Rollup of 10 pull requests

compiler/rustc_ast/src/ast.rs

@@ -2136,10 +2136,12 @@ pub enum TyKind {
     ImplicitSelf,
     /// A macro in the type position.
     MacCall(P<MacCall>),
-    /// Placeholder for a kind that has failed to be defined.
-    Err,
     /// Placeholder for a `va_list`.
     CVarArgs,
+    /// Sometimes we need a dummy value when no error has occurred.
+    Dummy,
+    /// Placeholder for a kind that has failed to be defined.
+    Err(ErrorGuaranteed),
 }
 
 impl TyKind {

compiler/rustc_ast/src/mut_visit.rs

@@ -481,7 +481,12 @@ pub fn noop_visit_ty<T: MutVisitor>(ty: &mut P<Ty>, vis: &mut T) {
     let Ty { id, kind, span, tokens } = ty.deref_mut();
     vis.visit_id(id);
     match kind {
-        TyKind::Infer | TyKind::ImplicitSelf | TyKind::Err | TyKind::Never | TyKind::CVarArgs => {}
+        TyKind::Infer
+        | TyKind::ImplicitSelf
+        | TyKind::Err(_)
+        | TyKind::Dummy
+        | TyKind::Never
+        | TyKind::CVarArgs => {}
         TyKind::Slice(ty) => vis.visit_ty(ty),
         TyKind::Ptr(mt) => vis.visit_mt(mt),
         TyKind::Ref(lt, mt) => {
@@ -1649,7 +1654,7 @@ impl DummyAstNode for Ty {
     fn dummy() -> Self {
         Ty {
             id: DUMMY_NODE_ID,
-            kind: TyKind::Err,
+            kind: TyKind::Dummy,
             span: Default::default(),
             tokens: Default::default(),
         }

compiler/rustc_ast/src/visit.rs

@@ -447,7 +447,7 @@ pub fn walk_ty<'a, V: Visitor<'a>>(visitor: &mut V, typ: &'a Ty) {
             walk_list!(visitor, visit_param_bound, bounds, BoundKind::Impl);
         }
         TyKind::Typeof(expression) => visitor.visit_anon_const(expression),
-        TyKind::Infer | TyKind::ImplicitSelf | TyKind::Err => {}
+        TyKind::Infer | TyKind::ImplicitSelf | TyKind::Dummy | TyKind::Err(_) => {}
         TyKind::MacCall(mac) => visitor.visit_mac_call(mac),
         TyKind::Never | TyKind::CVarArgs => {}
         TyKind::AnonStruct(_, ref fields) | TyKind::AnonUnion(_, ref fields) => {

compiler/rustc_ast_lowering/src/lib.rs

@@ -1286,7 +1286,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     fn lower_ty_direct(&mut self, t: &Ty, itctx: ImplTraitContext) -> hir::Ty<'hir> {
         let kind = match &t.kind {
             TyKind::Infer => hir::TyKind::Infer,
-            TyKind::Err => hir::TyKind::Err(self.dcx().has_errors().unwrap()),
+            TyKind::Err(guar) => hir::TyKind::Err(*guar),
             // Lower the anonymous structs or unions in a nested lowering context.
             //
             // ```
@@ -1504,6 +1504,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 );
                 hir::TyKind::Err(guar)
             }
+            TyKind::Dummy => panic!("`TyKind::Dummy` should never be lowered"),
         };
 
         hir::Ty { kind, span: self.lower_span(t.span), hir_id: self.lower_node_id(t.id) }

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -881,7 +881,8 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                         &item.vis,
                         errors::VisibilityNotPermittedNote::TraitImpl,
                     );
-                    if let TyKind::Err = self_ty.kind {
+                    // njn: use Dummy here
+                    if let TyKind::Err(_) = self_ty.kind {
                         this.dcx().emit_err(errors::ObsoleteAuto { span: item.span });
                     }
                     if let (&Unsafe::Yes(span), &ImplPolarity::Negative(sp)) = (unsafety, polarity)

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -1048,11 +1048,16 @@ impl<'a> State<'a> {
             ast::TyKind::Infer => {
                 self.word("_");
             }
-            ast::TyKind::Err => {
+            ast::TyKind::Err(_) => {
                 self.popen();
                 self.word("/*ERROR*/");
                 self.pclose();
             }
+            ast::TyKind::Dummy => {
+                self.popen();
+                self.word("/*DUMMY*/");
+                self.pclose();
+            }
             ast::TyKind::ImplicitSelf => {
                 self.word("Self");
             }

compiler/rustc_expand/src/base.rs

@@ -567,10 +567,13 @@ impl DummyResult {
     }
 
     /// A plain dummy type.
-    pub fn raw_ty(sp: Span, is_error: bool) -> P<ast::Ty> {
+    pub fn raw_ty(sp: Span) -> P<ast::Ty> {
+        // FIXME(nnethercote): you might expect `ast::TyKind::Dummy` to be used here, but some
+        // values produced here end up being lowered to HIR, which `ast::TyKind::Dummy` does not
+        // support, so we use an empty tuple instead.
         P(ast::Ty {
             id: ast::DUMMY_NODE_ID,
-            kind: if is_error { ast::TyKind::Err } else { ast::TyKind::Tup(ThinVec::new()) },
+            kind: ast::TyKind::Tup(ThinVec::new()),
             span: sp,
             tokens: None,
         })
@@ -611,7 +614,7 @@ impl MacResult for DummyResult {
     }
 
     fn make_ty(self: Box<DummyResult>) -> Option<P<ast::Ty>> {
-        Some(DummyResult::raw_ty(self.span, self.is_error))
+        Some(DummyResult::raw_ty(self.span))
     }
 
     fn make_arms(self: Box<DummyResult>) -> Option<SmallVec<[ast::Arm; 1]>> {

compiler/rustc_hir_typeck/src/_match.rs

@@ -79,7 +79,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             CoerceMany::with_coercion_sites(coerce_first, arms)
         };
 
-        let mut other_arms = vec![]; // Used only for diagnostics.
+        let mut prior_non_diverging_arms = vec![]; // Used only for diagnostics.
         let mut prior_arm = None;
         for arm in arms {
             if let Some(e) = &arm.guard {
@@ -118,9 +118,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         prior_arm_ty,
                         prior_arm_span,
                         scrut_span: scrut.span,
-                        scrut_hir_id: scrut.hir_id,
                         source: match_src,
-                        prior_arms: other_arms.clone(),
+                        prior_non_diverging_arms: prior_non_diverging_arms.clone(),
                         opt_suggest_box_span,
                     })),
                 ),
@@ -142,16 +141,16 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 false,
             );
 
-            other_arms.push(arm_span);
-            if other_arms.len() > 5 {
-                other_arms.remove(0);
-            }
-
             if !arm_ty.is_never() {
                 // When a match arm has type `!`, then it doesn't influence the expected type for
                 // the following arm. If all of the prior arms are `!`, then the influence comes
                 // from elsewhere and we shouldn't point to any previous arm.
                 prior_arm = Some((arm_block_id, arm_ty, arm_span));
+
+                prior_non_diverging_arms.push(arm_span);
+                if prior_non_diverging_arms.len() > 5 {
+                    prior_non_diverging_arms.remove(0);
+                }
             }
         }
 

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

@@ -777,10 +777,9 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                 prior_arm_span,
                 prior_arm_ty,
                 source,
-                ref prior_arms,
+                ref prior_non_diverging_arms,
                 opt_suggest_box_span,
                 scrut_span,
-                scrut_hir_id,
                 ..
             }) => match source {
                 hir::MatchSource::TryDesugar(scrut_hir_id) => {
@@ -817,12 +816,12 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                     });
                     let source_map = self.tcx.sess.source_map();
                     let mut any_multiline_arm = source_map.is_multiline(arm_span);
-                    if prior_arms.len() <= 4 {
-                        for sp in prior_arms {
+                    if prior_non_diverging_arms.len() <= 4 {
+                        for sp in prior_non_diverging_arms {
                             any_multiline_arm |= source_map.is_multiline(*sp);
                             err.span_label(*sp, format!("this is found to be of type `{t}`"));
                         }
-                    } else if let Some(sp) = prior_arms.last() {
+                    } else if let Some(sp) = prior_non_diverging_arms.last() {
                         any_multiline_arm |= source_map.is_multiline(*sp);
                         err.span_label(
                             *sp,
@@ -848,24 +847,15 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                     ) {
                         err.subdiagnostic(subdiag);
                     }
-                    if let hir::Node::Expr(m) = self.tcx.parent_hir_node(scrut_hir_id)
-                        && let hir::Node::Stmt(stmt) = self.tcx.parent_hir_node(m.hir_id)
-                        && let hir::StmtKind::Expr(_) = stmt.kind
-                    {
-                        err.span_suggestion_verbose(
-                            stmt.span.shrink_to_hi(),
-                            "consider using a semicolon here, but this will discard any values \
-                             in the match arms",
-                            ";",
-                            Applicability::MaybeIncorrect,
-                        );
-                    }
                     if let Some(ret_sp) = opt_suggest_box_span {
                         // Get return type span and point to it.
                         self.suggest_boxing_for_return_impl_trait(
                             err,
                             ret_sp,
-                            prior_arms.iter().chain(std::iter::once(&arm_span)).copied(),
+                            prior_non_diverging_arms
+                                .iter()
+                                .chain(std::iter::once(&arm_span))
+                                .copied(),
                         );
                     }
                 }

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

@@ -203,10 +203,10 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                     })
                 }
                 ObligationCauseCode::MatchExpressionArm(box MatchExpressionArmCause {
-                    prior_arms,
+                    prior_non_diverging_arms,
                     ..
                 }) => {
-                    if let [.., arm_span] = &prior_arms[..] {
+                    if let [.., arm_span] = &prior_non_diverging_arms[..] {
                         Some(ConsiderAddingAwait::BothFuturesSugg {
                             first: arm_span.shrink_to_hi(),
                             second: exp_span.shrink_to_hi(),
@@ -234,11 +234,14 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                     Some(ConsiderAddingAwait::FutureSugg { span: then_span.shrink_to_hi() })
                 }
                 ObligationCauseCode::MatchExpressionArm(box MatchExpressionArmCause {
-                    ref prior_arms,
+                    ref prior_non_diverging_arms,
                     ..
                 }) => Some({
                     ConsiderAddingAwait::FutureSuggMultiple {
-                        spans: prior_arms.iter().map(|arm| arm.shrink_to_hi()).collect(),
+                        spans: prior_non_diverging_arms
+                            .iter()
+                            .map(|arm| arm.shrink_to_hi())
+                            .collect(),
                     }
                 }),
                 _ => None,

compiler/rustc_middle/src/traits/mod.rs

@@ -569,9 +569,8 @@ pub struct MatchExpressionArmCause<'tcx> {
     pub prior_arm_ty: Ty<'tcx>,
     pub prior_arm_span: Span,
     pub scrut_span: Span,
-    pub scrut_hir_id: hir::HirId,
     pub source: hir::MatchSource,
-    pub prior_arms: Vec<Span>,
+    pub prior_non_diverging_arms: Vec<Span>,
     pub opt_suggest_box_span: Option<Span>,
 }
 

compiler/rustc_middle/src/ty/sty.rs

@@ -2363,28 +2363,42 @@ impl<'tcx> Ty<'tcx> {
     }
 
     /// When we create a closure, we record its kind (i.e., what trait
-    /// it implements) into its `ClosureArgs` using a type
+    /// it implements, constrained by how it uses its borrows) into its
+    /// [`ty::ClosureArgs`] or [`ty::CoroutineClosureArgs`] using a type
     /// parameter. This is kind of a phantom type, except that the
     /// most convenient thing for us to are the integral types. This
     /// function converts such a special type into the closure
-    /// kind. To go the other way, use `closure_kind.to_ty(tcx)`.
+    /// kind. To go the other way, use [`Ty::from_closure_kind`].
     ///
     /// Note that during type checking, we use an inference variable
     /// to represent the closure kind, because it has not yet been
     /// inferred. Once upvar inference (in `rustc_hir_analysis/src/check/upvar.rs`)
-    /// is complete, that type variable will be unified.
+    /// is complete, that type variable will be unified with one of
+    /// the integral types.
     ///
-    /// To be noted that you can use [`ClosureArgs::kind()`] or [`CoroutineClosureArgs::kind()`]
-    /// to get the same information, which you can get by calling [`GenericArgs::as_closure()`]
-    /// or [`GenericArgs::as_coroutine_closure()`], depending on the type of the closure.
+    /// ```rust,ignore (snippet of compiler code)
+    /// if let TyKind::Closure(def_id, args) = closure_ty.kind()
+    ///     && let Some(closure_kind) = args.as_closure().kind_ty().to_opt_closure_kind()
+    /// {
+    ///     println!("{closure_kind:?}");
+    /// } else if let TyKind::CoroutineClosure(def_id, args) = closure_ty.kind()
+    ///     && let Some(closure_kind) = args.as_coroutine_closure().kind_ty().to_opt_closure_kind()
+    /// {
+    ///     println!("{closure_kind:?}");
+    /// }
+    /// ```
     ///
-    /// Otherwise, this method can be used as follows:
+    /// After upvar analysis, you should instead use [`ClosureArgs::kind()`]
+    /// or [`CoroutineClosureArgs::kind()`] to assert that the `ClosureKind`
+    /// has been constrained instead of manually calling this method.
     ///
     /// ```rust,ignore (snippet of compiler code)
-    /// let TyKind::Closure(def_id, [closure_fn_kind_ty, ..]) = closure_ty.kind()
-    ///     && let Some(closure_kind) = closure_fn_kind_ty.expect_ty().to_opt_closure_kind()
+    /// if let TyKind::Closure(def_id, args) = closure_ty.kind()
+    /// {
+    ///     println!("{:?}", args.as_closure().kind());
+    /// } else if let TyKind::CoroutineClosure(def_id, args) = closure_ty.kind()
     /// {
-    ///     // your code
+    ///     println!("{:?}", args.as_coroutine_closure().kind());
     /// }
     /// ```
     pub fn to_opt_closure_kind(self) -> Option<ty::ClosureKind> {
@@ -2406,7 +2420,8 @@ impl<'tcx> Ty<'tcx> {
         }
     }
 
-    /// Inverse of [`Ty::to_opt_closure_kind`].
+    /// Inverse of [`Ty::to_opt_closure_kind`]. See docs on that method
+    /// for explanation of the relationship between `Ty` and [`ty::ClosureKind`].
     pub fn from_closure_kind(tcx: TyCtxt<'tcx>, kind: ty::ClosureKind) -> Ty<'tcx> {
         match kind {
             ty::ClosureKind::Fn => tcx.types.i8,

compiler/rustc_mir_transform/src/lib.rs

@@ -653,7 +653,6 @@ fn inner_optimized_mir(tcx: TyCtxt<'_>, did: LocalDefId) -> Body<'_> {
     debug!("about to call mir_drops_elaborated...");
     let body = tcx.mir_drops_elaborated_and_const_checked(did).steal();
     let mut body = remap_mir_for_const_eval_select(tcx, body, hir::Constness::NotConst);
-    debug!("body: {:#?}", body);
 
     if body.tainted_by_errors.is_some() {
         return body;

compiler/rustc_mir_transform/src/remove_noop_landing_pads.rs

@@ -15,7 +15,8 @@ impl<'tcx> MirPass<'tcx> for RemoveNoopLandingPads {
     }
 
     fn run_pass(&self, _tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-        debug!("remove_noop_landing_pads({:?})", body);
+        let def_id = body.source.def_id();
+        debug!(?def_id);
         self.remove_nop_landing_pads(body)
     }
 }
@@ -81,8 +82,6 @@ impl RemoveNoopLandingPads {
     }
 
     fn remove_nop_landing_pads(&self, body: &mut Body<'_>) {
-        debug!("body: {:#?}", body);
-
         // Skip the pass if there are no blocks with a resume terminator.
         let has_resume = body
             .basic_blocks