Automatically taint InferCtxt when errors are emitted

Author: oli-obk

compiler/rustc_borrowck/src/diagnostics/region_errors.rs

@@ -360,7 +360,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'_, '_, 'cx, 'tcx> {
                     let named_key = self.regioncx.name_regions(self.infcx.tcx, key);
                     let named_region = self.regioncx.name_regions(self.infcx.tcx, member_region);
                     let diag = unexpected_hidden_region_diagnostic(
-                        self.infcx.tcx,
+                        self.infcx,
                         self.mir_def_id(),
                         span,
                         named_ty,

compiler/rustc_borrowck/src/region_infer/opaque_types.rs

@@ -285,7 +285,7 @@ impl<'tcx> InferCtxt<'tcx> {
         }
 
         if let Err(guar) =
-            check_opaque_type_parameter_valid(self.tcx, opaque_type_key, instantiated_ty.span)
+            check_opaque_type_parameter_valid(self, opaque_type_key, instantiated_ty.span)
         {
             return Ty::new_error(self.tcx, guar);
         }
@@ -294,6 +294,10 @@ impl<'tcx> InferCtxt<'tcx> {
             .remap_generic_params_to_declaration_params(opaque_type_key, self.tcx, false)
             .ty;
 
+        if let Err(e) = definition_ty.error_reported() {
+            return Ty::new_error(self.tcx, e);
+        }
+
         // `definition_ty` does not live in of the current inference context,
         // so lets make sure that we don't accidentally misuse our current `infcx`.
         match check_opaque_type_well_formed(
@@ -387,10 +391,11 @@ fn check_opaque_type_well_formed<'tcx>(
 /// [rustc-dev-guide chapter]:
 /// https://rustc-dev-guide.rust-lang.org/opaque-types-region-infer-restrictions.html
 fn check_opaque_type_parameter_valid<'tcx>(
-    tcx: TyCtxt<'tcx>,
+    infcx: &InferCtxt<'tcx>,
     opaque_type_key: OpaqueTypeKey<'tcx>,
     span: Span,
 ) -> Result<(), ErrorGuaranteed> {
+    let tcx = infcx.tcx;
     let opaque_generics = tcx.generics_of(opaque_type_key.def_id);
     let opaque_env = LazyOpaqueTyEnv::new(tcx, opaque_type_key.def_id);
     let mut seen_params: FxIndexMap<_, Vec<_>> = FxIndexMap::default();
@@ -420,7 +425,7 @@ fn check_opaque_type_parameter_valid<'tcx>(
 
             opaque_env.param_is_error(i)?;
 
-            return Err(tcx.dcx().emit_err(NonGenericOpaqueTypeParam {
+            return Err(infcx.dcx().emit_err(NonGenericOpaqueTypeParam {
                 ty: arg,
                 kind,
                 span,
@@ -438,7 +443,7 @@ fn check_opaque_type_parameter_valid<'tcx>(
                 .collect();
             #[allow(rustc::diagnostic_outside_of_impl)]
             #[allow(rustc::untranslatable_diagnostic)]
-            return Err(tcx
+            return Err(infcx
                 .dcx()
                 .struct_span_err(span, "non-defining opaque type use in defining scope")
                 .with_span_note(spans, format!("{descr} used multiple times"))

compiler/rustc_errors/src/diagnostic.rs

@@ -510,7 +510,7 @@ pub struct Diag<'a, G: EmissionGuarantee = ErrorGuaranteed> {
 // would be bad.
 impl<G> !Clone for Diag<'_, G> {}
 
-rustc_data_structures::static_assert_size!(Diag<'_, ()>, 2 * std::mem::size_of::<usize>());
+rustc_data_structures::static_assert_size!(Diag<'_, ()>, 3 * std::mem::size_of::<usize>());
 
 impl<G: EmissionGuarantee> Deref for Diag<'_, G> {
     type Target = DiagInner;

compiler/rustc_errors/src/lib.rs

@@ -63,6 +63,7 @@ use rustc_span::source_map::SourceMap;
 use rustc_span::{Loc, Span, DUMMY_SP};
 use std::backtrace::{Backtrace, BacktraceStatus};
 use std::borrow::Cow;
+use std::cell::Cell;
 use std::error::Report;
 use std::fmt;
 use std::hash::Hash;
@@ -98,9 +99,9 @@ rustc_fluent_macro::fluent_messages! { "../messages.ftl" }
 
 // `PResult` is used a lot. Make sure it doesn't unintentionally get bigger.
 #[cfg(target_pointer_width = "64")]
-rustc_data_structures::static_assert_size!(PResult<'_, ()>, 16);
+rustc_data_structures::static_assert_size!(PResult<'_, ()>, 24);
 #[cfg(target_pointer_width = "64")]
-rustc_data_structures::static_assert_size!(PResult<'_, bool>, 16);
+rustc_data_structures::static_assert_size!(PResult<'_, bool>, 24);
 
 #[derive(Debug, PartialEq, Eq, Clone, Copy, Hash, Encodable, Decodable)]
 pub enum SuggestionStyle {
@@ -417,6 +418,7 @@ pub struct DiagCtxt {
 #[derive(Copy, Clone)]
 pub struct DiagCtxtHandle<'a> {
     dcx: &'a DiagCtxt,
+    tainted_with_errors: Option<&'a Cell<Option<ErrorGuaranteed>>>,
 }
 
 impl<'a> std::ops::Deref for DiagCtxtHandle<'a> {
@@ -752,7 +754,14 @@ impl DiagCtxt {
     }
 
     pub fn handle<'a>(&'a self) -> DiagCtxtHandle<'a> {
-        DiagCtxtHandle { dcx: self }
+        DiagCtxtHandle { dcx: self, tainted_with_errors: None }
+    }
+
+    pub fn taintable_handle<'a>(
+        &'a self,
+        tainted_with_errors: &'a Cell<Option<ErrorGuaranteed>>,
+    ) -> DiagCtxtHandle<'a> {
+        DiagCtxtHandle { dcx: self, tainted_with_errors: Some(tainted_with_errors) }
     }
 }
 
@@ -795,7 +804,9 @@ impl<'a> DiagCtxtHandle<'a> {
             // can be used to create a backtrace at the stashing site insted of whenever the
             // diagnostic context is dropped and thus delayed bugs are emitted.
             Error => Some(self.span_delayed_bug(span, format!("stashing {key:?}"))),
-            DelayedBug => return self.inner.borrow_mut().emit_diagnostic(diag),
+            DelayedBug => {
+                return self.inner.borrow_mut().emit_diagnostic(diag, self.tainted_with_errors);
+            }
             ForceWarning(_) | Warning | Note | OnceNote | Help | OnceHelp | FailureNote | Allow
             | Expect(_) => None,
         };
@@ -947,16 +958,19 @@ impl<'a> DiagCtxtHandle<'a> {
             (0, _) => {
                 // Use `ForceWarning` rather than `Warning` to guarantee emission, e.g. with a
                 // configuration like `--cap-lints allow --force-warn bare_trait_objects`.
-                inner.emit_diagnostic(DiagInner::new(
-                    ForceWarning(None),
-                    DiagMessage::Str(warnings),
-                ));
+                inner.emit_diagnostic(
+                    DiagInner::new(ForceWarning(None), DiagMessage::Str(warnings)),
+                    None,
+                );
             }
             (_, 0) => {
-                inner.emit_diagnostic(DiagInner::new(Error, errors));
+                inner.emit_diagnostic(DiagInner::new(Error, errors), self.tainted_with_errors);
             }
             (_, _) => {
-                inner.emit_diagnostic(DiagInner::new(Error, format!("{errors}; {warnings}")));
+                inner.emit_diagnostic(
+                    DiagInner::new(Error, format!("{errors}; {warnings}")),
+                    self.tainted_with_errors,
+                );
             }
         }
 
@@ -987,14 +1001,14 @@ impl<'a> DiagCtxtHandle<'a> {
                         "For more information about an error, try `rustc --explain {}`.",
                         &error_codes[0]
                     );
-                    inner.emit_diagnostic(DiagInner::new(FailureNote, msg1));
-                    inner.emit_diagnostic(DiagInner::new(FailureNote, msg2));
+                    inner.emit_diagnostic(DiagInner::new(FailureNote, msg1), None);
+                    inner.emit_diagnostic(DiagInner::new(FailureNote, msg2), None);
                 } else {
                     let msg = format!(
                         "For more information about this error, try `rustc --explain {}`.",
                         &error_codes[0]
                     );
-                    inner.emit_diagnostic(DiagInner::new(FailureNote, msg));
+                    inner.emit_diagnostic(DiagInner::new(FailureNote, msg), None);
                 }
             }
         }
@@ -1020,7 +1034,7 @@ impl<'a> DiagCtxtHandle<'a> {
     }
 
     pub fn emit_diagnostic(&self, diagnostic: DiagInner) -> Option<ErrorGuaranteed> {
-        self.inner.borrow_mut().emit_diagnostic(diagnostic)
+        self.inner.borrow_mut().emit_diagnostic(diagnostic, self.tainted_with_errors)
     }
 
     pub fn emit_artifact_notification(&self, path: &Path, artifact_type: &str) {
@@ -1080,7 +1094,7 @@ impl<'a> DiagCtxtHandle<'a> {
                 // Here the diagnostic is given back to `emit_diagnostic` where it was first
                 // intercepted. Now it should be processed as usual, since the unstable expectation
                 // id is now stable.
-                inner.emit_diagnostic(diag);
+                inner.emit_diagnostic(diag, self.tainted_with_errors);
             }
         }
 
@@ -1430,13 +1444,17 @@ impl DiagCtxtInner {
                     continue;
                 }
             }
-            guar = guar.or(self.emit_diagnostic(diag));
+            guar = guar.or(self.emit_diagnostic(diag, None));
         }
         guar
     }
 
     // Return value is only `Some` if the level is `Error` or `DelayedBug`.
-    fn emit_diagnostic(&mut self, mut diagnostic: DiagInner) -> Option<ErrorGuaranteed> {
+    fn emit_diagnostic(
+        &mut self,
+        mut diagnostic: DiagInner,
+        taint: Option<&Cell<Option<ErrorGuaranteed>>>,
+    ) -> Option<ErrorGuaranteed> {
         match diagnostic.level {
             Expect(expect_id) | ForceWarning(Some(expect_id)) => {
                 // The `LintExpectationId` can be stable or unstable depending on when it was
@@ -1609,6 +1627,9 @@ impl DiagCtxtInner {
                 if is_lint {
                     self.lint_err_guars.push(guar);
                 } else {
+                    if let Some(taint) = taint {
+                        taint.set(Some(guar));
+                    }
                     self.err_guars.push(guar);
                 }
                 self.panic_if_treat_err_as_bug();
@@ -1718,8 +1739,8 @@ impl DiagCtxtInner {
         // `-Ztreat-err-as-bug`, which we don't want.
         let note1 = "no errors encountered even though delayed bugs were created";
         let note2 = "those delayed bugs will now be shown as internal compiler errors";
-        self.emit_diagnostic(DiagInner::new(Note, note1));
-        self.emit_diagnostic(DiagInner::new(Note, note2));
+        self.emit_diagnostic(DiagInner::new(Note, note1), None);
+        self.emit_diagnostic(DiagInner::new(Note, note2), None);
 
         for bug in bugs {
             if let Some(out) = &mut out {
@@ -1752,7 +1773,7 @@ impl DiagCtxtInner {
             }
             bug.level = Bug;
 
-            self.emit_diagnostic(bug);
+            self.emit_diagnostic(bug, None);
         }
 
         // Panic with `DelayedBugPanic` to avoid "unexpected panic" messages.

compiler/rustc_hir_typeck/src/cast.rs

@@ -319,7 +319,7 @@ impl<'a, 'tcx> CastCheck<'tcx> {
                 } else {
                     errors::CannotCastToBoolHelp::Unsupported(self.span)
                 };
-                fcx.tcx.dcx().emit_err(errors::CannotCastToBool { span: self.span, expr_ty, help });
+                fcx.dcx().emit_err(errors::CannotCastToBool { span: self.span, expr_ty, help });
             }
             CastError::CastToChar => {
                 let mut err = type_error_struct!(

compiler/rustc_hir_typeck/src/expr.rs

@@ -638,7 +638,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 // Set expectation to error in that case and set tainted
                 // by error (#114529)
                 let coerce_to = opt_coerce_to.unwrap_or_else(|| {
-                    let guar = tcx.dcx().span_delayed_bug(
+                    let guar = self.dcx().span_delayed_bug(
                         expr.span,
                         "illegal break with value found but no error reported",
                     );
@@ -1716,7 +1716,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             } else {
                 error_happened = true;
                 let guar = if let Some(prev_span) = seen_fields.get(&ident) {
-                    tcx.dcx().emit_err(FieldMultiplySpecifiedInInitializer {
+                    self.dcx().emit_err(FieldMultiplySpecifiedInInitializer {
                         span: field.ident.span,
                         prev_span: *prev_span,
                         ident,
@@ -1757,7 +1757,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         if adt_kind == AdtKind::Union {
             if hir_fields.len() != 1 {
                 struct_span_code_err!(
-                    tcx.dcx(),
+                    self.dcx(),
                     span,
                     E0784,
                     "union expressions should have exactly one field",

compiler/rustc_hir_typeck/src/expr_use_visitor.rs

@@ -170,7 +170,7 @@ impl<'tcx> TypeInformationCtxt<'tcx> for &FnCtxt<'_, 'tcx> {
     }
 
     fn report_error(&self, span: Span, msg: impl ToString) -> Self::Error {
-        self.tcx.dcx().span_delayed_bug(span, msg.to_string())
+        self.dcx().span_delayed_bug(span, msg.to_string())
     }
 
     fn error_reported_in_ty(&self, ty: Ty<'tcx>) -> Result<(), Self::Error> {

compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs

@@ -1182,7 +1182,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     name: self.tcx.item_name(def.did()).to_ident_string(),
                 });
                 if ty.raw.has_param() {
-                    let guar = self.tcx.dcx().emit_err(errors::SelfCtorFromOuterItem {
+                    let guar = self.dcx().emit_err(errors::SelfCtorFromOuterItem {
                         span: path_span,
                         impl_span: tcx.def_span(impl_def_id),
                         sugg,
@@ -1207,7 +1207,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     // Check the visibility of the ctor.
                     let vis = tcx.visibility(ctor_def_id);
                     if !vis.is_accessible_from(tcx.parent_module(hir_id).to_def_id(), tcx) {
-                        tcx.dcx()
+                        self.dcx()
                             .emit_err(CtorIsPrivate { span, def: tcx.def_path_str(adt_def.did()) });
                     }
                     let new_res = Res::Def(DefKind::Ctor(CtorOf::Struct, ctor_kind), ctor_def_id);
@@ -1216,7 +1216,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     (new_res, Some(user_args.args))
                 }
                 _ => {
-                    let mut err = tcx.dcx().struct_span_err(
+                    let mut err = self.dcx().struct_span_err(
                         span,
                         "the `Self` constructor can only be used with tuple or unit structs",
                     );

compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs

@@ -238,7 +238,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     // Otherwise, there's a mismatch, so clear out what we're expecting, and set
                     // our input types to err_args so we don't blow up the error messages
                     let guar = struct_span_code_err!(
-                        tcx.dcx(),
+                        self.dcx(),
                         call_span,
                         E0059,
                         "cannot use call notation; the first type parameter \
@@ -453,7 +453,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     .map(|vars| self.resolve_vars_if_possible(vars)),
             );
 
-            self.set_tainted_by_errors(self.report_arg_errors(
+            self.report_arg_errors(
                 compatibility_diagonal,
                 formal_and_expected_inputs,
                 provided_args,
@@ -462,7 +462,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 fn_def_id,
                 call_span,
                 call_expr,
-            ));
+            );
         }
     }
 
@@ -788,7 +788,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             format!("arguments to this {call_name} are incorrect"),
                         );
                     } else {
-                        err = tcx.dcx().struct_span_err(
+                        err = self.dcx().struct_span_err(
                             full_call_span,
                             format!(
                                 "{call_name} takes {}{} but {} {} supplied",
@@ -848,7 +848,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 span_bug!(error_span, "expected errors from argument matrix");
             } else {
                 let mut err =
-                    tcx.dcx().create_err(errors::ArgMismatchIndeterminate { span: error_span });
+                    self.dcx().create_err(errors::ArgMismatchIndeterminate { span: error_span });
                 suggest_confusable(&mut err);
                 return err.emit();
             }
@@ -953,14 +953,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         let mut err = if formal_and_expected_inputs.len() == provided_args.len() {
             struct_span_code_err!(
-                tcx.dcx(),
+                self.dcx(),
                 full_call_span,
                 E0308,
                 "arguments to this {} are incorrect",
                 call_name,
             )
         } else {
-            tcx.dcx()
+            self.dcx()
                 .struct_span_err(
                     full_call_span,
                     format!(

compiler/rustc_hir_typeck/src/intrinsicck.rs

@@ -52,7 +52,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             // Note: this path is currently not reached in any test, so any
             // example that triggers this would be worth minimizing and
             // converting into a test.
-            tcx.dcx().span_bug(span, "argument to transmute has inference variables");
+            self.dcx().span_bug(span, "argument to transmute has inference variables");
         }
         // Transmutes that are only changing lifetimes are always ok.
         if from == to {
@@ -76,7 +76,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             if let (&ty::FnDef(..), SizeSkeleton::Known(size_to, _)) = (from.kind(), sk_to)
                 && size_to == Pointer(dl.instruction_address_space).size(&tcx)
             {
-                struct_span_code_err!(tcx.dcx(), span, E0591, "can't transmute zero-sized type")
+                struct_span_code_err!(self.dcx(), span, E0591, "can't transmute zero-sized type")
                     .with_note(format!("source type: {from}"))
                     .with_note(format!("target type: {to}"))
                     .with_help("cast with `as` to a pointer instead")
@@ -116,7 +116,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         };
 
         let mut err = struct_span_code_err!(
-            tcx.dcx(),
+            self.dcx(),
             span,
             E0512,
             "cannot transmute between types of different sizes, \