[Patch, Fortran] Allow ref'ing PDT's len() in parameter-initializer [PR102003]

[Andre Vehreschild <vehre@gmx.de>]

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Hi all,

while browsing the pdt meta-bug I came across 102003 and thought to myself:
Well, that one is easy. How foolish of me...

Anyway, the solution attached prevents a pdt_len (or pdt_kind) expression in a
function call (e.g. len() or kind()) to mark the whole expression as a pdt one.
The second part of the patch in simplify.cc then takes care of either generating
the correct component ref or when a constant expression (i.e.
gfc_init_expr_flag is set) is required to look this up from the actual symbol
(not from the type, because there the default value is stored).

Regtested ok on x86_64-linux-gnu/Fedora 37.

Regards,
	Andre
--
Andre Vehreschild * Email: vehre ad gmx dot de

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gcc/fortran/ChangeLog:

	* expr.cc (gfc_match_init_expr): Prevent PDT analysis for function
	calls.
	* simplify.cc (gfc_simplify_len): Replace len() of PDT with pdt
	component ref or constant.

gcc/testsuite/ChangeLog:

	* gfortran.dg/pdt_33.f03: New test.


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[-- Attachment #3: pr102003.patch --]
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diff --git a/gcc/fortran/expr.cc b/gcc/fortran/expr.cc
index e418f1f3301..fb6eb76cda7 100644
--- a/gcc/fortran/expr.cc
+++ b/gcc/fortran/expr.cc
@@ -3229,7 +3229,7 @@ gfc_match_init_expr (gfc_expr **result)
       return m;
     }

-  if (gfc_derived_parameter_expr (expr))
+  if (expr->expr_type != EXPR_FUNCTION && gfc_derived_parameter_expr (expr))
     {
       *result = expr;
       gfc_init_expr_flag = false;
diff --git a/gcc/fortran/simplify.cc b/gcc/fortran/simplify.cc
index 81680117f70..8fb453d0a54 100644
--- a/gcc/fortran/simplify.cc
+++ b/gcc/fortran/simplify.cc
@@ -4580,19 +4580,54 @@ gfc_simplify_len (gfc_expr *e, gfc_expr *kind)
       return range_check (result, "LEN");
     }
   else if (e->expr_type == EXPR_VARIABLE && e->ts.type == BT_CHARACTER
-	   && e->symtree->n.sym
-	   && e->symtree->n.sym->ts.type != BT_DERIVED
-	   && e->symtree->n.sym->assoc && e->symtree->n.sym->assoc->target
-	   && e->symtree->n.sym->assoc->target->ts.type == BT_DERIVED
-	   && e->symtree->n.sym->assoc->target->symtree->n.sym
-	   && UNLIMITED_POLY (e->symtree->n.sym->assoc->target->symtree->n.sym))
-
-    /* The expression in assoc->target points to a ref to the _data component
-       of the unlimited polymorphic entity.  To get the _len component the last
-       _data ref needs to be stripped and a ref to the _len component added.  */
-    return gfc_get_len_component (e->symtree->n.sym->assoc->target, k);
-  else
-    return NULL;
+	   && e->symtree->n.sym)
+    {
+      if (e->symtree->n.sym->ts.type != BT_DERIVED
+	     && e->symtree->n.sym->assoc && e->symtree->n.sym->assoc->target
+	     && e->symtree->n.sym->assoc->target->ts.type == BT_DERIVED
+	     && e->symtree->n.sym->assoc->target->symtree->n.sym
+	     && UNLIMITED_POLY (e->symtree->n.sym->assoc->target->symtree
+				->n.sym))
+	/* The expression in assoc->target points to a ref to the _data
+	   component of the unlimited polymorphic entity.  To get the _len
+	   component the last _data ref needs to be stripped and a ref to the
+	   _len component added.  */
+	return gfc_get_len_component (e->symtree->n.sym->assoc->target, k);
+      else if (e->symtree->n.sym->ts.type == BT_DERIVED
+	       && e->ref && e->ref->type == REF_COMPONENT
+	       && e->ref->u.c.component->attr.pdt_string
+	       && e->ref->u.c.component->ts.type == BT_CHARACTER
+	       && e->ref->u.c.component->ts.u.cl->length)
+	{
+	  if (gfc_init_expr_flag)
+	    {
+	      /* The actual length of a pdt is in its components.  In the
+		 initializer of the current ref is only the default value.
+		 Therefore traverse the chain of components and pick the correct
+		 one's initializer expressions.  */
+	      for (gfc_component *comp = e->symtree->n.sym->ts.u.derived
+		   ->components; comp != NULL; comp = comp->next)
+		{
+		  if (!strcmp (comp->name, e->ref->u.c.component->ts.u.cl
+			       ->length->symtree->name))
+		    return gfc_copy_expr (comp->initializer);
+		}
+	    }
+	  else
+	    {
+	      gfc_expr *len_expr = gfc_copy_expr (e);
+	      gfc_free_ref_list (len_expr->ref);
+	      len_expr->ref = NULL;
+	      gfc_find_component (len_expr->symtree->n.sym->ts.u.derived, e->ref
+				  ->u.c.component->ts.u.cl->length->symtree
+				  ->name,
+				  false, true, &len_expr->ref);
+	      len_expr->ts = len_expr->ref->u.c.component->ts;
+	      return len_expr;
+	    }
+	}
+    }
+  return NULL;
 }


diff --git a/gcc/testsuite/gfortran.dg/pdt_33.f03 b/gcc/testsuite/gfortran.dg/pdt_33.f03
new file mode 100644
index 00000000000..c12bd9b411c
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pdt_33.f03
@@ -0,0 +1,18 @@
+! { dg-do run }
+!
+! Test the fix for PR102003, where len parameters where not returned as constants.
+!
+! Contributed by Harald Anlauf  <anlauf@gcc.gnu.org>
+!
+program pr102003
+  type pdt(n)
+     integer, len     :: n = 8
+     character(len=n) :: c
+  end type pdt
+  type(pdt(42)) :: p
+  integer, parameter :: m = len (p% c)
+
+  if (m /= 42) stop 1
+  if (len (p% c) /= 42) stop 2
+end
+