[Patch, fortran] PR49213 - [OOP] gfortran rejects structure constructor expression

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

[-- Attachment #1: Type: text/plain, Size: 1456 bytes --]

Hi All,

I was looking through Neil Carlson's collection of gfortran bugs and
was shocked to find this rather fundamental PR. At 12 years old, it is
certainly a "golden oldie"!

The patch is rather straightforward and seems to do the job of
admitting derived, intrinsic and character expressions to allocatable
class components in structure constructors.

I have included the adjustment to 'gfc_is_ptr_fcn' and eliminating the
extra blank line, introduced by my last patch. I played safe and went
exclusively for class functions with attr.class_pointer set on the
grounds that these have had all the accoutrements checked and built
(ie. class_ok). I am still not sure if this is necessary or not.

OK for trunk?

Paul

Fortran: Enable class expressions in structure constructors [PR49213]

2023-06-24  Paul Thomas  <pault@gcc.gnu.org>

gcc/fortran
PR fortran/49213
* expr.cc (gfc_is_ptr_fcn): Guard pointer attribute to exclude
class expressions.
* resolve.cc (resolve_assoc_var): Call gfc_is_ptr_fcn to allow
associate names with pointer function targets to be used in
variable definition context.
* trans-decl.cc (get_symbol_decl): Remove extraneous line.
* trans-expr.cc (alloc_scalar_allocatable_subcomponent): Obtain
size of intrinsic and character expressions.
(gfc_trans_subcomponent_assign): Expand assignment to class
components to include intrinsic and character expressions.

gcc/testsuite/
PR fortran/49213
* gfortran.dg/pr49213.f90 : New test

[-- Attachment #2: pr49213.diff --]
[-- Type: text/x-patch, Size: 5161 bytes --]

diff --git a/gcc/fortran/expr.cc b/gcc/fortran/expr.cc
index c960dfeabd9..92061d69781 100644
--- a/gcc/fortran/expr.cc
+++ b/gcc/fortran/expr.cc
@@ -816,7 +816,7 @@ bool
 gfc_is_ptr_fcn (gfc_expr *e)
 {
   return e != NULL && e->expr_type == EXPR_FUNCTION
-	      && (gfc_expr_attr (e).pointer
+	      && ((e->ts.type != BT_CLASS && gfc_expr_attr (e).pointer)
 		  || (e->ts.type == BT_CLASS
 		      && CLASS_DATA (e)->attr.class_pointer));
 }
diff --git a/gcc/fortran/resolve.cc b/gcc/fortran/resolve.cc
index 82e6ac53aa1..217d69d4e0b 100644
--- a/gcc/fortran/resolve.cc
+++ b/gcc/fortran/resolve.cc
@@ -1350,6 +1350,9 @@ resolve_structure_cons (gfc_expr *expr, int init)
 	  && CLASS_DATA (comp)->as)
  	rank = CLASS_DATA (comp)->as->rank;
 
+      if (comp->ts.type == BT_CLASS && cons->expr->ts.type == BT_DERIVED)
+	  gfc_find_derived_vtab (cons->expr->ts.u.derived);
+
       if (cons->expr->expr_type != EXPR_NULL && rank != cons->expr->rank
 	  && (comp->attr.allocatable || cons->expr->rank))
 	{
@@ -1381,7 +1384,7 @@ resolve_structure_cons (gfc_expr *expr, int init)
 			 gfc_basic_typename (comp->ts.type));
 	      t = false;
 	    }
-	  else
+	  else if (!UNLIMITED_POLY (comp))
 	    {
 	      bool t2 = gfc_convert_type (cons->expr, &comp->ts, 1);
 	      if (t)
diff --git a/gcc/fortran/trans-decl.cc b/gcc/fortran/trans-decl.cc
index 18589e17843..b0fd25e92a3 100644
--- a/gcc/fortran/trans-decl.cc
+++ b/gcc/fortran/trans-decl.cc
@@ -1915,7 +1915,6 @@ gfc_get_symbol_decl (gfc_symbol * sym)
 	gcc_assert (!sym->value || sym->value->expr_type == EXPR_NULL);
     }
 
-
   gfc_finish_var_decl (decl, sym);
 
   if (sym->ts.type == BT_CHARACTER)
diff --git a/gcc/fortran/trans-expr.cc b/gcc/fortran/trans-expr.cc
index 3c209bcde97..5a1ff0c1d21 100644
--- a/gcc/fortran/trans-expr.cc
+++ b/gcc/fortran/trans-expr.cc
@@ -8781,6 +8781,7 @@ alloc_scalar_allocatable_subcomponent (stmtblock_t *block, tree comp,
   tree size;
   tree size_in_bytes;
   tree lhs_cl_size = NULL_TREE;
+  gfc_se se;
 
   if (!comp)
     return;
@@ -8815,16 +8816,26 @@ alloc_scalar_allocatable_subcomponent (stmtblock_t *block, tree comp,
     }
   else if (cm->ts.type == BT_CLASS)
     {
-      gcc_assert (expr2->ts.type == BT_CLASS || expr2->ts.type == BT_DERIVED);
-      if (expr2->ts.type == BT_DERIVED)
+      if (expr2->ts.type != BT_CLASS)
 	{
-	  tmp = gfc_get_symbol_decl (expr2->ts.u.derived);
-	  size = TYPE_SIZE_UNIT (tmp);
+	  if (expr2->ts.type == BT_CHARACTER)
+	    {
+	      gfc_init_se (&se, NULL);
+	      gfc_conv_expr (&se, expr2);
+	      size = fold_convert (size_type_node, se.string_length);
+	    }
+	  else
+	    {
+	      if (expr2->ts.type == BT_DERIVED)
+		tmp = gfc_get_symbol_decl (expr2->ts.u.derived);
+	      else
+		tmp = gfc_typenode_for_spec (&expr2->ts);
+	      size = TYPE_SIZE_UNIT (tmp);
+	    }
 	}
       else
 	{
 	  gfc_expr *e2vtab;
-	  gfc_se se;
 	  e2vtab = gfc_find_and_cut_at_last_class_ref (expr2);
 	  gfc_add_vptr_component (e2vtab);
 	  gfc_add_size_component (e2vtab);
@@ -8975,6 +8986,7 @@ gfc_trans_subcomponent_assign (tree dest, gfc_component * cm,
     {
       gfc_init_se (&se, NULL);
       gfc_conv_expr (&se, expr);
+      tree size;
 
       /* Take care about non-array allocatable components here.  The alloc_*
 	 routine below is motivated by the alloc_scalar_allocatable_for_
@@ -8990,7 +9002,7 @@ gfc_trans_subcomponent_assign (tree dest, gfc_component * cm,
 	  && expr->symtree->n.sym->attr.dummy)
 	se.expr = build_fold_indirect_ref_loc (input_location, se.expr);
 
-      if (cm->ts.type == BT_CLASS && expr->ts.type == BT_DERIVED)
+      if (cm->ts.type == BT_CLASS)
 	{
 	  tmp = gfc_class_data_get (dest);
 	  tmp = build_fold_indirect_ref_loc (input_location, tmp);
@@ -9005,7 +9017,6 @@ gfc_trans_subcomponent_assign (tree dest, gfc_component * cm,
       /* For deferred strings insert a memcpy.  */
       if (cm->ts.type == BT_CHARACTER && cm->ts.deferred)
 	{
-	  tree size;
 	  gcc_assert (se.string_length || expr->ts.u.cl->backend_decl);
 	  size = size_of_string_in_bytes (cm->ts.kind, se.string_length
 						? se.string_length
@@ -9013,6 +9024,29 @@ gfc_trans_subcomponent_assign (tree dest, gfc_component * cm,
 	  tmp = gfc_build_memcpy_call (tmp, se.expr, size);
 	  gfc_add_expr_to_block (&block, tmp);
 	}
+      else if (cm->ts.type == BT_CLASS)
+	{
+	  /* Fix the expression for memcpy.  */
+	  if (expr->expr_type != EXPR_VARIABLE)
+	    se.expr = gfc_evaluate_now (se.expr, &block);
+
+	  if (expr->ts.type == BT_CHARACTER)
+	    size = fold_convert (size_type_node, se.string_length);
+	  else
+	    size = TYPE_SIZE_UNIT (gfc_typenode_for_spec (&expr->ts));
+
+	  /* Now copy the expression to the constructor component _data.  */
+	  gfc_add_expr_to_block (&block,
+				 gfc_build_memcpy_call (tmp, se.expr, size));
+
+	  /* Fill the unlimited polymorphic _len field.  */
+	  if (UNLIMITED_POLY (cm))
+	    {
+	      tmp = gfc_class_len_get (gfc_get_class_from_expr (tmp));
+	      gfc_add_modify (&block, tmp,
+			      fold_convert (TREE_TYPE (tmp), size));
+	    }
+	}
       else
 	gfc_add_modify (&block, tmp,
 			fold_convert (TREE_TYPE (tmp), se.expr));

[-- Attachment #3: pr49213.f90 --]
[-- Type: text/x-fortran, Size: 1893 bytes --]

! { dg-do run }
!
! Contributed by Neil Carlson  <neil.n.carlson@gmail.com>
!
program main
  character(2) :: c

  type :: S
    integer :: n
  end type
  type(S) :: Sobj

  type, extends(S) :: S2
    integer :: m
  end type
  type(S2) :: S2obj

  type :: T
    class(S), allocatable :: x
  end type
  type(T) :: Tobj

  Sobj = S(1)
  Tobj = T(Sobj)

  S2obj = S2(1,2)
  Tobj = T(S2obj)            ! Failed here
  select type (x => Tobj%x)
    type is (S2)
      if ((x%n .ne. 1) .or. (x%m .ne. 2)) stop 1
    class default
      stop 2
  end select

  c = "  "
  call pass_it (T(Sobj))
  if (c .ne. "S ") stop 3
  call pass_it (T(S2obj))    ! and here
  if (c .ne. "S2") stop 4

  call bar

contains

  subroutine pass_it (foo)
    type(T), intent(in) :: foo
    select type (x => foo%x)
      type is (S)
        c = "S "
        if (x%n .ne. 1) stop 5
      type is (S2)
        c = "S2"
        if ((x%n .ne. 1) .or. (x%m .ne. 2)) stop 6
      class default
        stop 7
    end select
  end subroutine

  subroutine bar
   ! Test from comment #29 of the PR - due to Janus Weil
    type tContainer
      class(*), allocatable :: x
    end type
    integer, parameter :: i = 0
    character(7) :: chr = "goodbye"
    type(tContainer) :: cont

    cont%x = i ! linker error: undefined reference to `__copy_INTEGER_4_.3804'

    cont = tContainer(i+42) ! Failed here
    select type (z => cont%x)
      type is (integer)
        if (z .ne. 42) stop 8
      class default
        stop 9
    end select

    cont = tContainer('hello!')
    select type (z => cont%x)
      type is (character(*))
        if (z .ne. 'hello!') stop 10
      class default
        stop 11
    end select

    cont = tContainer(chr)
    select type (z => cont%x)
      type is (character(*))
        if (z .ne. 'goodbye') stop 12
      class default
        stop 13
    end select

  end subroutine bar
end program