Auto merge of rust-lang#99047 - matthiaskrgr:rollup-01vn70s, r=matthiaskrgr

Rollup of 6 pull requests

Successful merges:

 - rust-lang#95635 (sess: stabilize `--terminal-width` as `--diagnostic-width`)
 - rust-lang#98718 (Stabilize `into_future`)
 - rust-lang#98795 (A few cleanups)
 - rust-lang#98798 (Fix caching bug in `download-rustc = true`)
 - rust-lang#99019 (Add doc comments in `rustc_middle::mir`)
 - rust-lang#99026 (Add test for and fix rust-lang/rust-clippy#9131)

Failed merges:

 - rust-lang#98957 ( don't allow ZST in ScalarInt )

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_borrowck/src/region_infer/mod.rs

@@ -495,8 +495,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                     }
                 }
 
-                NllRegionVariableOrigin::RootEmptyRegion
-                | NllRegionVariableOrigin::Existential { .. } => {
+                NllRegionVariableOrigin::Existential { .. } => {
                     // For existential, regions, nothing to do.
                 }
             }
@@ -1410,8 +1409,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                     self.check_bound_universal_region(fr, placeholder, errors_buffer);
                 }
 
-                NllRegionVariableOrigin::RootEmptyRegion
-                | NllRegionVariableOrigin::Existential { .. } => {
+                NllRegionVariableOrigin::Existential { .. } => {
                     // nothing to check here
                 }
             }
@@ -1513,8 +1511,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                     self.check_bound_universal_region(fr, placeholder, errors_buffer);
                 }
 
-                NllRegionVariableOrigin::RootEmptyRegion
-                | NllRegionVariableOrigin::Existential { .. } => {
+                NllRegionVariableOrigin::Existential { .. } => {
                     // nothing to check here
                 }
             }
@@ -1788,9 +1785,9 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                 universe1.cannot_name(placeholder.universe)
             }
 
-            NllRegionVariableOrigin::RootEmptyRegion
-            | NllRegionVariableOrigin::FreeRegion
-            | NllRegionVariableOrigin::Existential { .. } => false,
+            NllRegionVariableOrigin::FreeRegion | NllRegionVariableOrigin::Existential { .. } => {
+                false
+            }
         }
     }
 
@@ -2152,8 +2149,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         let blame_source = match from_region_origin {
             NllRegionVariableOrigin::FreeRegion
             | NllRegionVariableOrigin::Existential { from_forall: false } => true,
-            NllRegionVariableOrigin::RootEmptyRegion
-            | NllRegionVariableOrigin::Placeholder(_)
+            NllRegionVariableOrigin::Placeholder(_)
             | NllRegionVariableOrigin::Existential { from_forall: true } => false,
         };