[Patch, fortran] PR69566 - Failure of SELECT TYPE with unlimited polymorphic function result

Paul Richard Thomas paul.richard.thomas@gmail.com
Tue Oct 18 14:30:00 GMT 2016


Dear All,

This bug was caused by 'associate name' and 'associate entity'
expressions being incomplete when the 'selector' was an intrinsic
function result. I tried to fix this at source, in match_select _type
and gfc_get_variable_expr, but caused a vast number of breakages.
Undoubtedly, this would be the ecologically sound way to proceed but
applying fixups in resolve_select_type, gfc_conv_class_to_class and
trans_associate_var proved to be the path of least resistance.

Depending on which form of select type is used, the defective
expressions either lacked the correct value for rank, a full array
reference, a symbol with an array spec or had type BT_DERIVED for a
polymorphic symbol; these either singly or in combination depending of
the form of select type.

The patch, taken with the ChangeLogs, is fairly self-explanatory.
Please note that I have suppressed whitespace changes (suppression of
trailing blanks), so use patch with the -l option.

Bootstraps and regtests on FC21/x86_64 - OK for trunk?

Best regards

Paul

2016-10-18  Paul Thomas  <pault@gcc.gnu.org>

    PR fortran/69566
    * resolve.c (fixup_array_ref): New function.
    (resolve_select_type): Gather up the rank and array reference,
    if any, from the selector. Fix up the 'associate name' and the
    'associate entities' as necessary.
    * trans-expr.c (gfc_conv_class_to_class): If the symbol backend
    decl is a FUNCTION_DECL, use the 'fake_result_decl' instead.
    * trans-stmt.c (trans_associate_var): Extend 'unlimited' to
    include expressions which are themsleves not unlimited
    polymorphic but the symbol is.

2016-10-18  Paul Thomas  <pault@gcc.gnu.org>

    PR fortran/69566
    * gfortran.dg/select_type_37.f03: New test.
-------------- next part --------------
Index: gcc/fortran/resolve.c
===================================================================
*** gcc/fortran/resolve.c	(revision 241274)
--- gcc/fortran/resolve.c	(working copy)
*************** resolve_assoc_var (gfc_symbol* sym, bool
*** 8327,8332 ****
--- 8327,8368 ----
  }


+ /* Ensure that SELECT TYPE expressions have the correct rank and a full
+    array reference, where necessary.  The symbols are artificial and so
+    the dimension attribute and arrayspec are also set.  */
+ static void
+ fixup_array_ref (gfc_expr **expr1, gfc_expr *expr2,
+ 		 int rank, gfc_ref *ref)
+ {
+   gfc_ref *nref = (*expr1)->ref;
+   gfc_symbol *sym1 = (*expr1)->symtree->n.sym;
+   gfc_symbol *sym2 = expr2 ? expr2->symtree->n.sym : NULL;
+   (*expr1)->rank = rank;
+   if (sym1->ts.type == BT_CLASS)
+     {
+       CLASS_DATA (sym1)->attr.dimension = 1;
+       if (CLASS_DATA (sym1)->as == NULL && sym2)
+ 	CLASS_DATA (sym1)->as
+ 		= gfc_copy_array_spec (CLASS_DATA (sym2)->as);
+     }
+   else
+     {
+       sym1->attr.dimension = 1;
+       if (sym1->as == NULL && sym2)
+ 	sym1->as = gfc_copy_array_spec (sym2->as);
+     }
+
+   for (; nref; nref = nref->next)
+     if (nref->next == NULL)
+       break;
+
+   if (ref && nref && nref->type != REF_ARRAY)
+     nref->next = gfc_copy_ref (ref);
+   else if (ref && !nref)
+     (*expr1)->ref = gfc_copy_ref (ref);
+ }
+
+
  /* Resolve a SELECT TYPE statement.  */

  static void
*************** resolve_select_type (gfc_code *code, gfc
*** 8341,8346 ****
--- 8377,8384 ----
    gfc_namespace *ns;
    int error = 0;
    int charlen = 0;
+   int rank = 0;
+   gfc_ref* ref = NULL;

    ns = code->ext.block.ns;
    gfc_resolve (ns);
*************** resolve_select_type (gfc_code *code, gfc
*** 8468,8473 ****
--- 8506,8536 ----
    else
      code->ext.block.assoc = NULL;

+   /* Ensure that the selector rank and arrayspec are available to
+      correct expressions in which they might be missing.  */
+   if (code->expr2 && code->expr2->rank)
+     {
+       rank = code->expr2->rank;
+       for (ref = code->expr2->ref; ref; ref = ref->next)
+ 	if (ref->next == NULL)
+ 	  break;
+       if (ref && ref->type == REF_ARRAY)
+ 	ref = gfc_copy_ref (ref);
+
+       /* Fixup expr1 if necessary.  */
+       if (rank)
+ 	fixup_array_ref (&code->expr1, code->expr2, rank, ref);
+     }
+   else if (code->expr1->rank)
+     {
+       rank = code->expr1->rank;
+       for (ref = code->expr1->ref; ref; ref = ref->next)
+ 	if (ref->next == NULL)
+ 	  break;
+       if (ref && ref->type == REF_ARRAY)
+ 	ref = gfc_copy_ref (ref);
+     }
+
    /* Add EXEC_SELECT to switch on type.  */
    new_st = gfc_get_code (code->op);
    new_st->expr1 = code->expr1;
*************** resolve_select_type (gfc_code *code, gfc
*** 8533,8539 ****
--- 8596,8607 ----
        st->n.sym->assoc->target = gfc_get_variable_expr (code->expr1->symtree);
        st->n.sym->assoc->target->where = code->expr1->where;
        if (c->ts.type != BT_CLASS && c->ts.type != BT_UNKNOWN)
+ 	{
  	  gfc_add_data_component (st->n.sym->assoc->target);
+ 	  /* Fixup the target expression if necessary.  */
+ 	  if (rank)
+ 	    fixup_array_ref (&st->n.sym->assoc->target, NULL, rank, ref);
+ 	}

        new_st = gfc_get_code (EXEC_BLOCK);
        new_st->ext.block.ns = gfc_build_block_ns (ns   else
Index: gcc/);
*************** resolve_select_type (gfc_code *code, gfc
*** 8672,8677 ****
--- 8740,8748 ----
    gfc_resolve_blocks (code->block, gfc_current_ns);
    gfc_current_ns = old_ns;

+   if (ref)
+     free (ref);
+
    resolve_select (code, true);
  }

Index: gcc/fortran/trans-expr.c
===================================================================
*** gcc/fortran/trans-expr.c	(revision 241273)
--- gcc/fortran/trans-expr.c	(working copy)
*************** gfc_conv_class_to_class (gfc_se *parmse,
*** 1033,1040 ****
--- 1033,1045 ----
  	&& e->symtree && e->symtree->n.sym->ts.type == BT_CLASS)
      {
        tmp = e->symtree->n.sym->backend_decl;
+
+       if (TREE_CODE (tmp) == FUNCTION_DECL)
+ 	tmp = gfc_get_fake_result_decl (e->symtree->n.sym, 0);
+
        if (DECL_LANG_SPECIFIC (tmp) && GFC_DECL_SAVED_DESCRIPTOR (tmp))
  	tmp = GFC_DECL_SAVED_DESCRIPTOR (tmp);
+
        slen = integer_zero_node;
      }
    else
Index: gcc/fortran/trans-stmt.c
===================================================================
*** gcc/fortran/trans-stmt.c	(revision 241273)
--- gcc/fortran/trans-stmt.c	(working copy)
*************** trans_associate_var (gfc_symbol *sym, gf
*** 1517,1523 ****
  		    && (gfc_is_class_scalar_expr (e)
  			|| gfc_is_class_array_ref (e, NULL));

!   unlimited = UNLIMITED_POLY (e);

    /* Assignments to the string length need to be generated, when
       ( sym is a char array or
--- 1517,1526 ----
  		    && (gfc_is_class_scalar_expr (e)
  			|| gfc_is_class_array_ref (e, NULL));

!   unlimited = UNLIMITED_POLY (e)
! 		|| (e->symtree && e->symtree->n.sym
! 		    && e->symtree->n.sym->ts.type == BT_CLASS
! 		    && UNLIMITED_POLY (e->symtree->n.sym));

    /* Assignments to the string length need to be generated, when
       ( sym is a char array or
Index: gcc/testsuite/gfortran.dg/select_type_37.f03
===================================================================
*** gcc/testsuite/gfortran.dg/select_type_37.f03	(revision 0)
--- gcc/testsuite/gfortran.dg/select_type_37.f03	(working copy)
***************
*** 0 ****
--- 1,83 ----
+ ! { dg-do run }
+ !
+ ! Checks the fix for PR69566 in which using implicit function results
+ ! in SELECT TYPE caused all sorts of problems, especially in the form
+ ! in 'return_pointer1' with "associate_name => selector". The original
+ ! PR is encapsulated in 'return_pointer'. Explicit results, such as in
+ ! 'return_pointer2' always worked.
+ !
+ ! Contributed by Janus Weil  <janus@gcc.gnu.org>
+ !
+ program pr69566
+   class(*), pointer :: ptr(:)
+   character(40) :: buffer1, buffer2
+   real :: cst1(2) = [1.0, 2.0]
+   real :: cst2(2) = [3.0, 4.0]
+   real :: cst3(2) = [5.0, 6.0]
+
+   write (buffer1, *) cst1
+   if (.not.associated(return_pointer1(cst1))) call abort
+   if (trim (buffer1) .ne. trim (buffer2)) call abort
+   select type (ptr)
+     type is (real)
+       if (any (ptr .ne. cst2)) call abort
+   end select
+   deallocate (ptr)
+
+   write (buffer1, *) cst2
+   if (.not.associated(return_pointer(cst2))) call abort
+   if (trim (buffer1) .ne. trim (buffer2)) call abort
+   select type (ptr)
+     type is (real)
+       if (any (ptr .ne. cst3)) call abort
+   end select
+   deallocate (ptr)
+
+   write (buffer1, *) cst1
+   if (.not.associated(return_pointer2(cst1))) call abort
+   if (trim (buffer1) .ne. trim (buffer2)) call abort
+   select type (ptr)
+     type is (real)
+       if (any (ptr .ne. cst2)) call abort
+   end select
+   deallocate (ptr)
+
+ contains
+
+   function return_pointer2(arg) result (res) ! Explicit result always worked.
+     class(*), pointer :: res(:)
+     real, intent(inout) :: arg(:)
+     allocate (res, source = arg)
+     ptr => res                               ! Check association and cleanup
+     select type (z => res)
+       type is (real(4))
+         write (buffer2, *) z                 ! Check associate expression is OK.
+         z = cst2                             ! Check associate is OK for lvalue.
+     end select
+   end function
+
+   function return_pointer1(arg)
+     class(*), pointer :: return_pointer1(:)
+     real, intent(inout) :: arg(:)
+     allocate (return_pointer1, source = arg)
+     ptr => return_pointer1
+     select type (z => return_pointer1) ! This caused a segfault in compilation.
+       type is (real(4))
+         write (buffer2, *) z
+         z = cst2
+     end select
+   end function
+
+   function return_pointer(arg) ! The form in the PR.
+     class(*), pointer :: return_pointer(:)
+     real, intent(inout) :: arg(:)
+     allocate (return_pointer, source = cst2)
+     ptr => return_pointer
+     select type (return_pointer)
+       type is (real(4)) ! Associate-name ‘__tmp_REAL_4’ at (1) is used as array
+         write (buffer2, *) return_pointer
+         return_pointer = cst3
+     end select
+   end function
+ end program
+


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