mruby-compiler: convert new_asgn to always use variable-sized nodes

Remove conditional logic from new_asgn() and inline new_asgn_var() helper
function for cleaner implementation. Assignment expressions maintain proper
value semantics while using more efficient memory allocation.

Changes:
- Remove var_nodes_enabled conditional in new_asgn()
- Inline new_asgn_var() logic directly into new_asgn()
- Remove new_asgn_var() function and declaration
- Remove NODE_ASGN case from main codegen() switch
- Update gen_asgn_var() to use direct struct field access
- Remove traditional codegen_asgn() function

Co-authored-by: Claude <noreply@anthropic.com>

mrbgems/mruby-compiler/core/codegen.c

@@ -3878,12 +3878,6 @@ codegen_regx(codegen_scope *s, node *tree, int val)
   }
 }
 
-static void
-codegen_asgn(codegen_scope *s, node *tree, int val)
-{
-  gen_assignment(s, tree->car, tree->cdr, 0, val);
-}
-
 static void
 codegen_def(codegen_scope *s, node *tree, int val)
 {
@@ -4714,10 +4708,9 @@ static void
 gen_asgn_var(codegen_scope *s, node *varnode, int val)
 {
   struct mrb_ast_asgn_node *asgn_n = asgn_node(varnode);
-  node *lhs = ASGN_NODE_LHS(asgn_n);
-  node *rhs = ASGN_NODE_RHS(asgn_n);
+  node *lhs = asgn_n->lhs;
+  node *rhs = asgn_n->rhs;
 
-  /* Use existing assignment generation logic */
   gen_assignment(s, lhs, rhs, 0, val);
 }
 
@@ -5822,7 +5815,6 @@ gen_undef_var(codegen_scope *s, const node *varnode, int val)
   gen_load_nil(s, val);
 }
 
-
 static void
 gen_sdef_var(codegen_scope *s, const node *varnode, int val)
 {
@@ -6221,10 +6213,6 @@ codegen(codegen_scope *s, node *tree, int val)
     codegen_scall(s, tree, val);
     break;
 
-  case NODE_ASGN:
-    codegen_asgn(s, tree, val);
-    break;
-
   case NODE_MASGN:
     codegen_masgn(s, tree, val);
     break;
@@ -6237,7 +6225,6 @@ codegen(codegen_scope *s, node *tree, int val)
     codegen_lvar(s, node_to_sym(tree), val);
     break;
 
-
   case NODE_DEF:
     codegen_def(s, tree, val);
     break;

mrbgems/mruby-compiler/core/parse.y

@@ -500,7 +500,6 @@ new_stmts(parser_state *p, node *body)
   return cons_head((node*)NODE_VARIABLE, (node*)n);
 }
 
-
 /* (:begin body) - Always use variable-sized nodes */
 static node*
 new_begin(parser_state *p, node *body)
@@ -608,7 +607,6 @@ new_alias(parser_state *p, mrb_sym a, mrb_sym b)
 
 /* Forward declarations for variable-sized AST node creation functions */
 static node* new_def_var(parser_state *p, mrb_sym name, node *args, node *body);
-static node* new_asgn_var(parser_state *p, node *lhs, node *rhs);
 static node* new_masgn_var(parser_state *p, node *lhs, node *rhs);
 static node* new_op_asgn_var(parser_state *p, node *lhs, mrb_sym op, node *rhs);
 
@@ -874,25 +872,6 @@ new_def_var(parser_state *p, mrb_sym name, node *args, node *body)
   return cons_head((node*)NODE_VARIABLE, (node*)n);
 }
 
-
-
-
-/* Variable-sized assignment node creation */
-static node*
-new_asgn_var(parser_state *p, node *lhs, node *rhs)
-{
-  size_t total_size = sizeof(struct mrb_ast_asgn_node);
-  enum mrb_ast_size_class class = size_to_class(total_size);
-
-  struct mrb_ast_asgn_node *n = (struct mrb_ast_asgn_node*)parser_alloc_var(p, total_size, class);
-
-  init_var_header(&n->header, p, NODE_ASGN, class);
-  n->lhs = lhs;
-  n->rhs = rhs;
-
-  return cons_head((node*)NODE_VARIABLE, (node*)n);
-}
-
 /* Variable-sized multiple assignment node creation */
 static node*
 new_masgn_var(parser_state *p, node *lhs, node *rhs)
@@ -1310,7 +1289,6 @@ new_lvar(parser_state *p, mrb_sym sym)
   return cons_head((node*)NODE_LVAR, sym_to_node(sym));
 }
 
-
 /* (:nvar . a) */
 static node*
 new_nvar(parser_state *p, int num)
@@ -1686,10 +1664,17 @@ static node*
 new_asgn(parser_state *p, node *a, node *b)
 {
   void_expr_error(p, b);
-  if (p->var_nodes_enabled) {
-    return new_asgn_var(p, a, b);
-  }
-  return cons_head((node*)NODE_ASGN, cons(a, b));
+
+  size_t total_size = sizeof(struct mrb_ast_asgn_node);
+  enum mrb_ast_size_class class = size_to_class(total_size);
+
+  struct mrb_ast_asgn_node *n = (struct mrb_ast_asgn_node*)parser_alloc_var(p, total_size, class);
+
+  init_var_header(&n->header, p, NODE_ASGN, class);
+  n->lhs = a;
+  n->rhs = b;
+
+  return cons_head((node*)NODE_VARIABLE, (node*)n);
 }
 
 /* (:masgn mlhs=(pre rest post)  mrhs) */