cgen: fix codegen for option unwrapped var passed to generic option type (fix #23972) (#24096)

vlib/v/gen/c/fn.v

@@ -2614,7 +2614,7 @@ fn (mut g Gen) keep_alive_call_postgen(node ast.CallExpr, tmp_cnt_save int) {
 
 @[inline]
 fn (mut g Gen) ref_or_deref_arg(arg ast.CallArg, expected_type ast.Type, lang ast.Language, is_smartcast bool) {
-	arg_typ := if arg.ct_expr {
+	mut arg_typ := if arg.ct_expr {
 		g.unwrap_generic(g.type_resolver.get_type(arg.expr))
 	} else {
 		g.unwrap_generic(arg.typ)
@@ -2754,6 +2754,13 @@ fn (mut g Gen) ref_or_deref_arg(arg ast.CallArg, expected_type ast.Type, lang as
 		if (arg_sym.info is ast.Alias || exp_sym.info is ast.Alias) && expected_type != arg_typ {
 			g.expr_opt_with_alias(arg.expr, arg_typ, expected_type)
 		} else {
+			if arg.expr is ast.Ident {
+				if arg.expr.obj is ast.Var {
+					if arg.expr.obj.smartcasts.len > 0 {
+						arg_typ = arg.expr.obj.smartcasts.last()
+					}
+				}
+			}
 			g.expr_with_opt(arg.expr, arg_typ, expected_type)
 		}
 		return

vlib/v/gen/c/infix.v

@@ -1030,14 +1030,23 @@ fn (mut g Gen) infix_expr_left_shift_op(node ast.InfixExpr) {
 			elem_sym := g.table.final_sym(array_info.elem_type)
 			elem_is_array_var := elem_sym.kind in [.array, .array_fixed] && node.right is ast.Ident
 			g.write('array_push${noscan}((array*)')
+			mut needs_addr := false
 			if !left.typ.is_ptr()
 				|| (node.left_type.has_flag(.shared_f) && !node.left_type.deref().is_ptr()) {
+				if node.left is ast.CallExpr {
+					g.write('ADDR(${g.styp(node.left_type)}, ')
+					needs_addr = true
+				} else {
 					g.write('&')
 				}
+			}
 			g.expr(node.left)
 			if node.left_type.has_flag(.shared_f) {
 				g.write('->val')
 			}
+			if needs_addr {
+				g.write(')')
+			}
 			if elem_sym.kind == .function {
 				g.write(', _MOV((voidptr[]){ ')
 			} else if elem_is_array_var {

vlib/v/tests/options/option_unwrapped_arg_generic_opt_test.v

@@ -0,0 +1,17 @@
+fn test_main() {
+	mut arr := ?[]int(none)
+	if arr == none {
+		arr = []int{}
+	} else {
+		ret := unwrap(arr)
+		assert ret == arr
+	}
+	assert arr?.len == 0
+}
+
+fn t(a ?int) {}
+
+@[inline]
+pub fn unwrap[T](t ?T) T {
+	return t or { panic('unexpected `none`') }
+}