rustc_error: make ErrorReported impossible to construct

There are a few places were we have to construct it, though, and a few
places that are more invasive to change. To do this, we create a
constructor with a long obvious name.

6 files changed, 24 insertions, 21 deletions

diff --git a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/different_lifetimes.rs b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/different_lifetimes.rs
index 0d6dbd8f343..7721e00c141 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/different_lifetimes.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/different_lifetimes.rs
@@ -147,8 +147,8 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
 
         self.suggest_adding_lifetime_params(sub, ty_sup, ty_sub, &mut err);
 
-        err.emit();
-        Some(ErrorGuaranteed)
+        let reported = err.emit();
+        Some(reported)
     }
 
     fn suggest_adding_lifetime_params(
diff --git a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/mismatched_static_lifetime.rs b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/mismatched_static_lifetime.rs
index 4710eae6189..467054e318b 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/mismatched_static_lifetime.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/mismatched_static_lifetime.rs
@@ -98,7 +98,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
             let impl_span = self.tcx().def_span(*impl_def_id);
             err.span_note(impl_span, "...does not necessarily outlive the static lifetime introduced by the compatible `impl`");
         }
-        err.emit();
-        Some(ErrorGuaranteed)
+        let reported = err.emit();
+        Some(reported)
     }
 }
diff --git a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/mod.rs b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/mod.rs
index c7bfa686c04..df81aea6ef9 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/mod.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/mod.rs
@@ -54,10 +54,7 @@ impl<'cx, 'tcx> NiceRegionError<'cx, 'tcx> {
 
     pub fn try_report(&self) -> Option<ErrorGuaranteed> {
         self.try_report_from_nll()
-            .map(|mut diag| {
-                diag.emit();
-                ErrorGuaranteed
-            })
+            .map(|mut diag| diag.emit())
             .or_else(|| self.try_report_impl_not_conforming_to_trait())
             .or_else(|| self.try_report_anon_anon_conflict())
             .or_else(|| self.try_report_static_impl_trait())
diff --git a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/static_impl_trait.rs b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/static_impl_trait.rs
index 99dd418015b..4fcdcb63666 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/static_impl_trait.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/static_impl_trait.rs
@@ -84,8 +84,8 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                         ),
                     );
                     if self.find_impl_on_dyn_trait(&mut err, param.param_ty, &ctxt) {
-                        err.emit();
-                        return Some(ErrorGuaranteed);
+                        let reported = err.emit();
+                        return Some(reported);
                     } else {
                         err.cancel();
                     }
@@ -276,8 +276,8 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
             Some((param.param_ty_span, param.param_ty.to_string())),
         );
 
-        err.emit();
-        Some(ErrorGuaranteed)
+        let reported = err.emit();
+        Some(reported)
     }
 }
 
diff --git a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/trait_impl_difference.rs b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/trait_impl_difference.rs
index 3f0f50bb75a..b1a42ee66c9 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/trait_impl_difference.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/trait_impl_difference.rs
@@ -33,13 +33,13 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
             ) = (sub_trace.values.ty(), sup_trace.values.ty(), sub_trace.cause.code())
             && sup_expected_found == sub_expected_found
         {
-            self.emit_err(
+            let guar = self.emit_err(
                 var_origin.span(),
                 sub_expected,
                 sub_found,
                 *trait_item_def_id,
             );
-            return Some(ErrorGuaranteed);
+            return Some(guar);
         }
         if let RegionResolutionError::ConcreteFailure(origin, _, _)
             | RegionResolutionError::GenericBoundFailure(origin, _, _) = error.clone()
@@ -49,18 +49,24 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                 trait_item_def_id,
             } = origin
         {
-            self.emit_associated_type_err(
+            let guar = self.emit_associated_type_err(
                 span,
                 self.infcx.tcx.item_name(impl_item_def_id),
                 impl_item_def_id,
                 trait_item_def_id,
             );
-            return Some(ErrorGuaranteed);
+            return Some(guar);
         }
         None
     }
 
-    fn emit_err(&self, sp: Span, expected: Ty<'tcx>, found: Ty<'tcx>, trait_def_id: DefId) {
+    fn emit_err(
+        &self,
+        sp: Span,
+        expected: Ty<'tcx>,
+        found: Ty<'tcx>,
+        trait_def_id: DefId,
+    ) -> ErrorGuaranteed {
         let trait_sp = self.tcx().def_span(trait_def_id);
         let mut err = self
             .tcx()
@@ -142,7 +148,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                  argument, the other inputs and its output",
             );
         }
-        err.emit();
+        err.emit()
     }
 
     fn emit_associated_type_err(
@@ -151,7 +157,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
         item_name: Symbol,
         impl_item_def_id: DefId,
         trait_item_def_id: DefId,
-    ) {
+    ) -> ErrorGuaranteed {
         let impl_sp = self.tcx().def_span(impl_item_def_id);
         let trait_sp = self.tcx().def_span(trait_item_def_id);
         let mut err = self
@@ -161,7 +167,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
         err.span_label(impl_sp, "found");
         err.span_label(trait_sp, "expected");
 
-        err.emit();
+        err.emit()
     }
 }
 
diff --git a/compiler/rustc_infer/src/infer/outlives/obligations.rs b/compiler/rustc_infer/src/infer/outlives/obligations.rs
index 0224aba01ef..5d8cc94e05c 100644
--- a/compiler/rustc_infer/src/infer/outlives/obligations.rs
+++ b/compiler/rustc_infer/src/infer/outlives/obligations.rs
@@ -189,7 +189,7 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
                 self.tcx.sess.delay_span_bug(
                     origin.span(),
                     &format!("no region-bound-pairs for {:?}", body_id),
-                )
+                );
             }
         }
     }