Rollup merge of #69697 - GuillaumeGomez:explanation-e0380, r=Dylan-DPC
Rollup merge of #69697 - GuillaumeGomez:explanation-e0380, r=Dylan-DPC

Add explanation for E0380

r? @Dylan-DPC

aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust