Rollup of 5 pull requests

compiler/rustc_ast_lowering/src/item.rs

@@ -266,7 +266,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     let body_id =
                         this.lower_maybe_async_body(span, &decl, asyncness, body.as_deref());
 
-                    let itctx = ImplTraitContext::Universal(this.current_hir_id_owner);
+                    let itctx = ImplTraitContext::Universal;
                     let (generics, decl) = this.lower_generics(generics, id, itctx, |this| {
                         let ret_id = asyncness.opt_return_id();
                         this.lower_fn_decl(&decl, Some(id), FnDeclKind::Fn, ret_id)
@@ -385,7 +385,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 // method, it will not be considered an in-band
                 // lifetime to be added, but rather a reference to a
                 // parent lifetime.
-                let itctx = ImplTraitContext::Universal(self.current_hir_id_owner);
+                let itctx = ImplTraitContext::Universal;
                 let (generics, (trait_ref, lowered_ty)) =
                     self.lower_generics(ast_generics, id, itctx, |this| {
                         let trait_ref = trait_ref.as_ref().map(|trait_ref| {
@@ -655,7 +655,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             kind: match i.kind {
                 ForeignItemKind::Fn(box Fn { ref sig, ref generics, .. }) => {
                     let fdec = &sig.decl;
-                    let itctx = ImplTraitContext::Universal(self.current_hir_id_owner);
+                    let itctx = ImplTraitContext::Universal;
                     let (generics, (fn_dec, fn_args)) =
                         self.lower_generics(generics, i.id, itctx, |this| {
                             (
@@ -1237,7 +1237,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         is_async: Option<NodeId>,
     ) -> (&'hir hir::Generics<'hir>, hir::FnSig<'hir>) {
         let header = self.lower_fn_header(sig.header);
-        let itctx = ImplTraitContext::Universal(self.current_hir_id_owner);
+        let itctx = ImplTraitContext::Universal;
         let (generics, decl) = self.lower_generics(generics, id, itctx, |this| {
             this.lower_fn_decl(&sig.decl, Some(id), kind, is_async)
         });

compiler/rustc_ast_lowering/src/lib.rs

@@ -46,7 +46,7 @@ use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::sorted_map::SortedMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::sync::Lrc;
-use rustc_errors::struct_span_err;
+use rustc_errors::{struct_span_err, Applicability};
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Namespace, PartialRes, PerNS, Res};
 use rustc_hir::def_id::{DefId, DefPathHash, LocalDefId, CRATE_DEF_ID};
@@ -253,7 +253,7 @@ enum ImplTraitContext {
     /// equivalent to a fresh universal parameter like `fn foo<T: Debug>(x: T)`.
     ///
     /// Newly generated parameters should be inserted into the given `Vec`.
-    Universal(LocalDefId),
+    Universal,
 
     /// Treat `impl Trait` as shorthand for a new opaque type.
     /// Example: `fn foo() -> impl Debug`, where `impl Debug` is conceptually
@@ -857,20 +857,14 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         itctx: ImplTraitContext,
     ) -> hir::TypeBinding<'hir> {
         debug!("lower_assoc_ty_constraint(constraint={:?}, itctx={:?})", constraint, itctx);
-
         // lower generic arguments of identifier in constraint
         let gen_args = if let Some(ref gen_args) = constraint.gen_args {
             let gen_args_ctor = match gen_args {
                 GenericArgs::AngleBracketed(ref data) => {
                     self.lower_angle_bracketed_parameter_data(data, ParamMode::Explicit, itctx).0
                 }
                 GenericArgs::Parenthesized(ref data) => {
-                    let mut err = self.sess.struct_span_err(
-                        gen_args.span(),
-                        "parenthesized generic arguments cannot be used in associated type constraints"
-                    );
-                    // FIXME: try to write a suggestion here
-                    err.emit();
+                    self.assoc_ty_contraint_param_error_emit(data);
                     self.lower_angle_bracketed_parameter_data(
                         &data.as_angle_bracketed_args(),
                         ParamMode::Explicit,
@@ -893,7 +887,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 hir::TypeBindingKind::Equality { term }
             }
             AssocConstraintKind::Bound { ref bounds } => {
-                let mut parent_def_id = self.current_hir_id_owner;
                 // Piggy-back on the `impl Trait` context to figure out the correct behavior.
                 let (desugar_to_impl_trait, itctx) = match itctx {
                     // We are in the return position:
@@ -913,10 +906,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     // so desugar to
                     //
                     //     fn foo(x: dyn Iterator<Item = impl Debug>)
-                    ImplTraitContext::Universal(parent) if self.is_in_dyn_type => {
-                        parent_def_id = parent;
-                        (true, itctx)
-                    }
+                    ImplTraitContext::Universal if self.is_in_dyn_type => (true, itctx),
 
                     // In `type Foo = dyn Iterator<Item: Debug>` we desugar to
                     // `type Foo = dyn Iterator<Item = impl Debug>` but we have to override the
@@ -942,6 +932,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     // Desugar `AssocTy: Bounds` into `AssocTy = impl Bounds`. We do this by
                     // constructing the HIR for `impl bounds...` and then lowering that.
 
+                    let parent_def_id = self.current_hir_id_owner;
                     let impl_trait_node_id = self.resolver.next_node_id();
                     self.resolver.create_def(
                         parent_def_id,
@@ -984,6 +975,42 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         }
     }
 
+    fn assoc_ty_contraint_param_error_emit(&self, data: &ParenthesizedArgs) -> () {
+        let mut err = self.sess.struct_span_err(
+            data.span,
+            "parenthesized generic arguments cannot be used in associated type constraints",
+        );
+        // Suggest removing empty parentheses: "Trait()" -> "Trait"
+        if data.inputs.is_empty() {
+            let parentheses_span =
+                data.inputs_span.shrink_to_lo().to(data.inputs_span.shrink_to_hi());
+            err.multipart_suggestion(
+                "remove these parentheses",
+                vec![(parentheses_span, String::new())],
+                Applicability::MaybeIncorrect,
+            );
+        }
+        // Suggest replacing parentheses with angle brackets `Trait(params...)` to `Trait<params...>`
+        else {
+            // Start of parameters to the 1st argument
+            let open_param = data.inputs_span.shrink_to_lo().to(data
+                .inputs
+                .first()
+                .unwrap()
+                .span
+                .shrink_to_lo());
+            // End of last argument to end of parameters
+            let close_param =
+                data.inputs.last().unwrap().span.shrink_to_hi().to(data.inputs_span.shrink_to_hi());
+            err.multipart_suggestion(
+                &format!("use angle brackets instead",),
+                vec![(open_param, String::from("<")), (close_param, String::from(">"))],
+                Applicability::MaybeIncorrect,
+            );
+        }
+        err.emit();
+    }
+
     fn lower_generic_arg(
         &mut self,
         arg: &ast::GenericArg,
@@ -1184,12 +1211,12 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                             |this| this.lower_param_bounds(bounds, nested_itctx),
                         )
                     }
-                    ImplTraitContext::Universal(parent_def_id) => {
+                    ImplTraitContext::Universal => {
                         // Add a definition for the in-band `Param`.
                         let def_id = self.resolver.local_def_id(def_node_id);
 
-                        let hir_bounds = self
-                            .lower_param_bounds(bounds, ImplTraitContext::Universal(parent_def_id));
+                        let hir_bounds =
+                            self.lower_param_bounds(bounds, ImplTraitContext::Universal);
                         // Set the name to `impl Bound1 + Bound2`.
                         let ident = Ident::from_str_and_span(&pprust::ty_to_string(t), span);
                         let param = hir::GenericParam {
@@ -1399,10 +1426,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         }
         let inputs = self.arena.alloc_from_iter(inputs.iter().map(|param| {
             if fn_node_id.is_some() {
-                self.lower_ty_direct(
-                    &param.ty,
-                    ImplTraitContext::Universal(self.current_hir_id_owner),
-                )
+                self.lower_ty_direct(&param.ty, ImplTraitContext::Universal)
             } else {
                 self.lower_ty_direct(
                     &param.ty,

compiler/rustc_hir/src/hir.rs

@@ -3004,13 +3004,12 @@ impl ItemKind<'_> {
         Some(match *self {
             ItemKind::Fn(_, ref generics, _)
             | ItemKind::TyAlias(_, ref generics)
-            | ItemKind::OpaqueTy(OpaqueTy {
-                ref generics, origin: OpaqueTyOrigin::TyAlias, ..
-            })
+            | ItemKind::OpaqueTy(OpaqueTy { ref generics, .. })
             | ItemKind::Enum(_, ref generics)
             | ItemKind::Struct(_, ref generics)
             | ItemKind::Union(_, ref generics)
             | ItemKind::Trait(_, _, ref generics, _, _)
+            | ItemKind::TraitAlias(ref generics, _)
             | ItemKind::Impl(Impl { ref generics, .. }) => generics,
             _ => return None,
         })
@@ -3210,13 +3209,8 @@ impl<'hir> OwnerNode<'hir> {
         }
     }
 
-    pub fn generics(&self) -> Option<&'hir Generics<'hir>> {
-        match self {
-            OwnerNode::TraitItem(TraitItem { generics, .. })
-            | OwnerNode::ImplItem(ImplItem { generics, .. }) => Some(generics),
-            OwnerNode::Item(item) => item.kind.generics(),
-            _ => None,
-        }
+    pub fn generics(self) -> Option<&'hir Generics<'hir>> {
+        Node::generics(self.into())
     }
 
     pub fn def_id(self) -> LocalDefId {
@@ -3403,9 +3397,12 @@ impl<'hir> Node<'hir> {
         }
     }
 
-    pub fn generics(&self) -> Option<&'hir Generics<'hir>> {
+    pub fn generics(self) -> Option<&'hir Generics<'hir>> {
         match self {
-            Node::TraitItem(TraitItem { generics, .. })
+            Node::ForeignItem(ForeignItem {
+                kind: ForeignItemKind::Fn(_, _, generics), ..
+            })
+            | Node::TraitItem(TraitItem { generics, .. })
             | Node::ImplItem(ImplItem { generics, .. }) => Some(generics),
             Node::Item(item) => item.kind.generics(),
             _ => None,

compiler/rustc_middle/src/hir/map/mod.rs

@@ -361,27 +361,7 @@ impl<'hir> Map<'hir> {
 
     pub fn get_generics(self, id: LocalDefId) -> Option<&'hir Generics<'hir>> {
         let node = self.tcx.hir_owner(id)?;
-        match node.node {
-            OwnerNode::ImplItem(impl_item) => Some(&impl_item.generics),
-            OwnerNode::TraitItem(trait_item) => Some(&trait_item.generics),
-            OwnerNode::ForeignItem(ForeignItem {
-                kind: ForeignItemKind::Fn(_, _, generics),
-                ..
-            })
-            | OwnerNode::Item(Item {
-                kind:
-                    ItemKind::Fn(_, generics, _)
-                    | ItemKind::TyAlias(_, generics)
-                    | ItemKind::Enum(_, generics)
-                    | ItemKind::Struct(_, generics)
-                    | ItemKind::Union(_, generics)
-                    | ItemKind::Trait(_, _, generics, ..)
-                    | ItemKind::TraitAlias(generics, _)
-                    | ItemKind::Impl(Impl { generics, .. }),
-                ..
-            }) => Some(generics),
-            _ => None,
-        }
+        node.node.generics()
     }
 
     pub fn item(self, id: ItemId) -> &'hir Item<'hir> {

compiler/rustc_mir_transform/src/inline.rs

@@ -158,11 +158,13 @@ impl<'tcx> Inliner<'tcx> {
             return Err("optimization fuel exhausted");
         }
 
-        let callee_body = callsite.callee.subst_mir_and_normalize_erasing_regions(
+        let Ok(callee_body) = callsite.callee.try_subst_mir_and_normalize_erasing_regions(
             self.tcx,
             self.param_env,
             callee_body.clone(),
-        );
+        ) else {
+            return Err("failed to normalize callee body");
+        };
 
         let old_blocks = caller_body.basic_blocks().next_index();
         self.inline_call(caller_body, &callsite, callee_body);
@@ -253,7 +255,7 @@ impl<'tcx> Inliner<'tcx> {
             let func_ty = func.ty(caller_body, self.tcx);
             if let ty::FnDef(def_id, substs) = *func_ty.kind() {
                 // To resolve an instance its substs have to be fully normalized.
-                let substs = self.tcx.normalize_erasing_regions(self.param_env, substs);
+                let substs = self.tcx.try_normalize_erasing_regions(self.param_env, substs).ok()?;
                 let callee =
                     Instance::resolve(self.tcx, self.param_env, def_id, substs).ok().flatten()?;
 
@@ -408,14 +410,17 @@ impl<'tcx> Inliner<'tcx> {
                     if let ty::FnDef(def_id, substs) =
                         *callsite.callee.subst_mir(self.tcx, &f.literal.ty()).kind()
                     {
-                        let substs = self.tcx.normalize_erasing_regions(self.param_env, substs);
-                        if let Ok(Some(instance)) =
-                            Instance::resolve(self.tcx, self.param_env, def_id, substs)
+                        if let Ok(substs) =
+                            self.tcx.try_normalize_erasing_regions(self.param_env, substs)
                         {
-                            if callsite.callee.def_id() == instance.def_id() {
-                                return Err("self-recursion");
-                            } else if self.history.contains(&instance) {
-                                return Err("already inlined");
+                            if let Ok(Some(instance)) =
+                                Instance::resolve(self.tcx, self.param_env, def_id, substs)
+                            {
+                                if callsite.callee.def_id() == instance.def_id() {
+                                    return Err("self-recursion");
+                                } else if self.history.contains(&instance) {
+                                    return Err("already inlined");
+                                }
                             }
                         }
                         // Don't give intrinsics the extra penalty for calls

compiler/rustc_typeck/src/collect.rs

@@ -1588,41 +1588,20 @@ fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
         _ => None,
     };
 
-    let mut opt_self = None;
-    let mut allow_defaults = false;
-
     let no_generics = hir::Generics::empty();
-    let ast_generics = match node {
-        Node::TraitItem(item) => &item.generics,
-
-        Node::ImplItem(item) => &item.generics,
-
+    let ast_generics = node.generics().unwrap_or(&no_generics);
+    let (opt_self, allow_defaults) = match node {
         Node::Item(item) => {
             match item.kind {
-                ItemKind::Fn(.., ref generics, _)
-                | ItemKind::Impl(hir::Impl { ref generics, .. }) => generics,
-
-                ItemKind::TyAlias(_, ref generics)
-                | ItemKind::Enum(_, ref generics)
-                | ItemKind::Struct(_, ref generics)
-                | ItemKind::OpaqueTy(hir::OpaqueTy { ref generics, .. })
-                | ItemKind::Union(_, ref generics) => {
-                    allow_defaults = true;
-                    generics
-                }
-
-                ItemKind::Trait(_, _, ref generics, ..)
-                | ItemKind::TraitAlias(ref generics, ..) => {
+                ItemKind::Trait(..) | ItemKind::TraitAlias(..) => {
                     // Add in the self type parameter.
                     //
                     // Something of a hack: use the node id for the trait, also as
                     // the node id for the Self type parameter.
-                    let param_id = item.def_id;
-
-                    opt_self = Some(ty::GenericParamDef {
+                    let opt_self = Some(ty::GenericParamDef {
                         index: 0,
                         name: kw::SelfUpper,
-                        def_id: param_id.to_def_id(),
+                        def_id,
                         pure_wrt_drop: false,
                         kind: ty::GenericParamDefKind::Type {
                             has_default: false,
@@ -1631,21 +1610,17 @@ fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
                         },
                     });
 
-                    allow_defaults = true;
-                    generics
+                    (opt_self, true)
                 }
-
-                _ => &no_generics,
+                ItemKind::TyAlias(..)
+                | ItemKind::Enum(..)
+                | ItemKind::Struct(..)
+                | ItemKind::OpaqueTy(..)
+                | ItemKind::Union(..) => (None, true),
+                _ => (None, false),
             }
         }
-
-        Node::ForeignItem(item) => match item.kind {
-            ForeignItemKind::Static(..) => &no_generics,
-            ForeignItemKind::Fn(_, _, ref generics) => generics,
-            ForeignItemKind::Type => &no_generics,
-        },
-
-        _ => &no_generics,
+        _ => (None, false),
     };
 
     let has_self = opt_self.is_some();

src/test/ui/generic-associated-types/gat-trait-path-parenthesised-args.rs

@@ -10,4 +10,9 @@ fn foo<'a>(arg: Box<dyn X<Y('a) = &'a ()>>) {}
   //~| ERROR this associated type takes 0 generic arguments but 1 generic argument
   //~| ERROR this associated type takes 1 lifetime argument but 0 lifetime arguments
 
+
+fn bar<'a>(arg: Box<dyn X<Y() = ()>>) {}
+  //~^ ERROR: parenthesized generic arguments cannot be used
+  //~| ERROR this associated type takes 1 lifetime argument but 0 lifetime arguments
+
 fn main() {}