement ();
                return;
--- 3081,3087 ----
            /* Add a component to the union for each map. */
            if (!gfc_add_component (un, gfc_new_block->name, &c))
              {
!               gfc_internal_error ("failed to create map component '%s'",
                    gfc_new_block->name);
                reject_statement ();
                return;
*************** static void
*** 5809,5814 ****
--- 5809,5817 ----
  set_syms_host_assoc (gfc_symbol *sym)
  {
    gfc_component *c;
+   const char dot[2] = ".";
+   char parent1[GFC_MAX_SYMBOL_LEN + 1];
+   char parent2[GFC_MAX_SYMBOL_LEN + 1];
  
    if (sym == NULL)
      return;
*************** set_syms_host_assoc (gfc_symbol *sym)
*** 5816,5831 ****
    if (sym->attr.module_procedure)
      sym->attr.external = 0;
  
- /*  sym->attr.access = ACCESS_PUBLIC;  */
- 
    sym->attr.use_assoc = 0;
    sym->attr.host_assoc = 1;
    sym->attr.used_in_submodule =1;
  
    if (sym->attr.flavor == FL_DERIVED)
      {
!       for (c = sym->components; c; c = c->next)
! 	c->attr.access = ACCESS_PUBLIC;
      }
  }
  
--- 5819,5850 ----
    if (sym->attr.module_procedure)
      sym->attr.external = 0;
  
    sym->attr.use_assoc = 0;
    sym->attr.host_assoc = 1;
    sym->attr.used_in_submodule =1;
  
    if (sym->attr.flavor == FL_DERIVED)
      {
!       /* Derived types with PRIVATE components that are declared in
! 	 modules other than the parent module must not be changed to be
! 	 PUBLIC. The 'use-assoc' attribute must be reset so that the
! 	 test in symbol.c(gfc_find_component) works correctly. This is
! 	 not necessary for PRIVATE symbols since they are not read from
! 	 the module.  */
!       memset(parent1, '\0', sizeof(parent1));
!       memset(parent2, '\0', sizeof(parent2));
!       strcpy (parent1, gfc_new_block->name);
!       strcpy (parent2, sym->module);
!       if (strcmp (strtok (parent1, dot), strtok (parent2, dot)) == 0)
! 	{
! 	  for (c = sym->components; c; c = c->next)
! 	    c->attr.access = ACCESS_PUBLIC;
! 	}
!       else
! 	{
! 	  sym->attr.use_assoc = 1;
! 	  sym->attr.host_assoc = 0;
! 	}
      }
  }
  
Index: gcc/testsuite/gfortran.dg/submodule_25.f08
===================================================================
*** gcc/testsuite/gfortran.dg/submodule_25.f08	(nonexistent)
--- gcc/testsuite/gfortran.dg/submodule_25.f08	(working copy)
***************
*** 0 ****
--- 1,43 ----
+ ! { dg-do compile }
+ ! Test the fix for PR79434 in which the PRIVATE attribute of the
+ ! component 'i' of the derived type 't' was not respected in the
+ ! submodule 's_u'.
+ !
+ ! Contributed by Reinhold Bader  <Bader@lrz.de>
+ !
+ module mod_encap_t
+   implicit none
+   type, public :: t
+     private
+     integer :: i
+   end type
+ end module
+ module mod_encap_u
+   use mod_encap_t
+   type, public, extends(t) :: u
+     private
+     integer :: j
+   end type
+   interface
+     module subroutine fu(this)
+       type(u), intent(inout) :: this
+     end subroutine
+   end interface
+ end module
+ submodule (mod_encap_u) s_u
+ contains
+   module procedure fu
+ !   the following statement should cause the compiler to
+ !   abort, pointing out a private component defined in
+ !   a USED module is being accessed
+     this%i = 2 ! { dg-error "is a PRIVATE component" }
+     this%j = 1
+     write(*, *) 'FAIL'
+   end procedure
+ end submodule
+ program p
+   use mod_encap_u
+   implicit none
+   type(u) :: x
+   call fu(x)
+ end program