Can't display {$cart.gift_message} in my cart template

[Rustandroid]

Hi everyone,

I'm really new to Prestashop and I ask for help in my work. 
Usually, I'm a javascript developper but exceptionnally in my work I have to replace someone.

I'm using Prestashop and my template engine is Smarty.

I just want to display a gift message defined in my cart. I tried {$cart.gift_message} but it doesn't work.
So I used {$cart|var_dump} and among all the variables, there is no sign of gift_message only ["is_gift"]=> bool(false). 

I don't know what to do. I think I should create a variable template for Smarty no ? 

Does someone can help me ? 

The current version of my Prestashop is 1.7.4

[Rustandroid]

Solution found, let me a day to post a clean solution