[Patch, fortran] PR80554 [f08] variable redefinition in submodule

[Paul Richard Thomas]

The attached bootstraps and regtests on FC23/x86_64 - OK for trunk and
later for 7-branch?

The comment in the patch and the ChangeLog are sufficiently clear that
no further explanation is needed here.

Cheers

Paul

2017-05-15  Paul Thomas  <pault@gcc.gnu.org>

    PR fortran/80554
    * decl.c (build_sym): In a submodule allow overriding of host
    associated symbols from the ancestor module with a new
    declaration.

2017-05-15  Paul Thomas  <pault@gcc.gnu.org>

    PR fortran/80554
    * gfortran.dg/submodule_29.f08: New test.
-------------- next part --------------
Index: gcc/fortran/decl.c
===================================================================
*** gcc/fortran/decl.c	(revision 246951)
--- gcc/fortran/decl.c	(working copy)
*************** build_sym (const char *name, gfc_charlen
*** 1383,1390 ****
    symbol_attribute attr;
    gfc_symbol *sym;
    int upper;
  
!   if (gfc_get_symbol (name, NULL, &sym))
      return false;
  
    /* Check if the name has already been defined as a type.  The
--- 1383,1410 ----
    symbol_attribute attr;
    gfc_symbol *sym;
    int upper;
+   gfc_symtree *st;
  
!   /* Symbols in a submodule are host associated from the parent module or
!      submodules. Therefore, they can be overridden by declarations in the
!      submodule scope. Deal with this by attaching the existing symbol to
!      a new symtree and recycling the old symtree with a new symbol...  */
!   st = gfc_find_symtree (gfc_current_ns->sym_root, name);
!   if (st != NULL && gfc_state_stack->state == COMP_SUBMODULE
!       && st->n.sym != NULL
!       && st->n.sym->attr.host_assoc && st->n.sym->attr.used_in_submodule)
!     {
!       gfc_symtree *s = gfc_get_unique_symtree (gfc_current_ns);
!       s->n.sym = st->n.sym;
!       sym = gfc_new_symbol (name, gfc_current_ns);
! 
! 
!       st->n.sym = sym;
!       sym->refs++;
!       gfc_set_sym_referenced (sym);
!     }
!   /* ...Otherwise generate a new symtree and new symbol.  */
!   else if (gfc_get_symbol (name, NULL, &sym))
      return false;
  
    /* Check if the name has already been defined as a type.  The
Index: gcc/testsuite/gfortran.dg/submodule_29.f08
===================================================================
*** gcc/testsuite/gfortran.dg/submodule_29.f08	(nonexistent)
--- gcc/testsuite/gfortran.dg/submodule_29.f08	(working copy)
***************
*** 0 ****
--- 1,56 ----
+ ! { dg-do run }
+ !
+ ! Test the fix for PR80554 in which it was not recognised that the symbol 'i'
+ ! is host associated in the submodule 's' so that the new declaration in the
+ ! submodule was rejected.
+ !
+ ! Contributed by Tamas Bela Feher  <tamas.bela.feher@ipp.mpg.de>
+ !
+ module M
+   implicit none
+   integer :: i = 0
+   character (100) :: buffer
+   interface
+     module subroutine write_i()
+     end subroutine
+   end interface
+   interface
+     module subroutine write_i_2()
+     end subroutine
+   end interface
+ contains
+   subroutine foo
+     integer :: i
+   end
+ end module
+ 
+ submodule (M) S
+     integer :: i = 137
+   contains
+     module subroutine write_i()
+        write (buffer,*) i
+     end subroutine
+ end submodule
+ 
+ submodule (M:S) S2
+     integer :: i = 1037
+   contains
+     module subroutine write_i_2()
+        write (buffer,*) i
+     end subroutine
+ end submodule
+ 
+ program test_submod_variable
+   use M
+   implicit none
+   integer :: j
+   i = 42
+   call write_i
+   read (buffer, *) j
+   if (i .ne. 42) call abort
+   if (j .ne. 137) call abort
+   call write_i_2
+   read (buffer, *) j
+   if (i .ne. 42) call abort
+   if (j .ne. 1037) call abort
+ end program