Auto merge of #116045 - notriddle:notriddle/issue-83556, r=cjgillot

diagnostics: avoid mismatch between variance index and hir generic

This happens because variances are constructed from ty generics, and ty generics are always constructed with lifetimes first.

https://github.com/rust-lang/rust/blob/b3aa8e7168a3d940122db3561289ffbf3f587262/compiler/rustc_hir_analysis/src/collect/generics_of.rs#L248-L269

Fixes #83556

Author: bors