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.

compiler/rustc_const_eval/src/const_eval/machine.rs

@@ -1,4 +1,3 @@
-use rustc_errors::ErrorGuaranteed;
 use rustc_hir::def::DefKind;
 use rustc_middle::mir;
 use rustc_middle::ty::{self, Ty};
@@ -247,11 +246,11 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
                 if ecx.tcx.is_ctfe_mir_available(def.did) {
                     Ok(ecx.tcx.mir_for_ctfe_opt_const_arg(def))
                 } else if ecx.tcx.def_kind(def.did) == DefKind::AssocConst {
-                    ecx.tcx.sess.delay_span_bug(
+                    let guar = ecx.tcx.sess.delay_span_bug(
                         rustc_span::DUMMY_SP,
                         "This is likely a const item that is missing from its impl",
                     );
-                    throw_inval!(AlreadyReported(ErrorGuaranteed {}));
+                    throw_inval!(AlreadyReported(guar));
                 } else {
                     let path = ecx.tcx.def_path_str(def.did);
                     Err(ConstEvalErrKind::NeedsRfc(format!("calling extern function `{}`", path))

compiler/rustc_const_eval/src/interpret/intern.rs

@@ -406,8 +406,11 @@ pub fn intern_const_alloc_recursive<
         } else if ecx.memory.dead_alloc_map.contains_key(&alloc_id) {
             // Codegen does not like dangling pointers, and generally `tcx` assumes that
             // all allocations referenced anywhere actually exist. So, make sure we error here.
-            ecx.tcx.sess.span_err(ecx.tcx.span, "encountered dangling pointer in final constant");
-            return Err(ErrorGuaranteed);
+            let reported = ecx
+                .tcx
+                .sess
+                .span_err(ecx.tcx.span, "encountered dangling pointer in final constant");
+            return Err(reported);
         } else if ecx.tcx.get_global_alloc(alloc_id).is_none() {
             // We have hit an `AllocId` that is neither in local or global memory and isn't
             // marked as dangling by local memory.  That should be impossible.

compiler/rustc_const_eval/src/interpret/operand.rs

@@ -4,12 +4,11 @@
 use std::convert::TryFrom;
 use std::fmt::Write;
 
-use rustc_errors::ErrorGuaranteed;
 use rustc_hir::def::Namespace;
 use rustc_macros::HashStable;
 use rustc_middle::ty::layout::{LayoutOf, PrimitiveExt, TyAndLayout};
 use rustc_middle::ty::print::{FmtPrinter, PrettyPrinter, Printer};
-use rustc_middle::ty::{ConstInt, Ty};
+use rustc_middle::ty::{ConstInt, DelaySpanBugEmitted, Ty};
 use rustc_middle::{mir, ty};
 use rustc_target::abi::{Abi, HasDataLayout, Size, TagEncoding};
 use rustc_target::abi::{VariantIdx, Variants};
@@ -565,7 +564,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
     ) -> InterpResult<'tcx, OpTy<'tcx, M::PointerTag>> {
         match val.val() {
             ty::ConstKind::Param(_) | ty::ConstKind::Bound(..) => throw_inval!(TooGeneric),
-            ty::ConstKind::Error(_) => throw_inval!(AlreadyReported(ErrorGuaranteed)),
+            ty::ConstKind::Error(DelaySpanBugEmitted { reported, .. }) => {
+                throw_inval!(AlreadyReported(reported))
+            }
             ty::ConstKind::Unevaluated(uv) => {
                 let instance = self.resolve(uv.def, uv.substs)?;
                 Ok(self.eval_to_allocation(GlobalId { instance, promoted: uv.promoted })?.into())

compiler/rustc_const_eval/src/transform/check_consts/check.rs

@@ -259,7 +259,7 @@ impl<'mir, 'tcx> Checker<'mir, 'tcx> {
                 self.tcx.sess.diagnostic().emit_diagnostic(&error);
             }
         } else {
-            assert!(self.tcx.sess.has_errors());
+            assert!(self.tcx.sess.has_errors().is_some());
         }
     }
 
@@ -327,8 +327,8 @@ impl<'mir, 'tcx> Checker<'mir, 'tcx> {
 
         match op.importance() {
             ops::DiagnosticImportance::Primary => {
-                self.error_emitted = Some(ErrorGuaranteed);
-                err.emit();
+                let reported = err.emit();
+                self.error_emitted = Some(reported);
             }
 
             ops::DiagnosticImportance::Secondary => err.buffer(&mut self.secondary_errors),