Rollup merge of #43741 - Gankro:fix-assert, r=eddyb
Rollup merge of #43741 - Gankro:fix-assert, r=eddyb

fix assertion - trait object pointers don't have infinite fields

r? @eddyb

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