Auto merge of #107652 - estebank:re_error, r=oli-obk

Introduce `ReError`

CC #69314

r? `@nagisa`

compiler/rustc_infer/src/errors/note_and_explain.rs

@@ -31,6 +31,8 @@ impl<'a> DescriptionCtx<'a> {
 
             ty::RePlaceholder(_) => return None,
 
+            ty::ReError(_) => return None,
+
             // FIXME(#13998) RePlaceholder should probably print like
             // ReFree rather than dumping Debug output on the user.
             //

compiler/rustc_infer/src/infer/canonical/canonicalizer.rs

@@ -369,6 +369,7 @@ impl<'cx, 'tcx> TypeFolder<'tcx> for Canonicalizer<'cx, 'tcx> {
 
             ty::ReStatic
             | ty::ReEarlyBound(..)
+            | ty::ReError(_)
             | ty::ReFree(_)
             | ty::RePlaceholder(..)
             | ty::ReErased => self.canonicalize_mode.canonicalize_free_region(self, r),

compiler/rustc_infer/src/infer/combine.rs

@@ -705,6 +705,10 @@ impl<'tcx> TypeRelation<'tcx> for Generalizer<'_, 'tcx> {
                 return Ok(r);
             }
 
+            ty::ReError(_) => {
+                return Ok(r);
+            }
+
             ty::RePlaceholder(..)
             | ty::ReVar(..)
             | ty::ReStatic
@@ -861,7 +865,7 @@ impl<'tcx> FallibleTypeFolder<'tcx> for ConstInferUnifier<'_, 'tcx> {
         match *r {
             // Never make variables for regions bound within the type itself,
             // nor for erased regions.
-            ty::ReLateBound(..) | ty::ReErased => {
+            ty::ReLateBound(..) | ty::ReErased | ty::ReError(_) => {
                 return Ok(r);
             }
 

compiler/rustc_infer/src/infer/error_reporting/mod.rs

@@ -134,6 +134,8 @@ pub(super) fn note_and_explain_region<'tcx>(
 
         ty::RePlaceholder(_) => return,
 
+        ty::ReError(_) => return,
+
         // FIXME(#13998) RePlaceholder should probably print like
         // ReFree rather than dumping Debug output on the user.
         //
@@ -313,6 +315,9 @@ pub fn unexpected_hidden_region_diagnostic<'tcx>(
                 )
             }
         }
+        ty::ReError(_) => {
+            err.delay_as_bug();
+        }
         _ => {
             // Ugh. This is a painful case: the hidden region is not one
             // that we can easily summarize or explain. This can happen
@@ -2546,7 +2551,11 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
             );
 
             err.note_expected_found(&"", sup_expected, &"", sup_found);
-            err.emit();
+            if sub_region.is_error() | sup_region.is_error() {
+                err.delay_as_bug();
+            } else {
+                err.emit();
+            }
             return;
         }
 
@@ -2562,7 +2571,11 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         );
 
         self.note_region_origin(&mut err, &sub_origin);
-        err.emit();
+        if sub_region.is_error() | sup_region.is_error() {
+            err.delay_as_bug();
+        } else {
+            err.emit();
+        }
     }
 
     /// Determine whether an error associated with the given span and definition

compiler/rustc_infer/src/infer/error_reporting/note.rs

@@ -78,7 +78,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         sub: Region<'tcx>,
         sup: Region<'tcx>,
     ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
-        match origin {
+        let mut err = match origin {
             infer::Subtype(box trace) => {
                 let terr = TypeError::RegionsDoesNotOutlive(sup, sub);
                 let mut err = self.report_and_explain_type_error(trace, terr);
@@ -299,7 +299,11 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                 );
                 err
             }
+        };
+        if sub.is_error() || sup.is_error() {
+            err.delay_as_bug();
         }
+        err
     }
 
     pub fn suggest_copy_trait_method_bounds(

compiler/rustc_infer/src/infer/freshen.rs

@@ -126,6 +126,7 @@ impl<'a, 'tcx> TypeFolder<'tcx> for TypeFreshener<'a, 'tcx> {
             | ty::ReFree(_)
             | ty::ReVar(_)
             | ty::RePlaceholder(..)
+            | ty::ReError(_)
             | ty::ReErased => {
                 // replace all free regions with 'erased
                 self.tcx().lifetimes.re_erased

compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs

@@ -17,7 +17,7 @@ use rustc_index::vec::{Idx, IndexVec};
 use rustc_middle::ty::fold::TypeFoldable;
 use rustc_middle::ty::PlaceholderRegion;
 use rustc_middle::ty::{self, Ty, TyCtxt};
-use rustc_middle::ty::{ReEarlyBound, ReErased, ReFree, ReStatic};
+use rustc_middle::ty::{ReEarlyBound, ReErased, ReError, ReFree, ReStatic};
 use rustc_middle::ty::{ReLateBound, RePlaceholder, ReVar};
 use rustc_middle::ty::{Region, RegionVid};
 use rustc_span::Span;
@@ -216,6 +216,8 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
                 Ok(self.tcx().lifetimes.re_static)
             }
 
+            ReError(_) => Ok(a_region),
+
             ReEarlyBound(_) | ReFree(_) => {
                 // All empty regions are less than early-bound, free,
                 // and scope regions.
@@ -436,7 +438,7 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
             }
             (VarValue::Value(a), VarValue::Empty(_)) => {
                 match *a {
-                    ReLateBound(..) | ReErased => {
+                    ReLateBound(..) | ReErased | ReError(_) => {
                         bug!("cannot relate region: {:?}", a);
                     }
 
@@ -465,7 +467,7 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
             }
             (VarValue::Empty(a_ui), VarValue::Value(b)) => {
                 match *b {
-                    ReLateBound(..) | ReErased => {
+                    ReLateBound(..) | ReErased | ReError(_) => {
                         bug!("cannot relate region: {:?}", b);
                     }
 
@@ -546,6 +548,10 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
                 );
             }
 
+            (ReError(_), _) => a,
+
+            (_, ReError(_)) => b,
+
             (ReStatic, _) | (_, ReStatic) => {
                 // nothing lives longer than `'static`
                 self.tcx().lifetimes.re_static
@@ -1040,7 +1046,7 @@ impl<'tcx> LexicalRegionResolutions<'tcx> {
             ty::ReVar(rid) => match self.values[rid] {
                 VarValue::Empty(_) => r,
                 VarValue::Value(r) => r,
-                VarValue::ErrorValue => tcx.lifetimes.re_static,
+                VarValue::ErrorValue => tcx.re_error_misc(),
             },
             _ => r,
         };

compiler/rustc_infer/src/infer/region_constraints/mod.rs

@@ -696,9 +696,11 @@ impl<'tcx> RegionConstraintCollector<'_, 'tcx> {
 
     pub fn universe(&self, region: Region<'tcx>) -> ty::UniverseIndex {
         match *region {
-            ty::ReStatic | ty::ReErased | ty::ReFree(..) | ty::ReEarlyBound(..) => {
-                ty::UniverseIndex::ROOT
-            }
+            ty::ReStatic
+            | ty::ReErased
+            | ty::ReFree(..)
+            | ty::ReEarlyBound(..)
+            | ty::ReError(_) => ty::UniverseIndex::ROOT,
             ty::RePlaceholder(placeholder) => placeholder.universe,
             ty::ReVar(vid) => self.var_universe(vid),
             ty::ReLateBound(..) => bug!("universe(): encountered bound region {:?}", region),