Auto merge of #72362 - matthewjasper:remove-rescope, r=nikomatsakis

Remove ReScope

`ReScope` is unnecessary now that AST borrowck is gone and we're erasing the results of region inference in function bodies. This removes about as much of the old regionck code as possible without having to enable NLL fully.

cc #68261

r? @nikomatsakis

Author: bors

src/librustc_infer/infer/canonical/canonicalizer.rs

@@ -332,7 +332,6 @@ impl<'cx, 'tcx> TypeFolder<'tcx> for Canonicalizer<'cx, 'tcx> {
             ty::ReStatic
             | ty::ReEarlyBound(..)
             | ty::ReFree(_)
-            | ty::ReScope(_)
             | ty::ReEmpty(_)
             | ty::RePlaceholder(..)
             | ty::ReErased => self.canonicalize_region_mode.canonicalize_free_region(self, r),

src/librustc_infer/infer/combine.rs

@@ -619,7 +619,6 @@ impl TypeRelation<'tcx> for Generalizer<'_, 'tcx> {
             | ty::ReVar(..)
             | ty::ReEmpty(_)
             | ty::ReStatic
-            | ty::ReScope(..)
             | ty::ReEarlyBound(..)
             | ty::ReFree(..) => {
                 // see common code below