Auto merge of #95056 - Dylan-DPC:rollup-swtuw2n, r=Dylan-DPC

Rollup of 10 pull requests

Successful merges:

 - #91133 (Improve `unsafe` diagnostic)
 - #93222 (Make ErrorReported impossible to construct outside `rustc_errors`)
 - #93745 (Stabilize ADX target feature)
 - #94309 ([generator_interior] Be more precise with scopes of borrowed places)
 - #94698 (Remove redundant code from copy-suggestions)
 - #94731 (Suggest adding `{ .. }` around a const function call with arguments)
 - #94960 (Fix many spelling mistakes)
 - #94982 (Add deprecated_safe feature gate and attribute, cc #94978)
 - #94997 (debuginfo: Fix ICE when generating name for type that produces a layout error.)
 - #95000 (Fixed wrong type name in comment)

Failed merges:

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

compiler/rustc_ast_lowering/src/item.rs

@@ -26,7 +26,7 @@ pub(super) struct ItemLowerer<'a, 'lowering, 'hir> {
 }
 
 /// When we have a ty alias we *may* have two where clauses. To give the best diagnostics, we set the span
-/// to the where clause that is prefered, if it exists. Otherwise, it sets the span to the other where
+/// to the where clause that is preferred, if it exists. Otherwise, it sets the span to the other where
 /// clause if it exists.
 fn add_ty_alias_where_clause(
     generics: &mut ast::Generics,

compiler/rustc_ast_lowering/src/lib.rs

@@ -952,7 +952,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                                 sess.diagnostic().delay_span_bug(
                                     span,
                                     "unexpected delimiter in key-value attribute's value",
-                                )
+                                );
                             }
                             unwrap_single_token(sess, tokens, span)
                         }

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -440,7 +440,7 @@ impl<'a> AstValidator<'a> {
                         attr.span,
                         "allow, cfg, cfg_attr, deny, \
                 forbid, and warn are the only allowed built-in attributes in function parameters",
-                    )
+                    );
                 }
             });
     }

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -252,11 +252,12 @@ impl<'a> PostExpansionVisitor<'a> {
                     "wasm ABI is experimental and subject to change"
                 );
             }
-            abi => self
-                .sess
-                .parse_sess
-                .span_diagnostic
-                .delay_span_bug(span, &format!("unrecognized ABI not caught in lowering: {}", abi)),
+            abi => {
+                self.sess.parse_sess.span_diagnostic.delay_span_bug(
+                    span,
+                    &format!("unrecognized ABI not caught in lowering: {}", abi),
+                );
+            }
         }
     }
 

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -12,9 +12,7 @@ use rustc_middle::mir::{
     FakeReadCause, LocalDecl, LocalInfo, LocalKind, Location, Operand, Place, PlaceRef,
     ProjectionElem, Rvalue, Statement, StatementKind, Terminator, TerminatorKind, VarBindingForm,
 };
-use rustc_middle::ty::{
-    self, suggest_constraining_type_param, suggest_constraining_type_params, PredicateKind, Ty,
-};
+use rustc_middle::ty::{self, suggest_constraining_type_params, PredicateKind, Ty};
 use rustc_mir_dataflow::move_paths::{InitKind, MoveOutIndex, MovePathIndex};
 use rustc_span::symbol::sym;
 use rustc_span::{BytePos, MultiSpan, Span};
@@ -285,27 +283,8 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                     Some(ref name) => format!("`{}`", name),
                     None => "value".to_owned(),
                 };
-                if let ty::Param(param_ty) = ty.kind() {
-                    let tcx = self.infcx.tcx;
-                    let generics = tcx.generics_of(self.mir_def_id());
-                    let param = generics.type_param(&param_ty, tcx);
-                    if let Some(generics) = tcx
-                        .typeck_root_def_id(self.mir_def_id().to_def_id())
-                        .as_local()
-                        .and_then(|def_id| tcx.hir().get_generics(def_id))
-                    {
-                        suggest_constraining_type_param(
-                            tcx,
-                            generics,
-                            &mut err,
-                            param.name.as_str(),
-                            "Copy",
-                            None,
-                        );
-                    }
-                } else {
-                    // Try to find predicates on *generic params* that would allow copying `ty`
 
+                // Try to find predicates on *generic params* that would allow copying `ty`
                 let tcx = self.infcx.tcx;
                 let generics = tcx.generics_of(self.mir_def_id());
                 if let Some(hir_generics) = tcx
@@ -342,10 +321,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                                     match predicate.self_ty().kind() {
                                         ty::Param(param_ty) => Ok((
                                             generics.type_param(param_ty, tcx),
-                                                predicate
-                                                    .trait_ref
-                                                    .print_only_trait_path()
-                                                    .to_string(),
+                                            predicate.trait_ref.print_only_trait_path().to_string(),
                                         )),
                                         _ => Err(()),
                                     }
@@ -366,7 +342,6 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                         );
                     }
                 }
-                }
 
                 let span = if let Some(local) = place.as_local() {
                     let decl = &self.body.local_decls[local];

compiler/rustc_borrowck/src/lib.rs

@@ -178,7 +178,7 @@ fn do_mir_borrowck<'a, 'tcx>(
 
     // Gather the upvars of a closure, if any.
     let tables = tcx.typeck_opt_const_arg(def);
-    if let Some(ErrorGuaranteed) = tables.tainted_by_errors {
+    if let Some(ErrorGuaranteed { .. }) = tables.tainted_by_errors {
         infcx.set_tainted_by_errors();
         errors.set_tainted_by_errors();
     }
@@ -2274,6 +2274,8 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
 }
 
 mod error {
+    use rustc_errors::ErrorGuaranteed;
+
     use super::*;
 
     pub struct BorrowckErrors<'tcx> {
@@ -2311,7 +2313,7 @@ mod error {
         // FIXME(eddyb) this is a suboptimal API because `tainted_by_errors` is
         // set before any emission actually happens (weakening the guarantee).
         pub fn buffer_error(&mut self, t: DiagnosticBuilder<'_, ErrorGuaranteed>) {
-            self.tainted_by_errors = Some(ErrorGuaranteed {});
+            self.tainted_by_errors = Some(ErrorGuaranteed::unchecked_claim_error_was_emitted());
             t.buffer(&mut self.buffered);
         }
 
@@ -2320,7 +2322,7 @@ mod error {
         }
 
         pub fn set_tainted_by_errors(&mut self) {
-            self.tainted_by_errors = Some(ErrorGuaranteed {});
+            self.tainted_by_errors = Some(ErrorGuaranteed::unchecked_claim_error_was_emitted());
         }
     }
 

compiler/rustc_codegen_cranelift/src/constant.rs

@@ -1,7 +1,6 @@
 //! Handling of `static`s, `const`s and promoted allocations
 
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
-use rustc_errors::ErrorGuaranteed;
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use rustc_middle::mir::interpret::{
     read_target_uint, AllocId, ConstAllocation, ConstValue, ErrorHandled, GlobalAlloc, Scalar,
@@ -54,7 +53,7 @@ pub(crate) fn check_constants(fx: &mut FunctionCx<'_, '_, '_>) -> bool {
                 {
                     all_constants_ok = false;
                     match err {
-                        ErrorHandled::Reported(ErrorGuaranteed) | ErrorHandled::Linted => {
+                        ErrorHandled::Reported(_) | ErrorHandled::Linted => {
                             fx.tcx.sess.span_err(constant.span, "erroneous constant encountered");
                         }
                         ErrorHandled::TooGeneric => {

compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs

@@ -74,9 +74,30 @@ fn push_debuginfo_type_name<'tcx>(
         ty::Float(float_ty) => output.push_str(float_ty.name_str()),
         ty::Foreign(def_id) => push_item_name(tcx, def_id, qualified, output),
         ty::Adt(def, substs) => {
-            let ty_and_layout = tcx.layout_of(ParamEnv::reveal_all().and(t)).expect("layout error");
+            // `layout_for_cpp_like_fallback` will be `Some` if we want to use the fallback encoding.
+            let layout_for_cpp_like_fallback = if cpp_like_debuginfo && def.is_enum() {
+                match tcx.layout_of(ParamEnv::reveal_all().and(t)) {
+                    Ok(layout) => {
+                        if !wants_c_like_enum_debuginfo(layout) {
+                            Some(layout)
+                        } else {
+                            // This is a C-like enum so we don't want to use the fallback encoding
+                            // for the name.
+                            None
+                        }
+                    }
+                    Err(e) => {
+                        // Computing the layout can still fail here, e.g. if the target architecture
+                        // cannot represent the type. See https://github.com/rust-lang/rust/issues/94961.
+                        tcx.sess.fatal(&format!("{}", e));
+                    }
+                }
+            } else {
+                // We are not emitting cpp-like debuginfo or this isn't even an enum.
+                None
+            };
 
-            if def.is_enum() && cpp_like_debuginfo && !wants_c_like_enum_debuginfo(ty_and_layout) {
+            if let Some(ty_and_layout) = layout_for_cpp_like_fallback {
                 msvc_enum_fallback(
                     tcx,
                     ty_and_layout,

compiler/rustc_codegen_ssa/src/mir/mod.rs

@@ -1,5 +1,4 @@
 use crate::traits::*;
-use rustc_errors::ErrorGuaranteed;
 use rustc_middle::mir;
 use rustc_middle::mir::interpret::ErrorHandled;
 use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt, TyAndLayout};
@@ -191,7 +190,7 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
             all_consts_ok = false;
             match err {
                 // errored or at least linted
-                ErrorHandled::Reported(ErrorGuaranteed) | ErrorHandled::Linted => {}
+                ErrorHandled::Reported(_) | ErrorHandled::Linted => {}
                 ErrorHandled::TooGeneric => {
                     span_bug!(const_.span, "codgen encountered polymorphic constant: {:?}", err)
                 }

compiler/rustc_codegen_ssa/src/target_features.rs

@@ -148,7 +148,7 @@ const AARCH64_TIED_FEATURES: &[&[&str]] = &[
 ];
 
 const X86_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
-    ("adx", Some(sym::adx_target_feature)),
+    ("adx", None),
     ("aes", None),
     ("avx", None),
     ("avx2", None),

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),

compiler/rustc_driver/src/lib.rs

@@ -235,7 +235,7 @@ fn run_compiler(
     };
 
     match make_input(config.opts.error_format, &matches.free) {
-        Err(ErrorGuaranteed) => return Err(ErrorGuaranteed),
+        Err(reported) => return Err(reported),
         Ok(Some((input, input_file_path))) => {
             config.input = input;
             config.input_path = input_file_path;
@@ -465,11 +465,11 @@ fn make_input(
             if io::stdin().read_to_string(&mut src).is_err() {
                 // Immediately stop compilation if there was an issue reading
                 // the input (for example if the input stream is not UTF-8).
-                early_error_no_abort(
+                let reported = early_error_no_abort(
                     error_format,
                     "couldn't read from stdin, as it did not contain valid UTF-8",
                 );
-                return Err(ErrorGuaranteed);
+                return Err(reported);
             }
             if let Ok(path) = env::var("UNSTABLE_RUSTDOC_TEST_PATH") {
                 let line = env::var("UNSTABLE_RUSTDOC_TEST_LINE").expect(
@@ -1128,7 +1128,7 @@ fn extra_compiler_flags() -> Option<(Vec<String>, bool)> {
 pub fn catch_fatal_errors<F: FnOnce() -> R, R>(f: F) -> Result<R, ErrorGuaranteed> {
     catch_unwind(panic::AssertUnwindSafe(f)).map_err(|value| {
         if value.is::<rustc_errors::FatalErrorMarker>() {
-            ErrorGuaranteed
+            ErrorGuaranteed::unchecked_claim_error_was_emitted()
         } else {
             panic::resume_unwind(value);
         }

compiler/rustc_errors/src/diagnostic_builder.rs

@@ -128,7 +128,7 @@ impl EmissionGuarantee for ErrorGuaranteed {
             DiagnosticBuilderState::Emittable(handler) => {
                 db.inner.state = DiagnosticBuilderState::AlreadyEmittedOrDuringCancellation;
 
-                handler.emit_diagnostic(&db.inner.diagnostic);
+                let guar = handler.emit_diagnostic(&db.inner.diagnostic);
 
                 // Only allow a guarantee if the `level` wasn't switched to a
                 // non-error - the field isn't `pub`, but the whole `Diagnostic`
@@ -139,7 +139,7 @@ impl EmissionGuarantee for ErrorGuaranteed {
                      from `DiagnosticBuilder<ErrorGuaranteed>`",
                     db.inner.diagnostic.level,
                 );
-                ErrorGuaranteed
+                guar.unwrap()
             }
             // `.emit()` was previously called, disallowed from repeating it,
             // but can take advantage of the previous `.emit()`'s guarantee
@@ -154,7 +154,7 @@ impl EmissionGuarantee for ErrorGuaranteed {
                      became non-error ({:?}), after original `.emit()`",
                     db.inner.diagnostic.level,
                 );
-                ErrorGuaranteed
+                ErrorGuaranteed::unchecked_claim_error_was_emitted()
             }
         }
     }

compiler/rustc_errors/src/lib.rs

@@ -399,7 +399,7 @@ impl fmt::Display for ExplicitBug {
 impl error::Error for ExplicitBug {}
 
 pub use diagnostic::{Diagnostic, DiagnosticId, DiagnosticStyledString, SubDiagnostic};
-pub use diagnostic_builder::DiagnosticBuilder;
+pub use diagnostic_builder::{DiagnosticBuilder, EmissionGuarantee};
 use std::backtrace::Backtrace;
 
 /// A handler deals with errors and other compiler output.
@@ -644,8 +644,8 @@ impl Handler {
     }
 
     /// Emit all stashed diagnostics.
-    pub fn emit_stashed_diagnostics(&self) {
-        self.inner.borrow_mut().emit_stashed_diagnostics();
+    pub fn emit_stashed_diagnostics(&self) -> Option<ErrorGuaranteed> {
+        self.inner.borrow_mut().emit_stashed_diagnostics()
     }
 
     /// Construct a builder at the `Warning` level at the given `span` and with the `msg`.
@@ -805,8 +805,8 @@ impl Handler {
         FatalError.raise()
     }
 
-    pub fn span_err(&self, span: impl Into<MultiSpan>, msg: &str) {
-        self.emit_diag_at_span(Diagnostic::new(Error { lint: false }, msg), span);
+    pub fn span_err(&self, span: impl Into<MultiSpan>, msg: &str) -> ErrorGuaranteed {
+        self.emit_diag_at_span(Diagnostic::new(Error { lint: false }, msg), span).unwrap()
     }
 
     pub fn span_err_with_code(&self, span: impl Into<MultiSpan>, msg: &str, code: DiagnosticId) {
@@ -829,7 +829,7 @@ impl Handler {
     }
 
     #[track_caller]
-    pub fn delay_span_bug(&self, span: impl Into<MultiSpan>, msg: &str) {
+    pub fn delay_span_bug(&self, span: impl Into<MultiSpan>, msg: &str) -> ErrorGuaranteed {
         self.inner.borrow_mut().delay_span_bug(span, msg)
     }
 
@@ -858,8 +858,8 @@ impl Handler {
         self.inner.borrow_mut().fatal(msg)
     }
 
-    pub fn err(&self, msg: &str) {
-        self.inner.borrow_mut().err(msg);
+    pub fn err(&self, msg: &str) -> ErrorGuaranteed {
+        self.inner.borrow_mut().err(msg)
     }
 
     pub fn warn(&self, msg: &str) {
@@ -880,11 +880,15 @@ impl Handler {
         self.inner.borrow().err_count()
     }
 
-    pub fn has_errors(&self) -> bool {
-        self.inner.borrow().has_errors()
+    pub fn has_errors(&self) -> Option<ErrorGuaranteed> {
+        if self.inner.borrow().has_errors() { Some(ErrorGuaranteed(())) } else { None }
+    }
+    pub fn has_errors_or_lint_errors(&self) -> Option<ErrorGuaranteed> {
+        if self.inner.borrow().has_errors_or_lint_errors() {
+            Some(ErrorGuaranteed(()))
+        } else {
+            None
         }
-    pub fn has_errors_or_lint_errors(&self) -> bool {
-        self.inner.borrow().has_errors_or_lint_errors()
     }
     pub fn has_errors_or_delayed_span_bugs(&self) -> bool {
         self.inner.borrow().has_errors_or_delayed_span_bugs()
@@ -915,13 +919,17 @@ impl Handler {
         self.inner.borrow_mut().force_print_diagnostic(db)
     }
 
-    pub fn emit_diagnostic(&self, diagnostic: &Diagnostic) {
+    pub fn emit_diagnostic(&self, diagnostic: &Diagnostic) -> Option<ErrorGuaranteed> {
         self.inner.borrow_mut().emit_diagnostic(diagnostic)
     }
 
-    fn emit_diag_at_span(&self, mut diag: Diagnostic, sp: impl Into<MultiSpan>) {
+    fn emit_diag_at_span(
+        &self,
+        mut diag: Diagnostic,
+        sp: impl Into<MultiSpan>,
+    ) -> Option<ErrorGuaranteed> {
         let mut inner = self.inner.borrow_mut();
-        inner.emit_diagnostic(diag.set_span(sp));
+        inner.emit_diagnostic(diag.set_span(sp))
     }
 
     pub fn emit_artifact_notification(&self, path: &Path, artifact_type: &str) {
@@ -990,13 +998,20 @@ impl HandlerInner {
     }
 
     /// Emit all stashed diagnostics.
-    fn emit_stashed_diagnostics(&mut self) {
+    fn emit_stashed_diagnostics(&mut self) -> Option<ErrorGuaranteed> {
         let diags = self.stashed_diagnostics.drain(..).map(|x| x.1).collect::<Vec<_>>();
-        diags.iter().for_each(|diag| self.emit_diagnostic(diag));
+        let mut reported = None;
+        diags.iter().for_each(|diag| {
+            if diag.is_error() {
+                reported = Some(ErrorGuaranteed(()));
+            }
+            self.emit_diagnostic(diag);
+        });
+        reported
     }
 
     // FIXME(eddyb) this should ideally take `diagnostic` by value.
-    fn emit_diagnostic(&mut self, diagnostic: &Diagnostic) {
+    fn emit_diagnostic(&mut self, diagnostic: &Diagnostic) -> Option<ErrorGuaranteed> {
         if diagnostic.level == Level::DelayedBug {
             // FIXME(eddyb) this should check for `has_errors` and stop pushing
             // once *any* errors were emitted (and truncate `delayed_span_bugs`
@@ -1005,7 +1020,7 @@ impl HandlerInner {
             self.delayed_span_bugs.push(diagnostic.clone());
 
             if !self.flags.report_delayed_bugs {
-                return;
+                return Some(ErrorGuaranteed::unchecked_claim_error_was_emitted());
             }
         }
 
@@ -1020,7 +1035,7 @@ impl HandlerInner {
             if diagnostic.has_future_breakage() {
                 (*TRACK_DIAGNOSTICS)(diagnostic);
             }
-            return;
+            return None;
         }
 
         // The `LintExpectationId` can be stable or unstable depending on when it was created.
@@ -1029,16 +1044,16 @@ impl HandlerInner {
         // a stable one by the `LintLevelsBuilder`.
         if let Level::Expect(LintExpectationId::Unstable { .. }) = diagnostic.level {
             self.unstable_expect_diagnostics.push(diagnostic.clone());
-            return;
+            return None;
         }
 
         (*TRACK_DIAGNOSTICS)(diagnostic);
 
         if let Level::Expect(expectation_id) = diagnostic.level {
             self.fulfilled_expectations.insert(expectation_id);
-            return;
+            return None;
         } else if diagnostic.level == Allow {
-            return;
+            return None;
         }
 
         if let Some(ref code) = diagnostic.code {
@@ -1068,8 +1083,12 @@ impl HandlerInner {
             } else {
                 self.bump_err_count();
             }
+
+            Some(ErrorGuaranteed::unchecked_claim_error_was_emitted())
         } else {
             self.bump_warn_count();
+
+            None
         }
     }
 
@@ -1191,7 +1210,7 @@ impl HandlerInner {
     }
 
     #[track_caller]
-    fn delay_span_bug(&mut self, sp: impl Into<MultiSpan>, msg: &str) {
+    fn delay_span_bug(&mut self, sp: impl Into<MultiSpan>, msg: &str) -> ErrorGuaranteed {
         // This is technically `self.treat_err_as_bug()` but `delay_span_bug` is called before
         // incrementing `err_count` by one, so we need to +1 the comparing.
         // FIXME: Would be nice to increment err_count in a more coherent way.
@@ -1202,7 +1221,7 @@ impl HandlerInner {
         let mut diagnostic = Diagnostic::new(Level::DelayedBug, msg);
         diagnostic.set_span(sp.into());
         diagnostic.note(&format!("delayed at {}", std::panic::Location::caller()));
-        self.emit_diagnostic(&diagnostic)
+        self.emit_diagnostic(&diagnostic).unwrap()
     }
 
     // FIXME(eddyb) note the comment inside `impl Drop for HandlerInner`, that's
@@ -1221,20 +1240,20 @@ impl HandlerInner {
     }
 
     fn fatal(&mut self, msg: &str) -> FatalError {
-        self.emit_error(Fatal, msg);
+        self.emit(Fatal, msg);
         FatalError
     }
 
-    fn err(&mut self, msg: &str) {
-        self.emit_error(Error { lint: false }, msg);
+    fn err(&mut self, msg: &str) -> ErrorGuaranteed {
+        self.emit(Error { lint: false }, msg)
     }
 
     /// Emit an error; level should be `Error` or `Fatal`.
-    fn emit_error(&mut self, level: Level, msg: &str) {
+    fn emit(&mut self, level: Level, msg: &str) -> ErrorGuaranteed {
         if self.treat_err_as_bug() {
             self.bug(msg);
         }
-        self.emit_diagnostic(&Diagnostic::new(level, msg));
+        self.emit_diagnostic(&Diagnostic::new(level, msg)).unwrap()
     }
 
     fn bug(&mut self, msg: &str) -> ! {
@@ -1433,9 +1452,17 @@ pub fn add_elided_lifetime_in_path_suggestion(
     );
 }
 
-// Useful type to use with `Result<>` indicate that an error has already
-// been reported to the user, so no need to continue checking.
-#[derive(Clone, Copy, Debug, Encodable, Decodable, Hash, PartialEq, Eq)]
-pub struct ErrorGuaranteed;
+/// Useful type to use with `Result<>` indicate that an error has already
+/// been reported to the user, so no need to continue checking.
+#[derive(Clone, Copy, Debug, Encodable, Decodable, Hash, PartialEq, Eq, PartialOrd, Ord)]
+pub struct ErrorGuaranteed(());
+
+impl ErrorGuaranteed {
+    /// To be used only if you really know what you are doing... ideally, we would find a way to
+    /// eliminate all calls to this method.
+    pub fn unchecked_claim_error_was_emitted() -> Self {
+        ErrorGuaranteed(())
+    }
+}
 
 rustc_data_structures::impl_stable_hash_via_hash!(ErrorGuaranteed);

compiler/rustc_expand/src/base.rs

@@ -1330,7 +1330,7 @@ pub fn parse_macro_name_and_helper_attrs(
     let attributes_attr = list.get(1);
     let proc_attrs: Vec<_> = if let Some(attr) = attributes_attr {
         if !attr.has_name(sym::attributes) {
-            diag.span_err(attr.span(), "second argument must be `attributes`")
+            diag.span_err(attr.span(), "second argument must be `attributes`");
         }
         attr.meta_item_list()
             .unwrap_or_else(|| {

compiler/rustc_expand/src/mbe/macro_rules.rs

@@ -534,10 +534,10 @@ pub fn compile_declarative_macro(
     let (transparency, transparency_error) = attr::find_transparency(&def.attrs, macro_rules);
     match transparency_error {
         Some(TransparencyError::UnknownTransparency(value, span)) => {
-            diag.span_err(span, &format!("unknown macro transparency: `{}`", value))
+            diag.span_err(span, &format!("unknown macro transparency: `{}`", value));
         }
         Some(TransparencyError::MultipleTransparencyAttrs(old_span, new_span)) => {
-            diag.span_err(vec![old_span, new_span], "multiple macro transparency attributes")
+            diag.span_err(vec![old_span, new_span], "multiple macro transparency attributes");
         }
         None => {}
     }
@@ -617,7 +617,9 @@ fn check_lhs_no_empty_seq(sess: &ParseSess, tts: &[mbe::TokenTree]) -> bool {
 fn check_rhs(sess: &ParseSess, rhs: &mbe::TokenTree) -> bool {
     match *rhs {
         mbe::TokenTree::Delimited(..) => return true,
-        _ => sess.span_diagnostic.span_err(rhs.span(), "macro rhs must be delimited"),
+        _ => {
+            sess.span_diagnostic.span_err(rhs.span(), "macro rhs must be delimited");
+        }
     }
     false
 }

compiler/rustc_expand/src/proc_macro.rs

@@ -31,8 +31,7 @@ impl base::ProcMacro for BangProcMacro {
             if let Some(s) = e.as_str() {
                 err.help(&format!("message: {}", s));
             }
-            err.emit();
-            ErrorGuaranteed
+            err.emit()
         })
     }
 }
@@ -58,8 +57,7 @@ impl base::AttrProcMacro for AttrProcMacro {
                 if let Some(s) = e.as_str() {
                     err.help(&format!("message: {}", s));
                 }
-                err.emit();
-                ErrorGuaranteed
+                err.emit()
             })
     }
 }

compiler/rustc_feature/src/accepted.rs

@@ -51,6 +51,8 @@ declare_features! (
     /// Allows the sysV64 ABI to be specified on all platforms
     /// instead of just the platforms on which it is the C ABI.
     (accepted, abi_sysv64, "1.24.0", Some(36167), None),
+    /// Allows using ADX intrinsics from `core::arch::{x86, x86_64}`.
+    (accepted, adx_target_feature, "1.61.0", Some(44839), None),
     /// Allows the definition of associated constants in `trait` or `impl` blocks.
     (accepted, associated_consts, "1.20.0", Some(29646), None),
     /// Allows using associated `type`s in `trait`s.

compiler/rustc_feature/src/active.rs

@@ -364,6 +364,8 @@ declare_features! (
     (active, default_alloc_error_handler, "1.48.0", Some(66741), None),
     /// Allows default type parameters to influence type inference.
     (active, default_type_parameter_fallback, "1.3.0", Some(27336), None),
+    /// Allows using `#[deprecated_safe]` to deprecate the safeness of a function or trait
+    (active, deprecated_safe, "1.61.0", Some(94978), None),
     /// Allows having using `suggestion` in the `#[deprecated]` attribute.
     (active, deprecated_suggestion, "1.61.0", Some(94785), None),
     /// Allows `#[derive(Default)]` and `#[default]` on enums.

compiler/rustc_feature/src/builtin_attrs.rs

@@ -452,6 +452,11 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
         "`default_method_body_is_const` is a temporary placeholder for declaring default bodies \
         as `const`, which may be removed or renamed in the future."
     ),
+    // lang-team MCP 147
+    gated!(
+        deprecated_safe, Normal, template!(List: r#"since = "version", note = "...""#), ErrorFollowing,
+        experimental!(deprecated_safe),
+    ),
 
     // ==========================================================================
     // Internal attributes: Stability, deprecation, and unsafe:

compiler/rustc_incremental/src/persist/fs.rs

@@ -225,12 +225,12 @@ pub fn prepare_session_directory(
     let crate_dir = match crate_dir.canonicalize() {
         Ok(v) => v,
         Err(err) => {
-            sess.err(&format!(
+            let reported = sess.err(&format!(
                 "incremental compilation: error canonicalizing path `{}`: {}",
                 crate_dir.display(),
                 err
             ));
-            return Err(ErrorGuaranteed);
+            return Err(reported);
         }
     };
 
@@ -489,14 +489,14 @@ fn create_dir(sess: &Session, path: &Path, dir_tag: &str) -> Result<(), ErrorGua
             Ok(())
         }
         Err(err) => {
-            sess.err(&format!(
+            let reported = sess.err(&format!(
                 "Could not create incremental compilation {} \
                                directory `{}`: {}",
                 dir_tag,
                 path.display(),
                 err
             ));
-            Err(ErrorGuaranteed)
+            Err(reported)
         }
     }
 }
@@ -545,8 +545,7 @@ fn lock_directory(
                     );
                 }
             }
-            err.emit();
-            Err(ErrorGuaranteed)
+            Err(err.emit())
         }
     }
 }

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(

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)
     }
 }

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())

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)
     }
 }
 

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()
     }
 }
 

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),
-                )
+                );
             }
         }
     }

compiler/rustc_interface/src/passes.rs

@@ -373,7 +373,7 @@ pub fn configure_and_expand(
         if recursion_limit_hit {
             // If we hit a recursion limit, exit early to avoid later passes getting overwhelmed
             // with a large AST
-            Err(ErrorGuaranteed)
+            Err(ErrorGuaranteed::unchecked_claim_error_was_emitted())
         } else {
             Ok(krate)
         }
@@ -413,7 +413,7 @@ pub fn configure_and_expand(
         );
 
         msg.warn("The generated documentation may be incorrect");
-        msg.emit()
+        msg.emit();
     } else {
         krate = sess.time("maybe_create_a_macro_crate", || {
             let is_test_crate = sess.opts.test;
@@ -742,29 +742,30 @@ pub fn prepare_outputs(
     if let Some(ref input_path) = compiler.input_path {
         if sess.opts.will_create_output_file() {
             if output_contains_path(&output_paths, input_path) {
-                sess.err(&format!(
+                let reported = sess.err(&format!(
                     "the input file \"{}\" would be overwritten by the generated \
                         executable",
                     input_path.display()
                 ));
-                return Err(ErrorGuaranteed);
+                return Err(reported);
             }
             if let Some(dir_path) = output_conflicts_with_dir(&output_paths) {
-                sess.err(&format!(
+                let reported = sess.err(&format!(
                     "the generated executable for the input file \"{}\" conflicts with the \
                         existing directory \"{}\"",
                     input_path.display(),
                     dir_path.display()
                 ));
-                return Err(ErrorGuaranteed);
+                return Err(reported);
             }
         }
     }
 
     if let Some(ref dir) = compiler.temps_dir {
         if fs::create_dir_all(dir).is_err() {
+            let reported =
                 sess.err("failed to find or create the directory specified by `--temps-dir`");
-            return Err(ErrorGuaranteed);
+            return Err(reported);
         }
     }
 
@@ -776,8 +777,9 @@ pub fn prepare_outputs(
     if !only_dep_info {
         if let Some(ref dir) = compiler.output_dir {
             if fs::create_dir_all(dir).is_err() {
+                let reported =
                     sess.err("failed to find or create the directory specified by `--out-dir`");
-                return Err(ErrorGuaranteed);
+                return Err(reported);
             }
         }
     }
@@ -987,8 +989,8 @@ fn analysis(tcx: TyCtxt<'_>, (): ()) -> Result<()> {
     // lot of annoying errors in the ui tests (basically,
     // lint warnings and so on -- kindck used to do this abort, but
     // kindck is gone now). -nmatsakis
-    if sess.has_errors() {
-        return Err(ErrorGuaranteed);
+    if let Some(reported) = sess.has_errors() {
+        return Err(reported);
     }
 
     sess.time("misc_checking_3", || {

compiler/rustc_interface/src/queries.rs

@@ -5,7 +5,6 @@ use rustc_ast as ast;
 use rustc_codegen_ssa::traits::CodegenBackend;
 use rustc_data_structures::svh::Svh;
 use rustc_data_structures::sync::{Lrc, OnceCell, WorkerLocal};
-use rustc_errors::ErrorGuaranteed;
 use rustc_hir::def_id::LOCAL_CRATE;
 use rustc_incremental::DepGraphFuture;
 use rustc_lint::LintStore;
@@ -121,10 +120,8 @@ impl<'tcx> Queries<'tcx> {
 
     pub fn parse(&self) -> Result<&Query<ast::Crate>> {
         self.parse.compute(|| {
-            passes::parse(self.session(), &self.compiler.input).map_err(|mut parse_error| {
-                parse_error.emit();
-                ErrorGuaranteed
-            })
+            passes::parse(self.session(), &self.compiler.input)
+                .map_err(|mut parse_error| parse_error.emit())
         })
     }
 

compiler/rustc_lint/src/builtin.rs

@@ -157,7 +157,7 @@ impl BoxPointers {
             if let GenericArgKind::Type(leaf_ty) = leaf.unpack() {
                 if leaf_ty.is_box() {
                     cx.struct_span_lint(BOX_POINTERS, span, |lint| {
-                        lint.build(&format!("type uses owned (Box type) pointers: {}", ty)).emit()
+                        lint.build(&format!("type uses owned (Box type) pointers: {}", ty)).emit();
                     });
                 }
             }
@@ -318,7 +318,7 @@ impl UnsafeCode {
         &self,
         cx: &EarlyContext<'_>,
         span: Span,
-        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
+        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
     ) {
         // This comes from a macro that has `#[allow_internal_unsafe]`.
         if span.allows_unsafe() {
@@ -350,7 +350,7 @@ impl EarlyLintPass for UnsafeCode {
                                                macros using unsafe without triggering \
                                                the `unsafe_code` lint at their call site",
                 )
-                .emit()
+                .emit();
             });
         }
     }
@@ -360,7 +360,7 @@ impl EarlyLintPass for UnsafeCode {
             // Don't warn about generated blocks; that'll just pollute the output.
             if blk.rules == ast::BlockCheckMode::Unsafe(ast::UserProvided) {
                 self.report_unsafe(cx, blk.span, |lint| {
-                    lint.build("usage of an `unsafe` block").emit()
+                    lint.build("usage of an `unsafe` block").emit();
                 });
             }
         }
@@ -370,12 +370,12 @@ impl EarlyLintPass for UnsafeCode {
         match it.kind {
             ast::ItemKind::Trait(box ast::Trait { unsafety: ast::Unsafe::Yes(_), .. }) => self
                 .report_unsafe(cx, it.span, |lint| {
-                    lint.build("declaration of an `unsafe` trait").emit()
+                    lint.build("declaration of an `unsafe` trait").emit();
                 }),
 
             ast::ItemKind::Impl(box ast::Impl { unsafety: ast::Unsafe::Yes(_), .. }) => self
                 .report_unsafe(cx, it.span, |lint| {
-                    lint.build("implementation of an `unsafe` trait").emit()
+                    lint.build("implementation of an `unsafe` trait").emit();
                 }),
 
             ast::ItemKind::Fn(..) => {
@@ -450,7 +450,9 @@ impl EarlyLintPass for UnsafeCode {
                 FnCtxt::Assoc(_) if body.is_none() => "declaration of an `unsafe` method",
                 FnCtxt::Assoc(_) => "implementation of an `unsafe` method",
             };
-            self.report_unsafe(cx, span, |lint| lint.build(msg).emit());
+            self.report_unsafe(cx, span, |lint| {
+                lint.build(msg).emit();
+            });
         }
     }
 }
@@ -559,7 +561,7 @@ impl MissingDoc {
                 MISSING_DOCS,
                 cx.tcx.sess.source_map().guess_head_span(sp),
                 |lint| {
-                    lint.build(&format!("missing documentation for {} {}", article, desc)).emit()
+                    lint.build(&format!("missing documentation for {} {}", article, desc)).emit();
                 },
             );
         }
@@ -777,7 +779,7 @@ impl<'tcx> LateLintPass<'tcx> for MissingCopyImplementations {
                     "type could implement `Copy`; consider adding `impl \
                           Copy`",
                 )
-                .emit()
+                .emit();
             })
         }
     }
@@ -858,7 +860,7 @@ impl<'tcx> LateLintPass<'tcx> for MissingDebugImplementations {
                      or a manual implementation",
                     cx.tcx.def_path_str(debug)
                 ))
-                .emit()
+                .emit();
             });
         }
     }
@@ -1278,7 +1280,9 @@ impl<'tcx> LateLintPass<'tcx> for MutableTransmutes {
             if to_mt == hir::Mutability::Mut && from_mt == hir::Mutability::Not {
                 let msg = "transmuting &T to &mut T is undefined behavior, \
                     even if the reference is unused, consider instead using an UnsafeCell";
-                cx.struct_span_lint(MUTABLE_TRANSMUTES, expr.span, |lint| lint.build(msg).emit());
+                cx.struct_span_lint(MUTABLE_TRANSMUTES, expr.span, |lint| {
+                    lint.build(msg).emit();
+                });
             }
         }
 
@@ -1328,7 +1332,7 @@ impl<'tcx> LateLintPass<'tcx> for UnstableFeatures {
             if let Some(items) = attr.meta_item_list() {
                 for item in items {
                     cx.struct_span_lint(UNSTABLE_FEATURES, item.span(), |lint| {
-                        lint.build("unstable feature").emit()
+                        lint.build("unstable feature").emit();
                     });
                 }
             }
@@ -1680,7 +1684,7 @@ impl<'tcx> LateLintPass<'tcx> for TrivialConstraints {
                                 or lifetime parameters",
                             predicate_kind_name, predicate
                         ))
-                        .emit()
+                        .emit();
                     });
                 }
             }
@@ -1915,7 +1919,7 @@ impl<'tcx> LateLintPass<'tcx> for UnnameableTestItems {
         let attrs = cx.tcx.hir().attrs(it.hir_id());
         if let Some(attr) = cx.sess().find_by_name(attrs, sym::rustc_test_marker) {
             cx.struct_span_lint(UNNAMEABLE_TEST_ITEMS, attr.span, |lint| {
-                lint.build("cannot test inner items").emit()
+                lint.build("cannot test inner items").emit();
             });
         }
     }
@@ -2040,7 +2044,7 @@ impl KeywordIdents {
                     format!("r#{}", ident),
                     Applicability::MachineApplicable,
                 )
-                .emit()
+                .emit();
         });
     }
 }
@@ -3055,7 +3059,7 @@ impl<'tcx> LateLintPass<'tcx> for ClashingExternDeclarations {
                                 "this signature doesn't match the previous declaration",
                             )
                             .note_expected_found(&"", expected_str, &"", found_str)
-                            .emit()
+                            .emit();
                         },
                     );
                 }

compiler/rustc_lint/src/context.rs

@@ -593,7 +593,7 @@ pub trait LintContext: Sized {
         &self,
         lint: &'static Lint,
         span: Option<impl Into<MultiSpan>>,
-        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
+        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
         diagnostic: BuiltinLintDiagnostics,
     ) {
         self.lookup(lint, span, |lint| {
@@ -840,19 +840,23 @@ pub trait LintContext: Sized {
         &self,
         lint: &'static Lint,
         span: Option<S>,
-        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
+        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
     );
 
     fn struct_span_lint<S: Into<MultiSpan>>(
         &self,
         lint: &'static Lint,
         span: S,
-        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
+        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
     ) {
         self.lookup(lint, Some(span), decorate);
     }
     /// Emit a lint at the appropriate level, with no associated span.
-    fn lint(&self, lint: &'static Lint, decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>)) {
+    fn lint(
+        &self,
+        lint: &'static Lint,
+        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
+    ) {
         self.lookup(lint, None as Option<Span>, decorate);
     }
 }
@@ -893,7 +897,7 @@ impl LintContext for LateContext<'_> {
         &self,
         lint: &'static Lint,
         span: Option<S>,
-        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
+        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
     ) {
         let hir_id = self.last_node_with_lint_attrs;
 
@@ -920,7 +924,7 @@ impl LintContext for EarlyContext<'_> {
         &self,
         lint: &'static Lint,
         span: Option<S>,
-        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
+        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
     ) {
         self.builder.struct_lint(lint, span.map(|s| s.into()), decorate)
     }

compiler/rustc_lint/src/early.rs

@@ -45,7 +45,9 @@ impl<'a, T: EarlyLintPass> EarlyContextAndPass<'a, T> {
             self.context.lookup_with_diagnostics(
                 lint_id.lint,
                 Some(span),
-                |lint| lint.build(&msg).emit(),
+                |lint| {
+                    lint.build(&msg).emit();
+                },
                 diagnostic,
             );
         }

compiler/rustc_lint/src/levels.rs

@@ -652,7 +652,7 @@ impl<'s> LintLevelsBuilder<'s> {
         &self,
         lint: &'static Lint,
         span: Option<MultiSpan>,
-        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
+        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
     ) {
         let (level, src) = self.lint_level(lint);
         struct_lint_level(self.sess, lint, level, src, span, decorate)

compiler/rustc_lint/src/non_ascii_idents.rs

@@ -180,13 +180,13 @@ impl EarlyLintPass for NonAsciiIdents {
             }
             has_non_ascii_idents = true;
             cx.struct_span_lint(NON_ASCII_IDENTS, sp, |lint| {
-                lint.build("identifier contains non-ASCII characters").emit()
+                lint.build("identifier contains non-ASCII characters").emit();
             });
             if check_uncommon_codepoints
                 && !symbol_str.chars().all(GeneralSecurityProfile::identifier_allowed)
             {
                 cx.struct_span_lint(UNCOMMON_CODEPOINTS, sp, |lint| {
-                    lint.build("identifier contains uncommon Unicode codepoints").emit()
+                    lint.build("identifier contains uncommon Unicode codepoints").emit();
                 })
             }
         }
@@ -337,7 +337,7 @@ impl EarlyLintPass for NonAsciiIdents {
                             let char_info = format!("'{}' (U+{:04X})", ch, ch as u32);
                             note += &char_info;
                         }
-                        lint.build(&message).note(&note).note("please recheck to make sure their usages are indeed what you want").emit()
+                        lint.build(&message).note(&note).note("please recheck to make sure their usages are indeed what you want").emit();
                     });
                 }
             }

compiler/rustc_lint/src/noop_method_call.rs

@@ -102,7 +102,7 @@ impl<'tcx> LateLintPass<'tcx> for NoopMethodCall {
             let method = &call.ident.name;
             let message =
                 format!("call to `.{}()` on a reference in this situation does nothing", &method,);
-            lint.build(&message).span_label(span, "unnecessary method call").note(&note).emit()
+            lint.build(&message).span_label(span, "unnecessary method call").note(&note).emit();
         });
     }
 }

compiler/rustc_lint/src/traits.rs

@@ -113,7 +113,7 @@ impl<'tcx> LateLintPass<'tcx> for DropTraitConstraints {
                         predicate,
                         cx.tcx.def_path_str(needs_drop)
                     );
-                    lint.build(&msg).emit()
+                    lint.build(&msg).emit();
                 });
             }
         }
@@ -135,7 +135,7 @@ impl<'tcx> LateLintPass<'tcx> for DropTraitConstraints {
                         instead using `{}` to detect whether a type is trivially dropped",
                         cx.tcx.def_path_str(needs_drop)
                     );
-                    lint.build(&msg).emit()
+                    lint.build(&msg).emit();
                 });
             }
         }

compiler/rustc_lint/src/types.rs

@@ -441,7 +441,7 @@ fn lint_uint_literal<'tcx>(
                     min,
                     max,
                 ))
-                .emit()
+                .emit();
         });
     }
 }
@@ -502,7 +502,7 @@ impl<'tcx> LateLintPass<'tcx> for TypeLimits {
             hir::ExprKind::Binary(binop, ref l, ref r) => {
                 if is_comparison(binop) && !check_limits(cx, binop, &l, &r) {
                     cx.struct_span_lint(UNUSED_COMPARISONS, e.span, |lint| {
-                        lint.build("comparison is useless due to type limits").emit()
+                        lint.build("comparison is useless due to type limits").emit();
                     });
                 }
             }
@@ -1382,7 +1382,7 @@ impl<'tcx> LateLintPass<'tcx> for VariantSizeDifferences {
                                           larger ({} bytes) than the next largest",
                             largest
                         ))
-                        .emit()
+                        .emit();
                     },
                 );
             }

compiler/rustc_lint/src/unused.rs

@@ -170,7 +170,7 @@ impl<'tcx> LateLintPass<'tcx> for UnusedResults {
 
         if !(type_permits_lack_of_use || fn_warned || op_warned) {
             cx.struct_span_lint(UNUSED_RESULTS, s.span, |lint| {
-                lint.build(&format!("unused result of type `{}`", ty)).emit()
+                lint.build(&format!("unused result of type `{}`", ty)).emit();
             });
         }
 
@@ -368,9 +368,9 @@ impl<'tcx> LateLintPass<'tcx> for PathStatements {
                         } else {
                             lint.span_help(s.span, "use `drop` to clarify the intent");
                         }
-                        lint.emit()
+                        lint.emit();
                     } else {
-                        lint.build("path statement with no effect").emit()
+                        lint.build("path statement with no effect").emit();
                     }
                 });
             }
@@ -1111,7 +1111,7 @@ impl UnusedImportBraces {
             };
 
             cx.struct_span_lint(UNUSED_IMPORT_BRACES, item.span, |lint| {
-                lint.build(&format!("braces around {} is unnecessary", node_name)).emit()
+                lint.build(&format!("braces around {} is unnecessary", node_name)).emit();
             });
         }
     }
@@ -1170,7 +1170,7 @@ impl<'tcx> LateLintPass<'tcx> for UnusedAllocation {
                             "unnecessary allocation, use `&mut` instead"
                         }
                     };
-                    lint.build(msg).emit()
+                    lint.build(msg).emit();
                 });
             }
         }

compiler/rustc_lint_defs/src/builtin.rs

@@ -3695,7 +3695,7 @@ declare_lint! {
     /// ### Explanation
     ///
     /// A duplicated attribute may erroneously originate from a copy-paste and the effect of it
-    /// being duplicated may not be obvious or desireable.
+    /// being duplicated may not be obvious or desirable.
     ///
     /// For instance, doubling the `#[test]` attributes registers the test to be run twice with no
     /// change to its environment.

compiler/rustc_metadata/src/creader.rs

@@ -825,11 +825,13 @@ impl<'a> CrateLoader<'a> {
         for (_, data) in self.cstore.iter_crate_data() {
             if data.has_global_allocator() {
                 match global_allocator {
-                    Some(other_crate) => self.sess.err(&format!(
+                    Some(other_crate) => {
+                        self.sess.err(&format!(
                         "the `#[global_allocator]` in {} conflicts with global allocator in: {}",
                         other_crate,
                         data.name()
-                    )),
+                    ));
+                    }
                     None => global_allocator = Some(data.name()),
                 }
             }
@@ -864,7 +866,7 @@ impl<'a> CrateLoader<'a> {
         // don't perform this validation if the session has errors, as one of
         // those errors may indicate a circular dependency which could cause
         // this to stack overflow.
-        if self.sess.has_errors() {
+        if self.sess.has_errors().is_some() {
             return;
         }
 

compiler/rustc_metadata/src/native_libs.rs

@@ -145,41 +145,49 @@ impl<'tcx> ItemLikeVisitor<'tcx> for Collector<'tcx> {
                             ("bundle", NativeLibKind::Static { bundle, .. }) => {
                                 *bundle = Some(value);
                             }
-                            ("bundle", _) => sess.span_err(
+                            ("bundle", _) => {
+                                sess.span_err(
                                     span,
                                     "bundle linking modifier is only compatible with \
                                 `static` linking kind",
-                            ),
+                                );
+                            }
 
                             ("verbatim", _) => lib.verbatim = Some(value),
 
                             ("whole-archive", NativeLibKind::Static { whole_archive, .. }) => {
                                 *whole_archive = Some(value);
                             }
-                            ("whole-archive", _) => sess.span_err(
+                            ("whole-archive", _) => {
+                                sess.span_err(
                                     span,
                                     "whole-archive linking modifier is only compatible with \
                                 `static` linking kind",
-                            ),
+                                );
+                            }
 
                             ("as-needed", NativeLibKind::Dylib { as_needed })
                             | ("as-needed", NativeLibKind::Framework { as_needed }) => {
                                 *as_needed = Some(value);
                             }
-                            ("as-needed", _) => sess.span_err(
+                            ("as-needed", _) => {
+                                sess.span_err(
                                     span,
                                     "as-needed linking modifier is only compatible with \
                                 `dylib` and `framework` linking kinds",
-                            ),
+                                );
+                            }
 
-                            _ => sess.span_err(
+                            _ => {
+                                sess.span_err(
                                     span,
                                     &format!(
                                         "unrecognized linking modifier `{}`, expected one \
                                     of: bundle, verbatim, whole-archive, as-needed",
                                         modifier
                                     ),
-                            ),
+                                );
+                            }
                         }
                     }
                 } else {
@@ -247,7 +255,9 @@ impl Collector<'_> {
                 Some(span) => {
                     struct_span_err!(self.tcx.sess, span, E0455, "{}", msg).emit();
                 }
-                None => self.tcx.sess.err(msg),
+                None => {
+                    self.tcx.sess.err(msg);
+                }
             }
         }
         if lib.cfg.is_some() && !self.tcx.features().link_cfg {

compiler/rustc_middle/src/lint.rs

@@ -2,7 +2,9 @@ use std::cmp;
 
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
-use rustc_errors::{Diagnostic, DiagnosticBuilder, DiagnosticId};
+use rustc_errors::{
+    Diagnostic, DiagnosticBuilder, DiagnosticId, EmissionGuarantee, ErrorGuaranteed,
+};
 use rustc_hir::HirId;
 use rustc_index::vec::IndexVec;
 use rustc_query_system::ich::StableHashingContext;
@@ -220,22 +222,28 @@ impl LintExpectation {
     }
 }
 
-pub struct LintDiagnosticBuilder<'a>(DiagnosticBuilder<'a, ()>);
+pub struct LintDiagnosticBuilder<'a, G: EmissionGuarantee>(DiagnosticBuilder<'a, G>);
 
-impl<'a> LintDiagnosticBuilder<'a> {
-    /// Return the inner DiagnosticBuilder, first setting the primary message to `msg`.
-    pub fn build(mut self, msg: &str) -> DiagnosticBuilder<'a, ()> {
+impl<'a, G: EmissionGuarantee> LintDiagnosticBuilder<'a, G> {
+    /// Return the inner `DiagnosticBuilder`, first setting the primary message to `msg`.
+    pub fn build(mut self, msg: &str) -> DiagnosticBuilder<'a, G> {
         self.0.set_primary_message(msg);
         self.0.set_is_lint();
         self.0
     }
 
-    /// Create a LintDiagnosticBuilder from some existing DiagnosticBuilder.
-    pub fn new(err: DiagnosticBuilder<'a, ()>) -> LintDiagnosticBuilder<'a> {
+    /// Create a `LintDiagnosticBuilder` from some existing `DiagnosticBuilder`.
+    pub fn new(err: DiagnosticBuilder<'a, G>) -> LintDiagnosticBuilder<'a, G> {
         LintDiagnosticBuilder(err)
     }
 }
 
+impl<'a> LintDiagnosticBuilder<'a, ErrorGuaranteed> {
+    pub fn forget_guarantee(self) -> LintDiagnosticBuilder<'a, ()> {
+        LintDiagnosticBuilder(self.0.forget_guarantee())
+    }
+}
+
 pub fn explain_lint_level_source(
     sess: &Session,
     lint: &'static Lint,
@@ -316,7 +324,7 @@ pub fn struct_lint_level<'s, 'd>(
     level: Level,
     src: LintLevelSource,
     span: Option<MultiSpan>,
-    decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>) + 'd,
+    decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>) + 'd,
 ) {
     // Avoid codegen bloat from monomorphization by immediately doing dyn dispatch of `decorate` to
     // the "real" work.
@@ -326,7 +334,7 @@ pub fn struct_lint_level<'s, 'd>(
         level: Level,
         src: LintLevelSource,
         span: Option<MultiSpan>,
-        decorate: Box<dyn for<'b> FnOnce(LintDiagnosticBuilder<'b>) + 'd>,
+        decorate: Box<dyn for<'b> FnOnce(LintDiagnosticBuilder<'b, ()>) + 'd>,
     ) {
         // Check for future incompatibility lints and issue a stronger warning.
         let future_incompatible = lint.future_incompatible;

compiler/rustc_middle/src/middle/stability.rs

@@ -258,7 +258,7 @@ fn late_report_deprecation(
             let kind = tcx.def_kind(def_id).descr(def_id);
             deprecation_suggestion(&mut diag, kind, suggestion, method_span);
         }
-        diag.emit()
+        diag.emit();
     });
 }
 
@@ -483,7 +483,7 @@ impl<'tcx> TyCtxt<'tcx> {
     ) {
         let soft_handler = |lint, span, msg: &_| {
             self.struct_span_lint_hir(lint, id.unwrap_or(hir::CRATE_HIR_ID), span, |lint| {
-                lint.build(msg).emit()
+                lint.build(msg).emit();
             })
         };
         match self.eval_stability(def_id, id, span, method_span) {

compiler/rustc_middle/src/mir/interpret/error.rs

@@ -91,7 +91,7 @@ fn print_backtrace(backtrace: &Backtrace) {
 impl From<ErrorHandled> for InterpErrorInfo<'_> {
     fn from(err: ErrorHandled) -> Self {
         match err {
-            ErrorHandled::Reported(ErrorGuaranteed) | ErrorHandled::Linted => {
+            ErrorHandled::Reported(ErrorGuaranteed { .. }) | ErrorHandled::Linted => {
                 err_inval!(ReferencedConstant)
             }
             ErrorHandled::TooGeneric => err_inval!(TooGeneric),
@@ -160,7 +160,7 @@ impl fmt::Display for InvalidProgramInfo<'_> {
         match self {
             TooGeneric => write!(f, "encountered overly generic constant"),
             ReferencedConstant => write!(f, "referenced constant has errors"),
-            AlreadyReported(ErrorGuaranteed) => {
+            AlreadyReported(ErrorGuaranteed { .. }) => {
                 write!(f, "encountered constants with type errors, stopping evaluation")
             }
             Layout(ref err) => write!(f, "{}", err),

compiler/rustc_middle/src/mir/interpret/pointer.rs

@@ -99,7 +99,7 @@ impl<T: HasDataLayout> PointerArithmetic for T {}
 /// mostly opaque; the `Machine` trait extends it with some more operations that also have access to
 /// some global state.
 /// We don't actually care about this `Debug` bound (we use `Provenance::fmt` to format the entire
-/// pointer), but `derive` adds some unecessary bounds.
+/// pointer), but `derive` adds some unnecessary bounds.
 pub trait Provenance: Copy + fmt::Debug {
     /// Says whether the `offset` field of `Pointer`s with this provenance is the actual physical address.
     /// If `true, ptr-to-int casts work by simply discarding the provenance.

compiler/rustc_middle/src/query/mod.rs

@@ -252,7 +252,9 @@ rustc_queries! {
     }
 
     /// Fetch the THIR for a given body. If typeck for that body failed, returns an empty `Thir`.
-    query thir_body(key: ty::WithOptConstParam<LocalDefId>) -> (&'tcx Steal<thir::Thir<'tcx>>, thir::ExprId) {
+    query thir_body(key: ty::WithOptConstParam<LocalDefId>)
+        -> Result<(&'tcx Steal<thir::Thir<'tcx>>, thir::ExprId), ErrorGuaranteed>
+    {
         // Perf tests revealed that hashing THIR is inefficient (see #85729).
         no_hash
         desc { |tcx| "building THIR for `{}`", tcx.def_path_str(key.did.to_def_id()) }

compiler/rustc_middle/src/traits/specialization_graph.rs

@@ -31,12 +31,12 @@ pub struct Graph {
     pub children: DefIdMap<Children>,
 
     /// Whether an error was emitted while constructing the graph.
-    pub has_errored: bool,
+    pub has_errored: Option<ErrorGuaranteed>,
 }
 
 impl Graph {
     pub fn new() -> Graph {
-        Graph { parent: Default::default(), children: Default::default(), has_errored: false }
+        Graph { parent: Default::default(), children: Default::default(), has_errored: None }
     }
 
     /// The parent of a given impl, which is the `DefId` of the trait when the
@@ -246,8 +246,10 @@ pub fn ancestors<'tcx>(
 ) -> Result<Ancestors<'tcx>, ErrorGuaranteed> {
     let specialization_graph = tcx.specialization_graph_of(trait_def_id);
 
-    if specialization_graph.has_errored || tcx.type_of(start_from_impl).references_error() {
-        Err(ErrorGuaranteed)
+    if let Some(reported) = specialization_graph.has_errored {
+        Err(reported)
+    } else if let Some(reported) = tcx.type_of(start_from_impl).error_reported() {
+        Err(reported)
     } else {
         Ok(Ancestors {
             trait_def_id,

compiler/rustc_middle/src/ty/adt.rs

@@ -7,7 +7,6 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::intern::Interned;
 use rustc_data_structures::stable_hasher::HashingControls;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
-use rustc_errors::ErrorGuaranteed;
 use rustc_hir as hir;
 use rustc_hir::def::{CtorKind, DefKind, Res};
 use rustc_hir::def_id::DefId;
@@ -453,7 +452,7 @@ impl<'tcx> AdtDef<'tcx> {
             }
             Err(err) => {
                 let msg = match err {
-                    ErrorHandled::Reported(ErrorGuaranteed) | ErrorHandled::Linted => {
+                    ErrorHandled::Reported(_) | ErrorHandled::Linted => {
                         "enum discriminant evaluation failed"
                     }
                     ErrorHandled::TooGeneric => "enum discriminant depends on generics",

compiler/rustc_middle/src/ty/consts.rs

@@ -264,7 +264,7 @@ impl<'tcx> Const<'tcx> {
         if let Some(val) = self.val().try_eval(tcx, param_env) {
             match val {
                 Ok(val) => Const::from_value(tcx, val, self.ty()),
-                Err(ErrorGuaranteed) => tcx.const_error(self.ty()),
+                Err(ErrorGuaranteed { .. }) => tcx.const_error(self.ty()),
             }
         } else {
             self

compiler/rustc_middle/src/ty/context.rs

@@ -91,7 +91,10 @@ pub trait OnDiskCache<'tcx>: rustc_data_structures::sync::Sync {
 /// except through the error-reporting functions on a [`tcx`][TyCtxt].
 #[derive(Copy, Clone, Debug, Eq, Hash, PartialEq, PartialOrd, Ord)]
 #[derive(TyEncodable, TyDecodable, HashStable)]
-pub struct DelaySpanBugEmitted(());
+pub struct DelaySpanBugEmitted {
+    pub reported: ErrorGuaranteed,
+    _priv: (),
+}
 
 type InternedSet<'tcx, T> = ShardedHashMap<InternedInSet<'tcx, T>, ()>;
 
@@ -1236,8 +1239,8 @@ impl<'tcx> TyCtxt<'tcx> {
     /// ensure it gets used.
     #[track_caller]
     pub fn ty_error_with_message<S: Into<MultiSpan>>(self, span: S, msg: &str) -> Ty<'tcx> {
-        self.sess.delay_span_bug(span, msg);
-        self.mk_ty(Error(DelaySpanBugEmitted(())))
+        let reported = self.sess.delay_span_bug(span, msg);
+        self.mk_ty(Error(DelaySpanBugEmitted { reported, _priv: () }))
     }
 
     /// Like [TyCtxt::ty_error] but for constants.
@@ -1258,8 +1261,11 @@ impl<'tcx> TyCtxt<'tcx> {
         span: S,
         msg: &str,
     ) -> Const<'tcx> {
-        self.sess.delay_span_bug(span, msg);
-        self.mk_const(ty::ConstS { val: ty::ConstKind::Error(DelaySpanBugEmitted(())), ty })
+        let reported = self.sess.delay_span_bug(span, msg);
+        self.mk_const(ty::ConstS {
+            val: ty::ConstKind::Error(DelaySpanBugEmitted { reported, _priv: () }),
+            ty,
+        })
     }
 
     pub fn consider_optimizing<T: Fn() -> String>(self, msg: T) -> bool {
@@ -2733,7 +2739,7 @@ impl<'tcx> TyCtxt<'tcx> {
         lint: &'static Lint,
         hir_id: HirId,
         span: impl Into<MultiSpan>,
-        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
+        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
     ) {
         let (level, src) = self.lint_level_at_node(lint, hir_id);
         struct_lint_level(self.sess, lint, level, src, Some(span.into()), decorate);
@@ -2743,7 +2749,7 @@ impl<'tcx> TyCtxt<'tcx> {
         self,
         lint: &'static Lint,
         id: HirId,
-        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
+        decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
     ) {
         let (level, src) = self.lint_level_at_node(lint, id);
         struct_lint_level(self.sess, lint, level, src, None, decorate);

compiler/rustc_middle/src/ty/fold.rs

@@ -51,6 +51,7 @@
 //! ```
 use crate::mir;
 use crate::ty::{self, flags::FlagComputation, Binder, Ty, TyCtxt, TypeFlags};
+use rustc_errors::ErrorGuaranteed;
 use rustc_hir::def_id::DefId;
 
 use rustc_data_structures::fx::FxHashSet;
@@ -151,6 +152,13 @@ pub trait TypeFoldable<'tcx>: fmt::Debug + Clone {
     fn references_error(&self) -> bool {
         self.has_type_flags(TypeFlags::HAS_ERROR)
     }
+    fn error_reported(&self) -> Option<ErrorGuaranteed> {
+        if self.references_error() {
+            Some(ErrorGuaranteed::unchecked_claim_error_was_emitted())
+        } else {
+            None
+        }
+    }
     fn has_param_types_or_consts(&self) -> bool {
         self.has_type_flags(TypeFlags::HAS_TY_PARAM | TypeFlags::HAS_CT_PARAM)
     }

compiler/rustc_middle/src/ty/query.rs

@@ -337,7 +337,7 @@ rustc_query_append! { [define_callbacks!][<'tcx>] }
 mod sealed {
     use super::{DefId, LocalDefId};
 
-    /// An analogue of the `Into` trait that's intended only for query paramaters.
+    /// An analogue of the `Into` trait that's intended only for query parameters.
     ///
     /// This exists to allow queries to accept either `DefId` or `LocalDefId` while requiring that the
     /// user call `to_def_id` to convert between them everywhere else.

compiler/rustc_middle/src/ty/subst.rs

@@ -61,7 +61,7 @@ pub fn ty_slice_as_generic_args<'a, 'tcx>(ts: &'a [Ty<'tcx>]) -> &'a [GenericArg
 }
 
 impl<'tcx> List<Ty<'tcx>> {
-    /// Allows to freely switch betwen `List<Ty<'tcx>>` and `List<GenericArg<'tcx>>`.
+    /// Allows to freely switch between `List<Ty<'tcx>>` and `List<GenericArg<'tcx>>`.
     ///
     /// As lists are interned, `List<Ty<'tcx>>` and `List<GenericArg<'tcx>>` have
     /// be interned together, see `intern_type_list` for more details.

compiler/rustc_middle/src/ty/util.rs

@@ -486,7 +486,7 @@ impl<'tcx> TyCtxt<'tcx> {
     }
 
     /// Given the `DefId`, returns the `DefId` of the innermost item that
-    /// has its own type-checking context or "inference enviornment".
+    /// has its own type-checking context or "inference environment".
     ///
     /// For example, a closure has its own `DefId`, but it is type-checked
     /// with the containing item. Similarly, an inline const block has its

compiler/rustc_mir_build/src/build/mod.rs

@@ -118,7 +118,9 @@ fn mir_build(tcx: TyCtxt<'_>, def: ty::WithOptConstParam<LocalDefId>) -> Body<'_
             };
 
             let body = tcx.hir().body(body_id);
-            let (thir, expr) = tcx.thir_body(def);
+            let (thir, expr) = tcx
+                .thir_body(def)
+                .unwrap_or_else(|_| (tcx.alloc_steal_thir(Thir::new()), ExprId::from_u32(0)));
             // We ran all queries that depended on THIR at the beginning
             // of `mir_build`, so now we can steal it
             let thir = thir.steal();
@@ -229,7 +231,9 @@ fn mir_build(tcx: TyCtxt<'_>, def: ty::WithOptConstParam<LocalDefId>) -> Body<'_
 
             let return_ty = typeck_results.node_type(id);
 
-            let (thir, expr) = tcx.thir_body(def);
+            let (thir, expr) = tcx
+                .thir_body(def)
+                .unwrap_or_else(|_| (tcx.alloc_steal_thir(Thir::new()), ExprId::from_u32(0)));
             // We ran all queries that depended on THIR at the beginning
             // of `mir_build`, so now we can steal it
             let thir = thir.steal();

compiler/rustc_mir_build/src/check_unsafety.rs

@@ -405,7 +405,9 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for UnsafetyVisitor<'a, 'tcx> {
                 } else {
                     ty::WithOptConstParam::unknown(closure_id)
                 };
-                let (closure_thir, expr) = self.tcx.thir_body(closure_def);
+                let (closure_thir, expr) = self.tcx.thir_body(closure_def).unwrap_or_else(|_| {
+                    (self.tcx.alloc_steal_thir(Thir::new()), ExprId::from_u32(0))
+                });
                 let closure_thir = &closure_thir.borrow();
                 let hir_context = self.tcx.hir().local_def_id_to_hir_id(closure_id);
                 let mut closure_visitor =
@@ -606,7 +608,10 @@ pub fn check_unsafety<'tcx>(tcx: TyCtxt<'tcx>, def: ty::WithOptConstParam<LocalD
         return;
     }
 
-    let (thir, expr) = tcx.thir_body(def);
+    let (thir, expr) = match tcx.thir_body(def) {
+        Ok(body) => body,
+        Err(_) => return,
+    };
     let thir = &thir.borrow();
     // If `thir` is empty, a type error occurred, skip this body.
     if thir.exprs.is_empty() {

compiler/rustc_mir_build/src/thir/cx/mod.rs

@@ -7,6 +7,7 @@ use crate::thir::util::UserAnnotatedTyHelpers;
 
 use rustc_ast as ast;
 use rustc_data_structures::steal::Steal;
+use rustc_errors::ErrorGuaranteed;
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::HirId;
@@ -20,22 +21,25 @@ use rustc_span::Span;
 crate fn thir_body<'tcx>(
     tcx: TyCtxt<'tcx>,
     owner_def: ty::WithOptConstParam<LocalDefId>,
-) -> (&'tcx Steal<Thir<'tcx>>, ExprId) {
+) -> Result<(&'tcx Steal<Thir<'tcx>>, ExprId), ErrorGuaranteed> {
     let hir = tcx.hir();
     let body = hir.body(hir.body_owned_by(hir.local_def_id_to_hir_id(owner_def.did)));
     let mut cx = Cx::new(tcx, owner_def);
-    if cx.typeck_results.tainted_by_errors.is_some() {
-        return (tcx.alloc_steal_thir(Thir::new()), ExprId::from_u32(0));
+    if let Some(reported) = cx.typeck_results.tainted_by_errors {
+        return Err(reported);
     }
     let expr = cx.mirror_expr(&body.value);
-    (tcx.alloc_steal_thir(cx.thir), expr)
+    Ok((tcx.alloc_steal_thir(cx.thir), expr))
 }
 
 crate fn thir_tree<'tcx>(
     tcx: TyCtxt<'tcx>,
     owner_def: ty::WithOptConstParam<LocalDefId>,
 ) -> String {
-    format!("{:#?}", thir_body(tcx, owner_def).0.steal())
+    match thir_body(tcx, owner_def) {
+        Ok((thir, _)) => format!("{:#?}", thir.steal()),
+        Err(_) => "error".into(),
+    }
 }
 
 struct Cx<'tcx> {

compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs

@@ -194,7 +194,9 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
                         lint::builtin::INDIRECT_STRUCTURAL_MATCH,
                         self.id,
                         self.span,
-                        |lint| lint.build(&msg).emit(),
+                        |lint| {
+                            lint.build(&msg).emit();
+                        },
                     );
                 } else {
                     debug!(
@@ -272,7 +274,9 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
                         lint::builtin::ILLEGAL_FLOATING_POINT_LITERAL_PATTERN,
                         id,
                         span,
-                        |lint| lint.build("floating-point types cannot be used in patterns").emit(),
+                        |lint| {
+                            lint.build("floating-point types cannot be used in patterns").emit();
+                        },
                     );
                 }
                 PatKind::Constant { value: cv }
@@ -284,7 +288,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
                 if self.include_lint_checks {
                     tcx.sess.span_err(span, msg);
                 } else {
-                    tcx.sess.delay_span_bug(span, msg)
+                    tcx.sess.delay_span_bug(span, msg);
                 }
                 PatKind::Wild
             }
@@ -301,7 +305,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
                 if self.include_lint_checks {
                     tcx.sess.span_err(self.span, &msg);
                 } else {
-                    tcx.sess.delay_span_bug(self.span, &msg)
+                    tcx.sess.delay_span_bug(self.span, &msg);
                 }
                 PatKind::Wild
             }
@@ -331,7 +335,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
                                 cv.ty(),
                                 cv.ty(),
                             );
-                            lint.build(&msg).emit()
+                            lint.build(&msg).emit();
                         },
                     );
                 }
@@ -356,7 +360,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
                 if self.include_lint_checks {
                     tcx.sess.span_err(span, &msg);
                 } else {
-                    tcx.sess.delay_span_bug(span, &msg)
+                    tcx.sess.delay_span_bug(span, &msg);
                 }
                 PatKind::Wild
             }
@@ -393,7 +397,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
                     if self.include_lint_checks {
                         tcx.sess.span_err(span, &msg);
                     } else {
-                        tcx.sess.delay_span_bug(span, &msg)
+                        tcx.sess.delay_span_bug(span, &msg);
                     }
                     PatKind::Wild
                 }
@@ -471,7 +475,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
                                 lint::builtin::INDIRECT_STRUCTURAL_MATCH,
                                 self.id,
                                 self.span,
-                                |lint| lint.build(&msg).emit(),
+                                |lint| {lint.build(&msg).emit();},
                             );
                         }
                         PatKind::Constant { value: cv }
@@ -482,7 +486,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
                             if self.include_lint_checks {
                                 tcx.sess.span_err(span, &msg);
                             } else {
-                                tcx.sess.delay_span_bug(span, &msg)
+                                tcx.sess.delay_span_bug(span, &msg);
                             }
                         }
                         PatKind::Wild
@@ -523,7 +527,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
             ty::RawPtr(pointee) if pointee.ty.is_sized(tcx.at(span), param_env) => {
                 PatKind::Constant { value: cv }
             }
-            // FIXME: these can have very suprising behaviour where optimization levels or other
+            // FIXME: these can have very surprising behaviour where optimization levels or other
             // compilation choices change the runtime behaviour of the match.
             // See https://github.com/rust-lang/rust/issues/70861 for examples.
             ty::FnPtr(..) | ty::RawPtr(..) => {
@@ -539,7 +543,9 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
                         lint::builtin::POINTER_STRUCTURAL_MATCH,
                         id,
                         span,
-                        |lint| lint.build(&msg).emit(),
+                        |lint| {
+                            lint.build(&msg).emit();
+                        },
                     );
                 }
                 PatKind::Constant { value: cv }
@@ -550,7 +556,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
                 if self.include_lint_checks {
                     tcx.sess.span_err(span, &msg);
                 } else {
-                    tcx.sess.delay_span_bug(span, &msg)
+                    tcx.sess.delay_span_bug(span, &msg);
                 }
                 PatKind::Wild
             }
@@ -575,7 +581,9 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
                 lint::builtin::NONTRIVIAL_STRUCTURAL_MATCH,
                 id,
                 span,
-                |lint| lint.build(&msg).emit(),
+                |lint| {
+                    lint.build(&msg).emit();
+                },
             );
         }
 

compiler/rustc_mir_transform/src/check_const_item_mutation.rs

@@ -64,7 +64,7 @@ impl<'tcx> ConstMutationChecker<'_, 'tcx> {
         place: &Place<'tcx>,
         const_item: DefId,
         location: Location,
-        decorate: impl for<'b> FnOnce(LintDiagnosticBuilder<'b>) -> DiagnosticBuilder<'b, ()>,
+        decorate: impl for<'b> FnOnce(LintDiagnosticBuilder<'b, ()>) -> DiagnosticBuilder<'b, ()>,
     ) {
         // Don't lint on borrowing/assigning when a dereference is involved.
         // If we 'leave' the temporary via a dereference, we must
@@ -88,7 +88,7 @@ impl<'tcx> ConstMutationChecker<'_, 'tcx> {
                 |lint| {
                     decorate(lint)
                         .span_note(self.tcx.def_span(const_item), "`const` item defined here")
-                        .emit()
+                        .emit();
                 },
             );
         }

compiler/rustc_mir_transform/src/check_packed_ref.rs

@@ -46,7 +46,7 @@ fn unsafe_derive_on_repr_packed(tcx: TyCtxt<'_>, def_id: LocalDefId) {
              does not derive Copy (error E0133)"
                 .to_string()
         };
-        lint.build(&message).emit()
+        lint.build(&message).emit();
     });
 }
 
@@ -110,7 +110,7 @@ impl<'tcx> Visitor<'tcx> for PackedRefChecker<'_, 'tcx> {
                                     reference with a raw pointer and use `read_unaligned`/`write_unaligned` \
                                     (loads and stores via `*p` must be properly aligned even when using raw pointers)"
                                 )
-                                .emit()
+                                .emit();
                         },
                     );
                 }

compiler/rustc_mir_transform/src/check_unsafety.rs

@@ -156,7 +156,7 @@ impl<'tcx> Visitor<'tcx> for UnsafetyChecker<'_, 'tcx> {
         // temporary holding the static pointer to avoid duplicate errors
         // <https://github.com/rust-lang/rust/pull/78068#issuecomment-731753506>.
         if decl.internal && place.projection.first() == Some(&ProjectionElem::Deref) {
-            // If the projection root is an artifical local that we introduced when
+            // If the projection root is an artificial local that we introduced when
             // desugaring `static`, give a more specific error message
             // (avoid the general "raw pointer" clause below, that would only be confusing).
             if let Some(box LocalInfo::StaticRef { def_id, .. }) = decl.local_info {

compiler/rustc_mir_transform/src/const_debuginfo.rs

@@ -60,7 +60,7 @@ fn find_optimization_oportunities<'tcx>(body: &Body<'tcx>) -> Vec<(Local, Consta
         }
     }
 
-    let mut eligable_locals = Vec::new();
+    let mut eligible_locals = Vec::new();
     for (local, mutating_uses) in visitor.local_mutating_uses.drain_enumerated(..) {
         if mutating_uses != 1 || !locals_to_debuginfo.contains(local) {
             continue;
@@ -78,13 +78,13 @@ fn find_optimization_oportunities<'tcx>(body: &Body<'tcx>) -> Vec<(Local, Consta
                 &bb.statements[location.statement_index].kind
             {
                 if let Some(local) = p.as_local() {
-                    eligable_locals.push((local, *c));
+                    eligible_locals.push((local, *c));
                 }
             }
         }
     }
 
-    eligable_locals
+    eligible_locals
 }
 
 impl Visitor<'_> for LocalUseVisitor {

compiler/rustc_mir_transform/src/const_prop.rs

@@ -538,7 +538,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
             self.tcx.struct_span_lint_hir(lint, lint_root, source_info.span, |lint| {
                 let mut err = lint.build(message);
                 err.span_label(source_info.span, format!("{:?}", panic));
-                err.emit()
+                err.emit();
             });
         }
     }

compiler/rustc_mir_transform/src/early_otherwise_branch.rs

@@ -359,7 +359,7 @@ fn verify_candidate_branch<'tcx>(
     if branch.statements.len() != 1 {
         return false;
     }
-    // ...assign the descriminant of `place` in that statement
+    // ...assign the discriminant of `place` in that statement
     let StatementKind::Assign(boxed) = &branch.statements[0].kind else {
         return false
     };

compiler/rustc_mir_transform/src/simplify_try.rs

@@ -362,7 +362,7 @@ fn optimization_applies<'tcx>(
         return false;
     } else if last_assigned_to != opt_info.local_tmp_s1 {
         trace!(
-            "NO: end of assignemnt chain does not match written enum temp: {:?} != {:?}",
+            "NO: end of assignment chain does not match written enum temp: {:?} != {:?}",
             last_assigned_to,
             opt_info.local_tmp_s1
         );

compiler/rustc_monomorphize/src/collector.rs

@@ -180,7 +180,7 @@
 
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::sync::{par_iter, MTLock, MTRef, ParallelIterator};
-use rustc_errors::{ErrorGuaranteed, FatalError};
+use rustc_errors::FatalError;
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, DefIdMap, LocalDefId, LOCAL_CRATE};
 use rustc_hir::itemlikevisit::ItemLikeVisitor;
@@ -716,9 +716,7 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirNeighborCollector<'a, 'tcx> {
                     match self.tcx.const_eval_resolve(param_env, ct, None) {
                         // The `monomorphize` call should have evaluated that constant already.
                         Ok(val) => val,
-                        Err(ErrorHandled::Reported(ErrorGuaranteed) | ErrorHandled::Linted) => {
-                            return;
-                        }
+                        Err(ErrorHandled::Reported(_) | ErrorHandled::Linted) => return,
                         Err(ErrorHandled::TooGeneric) => span_bug!(
                             self.body.source_info(location).span,
                             "collection encountered polymorphic constant: {:?}",
@@ -750,7 +748,7 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirNeighborCollector<'a, 'tcx> {
                         substituted_constant,
                         val
                     ),
-                    Err(ErrorHandled::Reported(ErrorGuaranteed) | ErrorHandled::Linted) => {}
+                    Err(ErrorHandled::Reported(_) | ErrorHandled::Linted) => {}
                     Err(ErrorHandled::TooGeneric) => span_bug!(
                         self.body.source_info(location).span,
                         "collection encountered polymorphic constant: {}",
@@ -864,7 +862,7 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirNeighborCollector<'a, 'tcx> {
                     |lint| {
                         let mut err = lint.build(&format!("moving {} bytes", layout.size.bytes()));
                         err.span_label(source_info.span, "value moved from here");
-                        err.emit()
+                        err.emit();
                     },
                 );
             }

compiler/rustc_parse/src/lexer/unescape_error_reporting.rs

@@ -202,7 +202,7 @@ pub(crate) fn emit_unescape_error(
             diag.emit();
         }
         EscapeError::TooShortHexEscape => {
-            handler.span_err(span, "numeric character escape is too short")
+            handler.span_err(span, "numeric character escape is too short");
         }
         EscapeError::InvalidCharInHexEscape | EscapeError::InvalidCharInUnicodeEscape => {
             let (c, span) = last_char();

compiler/rustc_parse/src/parser/attr.rs

@@ -151,7 +151,7 @@ impl<'a> Parser<'a> {
         span: Span,
         attr_type: OuterAttributeType,
     ) -> Option<Span> {
-        let mut snapshot = self.clone();
+        let mut snapshot = self.create_snapshot_for_diagnostic();
         let lo = span.lo()
             + BytePos(match attr_type {
                 OuterAttributeType::Attribute => 1,

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -5,6 +5,7 @@ use super::{
     SemiColonMode, SeqSep, TokenExpectType, TokenType,
 };
 
+use crate::lexer::UnmatchedBrace;
 use rustc_ast as ast;
 use rustc_ast::ptr::P;
 use rustc_ast::token::{self, Lit, LitKind, TokenKind};
@@ -21,6 +22,7 @@ use rustc_errors::{Applicability, DiagnosticBuilder, Handler, PResult};
 use rustc_span::source_map::Spanned;
 use rustc_span::symbol::{kw, Ident};
 use rustc_span::{MultiSpan, Span, SpanSnippetError, DUMMY_SP};
+use std::ops::{Deref, DerefMut};
 
 use std::mem::take;
 
@@ -154,6 +156,28 @@ impl AttemptLocalParseRecovery {
     }
 }
 
+// SnapshotParser is used to create a snapshot of the parser
+// without causing duplicate errors being emitted when the `Parser`
+// is dropped.
+pub(super) struct SnapshotParser<'a> {
+    parser: Parser<'a>,
+    unclosed_delims: Vec<UnmatchedBrace>,
+}
+
+impl<'a> Deref for SnapshotParser<'a> {
+    type Target = Parser<'a>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.parser
+    }
+}
+
+impl<'a> DerefMut for SnapshotParser<'a> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.parser
+    }
+}
+
 impl<'a> Parser<'a> {
     pub(super) fn span_err<S: Into<MultiSpan>>(
         &self,
@@ -179,6 +203,25 @@ impl<'a> Parser<'a> {
         &self.sess.span_diagnostic
     }
 
+    /// Relace `self` with `snapshot.parser` and extend `unclosed_delims` with `snapshot.unclosed_delims`.
+    /// This is to avoid losing unclosed delims errors `create_snapshot_for_diagnostic` clears.
+    pub(super) fn restore_snapshot(&mut self, snapshot: SnapshotParser<'a>) {
+        *self = snapshot.parser;
+        self.unclosed_delims.extend(snapshot.unclosed_delims.clone());
+    }
+
+    /// Create a snapshot of the `Parser`.
+    pub(super) fn create_snapshot_for_diagnostic(&self) -> SnapshotParser<'a> {
+        let mut snapshot = self.clone();
+        let unclosed_delims = self.unclosed_delims.clone();
+        // Clear `unclosed_delims` in snapshot to avoid
+        // duplicate errors being emitted when the `Parser`
+        // is dropped (which may or may not happen, depending
+        // if the parsing the snapshot is created for is successful)
+        snapshot.unclosed_delims.clear();
+        SnapshotParser { parser: snapshot, unclosed_delims }
+    }
+
     pub(super) fn span_to_snippet(&self, span: Span) -> Result<String, SpanSnippetError> {
         self.sess.source_map().span_to_snippet(span)
     }
@@ -438,7 +481,7 @@ impl<'a> Parser<'a> {
             // fn foo() -> Foo {
             //     field: value,
             // }
-            let mut snapshot = self.clone();
+            let mut snapshot = self.create_snapshot_for_diagnostic();
             let path =
                 Path { segments: vec![], span: self.prev_token.span.shrink_to_lo(), tokens: None };
             let struct_expr = snapshot.parse_struct_expr(None, path, AttrVec::new(), false);
@@ -464,7 +507,7 @@ impl<'a> Parser<'a> {
                             Applicability::MaybeIncorrect,
                         )
                         .emit();
-                    *self = snapshot;
+                    self.restore_snapshot(snapshot);
                     let mut tail = self.mk_block(
                         vec![self.mk_stmt_err(expr.span)],
                         s,
@@ -678,7 +721,7 @@ impl<'a> Parser<'a> {
     /// angle brackets.
     pub(super) fn check_turbofish_missing_angle_brackets(&mut self, segment: &mut PathSegment) {
         if token::ModSep == self.token.kind && segment.args.is_none() {
-            let snapshot = self.clone();
+            let snapshot = self.create_snapshot_for_diagnostic();
             self.bump();
             let lo = self.token.span;
             match self.parse_angle_args(None) {
@@ -712,14 +755,14 @@ impl<'a> Parser<'a> {
                         .emit();
                     } else {
                         // This doesn't look like an invalid turbofish, can't recover parse state.
-                        *self = snapshot;
+                        self.restore_snapshot(snapshot);
                     }
                 }
                 Err(err) => {
                     // We couldn't parse generic parameters, unlikely to be a turbofish. Rely on
                     // generic parse error instead.
                     err.cancel();
-                    *self = snapshot;
+                    self.restore_snapshot(snapshot);
                 }
             }
         }
@@ -825,7 +868,7 @@ impl<'a> Parser<'a> {
                 // `x == y < z`
                 (BinOpKind::Eq, AssocOp::Less | AssocOp::LessEqual | AssocOp::Greater | AssocOp::GreaterEqual) => {
                     // Consume `z`/outer-op-rhs.
-                    let snapshot = self.clone();
+                    let snapshot = self.create_snapshot_for_diagnostic();
                     match self.parse_expr() {
                         Ok(r2) => {
                             // We are sure that outer-op-rhs could be consumed, the suggestion is
@@ -835,14 +878,14 @@ impl<'a> Parser<'a> {
                         }
                         Err(expr_err) => {
                             expr_err.cancel();
-                            *self = snapshot;
+                            self.restore_snapshot(snapshot);
                             false
                         }
                     }
                 }
                 // `x > y == z`
                 (BinOpKind::Lt | BinOpKind::Le | BinOpKind::Gt | BinOpKind::Ge, AssocOp::Equal) => {
-                    let snapshot = self.clone();
+                    let snapshot = self.create_snapshot_for_diagnostic();
                     // At this point it is always valid to enclose the lhs in parentheses, no
                     // further checks are necessary.
                     match self.parse_expr() {
@@ -852,7 +895,7 @@ impl<'a> Parser<'a> {
                         }
                         Err(expr_err) => {
                             expr_err.cancel();
-                            *self = snapshot;
+                            self.restore_snapshot(snapshot);
                             false
                         }
                     }
@@ -917,7 +960,7 @@ impl<'a> Parser<'a> {
                     || outer_op.node == AssocOp::Greater
                 {
                     if outer_op.node == AssocOp::Less {
-                        let snapshot = self.clone();
+                        let snapshot = self.create_snapshot_for_diagnostic();
                         self.bump();
                         // So far we have parsed `foo<bar<`, consume the rest of the type args.
                         let modifiers =
@@ -929,7 +972,7 @@ impl<'a> Parser<'a> {
                         {
                             // We don't have `foo< bar >(` or `foo< bar >::`, so we rewind the
                             // parser and bail out.
-                            *self = snapshot.clone();
+                            self.restore_snapshot(snapshot);
                         }
                     }
                     return if token::ModSep == self.token.kind {
@@ -937,7 +980,7 @@ impl<'a> Parser<'a> {
                         // `foo< bar >::`
                         suggest(&mut err);
 
-                        let snapshot = self.clone();
+                        let snapshot = self.create_snapshot_for_diagnostic();
                         self.bump(); // `::`
 
                         // Consume the rest of the likely `foo<bar>::new()` or return at `foo<bar>`.
@@ -954,7 +997,7 @@ impl<'a> Parser<'a> {
                                 expr_err.cancel();
                                 // Not entirely sure now, but we bubble the error up with the
                                 // suggestion.
-                                *self = snapshot;
+                                self.restore_snapshot(snapshot);
                                 Err(err)
                             }
                         }
@@ -1008,7 +1051,7 @@ impl<'a> Parser<'a> {
     }
 
     fn consume_fn_args(&mut self) -> Result<(), ()> {
-        let snapshot = self.clone();
+        let snapshot = self.create_snapshot_for_diagnostic();
         self.bump(); // `(`
 
         // Consume the fn call arguments.
@@ -1018,7 +1061,7 @@ impl<'a> Parser<'a> {
 
         if self.token.kind == token::Eof {
             // Not entirely sure that what we consumed were fn arguments, rollback.
-            *self = snapshot;
+            self.restore_snapshot(snapshot);
             Err(())
         } else {
             // 99% certain that the suggestion is correct, continue parsing.
@@ -1959,12 +2002,12 @@ impl<'a> Parser<'a> {
     }
 
     fn recover_const_param_decl(&mut self, ty_generics: Option<&Generics>) -> Option<GenericArg> {
-        let snapshot = self.clone();
+        let snapshot = self.create_snapshot_for_diagnostic();
         let param = match self.parse_const_param(vec![]) {
             Ok(param) => param,
             Err(err) => {
                 err.cancel();
-                *self = snapshot;
+                self.restore_snapshot(snapshot);
                 return None;
             }
         };
@@ -2056,7 +2099,7 @@ impl<'a> Parser<'a> {
             // We perform these checks and early return to avoid taking a snapshot unnecessarily.
             return Err(err);
         }
-        let snapshot = self.clone();
+        let snapshot = self.create_snapshot_for_diagnostic();
         if is_op_or_dot {
             self.bump();
         }
@@ -2101,7 +2144,7 @@ impl<'a> Parser<'a> {
                 err.cancel();
             }
         }
-        *self = snapshot;
+        self.restore_snapshot(snapshot);
         Err(err)
     }
 
@@ -2161,7 +2204,7 @@ impl<'a> Parser<'a> {
         let span = self.token.span;
         // We only emit "unexpected `:`" error here if we can successfully parse the
         // whole pattern correctly in that case.
-        let snapshot = self.clone();
+        let snapshot = self.create_snapshot_for_diagnostic();
 
         // Create error for "unexpected `:`".
         match self.expected_one_of_not_found(&[], &[]) {
@@ -2173,7 +2216,7 @@ impl<'a> Parser<'a> {
                         // reasonable error.
                         inner_err.cancel();
                         err.cancel();
-                        *self = snapshot;
+                        self.restore_snapshot(snapshot);
                     }
                     Ok(mut pat) => {
                         // We've parsed the rest of the pattern.
@@ -2252,7 +2295,7 @@ impl<'a> Parser<'a> {
             }
             _ => {
                 // Carry on as if we had not done anything. This should be unreachable.
-                *self = snapshot;
+                self.restore_snapshot(snapshot);
             }
         };
         first_pat

compiler/rustc_parse/src/parser/expr.rs

@@ -703,7 +703,7 @@ impl<'a> Parser<'a> {
                         ExprKind::Path(None, ast::Path { segments, .. }),
                         TokenKind::Ident(kw::For | kw::Loop | kw::While, false),
                     ) if segments.len() == 1 => {
-                        let snapshot = self.clone();
+                        let snapshot = self.create_snapshot_for_diagnostic();
                         let label = Label {
                             ident: Ident::from_str_and_span(
                                 &format!("'{}", segments[0].ident),
@@ -725,7 +725,7 @@ impl<'a> Parser<'a> {
                             }
                             Err(err) => {
                                 err.cancel();
-                                *self = snapshot;
+                                self.restore_snapshot(snapshot);
                             }
                         }
                     }
@@ -1885,7 +1885,7 @@ impl<'a> Parser<'a> {
         lo: Span,
         attrs: AttrVec,
     ) -> Option<P<Expr>> {
-        let mut snapshot = self.clone();
+        let mut snapshot = self.create_snapshot_for_diagnostic();
         match snapshot.parse_array_or_repeat_expr(attrs, token::Brace) {
             Ok(arr) => {
                 let hi = snapshot.prev_token.span;
@@ -1901,7 +1901,7 @@ impl<'a> Parser<'a> {
                 .note("to define an array, one would use square brackets instead of curly braces")
                 .emit();
 
-                *self = snapshot;
+                self.restore_snapshot(snapshot);
                 Some(self.mk_expr_err(arr.span))
             }
             Err(e) => {
@@ -2369,7 +2369,7 @@ impl<'a> Parser<'a> {
         if self.token.kind != token::Semi {
             return None;
         }
-        let start_snapshot = self.clone();
+        let start_snapshot = self.create_snapshot_for_diagnostic();
         let semi_sp = self.token.span;
         self.bump(); // `;`
         let mut stmts =
@@ -2417,15 +2417,15 @@ impl<'a> Parser<'a> {
                 return Some(err(self, stmts));
             }
             if self.token.kind == token::Comma {
-                *self = start_snapshot;
+                self.restore_snapshot(start_snapshot);
                 return None;
             }
-            let pre_pat_snapshot = self.clone();
+            let pre_pat_snapshot = self.create_snapshot_for_diagnostic();
             match self.parse_pat_no_top_alt(None) {
                 Ok(_pat) => {
                     if self.token.kind == token::FatArrow {
                         // Reached arm end.
-                        *self = pre_pat_snapshot;
+                        self.restore_snapshot(pre_pat_snapshot);
                         return Some(err(self, stmts));
                     }
                 }
@@ -2434,21 +2434,21 @@ impl<'a> Parser<'a> {
                 }
             }
 
-            *self = pre_pat_snapshot;
+            self.restore_snapshot(pre_pat_snapshot);
             match self.parse_stmt_without_recovery(true, ForceCollect::No) {
                 // Consume statements for as long as possible.
                 Ok(Some(stmt)) => {
                     stmts.push(stmt);
                 }
                 Ok(None) => {
-                    *self = start_snapshot;
+                    self.restore_snapshot(start_snapshot);
                     break;
                 }
                 // We couldn't parse either yet another statement missing it's
                 // enclosing block nor the next arm's pattern or closing brace.
                 Err(stmt_err) => {
                     stmt_err.cancel();
-                    *self = start_snapshot;
+                    self.restore_snapshot(start_snapshot);
                     break;
                 }
             }

compiler/rustc_parse/src/parser/item.rs

@@ -212,10 +212,10 @@ impl<'a> Parser<'a> {
             if let Err(mut e) = self.expect_semi() {
                 match tree.kind {
                     UseTreeKind::Glob => {
-                        e.note("the wildcard token must be last on the path").emit();
+                        e.note("the wildcard token must be last on the path");
                     }
                     UseTreeKind::Nested(..) => {
-                        e.note("glob-like brace syntax must be last on the path").emit();
+                        e.note("glob-like brace syntax must be last on the path");
                     }
                     _ => (),
                 }
@@ -999,11 +999,33 @@ impl<'a> Parser<'a> {
         attrs: &mut Vec<Attribute>,
         unsafety: Unsafe,
     ) -> PResult<'a, ItemInfo> {
+        let sp_start = self.prev_token.span;
         let abi = self.parse_abi(); // ABI?
-        let items = self.parse_item_list(attrs, |p| p.parse_foreign_item(ForceCollect::No))?;
+        match self.parse_item_list(attrs, |p| p.parse_foreign_item(ForceCollect::No)) {
+            Ok(items) => {
                 let module = ast::ForeignMod { unsafety, abi, items };
                 Ok((Ident::empty(), ItemKind::ForeignMod(module)))
             }
+            Err(mut err) => {
+                let current_qual_sp = self.prev_token.span;
+                let current_qual_sp = current_qual_sp.to(sp_start);
+                if let Ok(current_qual) = self.span_to_snippet(current_qual_sp) {
+                    if err.message() == "expected `{`, found keyword `unsafe`" {
+                        let invalid_qual_sp = self.token.uninterpolated_span();
+                        let invalid_qual = self.span_to_snippet(invalid_qual_sp).unwrap();
+
+                        err.span_suggestion(
+                                current_qual_sp.to(invalid_qual_sp),
+                                &format!("`{}` must come before `{}`", invalid_qual, current_qual),
+                                format!("{} {}", invalid_qual, current_qual),
+                                Applicability::MachineApplicable,
+                            ).note("keyword order for functions declaration is `default`, `pub`, `const`, `async`, `unsafe`, `extern`");
+                    }
+                }
+                Err(err)
+            }
+        }
+    }
 
     /// Parses a foreign item (one in an `extern { ... }` block).
     pub fn parse_foreign_item(
@@ -1485,7 +1507,7 @@ impl<'a> Parser<'a> {
                     // Make sure an error was emitted (either by recovering an angle bracket,
                     // or by finding an identifier as the next token), since we're
                     // going to continue parsing
-                    assert!(self.sess.span_diagnostic.has_errors());
+                    assert!(self.sess.span_diagnostic.has_errors().is_some());
                 } else {
                     return Err(err);
                 }
@@ -1948,7 +1970,7 @@ impl<'a> Parser<'a> {
         // We use an over-approximation here.
         // `const const`, `fn const` won't parse, but we're not stepping over other syntax either.
         // `pub` is added in case users got confused with the ordering like `async pub fn`,
-        // only if it wasn't preceeded by `default` as `default pub` is invalid.
+        // only if it wasn't preceded by `default` as `default pub` is invalid.
         let quals: &[Symbol] = if check_pub {
             &[kw::Pub, kw::Const, kw::Async, kw::Unsafe, kw::Extern]
         } else {

compiler/rustc_parse/src/parser/path.rs

@@ -624,9 +624,18 @@ impl<'a> Parser<'a> {
             GenericArg::Const(self.parse_const_arg()?)
         } else if self.check_type() {
             // Parse type argument.
+            let is_const_fn = self.look_ahead(1, |t| t.kind == token::OpenDelim(token::Paren));
+            let mut snapshot = self.create_snapshot_for_diagnostic();
             match self.parse_ty() {
                 Ok(ty) => GenericArg::Type(ty),
                 Err(err) => {
+                    if is_const_fn {
+                        if let Ok(expr) = (*snapshot).parse_expr_res(Restrictions::CONST_EXPR, None)
+                        {
+                            self.restore_snapshot(snapshot);
+                            return Ok(Some(self.dummy_const_arg_needs_braces(err, expr.span)));
+                        }
+                    }
                     // Try to recover from possible `const` arg without braces.
                     return self.recover_const_arg(start, err).map(Some);
                 }
@@ -636,7 +645,7 @@ impl<'a> Parser<'a> {
         } else {
             // Fall back by trying to parse a const-expr expression. If we successfully do so,
             // then we should report an error that it needs to be wrapped in braces.
-            let snapshot = self.clone();
+            let snapshot = self.create_snapshot_for_diagnostic();
             match self.parse_expr_res(Restrictions::CONST_EXPR, None) {
                 Ok(expr) => {
                     return Ok(Some(self.dummy_const_arg_needs_braces(
@@ -645,7 +654,7 @@ impl<'a> Parser<'a> {
                     )));
                 }
                 Err(err) => {
-                    *self = snapshot;
+                    self.restore_snapshot(snapshot);
                     err.cancel();
                     return Ok(None);
                 }

compiler/rustc_passes/src/check_attr.rs

@@ -169,7 +169,7 @@ impl CheckAttrVisitor<'_> {
                             }
                             ast::AttrStyle::Inner => "crate-level attribute should be in the root module",
                         };
-                        lint.build(msg).emit()
+                        lint.build(msg).emit();
                     });
                 }
             }
@@ -236,7 +236,7 @@ impl CheckAttrVisitor<'_> {
             | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
             Target::Method(MethodKind::Trait { body: false }) | Target::ForeignFn => {
                 self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| {
-                    lint.build("`#[inline]` is ignored on function prototypes").emit()
+                    lint.build("`#[inline]` is ignored on function prototypes").emit();
                 });
                 true
             }

compiler/rustc_passes/src/liveness.rs

@@ -1588,7 +1588,7 @@ impl<'tcx> Liveness<'_, 'tcx> {
                                 shorthands,
                                 Applicability::MachineApplicable,
                             );
-                            err.emit()
+                            err.emit();
                         },
                     );
                 } else {
@@ -1611,7 +1611,7 @@ impl<'tcx> Liveness<'_, 'tcx> {
                                 non_shorthands,
                                 Applicability::MachineApplicable,
                             );
-                            err.emit()
+                            err.emit();
                         },
                     );
                 }

compiler/rustc_passes/src/stability.rs

@@ -128,7 +128,7 @@ impl<'a, 'tcx> Annotator<'a, 'tcx> {
                             String::new(),
                             rustc_errors::Applicability::MachineApplicable,
                         )
-                        .emit()
+                        .emit();
                 });
             }
 
@@ -728,10 +728,10 @@ impl<'tcx> Visitor<'tcx> for Checker<'tcx> {
                                 INEFFECTIVE_UNSTABLE_TRAIT_IMPL,
                                 item.hir_id(),
                                 span,
-                                |lint| lint
+                                |lint| {lint
                                     .build("an `#[unstable]` annotation here has no effect")
                                     .note("see issue #55436 <https://github.com/rust-lang/rust/issues/55436> for more information")
-                                    .emit()
+                                    .emit();}
                             );
                         }
                     }

compiler/rustc_privacy/src/lib.rs

@@ -1742,7 +1742,7 @@ impl SearchInterfaceForPrivateItemsVisitor<'_> {
                         descr,
                         self.tcx.crate_name(def_id.krate)
                     ))
-                    .emit()
+                    .emit();
                 },
             );
         }
@@ -1786,7 +1786,9 @@ impl SearchInterfaceForPrivateItemsVisitor<'_> {
                     lint::builtin::PRIVATE_IN_PUBLIC,
                     hir_id,
                     span,
-                    |lint| lint.build(&format!("{} (error {})", make_msg(), err_code)).emit(),
+                    |lint| {
+                        lint.build(&format!("{} (error {})", make_msg(), err_code)).emit();
+                    },
                 );
             }
         }

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -1997,7 +1997,7 @@ impl<'tcx> LifetimeContext<'_, 'tcx> {
                     Vec::new(),
                     &[],
                 );
-                db.emit()
+                db.emit();
             },
         );
     }

compiler/rustc_resolve/src/late/lifetimes.rs

@@ -2002,7 +2002,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
                                     if !matches!(opaque.origin, hir::OpaqueTyOrigin::AsyncFn(..)) {
                                         continue 'lifetimes;
                                     }
-                                    // We want to do this only if the liftime identifier is already defined
+                                    // We want to do this only if the lifetime identifier is already defined
                                     // in the async function that generated this. Otherwise it could be
                                     // an opaque type defined by the developer and we still want this
                                     // lint to fail compilation
@@ -3143,10 +3143,12 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
             for bound in lifetime_i.bounds {
                 match bound {
                     hir::GenericBound::Outlives(ref lt) => match lt.name {
-                        hir::LifetimeName::Underscore => self.tcx.sess.delay_span_bug(
+                        hir::LifetimeName::Underscore => {
+                            self.tcx.sess.delay_span_bug(
                                 lt.span,
                                 "use of `'_` in illegal place, but not caught by lowering",
-                        ),
+                            );
+                        }
                         hir::LifetimeName::Static => {
                             self.insert_lifetime(lt, Region::Static);
                             self.tcx
@@ -3172,7 +3174,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
                                 lt.span,
                                 "lowering generated `ImplicitObjectLifetimeDefault` \
                                  outside of an object type",
-                            )
+                            );
                         }
                         hir::LifetimeName::Error => {
                             // No need to do anything, error already reported.

compiler/rustc_session/src/options.rs

@@ -223,7 +223,7 @@ top_level_options!(
         /// `true` if we're emitting a JSON blob containing the unused externs
         json_unused_externs: bool [UNTRACKED],
 
-        /// `true` if we're emitting a JSON job containg a future-incompat report for lints
+        /// `true` if we're emitting a JSON job containing a future-incompat report for lints
         json_future_incompat: bool [TRACKED],
 
         pretty: Option<PpMode> [UNTRACKED],

compiler/rustc_session/src/output.rs

@@ -100,7 +100,7 @@ pub fn validate_crate_name(sess: &Session, s: &str, sp: Option<Span>) {
             match sp {
                 Some(sp) => sess.span_err(sp, s),
                 None => sess.err(s),
-            }
+            };
             err_count += 1;
         };
         if s.is_empty() {

compiler/rustc_session/src/parse.rs

@@ -69,7 +69,7 @@ pub struct SymbolGallery {
 
 impl SymbolGallery {
     /// Insert a symbol and its span into symbol gallery.
-    /// If the symbol has occurred before, ignore the new occurrance.
+    /// If the symbol has occurred before, ignore the new occurrence.
     pub fn insert(&self, symbol: Symbol, span: Span) {
         self.symbols.lock().entry(symbol).or_insert(span);
     }

compiler/rustc_session/src/session.rs

@@ -262,7 +262,7 @@ impl Session {
             }
             diag.emit();
             // If we should err, make sure we did.
-            if must_err && !self.has_errors() {
+            if must_err && !self.has_errors().is_some() {
                 // We have skipped a feature gate, and not run into other errors... reject.
                 self.err(
                     "`-Zunleash-the-miri-inside-of-you` may not be used to circumvent feature \
@@ -404,13 +404,13 @@ impl Session {
             self.span_err(sp, msg);
         }
     }
-    pub fn span_err<S: Into<MultiSpan>>(&self, sp: S, msg: &str) {
+    pub fn span_err<S: Into<MultiSpan>>(&self, sp: S, msg: &str) -> ErrorGuaranteed {
         self.diagnostic().span_err(sp, msg)
     }
     pub fn span_err_with_code<S: Into<MultiSpan>>(&self, sp: S, msg: &str, code: DiagnosticId) {
         self.diagnostic().span_err_with_code(sp, &msg, code)
     }
-    pub fn err(&self, msg: &str) {
+    pub fn err(&self, msg: &str) -> ErrorGuaranteed {
         self.diagnostic().err(msg)
     }
     pub fn emit_err<'a>(&'a self, err: impl SessionDiagnostic<'a>) -> ErrorGuaranteed {
@@ -420,7 +420,7 @@ impl Session {
     pub fn err_count(&self) -> usize {
         self.diagnostic().err_count()
     }
-    pub fn has_errors(&self) -> bool {
+    pub fn has_errors(&self) -> Option<ErrorGuaranteed> {
         self.diagnostic().has_errors()
     }
     pub fn has_errors_or_delayed_span_bugs(&self) -> bool {
@@ -430,9 +430,9 @@ impl Session {
         self.diagnostic().abort_if_errors();
     }
     pub fn compile_status(&self) -> Result<(), ErrorGuaranteed> {
-        if self.diagnostic().has_errors_or_lint_errors() {
-            self.diagnostic().emit_stashed_diagnostics();
-            Err(ErrorGuaranteed)
+        if let Some(reported) = self.diagnostic().has_errors_or_lint_errors() {
+            let _ = self.diagnostic().emit_stashed_diagnostics();
+            Err(reported)
         } else {
             Ok(())
         }
@@ -444,7 +444,11 @@ impl Session {
     {
         let old_count = self.err_count();
         let result = f();
-        if self.err_count() == old_count { Ok(result) } else { Err(ErrorGuaranteed) }
+        if self.err_count() == old_count {
+            Ok(result)
+        } else {
+            Err(ErrorGuaranteed::unchecked_claim_error_was_emitted())
+        }
     }
     pub fn span_warn<S: Into<MultiSpan>>(&self, sp: S, msg: &str) {
         self.diagnostic().span_warn(sp, msg)
@@ -457,7 +461,7 @@ impl Session {
     }
     /// Delay a span_bug() call until abort_if_errors()
     #[track_caller]
-    pub fn delay_span_bug<S: Into<MultiSpan>>(&self, sp: S, msg: &str) {
+    pub fn delay_span_bug<S: Into<MultiSpan>>(&self, sp: S, msg: &str) -> ErrorGuaranteed {
         self.diagnostic().delay_span_bug(sp, msg)
     }
 
@@ -1387,12 +1391,18 @@ fn validate_commandline_args_with_session_available(sess: &Session) {
     let unsupported_sanitizers = sess.opts.debugging_opts.sanitizer - supported_sanitizers;
     match unsupported_sanitizers.into_iter().count() {
         0 => {}
-        1 => sess
-            .err(&format!("{} sanitizer is not supported for this target", unsupported_sanitizers)),
-        _ => sess.err(&format!(
+        1 => {
+            sess.err(&format!(
+                "{} sanitizer is not supported for this target",
+                unsupported_sanitizers
+            ));
+        }
+        _ => {
+            sess.err(&format!(
                 "{} sanitizers are not supported for this target",
                 unsupported_sanitizers
-        )),
+            ));
+        }
     }
     // Cannot mix and match sanitizers.
     let mut sanitizer_iter = sess.opts.debugging_opts.sanitizer.into_iter();
@@ -1446,7 +1456,7 @@ pub enum IncrCompSession {
     InvalidBecauseOfErrors { session_directory: PathBuf },
 }
 
-pub fn early_error_no_abort(output: config::ErrorOutputType, msg: &str) {
+pub fn early_error_no_abort(output: config::ErrorOutputType, msg: &str) -> ErrorGuaranteed {
     let emitter: Box<dyn Emitter + sync::Send> = match output {
         config::ErrorOutputType::HumanReadable(kind) => {
             let (short, color_config) = kind.unzip();
@@ -1457,7 +1467,8 @@ pub fn early_error_no_abort(output: config::ErrorOutputType, msg: &str) {
         }
     };
     let handler = rustc_errors::Handler::with_emitter(true, None, emitter);
-    handler.struct_fatal(msg).emit();
+    let reported = handler.struct_fatal(msg).emit();
+    reported
 }
 
 pub fn early_error(output: config::ErrorOutputType, msg: &str) -> ! {

compiler/rustc_session/src/utils.rs

@@ -29,14 +29,14 @@ pub enum NativeLibKind {
     /// Dynamic library (e.g. `libfoo.so` on Linux)
     /// or an import library corresponding to a dynamic library (e.g. `foo.lib` on Windows/MSVC).
     Dylib {
-        /// Whether the dynamic library will be linked only if it satifies some undefined symbols
+        /// Whether the dynamic library will be linked only if it satisfies some undefined symbols
         as_needed: Option<bool>,
     },
     /// Dynamic library (e.g. `foo.dll` on Windows) without a corresponding import library.
     RawDylib,
     /// A macOS-specific kind of dynamic libraries.
     Framework {
-        /// Whether the framework will be linked only if it satifies some undefined symbols
+        /// Whether the framework will be linked only if it satisfies some undefined symbols
         as_needed: Option<bool>,
     },
     /// The library kind wasn't specified, `Dylib` is currently used as a default.

compiler/rustc_span/src/symbol.rs

@@ -563,6 +563,7 @@ symbols! {
         delay_span_bug_from_inside_query,
         deny,
         deprecated,
+        deprecated_safe,
         deprecated_suggestion,
         deref,
         deref_method,

compiler/rustc_symbol_mangling/src/lib.rs

@@ -226,7 +226,7 @@ fn compute_symbol_name<'tcx>(
 
         // If we're dealing with an instance of a function that's inlined from
         // another crate but we're marking it as globally shared to our
-        // compliation (aka we're not making an internal copy in each of our
+        // compilation (aka we're not making an internal copy in each of our
         // codegen units) then this symbol may become an exported (but hidden
         // visibility) symbol. This means that multiple crates may do the same
         // and we want to be sure to avoid any symbol conflicts here.

compiler/rustc_target/src/abi/mod.rs

@@ -1105,7 +1105,7 @@ impl Niche {
 
         // Extend the range of valid values being reserved by moving either `v.start` or `v.end` bound.
         // Given an eventual `Option<T>`, we try to maximize the chance for `None` to occupy the niche of zero.
-        // This is accomplished by prefering enums with 2 variants(`count==1`) and always taking the shortest path to niche zero.
+        // This is accomplished by preferring enums with 2 variants(`count==1`) and always taking the shortest path to niche zero.
         // Having `None` in niche zero can enable some special optimizations.
         //
         // Bound selection criteria:

compiler/rustc_trait_selection/src/traits/codegen.rs

@@ -51,7 +51,7 @@ pub fn codegen_fulfill_obligation<'tcx>(
                 // leading to an ambiguous result. So report this as an
                 // overflow bug, since I believe this is the only case
                 // where ambiguity can result.
-                infcx.tcx.sess.delay_span_bug(
+                let reported = infcx.tcx.sess.delay_span_bug(
                     rustc_span::DUMMY_SP,
                     &format!(
                         "encountered ambiguity selecting `{:?}` during codegen, presuming due to \
@@ -59,21 +59,21 @@ pub fn codegen_fulfill_obligation<'tcx>(
                         trait_ref
                     ),
                 );
-                return Err(ErrorGuaranteed);
+                return Err(reported);
             }
             Err(Unimplemented) => {
                 // This can trigger when we probe for the source of a `'static` lifetime requirement
                 // on a trait object: `impl Foo for dyn Trait {}` has an implicit `'static` bound.
                 // This can also trigger when we have a global bound that is not actually satisfied,
                 // but was included during typeck due to the trivial_bounds feature.
-                infcx.tcx.sess.delay_span_bug(
+                let guar = infcx.tcx.sess.delay_span_bug(
                     rustc_span::DUMMY_SP,
                     &format!(
                         "Encountered error `Unimplemented` selecting `{:?}` during codegen",
                         trait_ref
                     ),
                 );
-                return Err(ErrorGuaranteed);
+                return Err(guar);
             }
             Err(e) => {
                 bug!("Encountered error `{:?}` selecting `{:?}` during codegen", e, trait_ref)

compiler/rustc_trait_selection/src/traits/const_evaluatable.rs

@@ -18,7 +18,7 @@ use rustc_middle::mir::interpret::ErrorHandled;
 use rustc_middle::thir;
 use rustc_middle::thir::abstract_const::{self, Node, NodeId, NotConstEvaluatable};
 use rustc_middle::ty::subst::{Subst, SubstsRef};
-use rustc_middle::ty::{self, TyCtxt, TypeFoldable};
+use rustc_middle::ty::{self, DelaySpanBugEmitted, TyCtxt, TypeFoldable};
 use rustc_session::lint;
 use rustc_span::def_id::LocalDefId;
 use rustc_span::Span;
@@ -177,8 +177,9 @@ pub fn is_const_evaluatable<'cx, 'tcx>(
             false => NotConstEvaluatable::MentionsParam,
         }),
         Err(ErrorHandled::Linted) => {
+            let reported =
                 infcx.tcx.sess.delay_span_bug(span, "constant in type had error reported as lint");
-            Err(NotConstEvaluatable::Error(ErrorGuaranteed))
+            Err(NotConstEvaluatable::Error(reported))
         }
         Err(ErrorHandled::Reported(e)) => Err(NotConstEvaluatable::Error(e)),
         Ok(_) => Ok(()),
@@ -244,7 +245,7 @@ impl<'tcx> AbstractConst<'tcx> {
     ) -> Result<Option<AbstractConst<'tcx>>, ErrorGuaranteed> {
         match ct.val() {
             ty::ConstKind::Unevaluated(uv) => AbstractConst::new(tcx, uv.shrink()),
-            ty::ConstKind::Error(_) => Err(ErrorGuaranteed),
+            ty::ConstKind::Error(DelaySpanBugEmitted { reported, .. }) => Err(reported),
             _ => Ok(None),
         }
     }
@@ -280,17 +281,19 @@ impl<'a, 'tcx> AbstractConstBuilder<'a, 'tcx> {
     }
 
     fn error(&mut self, span: Span, msg: &str) -> Result<!, ErrorGuaranteed> {
-        self.tcx
+        let reported = self
+            .tcx
             .sess
             .struct_span_err(self.root_span(), "overly complex generic constant")
             .span_label(span, msg)
             .help("consider moving this anonymous constant into a `const` function")
             .emit();
 
-        Err(ErrorGuaranteed)
+        Err(reported)
     }
     fn maybe_supported_error(&mut self, span: Span, msg: &str) -> Result<!, ErrorGuaranteed> {
-        self.tcx
+        let reported = self
+            .tcx
             .sess
             .struct_span_err(self.root_span(), "overly complex generic constant")
             .span_label(span, msg)
@@ -298,7 +301,7 @@ impl<'a, 'tcx> AbstractConstBuilder<'a, 'tcx> {
             .note("this operation may be supported in the future")
             .emit();
 
-        Err(ErrorGuaranteed)
+        Err(reported)
     }
 
     fn new(
@@ -553,11 +556,7 @@ pub(super) fn thir_abstract_const<'tcx>(
             _ => return Ok(None),
         }
 
-        let body = tcx.thir_body(def);
-        if body.0.borrow().exprs.is_empty() {
-            // type error in constant, there is no thir
-            return Err(ErrorGuaranteed);
-        }
+        let body = tcx.thir_body(def)?;
 
         AbstractConstBuilder::new(tcx, (&*body.0.borrow(), body.1))?
             .map(AbstractConstBuilder::build)
@@ -580,7 +579,7 @@ pub(super) fn try_unify_abstract_consts<'tcx>(
 
         Ok(false)
     })()
-    .unwrap_or_else(|ErrorGuaranteed| true)
+    .unwrap_or_else(|_: ErrorGuaranteed| true)
     // FIXME(generic_const_exprs): We should instead have this
     // method return the resulting `ty::Const` and return `ConstKind::Error`
     // on `ErrorGuaranteed`.

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -63,7 +63,7 @@ pub trait InferCtxtExt<'tcx> {
         errors: &[FulfillmentError<'tcx>],
         body_id: Option<hir::BodyId>,
         fallback_has_occurred: bool,
-    );
+    ) -> ErrorGuaranteed;
 
     fn report_overflow_error<T>(
         &self,
@@ -111,7 +111,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
         errors: &[FulfillmentError<'tcx>],
         body_id: Option<hir::BodyId>,
         fallback_has_occurred: bool,
-    ) {
+    ) -> ErrorGuaranteed {
         #[derive(Debug)]
         struct ErrorDescriptor<'tcx> {
             predicate: ty::Predicate<'tcx>,
@@ -190,6 +190,8 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                 self.report_fulfillment_error(error, body_id, fallback_has_occurred);
             }
         }
+
+        self.tcx.sess.delay_span_bug(DUMMY_SP, "expected fullfillment errors")
     }
 
     /// Reports that an overflow has occurred and halts compilation. We
@@ -312,7 +314,9 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                         let predicate_is_const = ty::BoundConstness::ConstIfConst
                             == trait_predicate.skip_binder().constness;
 
-                        if self.tcx.sess.has_errors() && trait_predicate.references_error() {
+                        if self.tcx.sess.has_errors().is_some()
+                            && trait_predicate.references_error()
+                        {
                             return;
                         }
                         let trait_ref = trait_predicate.to_poly_trait_ref();
@@ -919,7 +923,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
             }
 
             // Already reported in the query.
-            SelectionError::NotConstEvaluatable(NotConstEvaluatable::Error(ErrorGuaranteed)) => {
+            SelectionError::NotConstEvaluatable(NotConstEvaluatable::Error(_)) => {
                 // FIXME(eddyb) remove this once `ErrorGuaranteed` becomes a proof token.
                 self.tcx.sess.delay_span_bug(span, "`ErrorGuaranteed` without an error");
                 return;
@@ -1857,7 +1861,7 @@ impl<'a, 'tcx> InferCtxtPrivExt<'a, 'tcx> for InferCtxt<'a, 'tcx> {
                 // Same hacky approach as above to avoid deluging user
                 // with error messages.
                 if arg.references_error()
-                    || self.tcx.sess.has_errors()
+                    || self.tcx.sess.has_errors().is_some()
                     || self.is_tainted_by_errors()
                 {
                     return;
@@ -1868,7 +1872,7 @@ impl<'a, 'tcx> InferCtxtPrivExt<'a, 'tcx> for InferCtxt<'a, 'tcx> {
 
             ty::PredicateKind::Subtype(data) => {
                 if data.references_error()
-                    || self.tcx.sess.has_errors()
+                    || self.tcx.sess.has_errors().is_some()
                     || self.is_tainted_by_errors()
                 {
                     // no need to overload user in such cases
@@ -1910,7 +1914,7 @@ impl<'a, 'tcx> InferCtxtPrivExt<'a, 'tcx> for InferCtxt<'a, 'tcx> {
             }
 
             _ => {
-                if self.tcx.sess.has_errors() || self.is_tainted_by_errors() {
+                if self.tcx.sess.has_errors().is_some() || self.is_tainted_by_errors() {
                     return;
                 }
                 let mut err = struct_span_err!(

compiler/rustc_trait_selection/src/traits/fulfill.rs

@@ -3,7 +3,6 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::obligation_forest::ProcessResult;
 use rustc_data_structures::obligation_forest::{Error, ForestObligation, Outcome};
 use rustc_data_structures::obligation_forest::{ObligationForest, ObligationProcessor};
-use rustc_errors::ErrorGuaranteed;
 use rustc_infer::traits::ProjectionCacheKey;
 use rustc_infer::traits::{SelectionError, TraitEngine, TraitEngineExt as _, TraitObligation};
 use rustc_middle::mir::interpret::ErrorHandled;
@@ -630,14 +629,12 @@ impl<'a, 'b, 'tcx> FulfillProcessor<'a, 'b, 'tcx> {
                                 ),
                             }
                         }
-                        (Err(ErrorHandled::Reported(ErrorGuaranteed)), _)
-                        | (_, Err(ErrorHandled::Reported(ErrorGuaranteed))) => {
-                            ProcessResult::Error(CodeSelectionError(
-                                SelectionError::NotConstEvaluatable(NotConstEvaluatable::Error(
-                                    ErrorGuaranteed,
+                        (Err(ErrorHandled::Reported(reported)), _)
+                        | (_, Err(ErrorHandled::Reported(reported))) => ProcessResult::Error(
+                            CodeSelectionError(SelectionError::NotConstEvaluatable(
+                                NotConstEvaluatable::Error(reported),
                             )),
-                            ))
-                        }
+                        ),
                         (Err(ErrorHandled::Linted), _) | (_, Err(ErrorHandled::Linted)) => {
                             span_bug!(
                                 obligation.cause.span(self.selcx.tcx()),

compiler/rustc_trait_selection/src/traits/mod.rs

@@ -231,8 +231,8 @@ fn do_normalize_predicates<'tcx>(
             match fully_normalize(&infcx, fulfill_cx, cause, elaborated_env, predicates) {
                 Ok(predicates) => predicates,
                 Err(errors) => {
-                    infcx.report_fulfillment_errors(&errors, None, false);
-                    return Err(ErrorGuaranteed);
+                    let reported = infcx.report_fulfillment_errors(&errors, None, false);
+                    return Err(reported);
                 }
             };
 
@@ -258,13 +258,15 @@ fn do_normalize_predicates<'tcx>(
                 // represents a legitimate failure due to some kind of
                 // unconstrained variable, and it seems better not to ICE,
                 // all things considered.
-                tcx.sess.span_err(span, &fixup_err.to_string());
-                return Err(ErrorGuaranteed);
+                let reported = tcx.sess.span_err(span, &fixup_err.to_string());
+                return Err(reported);
             }
         };
         if predicates.needs_infer() {
-            tcx.sess.delay_span_bug(span, "encountered inference variables after `fully_resolve`");
-            Err(ErrorGuaranteed)
+            let reported = tcx
+                .sess
+                .delay_span_bug(span, "encountered inference variables after `fully_resolve`");
+            Err(reported)
         } else {
             Ok(predicates)
         }
@@ -536,7 +538,7 @@ fn prepare_vtable_segments<'tcx, T>(
 
     // the main traversal loop:
     // basically we want to cut the inheritance directed graph into a few non-overlapping slices of nodes
-    // that each node is emited after all its descendents have been emitted.
+    // that each node is emitted after all its descendents have been emitted.
     // so we convert the directed graph into a tree by skipping all previously visted nodes using a visited set.
     // this is done on the fly.
     // Each loop run emits a slice - it starts by find a "childless" unvisited node, backtracking upwards, and it
@@ -551,10 +553,10 @@ fn prepare_vtable_segments<'tcx, T>(
     // Starting point 0 stack [D]
     // Loop run #0: Stack after diving in is [D B A], A is "childless"
     // after this point, all newly visited nodes won't have a vtable that equals to a prefix of this one.
-    // Loop run #0: Emiting the slice [B A] (in reverse order), B has a next-sibling node, so this slice stops here.
+    // Loop run #0: Emitting the slice [B A] (in reverse order), B has a next-sibling node, so this slice stops here.
     // Loop run #0: Stack after exiting out is [D C], C is the next starting point.
     // Loop run #1: Stack after diving in is [D C], C is "childless", since its child A is skipped(already emitted).
-    // Loop run #1: Emiting the slice [D C] (in reverse order). No one has a next-sibling node.
+    // Loop run #1: Emitting the slice [D C] (in reverse order). No one has a next-sibling node.
     // Loop run #1: Stack after exiting out is []. Now the function exits.
 
     loop {

compiler/rustc_trait_selection/src/traits/on_unimplemented.rs

@@ -6,7 +6,7 @@ use rustc_hir::def_id::DefId;
 use rustc_middle::ty::{self, GenericParamDefKind, TyCtxt};
 use rustc_parse_format::{ParseMode, Parser, Piece, Position};
 use rustc_span::symbol::{kw, sym, Symbol};
-use rustc_span::Span;
+use rustc_span::{Span, DUMMY_SP};
 
 #[derive(Clone, Debug)]
 pub struct OnUnimplementedFormatString(Symbol);
@@ -47,8 +47,7 @@ fn parse_error(
     if let Some(note) = note {
         diag.note(note);
     }
-    diag.emit();
-    ErrorGuaranteed
+    diag.emit()
 }
 
 impl<'tcx> OnUnimplementedDirective {
@@ -59,7 +58,7 @@ impl<'tcx> OnUnimplementedDirective {
         span: Span,
         is_root: bool,
     ) -> Result<Self, ErrorGuaranteed> {
-        let mut errored = false;
+        let mut errored = None;
         let mut item_iter = items.iter();
 
         let parse_value = |value_str| {
@@ -91,8 +90,8 @@ impl<'tcx> OnUnimplementedDirective {
                     )
                 })?;
             attr::eval_condition(cond, &tcx.sess.parse_sess, Some(tcx.features()), &mut |item| {
-                if let Some(symbol) = item.value_str() && parse_value(symbol).is_err() {
-                    errored = true;
+                if let Some(symbol) = item.value_str() && let Err(guar) = parse_value(symbol) {
+                    errored = Some(guar);
                 }
                 true
             });
@@ -134,13 +133,10 @@ impl<'tcx> OnUnimplementedDirective {
                 && note.is_none()
             {
                 if let Some(items) = item.meta_item_list() {
-                    if let Ok(subcommand) =
-                        Self::parse(tcx, item_def_id, &items, item.span(), false)
-                    {
-                        subcommands.push(subcommand);
-                    } else {
-                        errored = true;
-                    }
+                    match Self::parse(tcx, item_def_id, &items, item.span(), false) {
+                        Ok(subcommand) => subcommands.push(subcommand),
+                        Err(reported) => errored = Some(reported),
+                    };
                     continue;
                 }
             } else if item.has_name(sym::append_const_msg) && append_const_msg.is_none() {
@@ -163,8 +159,8 @@ impl<'tcx> OnUnimplementedDirective {
             );
         }
 
-        if errored {
-            Err(ErrorGuaranteed)
+        if let Some(reported) = errored {
+            Err(reported)
         } else {
             Ok(OnUnimplementedDirective {
                 condition,
@@ -203,7 +199,9 @@ impl<'tcx> OnUnimplementedDirective {
                 append_const_msg: None,
             }))
         } else {
-            return Err(ErrorGuaranteed);
+            let reported =
+                tcx.sess.delay_span_bug(DUMMY_SP, "of_item: neither meta_item_list nor value_str");
+            return Err(reported);
         };
         debug!("of_item({:?}) = {:?}", item_def_id, result);
         result
@@ -327,7 +325,7 @@ impl<'tcx> OnUnimplementedFormatString {
                         match generics.params.iter().find(|param| param.name == s) {
                             Some(_) => (),
                             None => {
-                                struct_span_err!(
+                                let reported = struct_span_err!(
                                     tcx.sess,
                                     span,
                                     E0230,
@@ -340,20 +338,20 @@ impl<'tcx> OnUnimplementedFormatString {
                                     }
                                 )
                                 .emit();
-                                result = Err(ErrorGuaranteed);
+                                result = Err(reported);
                             }
                         }
                     }
                     // `{:1}` and `{}` are not to be used
                     Position::ArgumentIs(_) | Position::ArgumentImplicitlyIs(_) => {
-                        struct_span_err!(
+                        let reported = struct_span_err!(
                             tcx.sess,
                             span,
                             E0231,
                             "only named substitution parameters are allowed"
                         )
                         .emit();
-                        result = Err(ErrorGuaranteed);
+                        result = Err(reported);
                     }
                 },
             }

compiler/rustc_trait_selection/src/traits/project.rs

@@ -1396,7 +1396,7 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
                 // `rustc_ty_utils::instance::resolve_associated_item()`.
                 let node_item =
                     assoc_def(selcx, impl_data.impl_def_id, obligation.predicate.item_def_id)
-                        .map_err(|ErrorGuaranteed| ())?;
+                        .map_err(|ErrorGuaranteed { .. }| ())?;
 
                 if node_item.is_final() {
                     // Non-specializable items are always projectable.

compiler/rustc_trait_selection/src/traits/select/confirmation.rs

@@ -719,7 +719,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             // TraitA+Kx+'a -> TraitB+Ky+'b (trait upcasting coercion).
             (&ty::Dynamic(ref data_a, r_a), &ty::Dynamic(ref data_b, r_b)) => {
                 // See `assemble_candidates_for_unsizing` for more info.
-                // We already checked the compatiblity of auto traits within `assemble_candidates_for_unsizing`.
+                // We already checked the compatibility of auto traits within `assemble_candidates_for_unsizing`.
                 let principal_a = data_a.principal().unwrap();
                 source_trait_ref = principal_a.with_self_ty(tcx, source);
                 upcast_trait_ref = util::supertraits(tcx, source_trait_ref).nth(idx).unwrap();
@@ -823,7 +823,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             // Trait+Kx+'a -> Trait+Ky+'b (auto traits and lifetime subtyping).
             (&ty::Dynamic(ref data_a, r_a), &ty::Dynamic(ref data_b, r_b)) => {
                 // See `assemble_candidates_for_unsizing` for more info.
-                // We already checked the compatiblity of auto traits within `assemble_candidates_for_unsizing`.
+                // We already checked the compatibility of auto traits within `assemble_candidates_for_unsizing`.
                 let iter = data_a
                     .principal()
                     .map(|b| b.map_bound(ty::ExistentialPredicate::Trait))
@@ -1084,7 +1084,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 | ty::Foreign(_) => {}
 
                 // These types are built-in, so we can fast-track by registering
-                // nested predicates for their constituient type(s)
+                // nested predicates for their constituent type(s)
                 ty::Array(ty, _) | ty::Slice(ty) => {
                     stack.push(ty);
                 }

compiler/rustc_trait_selection/src/traits/select/mod.rs

@@ -29,7 +29,7 @@ use crate::traits::project::ProjectionCacheKeyExt;
 use crate::traits::ProjectionCacheKey;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::stack::ensure_sufficient_stack;
-use rustc_errors::{Diagnostic, ErrorGuaranteed};
+use rustc_errors::Diagnostic;
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_infer::infer::LateBoundRegionConversionTime;
@@ -553,7 +553,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                     match project::poly_project_and_unify_type(self, &project_obligation) {
                         Ok(Ok(Some(mut subobligations))) => {
                             'compute_res: {
-                                // If we've previously marked this projection as 'complete', thne
+                                // If we've previously marked this projection as 'complete', then
                                 // use the final cached result (either `EvaluatedToOk` or
                                 // `EvaluatedToOkModuloRegions`), and skip re-evaluating the
                                 // sub-obligations.
@@ -674,8 +674,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                                 Err(_) => Ok(EvaluatedToErr),
                             }
                         }
-                        (Err(ErrorHandled::Reported(ErrorGuaranteed)), _)
-                        | (_, Err(ErrorHandled::Reported(ErrorGuaranteed))) => Ok(EvaluatedToErr),
+                        (Err(ErrorHandled::Reported(_)), _)
+                        | (_, Err(ErrorHandled::Reported(_))) => Ok(EvaluatedToErr),
                         (Err(ErrorHandled::Linted), _) | (_, Err(ErrorHandled::Linted)) => {
                             span_bug!(
                                 obligation.cause.span(self.tcx()),

compiler/rustc_trait_selection/src/traits/specialize/mod.rs

@@ -16,14 +16,14 @@ use crate::infer::{InferCtxt, InferOk, TyCtxtInferExt};
 use crate::traits::select::IntercrateAmbiguityCause;
 use crate::traits::{self, coherence, FutureCompatOverlapErrorKind, ObligationCause, TraitEngine};
 use rustc_data_structures::fx::FxHashSet;
-use rustc_errors::struct_span_err;
+use rustc_errors::{struct_span_err, EmissionGuarantee};
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_middle::lint::LintDiagnosticBuilder;
 use rustc_middle::ty::subst::{InternalSubsts, Subst, SubstsRef};
 use rustc_middle::ty::{self, TyCtxt};
 use rustc_session::lint::builtin::COHERENCE_LEAK_CHECK;
 use rustc_session::lint::builtin::ORDER_DEPENDENT_TRAIT_OBJECTS;
-use rustc_span::DUMMY_SP;
+use rustc_span::{Span, DUMMY_SP};
 
 use super::util::impl_trait_ref_and_oblig;
 use super::{FulfillmentContext, SelectionContext};
@@ -377,8 +377,7 @@ fn report_negative_positive_conflict(
         }
     }
 
-    sg.has_errored = true;
-    err.emit();
+    sg.has_errored = Some(err.emit());
 }
 
 fn report_conflicting_impls(
@@ -394,7 +393,13 @@ fn report_conflicting_impls(
     // Work to be done after we've built the DiagnosticBuilder. We have to define it
     // now because the struct_lint methods don't return back the DiagnosticBuilder
     // that's passed in.
-    let decorate = |err: LintDiagnosticBuilder<'_>| {
+    fn decorate<G: EmissionGuarantee>(
+        tcx: TyCtxt<'_>,
+        overlap: OverlapError,
+        used_to_be_allowed: Option<FutureCompatOverlapErrorKind>,
+        impl_span: Span,
+        err: LintDiagnosticBuilder<'_, G>,
+    ) -> G {
         let msg = format!(
             "conflicting implementations of trait `{}`{}{}",
             overlap.trait_desc,
@@ -440,17 +445,25 @@ fn report_conflicting_impls(
             coherence::add_placeholder_note(&mut err);
         }
         err.emit()
-    };
+    }
 
     match used_to_be_allowed {
         None => {
-            sg.has_errored = true;
-            if overlap.with_impl.is_local() || !tcx.orphan_check_crate(()).contains(&impl_def_id) {
+            let reported = if overlap.with_impl.is_local()
+                || !tcx.orphan_check_crate(()).contains(&impl_def_id)
+            {
                 let err = struct_span_err!(tcx.sess, impl_span, E0119, "");
-                decorate(LintDiagnosticBuilder::new(err.forget_guarantee()));
+                Some(decorate(
+                    tcx,
+                    overlap,
+                    used_to_be_allowed,
+                    impl_span,
+                    LintDiagnosticBuilder::new(err),
+                ))
             } else {
-                tcx.sess.delay_span_bug(impl_span, "impl should have failed the orphan check");
-            }
+                Some(tcx.sess.delay_span_bug(impl_span, "impl should have failed the orphan check"))
+            };
+            sg.has_errored = reported;
         }
         Some(kind) => {
             let lint = match kind {
@@ -461,8 +474,10 @@ fn report_conflicting_impls(
                 lint,
                 tcx.hir().local_def_id_to_hir_id(impl_def_id),
                 impl_span,
-                decorate,
-            )
+                |ldb| {
+                    decorate(tcx, overlap, used_to_be_allowed, impl_span, ldb);
+                },
+            );
         }
     };
 }

compiler/rustc_ty_utils/src/instance.rs

@@ -306,9 +306,9 @@ fn resolve_associated_item<'tcx>(
                         resolved_ty,
                     );
                     let span = tcx.def_span(leaf_def.item.def_id);
-                    tcx.sess.delay_span_bug(span, &msg);
+                    let reported = tcx.sess.delay_span_bug(span, &msg);
 
-                    return Err(ErrorGuaranteed);
+                    return Err(reported);
                 }
             }