gfortran: Allow ref'ing PDT's len() in parameter-initializer.

Fix declaring a parameter initialized using a pdt_len reference
not simplifying the reference to a constant.

2023-07-12  Andre Vehreschild  <vehre@gcc.gnu.org>

gcc/fortran/ChangeLog:

	PR fortran/102003
	* expr.cc (find_inquiry_ref): Replace len of pdt_string by
	constant.
	(simplify_ref_chain): Ensure input to find_inquiry_ref is
	NULL.
	(gfc_match_init_expr): Prevent PDT analysis for function calls.
	(gfc_pdt_find_component_copy_initializer): Get the initializer
	value for given component.
	* gfortran.h (gfc_pdt_find_component_copy_initializer): New
	function.
	* 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.

1 files changed, 28 insertions, 3 deletions

diff --git a/gcc/fortran/expr.cc b/gcc/fortran/expr.cc
index e418f1f..663fe63 100644
--- a/gcc/fortran/expr.cc
+++ b/gcc/fortran/expr.cc
@@ -1862,6 +1862,13 @@ find_inquiry_ref (gfc_expr *p, gfc_expr **newp)
 	  else if (tmp->expr_type == EXPR_CONSTANT)
 	    *newp = gfc_get_int_expr (gfc_default_integer_kind,
 				      NULL, tmp->value.character.length);
+	  else if (gfc_init_expr_flag
+		   && tmp->ts.u.cl->length->symtree->n.sym->attr.pdt_len)
+	    *newp = gfc_pdt_find_component_copy_initializer (tmp->symtree->n
+							     .sym,
+							     tmp->ts.u.cl
+							     ->length->symtree
+							     ->n.sym->name);
 	  else
 	    goto cleanup;
 
@@ -1902,7 +1909,9 @@ find_inquiry_ref (gfc_expr *p, gfc_expr **newp)
 		    mpc_imagref (tmp->value.complex), GFC_RND_MODE);
 	  break;
 	}
-      tmp = gfc_copy_expr (*newp);
+      // TODO: Fix leaking expr tmp, when simplify is done twice.
+      if (inquiry->next)
+	gfc_replace_expr (tmp, *newp);
     }
 
   if (!(*newp))
@@ -2067,7 +2076,7 @@ static bool
 simplify_ref_chain (gfc_ref *ref, int type, gfc_expr **p)
 {
   int n;
-  gfc_expr *newp;
+  gfc_expr *newp = NULL;
 
   for (; ref; ref = ref->next)
     {
@@ -3229,7 +3238,7 @@ 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;
@@ -6556,3 +6565,19 @@ gfc_check_vardef_context (gfc_expr* e, bool pointer, bool alloc_obj,
 
   return true;
 }
+
+gfc_expr*
+gfc_pdt_find_component_copy_initializer (gfc_symbol *sym, const char *name)
+{
+  /* 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 = sym->ts.u.derived->components; comp != NULL;
+       comp = comp->next)
+    {
+      if (!strcmp (comp->name, name))
+	return gfc_copy_expr (comp->initializer);
+    }
+  return NULL;
+}