Rollup of 8 pull requests

compiler/rustc_ast/src/ast.rs

@@ -167,9 +167,6 @@ pub enum GenericArgs {
     AngleBracketed(AngleBracketedArgs),
     /// The `(A, B)` and `C` in `Foo(A, B) -> C`.
     Parenthesized(ParenthesizedArgs),
-    /// Associated return type bounds, like `T: Trait<method(..): Send>`
-    /// which applies the `Send` bound to the return-type of `method`.
-    ReturnTypeNotation(Span),
 }
 
 impl GenericArgs {
@@ -181,7 +178,6 @@ impl GenericArgs {
         match self {
             AngleBracketed(data) => data.span,
             Parenthesized(data) => data.span,
-            ReturnTypeNotation(span) => *span,
         }
     }
 }

compiler/rustc_ast/src/format.rs

@@ -94,7 +94,7 @@ impl FormatArguments {
         }
         if !matches!(arg.kind, FormatArgumentKind::Captured(..)) {
             // This is an explicit argument.
-            // Make sure that all arguments so far are explcit.
+            // Make sure that all arguments so far are explicit.
             assert_eq!(
                 self.num_explicit_args,
                 self.arguments.len(),

compiler/rustc_ast/src/mut_visit.rs

@@ -561,7 +561,6 @@ pub fn noop_visit_generic_args<T: MutVisitor>(generic_args: &mut GenericArgs, vi
     match generic_args {
         GenericArgs::AngleBracketed(data) => vis.visit_angle_bracketed_parameter_data(data),
         GenericArgs::Parenthesized(data) => vis.visit_parenthesized_parameter_data(data),
-        GenericArgs::ReturnTypeNotation(_span) => {}
     }
 }
 

compiler/rustc_ast/src/visit.rs

@@ -482,7 +482,6 @@ where
             walk_list!(visitor, visit_ty, &data.inputs);
             walk_fn_ret_ty(visitor, &data.output);
         }
-        GenericArgs::ReturnTypeNotation(_span) => {}
     }
 }
 

compiler/rustc_ast_lowering/src/errors.rs

@@ -137,7 +137,7 @@ pub struct AsyncNonMoveClosureNotSupported {
 
 #[derive(Diagnostic, Clone, Copy)]
 #[diag(ast_lowering_functional_record_update_destructuring_assignment)]
-pub struct FunctionalRecordUpdateDestructuringAssignemnt {
+pub struct FunctionalRecordUpdateDestructuringAssignment {
     #[primary_span]
     #[suggestion(code = "", applicability = "machine-applicable")]
     pub span: Span,
@@ -353,13 +353,7 @@ pub enum BadReturnTypeNotation {
     #[diag(ast_lowering_bad_return_type_notation_inputs)]
     Inputs {
         #[primary_span]
-        #[suggestion(code = "(..)", applicability = "maybe-incorrect")]
-        span: Span,
-    },
-    #[diag(ast_lowering_bad_return_type_notation_needs_dots)]
-    NeedsDots {
-        #[primary_span]
-        #[suggestion(code = "(..)", applicability = "maybe-incorrect")]
+        #[suggestion(code = "()", applicability = "maybe-incorrect")]
         span: Span,
     },
     #[diag(ast_lowering_bad_return_type_notation_output)]

compiler/rustc_ast_lowering/src/expr.rs

@@ -1,6 +1,6 @@
 use super::errors::{
     AsyncGeneratorsNotSupported, AsyncNonMoveClosureNotSupported, AwaitOnlyInAsyncFnAndBlocks,
-    BaseExpressionDoubleDot, ClosureCannotBeStatic, FunctionalRecordUpdateDestructuringAssignemnt,
+    BaseExpressionDoubleDot, ClosureCannotBeStatic, FunctionalRecordUpdateDestructuringAssignment,
     GeneratorTooManyParameters, InclusiveRangeWithNoEnd, NotSupportedForLifetimeBinderAsyncClosure,
     UnderscoreExprLhsAssign,
 };
@@ -434,7 +434,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         // `if let pat = val` or `if foo && let pat = val`, as we _do_ want `val` to live beyond the
         // condition in this case.
         //
-        // In order to mantain the drop behavior for the non `let` parts of the condition,
+        // In order to maintain the drop behavior for the non `let` parts of the condition,
         // we still wrap them in terminating scopes, e.g. `if foo && let pat = val` essentially
         // gets transformed into `if { let _t = foo; _t } && let pat = val`
         match &cond.kind {
@@ -1232,7 +1232,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 );
                 let fields_omitted = match &se.rest {
                     StructRest::Base(e) => {
-                        self.tcx.sess.emit_err(FunctionalRecordUpdateDestructuringAssignemnt {
+                        self.tcx.sess.emit_err(FunctionalRecordUpdateDestructuringAssignment {
                             span: e.span,
                         });
                         true

compiler/rustc_ast_lowering/src/lib.rs

@@ -987,15 +987,22 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 GenericArgs::AngleBracketed(data) => {
                     self.lower_angle_bracketed_parameter_data(data, ParamMode::Explicit, itctx).0
                 }
-                &GenericArgs::ReturnTypeNotation(span) => GenericArgsCtor {
-                    args: Default::default(),
-                    bindings: &[],
-                    parenthesized: hir::GenericArgsParentheses::ReturnTypeNotation,
-                    span,
-                },
                 GenericArgs::Parenthesized(data) => {
-                    if let Some(start_char) = constraint.ident.as_str().chars().next()
-                        && start_char.is_ascii_lowercase()
+                    if data.inputs.is_empty() && matches!(data.output, FnRetTy::Default(..)) {
+                        let parenthesized = if self.tcx.features().return_type_notation {
+                            hir::GenericArgsParentheses::ReturnTypeNotation
+                        } else {
+                            self.emit_bad_parenthesized_trait_in_assoc_ty(data);
+                            hir::GenericArgsParentheses::No
+                        };
+                        GenericArgsCtor {
+                            args: Default::default(),
+                            bindings: &[],
+                            parenthesized,
+                            span: data.inputs_span,
+                        }
+                    } else if let Some(first_char) = constraint.ident.as_str().chars().next()
+                        && first_char.is_ascii_lowercase()
                     {
                         let mut err = if !data.inputs.is_empty() {
                             self.tcx.sess.create_err(errors::BadReturnTypeNotation::Inputs {
@@ -1006,9 +1013,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                                 span: data.inputs_span.shrink_to_hi().to(ty.span),
                             })
                         } else {
-                            self.tcx.sess.create_err(errors::BadReturnTypeNotation::NeedsDots {
-                                span: data.inputs_span,
-                            })
+                            unreachable!("inputs are empty and return type is not provided")
                         };
                         if !self.tcx.features().return_type_notation
                             && self.tcx.sess.is_nightly_build()

compiler/rustc_ast_lowering/src/path.rs

@@ -13,7 +13,6 @@ use rustc_span::symbol::{kw, sym, Ident};
 use rustc_span::{BytePos, Span, DUMMY_SP};
 
 use smallvec::{smallvec, SmallVec};
-use thin_vec::ThinVec;
 
 impl<'a, 'hir> LoweringContext<'a, 'hir> {
     #[instrument(level = "trace", skip(self))]
@@ -219,18 +218,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                         )
                     }
                 },
-                &GenericArgs::ReturnTypeNotation(span) => {
-                    self.tcx.sess.emit_err(GenericTypeWithParentheses { span, sub: None });
-                    (
-                        self.lower_angle_bracketed_parameter_data(
-                            &AngleBracketedArgs { span, args: ThinVec::default() },
-                            param_mode,
-                            itctx,
-                        )
-                        .0,
-                        false,
-                    )
-                }
             }
         } else {
             (

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -1080,7 +1080,6 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                     self.with_impl_trait(None, |this| this.visit_ty(ty));
                 }
             }
-            GenericArgs::ReturnTypeNotation(_span) => {}
         }
     }
 
@@ -1391,7 +1390,6 @@ fn deny_equality_constraints(
                                     match &mut assoc_path.segments[len].args {
                                         Some(args) => match args.deref_mut() {
                                             GenericArgs::Parenthesized(_) => continue,
-                                            GenericArgs::ReturnTypeNotation(_span) => continue,
                                             GenericArgs::AngleBracketed(args) => {
                                                 args.args.push(arg);
                                             }

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -121,24 +121,34 @@ impl<'a> PostExpansionVisitor<'a> {
     }
 
     /// Feature gate `impl Trait` inside `type Alias = $type_expr;`.
-    fn check_impl_trait(&self, ty: &ast::Ty) {
+    fn check_impl_trait(&self, ty: &ast::Ty, in_associated_ty: bool) {
         struct ImplTraitVisitor<'a> {
             vis: &'a PostExpansionVisitor<'a>,
+            in_associated_ty: bool,
         }
         impl Visitor<'_> for ImplTraitVisitor<'_> {
             fn visit_ty(&mut self, ty: &ast::Ty) {
                 if let ast::TyKind::ImplTrait(..) = ty.kind {
-                    gate_feature_post!(
-                        &self.vis,
-                        type_alias_impl_trait,
-                        ty.span,
-                        "`impl Trait` in type aliases is unstable"
-                    );
+                    if self.in_associated_ty {
+                        gate_feature_post!(
+                            &self.vis,
+                            impl_trait_in_assoc_type,
+                            ty.span,
+                            "`impl Trait` in associated types is unstable"
+                        );
+                    } else {
+                        gate_feature_post!(
+                            &self.vis,
+                            type_alias_impl_trait,
+                            ty.span,
+                            "`impl Trait` in type aliases is unstable"
+                        );
+                    }
                 }
                 visit::walk_ty(self, ty);
             }
         }
-        ImplTraitVisitor { vis: self }.visit_ty(ty);
+        ImplTraitVisitor { vis: self, in_associated_ty }.visit_ty(ty);
     }
 
     fn check_late_bound_lifetime_defs(&self, params: &[ast::GenericParam]) {
@@ -294,7 +304,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
             }
 
             ast::ItemKind::TyAlias(box ast::TyAlias { ty: Some(ty), .. }) => {
-                self.check_impl_trait(&ty)
+                self.check_impl_trait(&ty, false)
             }
 
             _ => {}
@@ -485,20 +495,23 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
 
     fn visit_assoc_constraint(&mut self, constraint: &'a AssocConstraint) {
         if let AssocConstraintKind::Bound { .. } = constraint.kind {
-            if let Some(args) = constraint.gen_args.as_ref()
-                && matches!(
-                    args,
-                    ast::GenericArgs::ReturnTypeNotation(..)
-                )
+            if let Some(ast::GenericArgs::Parenthesized(args)) = constraint.gen_args.as_ref()
+                && args.inputs.is_empty()
+                && matches!(args.output, ast::FnRetTy::Default(..))
             {
-                // RTN is gated below with a `gate_all`.
+                gate_feature_post!(
+                    &self,
+                    return_type_notation,
+                    constraint.span,
+                    "return type notation is experimental"
+                );
             } else {
                 gate_feature_post!(
                     &self,
                     associated_type_bounds,
                     constraint.span,
                     "associated type bounds are unstable"
-                )
+                );
             }
         }
         visit::walk_assoc_constraint(self, constraint)
@@ -517,7 +530,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                     );
                 }
                 if let Some(ty) = ty {
-                    self.check_impl_trait(ty);
+                    self.check_impl_trait(ty, true);
                 }
                 false
             }
@@ -589,7 +602,6 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session) {
     gate_all!(yeet_expr, "`do yeet` expression is experimental");
     gate_all!(dyn_star, "`dyn*` trait objects are experimental");
     gate_all!(const_closures, "const closures are experimental");
-    gate_all!(return_type_notation, "return type notation is experimental");
 
     // All uses of `gate_all!` below this point were added in #65742,
     // and subsequently disabled (with the non-early gating readded).
@@ -605,6 +617,7 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session) {
 
     gate_all!(trait_alias, "trait aliases are experimental");
     gate_all!(associated_type_bounds, "associated type bounds are unstable");
+    gate_all!(return_type_notation, "return type notation is experimental");
     gate_all!(decl_macro, "`macro` is experimental");
     gate_all!(box_patterns, "box pattern syntax is experimental");
     gate_all!(exclusive_range_pattern, "exclusive range pattern syntax is experimental");

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -936,10 +936,6 @@ impl<'a> PrintState<'a> for State<'a> {
                 self.word(")");
                 self.print_fn_ret_ty(&data.output);
             }
-
-            ast::GenericArgs::ReturnTypeNotation(_span) => {
-                self.word("(..)");
-            }
         }
     }
 }