Merge remote-tracking branch 'origin/master' into mpk/add-long-error-message-for-E0311

10 files changed, 321 insertions, 173 deletions

diff --git a/compiler/rustc_parse/src/parser/attr.rs b/compiler/rustc_parse/src/parser/attr.rs
index 72ab96b5ca6..5fd69b15ecc 100644
--- a/compiler/rustc_parse/src/parser/attr.rs
+++ b/compiler/rustc_parse/src/parser/attr.rs
@@ -7,8 +7,6 @@ use rustc_errors::{error_code, Diagnostic, PResult};
 use rustc_span::{sym, BytePos, Span};
 use std::convert::TryInto;
 
-use tracing::debug;
-
 // Public for rustfmt usage
 #[derive(Debug)]
 pub enum InnerAttrPolicy<'a> {
@@ -89,6 +87,7 @@ impl<'a> Parser<'a> {
                 // Always make an outer attribute - this allows us to recover from a misplaced
                 // inner attribute.
                 Some(attr::mk_doc_comment(
+                    &self.sess.attr_id_generator,
                     comment_kind,
                     ast::AttrStyle::Outer,
                     data,
@@ -140,7 +139,13 @@ impl<'a> Parser<'a> {
                     this.error_on_forbidden_inner_attr(attr_sp, inner_parse_policy);
                 }
 
-                Ok(attr::mk_attr_from_item(item, None, style, attr_sp))
+                Ok(attr::mk_attr_from_item(
+                    &self.sess.attr_id_generator,
+                    item,
+                    None,
+                    style,
+                    attr_sp,
+                ))
             } else {
                 let token_str = pprust::token_to_string(&this.token);
                 let msg = &format!("expected `#`, found `{token_str}`");
@@ -293,7 +298,13 @@ impl<'a> Parser<'a> {
             } else if let token::DocComment(comment_kind, attr_style, data) = self.token.kind {
                 if attr_style == ast::AttrStyle::Inner {
                     self.bump();
-                    Some(attr::mk_doc_comment(comment_kind, attr_style, data, self.prev_token.span))
+                    Some(attr::mk_doc_comment(
+                        &self.sess.attr_id_generator,
+                        comment_kind,
+                        attr_style,
+                        data,
+                        self.prev_token.span,
+                    ))
                 } else {
                     None
                 }
@@ -303,9 +314,9 @@ impl<'a> Parser<'a> {
             if let Some(attr) = attr {
                 let end_pos: u32 = self.token_cursor.num_next_calls.try_into().unwrap();
                 // If we are currently capturing tokens, mark the location of this inner attribute.
-                // If capturing ends up creating a `LazyTokenStream`, we will include
+                // If capturing ends up creating a `LazyAttrTokenStream`, we will include
                 // this replace range with it, removing the inner attribute from the final
-                // `AttrAnnotatedTokenStream`. Inner attributes are stored in the parsed AST note.
+                // `AttrTokenStream`. Inner attributes are stored in the parsed AST note.
                 // During macro expansion, they are selectively inserted back into the
                 // token stream (the first inner attribute is removed each time we invoke the
                 // corresponding macro).
diff --git a/compiler/rustc_parse/src/parser/attr_wrapper.rs b/compiler/rustc_parse/src/parser/attr_wrapper.rs
index b564f4ad92c..86c386b94c8 100644
--- a/compiler/rustc_parse/src/parser/attr_wrapper.rs
+++ b/compiler/rustc_parse/src/parser/attr_wrapper.rs
@@ -1,7 +1,7 @@
 use super::{Capturing, FlatToken, ForceCollect, Parser, ReplaceRange, TokenCursor, TrailingToken};
 use rustc_ast::token::{self, Delimiter, Token, TokenKind};
-use rustc_ast::tokenstream::{AttrAnnotatedTokenStream, AttributesData, CreateTokenStream};
-use rustc_ast::tokenstream::{AttrAnnotatedTokenTree, DelimSpan, LazyTokenStream, Spacing};
+use rustc_ast::tokenstream::{AttrTokenStream, AttributesData, ToAttrTokenStream};
+use rustc_ast::tokenstream::{AttrTokenTree, DelimSpan, LazyAttrTokenStream, Spacing};
 use rustc_ast::{self as ast};
 use rustc_ast::{AttrVec, Attribute, HasAttrs, HasTokens};
 use rustc_errors::PResult;
@@ -52,7 +52,7 @@ impl AttrWrapper {
     // Prepend `self.attrs` to `attrs`.
     // FIXME: require passing an NT to prevent misuse of this method
     pub(crate) fn prepend_to_nt_inner(self, attrs: &mut AttrVec) {
-        let mut self_attrs = self.attrs.clone();
+        let mut self_attrs = self.attrs;
         std::mem::swap(attrs, &mut self_attrs);
         attrs.extend(self_attrs);
     }
@@ -88,7 +88,7 @@ fn has_cfg_or_cfg_attr(attrs: &[Attribute]) -> bool {
 // This also makes `Parser` very cheap to clone, since
 // there is no intermediate collection buffer to clone.
 #[derive(Clone)]
-struct LazyTokenStreamImpl {
+struct LazyAttrTokenStreamImpl {
     start_token: (Token, Spacing),
     cursor_snapshot: TokenCursor,
     num_calls: usize,
@@ -97,10 +97,10 @@ struct LazyTokenStreamImpl {
 }
 
 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
-rustc_data_structures::static_assert_size!(LazyTokenStreamImpl, 144);
+rustc_data_structures::static_assert_size!(LazyAttrTokenStreamImpl, 144);
 
-impl CreateTokenStream for LazyTokenStreamImpl {
-    fn create_token_stream(&self) -> AttrAnnotatedTokenStream {
+impl ToAttrTokenStream for LazyAttrTokenStreamImpl {
+    fn to_attr_token_stream(&self) -> AttrTokenStream {
         // The token produced by the final call to `{,inlined_}next` was not
         // actually consumed by the callback. The combination of chaining the
         // initial token and using `take` produces the desired result - we
@@ -179,7 +179,7 @@ impl CreateTokenStream for LazyTokenStreamImpl {
 impl<'a> Parser<'a> {
     /// Records all tokens consumed by the provided callback,
     /// including the current token. These tokens are collected
-    /// into a `LazyTokenStream`, and returned along with the result
+    /// into a `LazyAttrTokenStream`, and returned along with the result
     /// of the callback.
     ///
     /// Note: If your callback consumes an opening delimiter
@@ -297,8 +297,8 @@ impl<'a> Parser<'a> {
 
         // If we 'broke' the last token (e.g. breaking a '>>' token to two '>' tokens),
         // then extend the range of captured tokens to include it, since the parser
-        // was not actually bumped past it. When the `LazyTokenStream` gets converted
-        // into an `AttrAnnotatedTokenStream`, we will create the proper token.
+        // was not actually bumped past it. When the `LazyAttrTokenStream` gets converted
+        // into an `AttrTokenStream`, we will create the proper token.
         if self.token_cursor.break_last_token {
             assert_eq!(
                 trailing,
@@ -316,8 +316,8 @@ impl<'a> Parser<'a> {
             Box::new([])
         } else {
             // Grab any replace ranges that occur *inside* the current AST node.
-            // We will perform the actual replacement when we convert the `LazyTokenStream`
-            // to an `AttrAnnotatedTokenStream`
+            // We will perform the actual replacement when we convert the `LazyAttrTokenStream`
+            // to an `AttrTokenStream`.
             let start_calls: u32 = cursor_snapshot_next_calls.try_into().unwrap();
             self.capture_state.replace_ranges[replace_ranges_start..replace_ranges_end]
                 .iter()
@@ -329,7 +329,7 @@ impl<'a> Parser<'a> {
                 .collect()
         };
 
-        let tokens = LazyTokenStream::new(LazyTokenStreamImpl {
+        let tokens = LazyAttrTokenStream::new(LazyAttrTokenStreamImpl {
             start_token,
             num_calls,
             cursor_snapshot,
@@ -355,7 +355,7 @@ impl<'a> Parser<'a> {
             && matches!(self.capture_state.capturing, Capturing::Yes)
             && has_cfg_or_cfg_attr(final_attrs)
         {
-            let attr_data = AttributesData { attrs: final_attrs.to_vec().into(), tokens };
+            let attr_data = AttributesData { attrs: final_attrs.iter().cloned().collect(), tokens };
 
             // Replace the entire AST node that we just parsed, including attributes,
             // with a `FlatToken::AttrTarget`. If this AST node is inside an item
@@ -392,12 +392,12 @@ impl<'a> Parser<'a> {
 fn make_token_stream(
     mut iter: impl Iterator<Item = (FlatToken, Spacing)>,
     break_last_token: bool,
-) -> AttrAnnotatedTokenStream {
+) -> AttrTokenStream {
     #[derive(Debug)]
     struct FrameData {
         // This is `None` for the first frame, `Some` for all others.
         open_delim_sp: Option<(Delimiter, Span)>,
-        inner: Vec<(AttrAnnotatedTokenTree, Spacing)>,
+        inner: Vec<AttrTokenTree>,
     }
     let mut stack = vec![FrameData { open_delim_sp: None, inner: vec![] }];
     let mut token_and_spacing = iter.next();
@@ -418,48 +418,46 @@ fn make_token_stream(
                     open_delim, span
                 );
                 let dspan = DelimSpan::from_pair(open_sp, span);
-                let stream = AttrAnnotatedTokenStream::new(frame_data.inner);
-                let delimited = AttrAnnotatedTokenTree::Delimited(dspan, delim, stream);
+                let stream = AttrTokenStream::new(frame_data.inner);
+                let delimited = AttrTokenTree::Delimited(dspan, delim, stream);
                 stack
                     .last_mut()
                     .unwrap_or_else(|| {
                         panic!("Bottom token frame is missing for token: {:?}", token)
                     })
                     .inner
-                    .push((delimited, Spacing::Alone));
+                    .push(delimited);
             }
             FlatToken::Token(token) => stack
                 .last_mut()
                 .expect("Bottom token frame is missing!")
                 .inner
-                .push((AttrAnnotatedTokenTree::Token(token), spacing)),
+                .push(AttrTokenTree::Token(token, spacing)),
             FlatToken::AttrTarget(data) => stack
                 .last_mut()
                 .expect("Bottom token frame is missing!")
                 .inner
-                .push((AttrAnnotatedTokenTree::Attributes(data), spacing)),
+                .push(AttrTokenTree::Attributes(data)),
             FlatToken::Empty => {}
         }
         token_and_spacing = iter.next();
     }
     let mut final_buf = stack.pop().expect("Missing final buf!");
     if break_last_token {
-        let (last_token, spacing) = final_buf.inner.pop().unwrap();
-        if let AttrAnnotatedTokenTree::Token(last_token) = last_token {
+        let last_token = final_buf.inner.pop().unwrap();
+        if let AttrTokenTree::Token(last_token, spacing) = last_token {
             let unglued_first = last_token.kind.break_two_token_op().unwrap().0;
 
             // An 'unglued' token is always two ASCII characters
             let mut first_span = last_token.span.shrink_to_lo();
             first_span = first_span.with_hi(first_span.lo() + rustc_span::BytePos(1));
 
-            final_buf.inner.push((
-                AttrAnnotatedTokenTree::Token(Token::new(unglued_first, first_span)),
-                spacing,
-            ));
+            final_buf
+                .inner
+                .push(AttrTokenTree::Token(Token::new(unglued_first, first_span), spacing));
         } else {
             panic!("Unexpected last token {:?}", last_token)
         }
     }
-    assert!(stack.is_empty(), "Stack should be empty: final_buf={:?} stack={:?}", final_buf, stack);
-    AttrAnnotatedTokenStream::new(final_buf.inner)
+    AttrTokenStream::new(final_buf.inner)
 }
diff --git a/compiler/rustc_parse/src/parser/diagnostics.rs b/compiler/rustc_parse/src/parser/diagnostics.rs
index f0ea1dfe297..ccdffb8ce07 100644
--- a/compiler/rustc_parse/src/parser/diagnostics.rs
+++ b/compiler/rustc_parse/src/parser/diagnostics.rs
@@ -10,9 +10,9 @@ use rustc_ast::ptr::P;
 use rustc_ast::token::{self, Delimiter, Lit, LitKind, TokenKind};
 use rustc_ast::util::parser::AssocOp;
 use rustc_ast::{
-    AngleBracketedArg, AngleBracketedArgs, AnonConst, AttrVec, BinOpKind, BindingMode, Block,
-    BlockCheckMode, Expr, ExprKind, GenericArg, Generics, Item, ItemKind, Mutability, Param, Pat,
-    PatKind, Path, PathSegment, QSelf, Ty, TyKind,
+    AngleBracketedArg, AngleBracketedArgs, AnonConst, AttrVec, BinOpKind, BindingAnnotation, Block,
+    BlockCheckMode, Expr, ExprKind, GenericArg, Generics, Item, ItemKind, Param, Pat, PatKind,
+    Path, PathSegment, QSelf, Ty, TyKind,
 };
 use rustc_ast_pretty::pprust;
 use rustc_data_structures::fx::FxHashSet;
@@ -20,7 +20,7 @@ use rustc_errors::{
     fluent, Applicability, DiagnosticBuilder, DiagnosticMessage, Handler, MultiSpan, PResult,
 };
 use rustc_errors::{pluralize, struct_span_err, Diagnostic, ErrorGuaranteed};
-use rustc_macros::{SessionDiagnostic, SessionSubdiagnostic};
+use rustc_macros::{Diagnostic, Subdiagnostic};
 use rustc_span::source_map::Spanned;
 use rustc_span::symbol::{kw, sym, Ident};
 use rustc_span::{Span, SpanSnippetError, DUMMY_SP};
@@ -29,7 +29,6 @@ use std::ops::{Deref, DerefMut};
 use std::mem::take;
 
 use crate::parser;
-use tracing::{debug, trace};
 
 const TURBOFISH_SUGGESTION_STR: &str =
     "use `::<...>` instead of `<...>` to specify lifetime, type, or const arguments";
@@ -38,7 +37,7 @@ const TURBOFISH_SUGGESTION_STR: &str =
 pub(super) fn dummy_arg(ident: Ident) -> Param {
     let pat = P(Pat {
         id: ast::DUMMY_NODE_ID,
-        kind: PatKind::Ident(BindingMode::ByValue(Mutability::Not), ident, None),
+        kind: PatKind::Ident(BindingAnnotation::NONE, ident, None),
         span: ident.span,
         tokens: None,
     });
@@ -243,7 +242,7 @@ impl MultiSugg {
     }
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::maybe_report_ambiguous_plus)]
 struct AmbiguousPlus {
     pub sum_ty: String,
@@ -252,7 +251,7 @@ struct AmbiguousPlus {
     pub span: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::maybe_recover_from_bad_type_plus, code = "E0178")]
 struct BadTypePlus {
     pub ty: String,
@@ -262,7 +261,7 @@ struct BadTypePlus {
     pub sub: BadTypePlusSub,
 }
 
-#[derive(SessionSubdiagnostic)]
+#[derive(Subdiagnostic)]
 pub enum BadTypePlusSub {
     #[suggestion(
         parser::add_paren,
@@ -286,35 +285,35 @@ pub enum BadTypePlusSub {
     },
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::maybe_recover_from_bad_qpath_stage_2)]
 struct BadQPathStage2 {
     #[primary_span]
-    #[suggestion(applicability = "maybe-incorrect")]
+    #[suggestion(code = "", applicability = "maybe-incorrect")]
     span: Span,
     ty: String,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::incorrect_semicolon)]
 struct IncorrectSemicolon<'a> {
     #[primary_span]
-    #[suggestion_short(applicability = "machine-applicable")]
+    #[suggestion_short(code = "", applicability = "machine-applicable")]
     span: Span,
     #[help]
     opt_help: Option<()>,
     name: &'a str,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::incorrect_use_of_await)]
 struct IncorrectUseOfAwait {
     #[primary_span]
-    #[suggestion(parser::parentheses_suggestion, applicability = "machine-applicable")]
+    #[suggestion(parser::parentheses_suggestion, code = "", applicability = "machine-applicable")]
     span: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::incorrect_use_of_await)]
 struct IncorrectAwait {
     #[primary_span]
@@ -325,16 +324,16 @@ struct IncorrectAwait {
     question_mark: &'static str,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::in_in_typo)]
 struct InInTypo {
     #[primary_span]
     span: Span,
-    #[suggestion(applicability = "machine-applicable")]
+    #[suggestion(code = "", applicability = "machine-applicable")]
     sugg_span: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::invalid_variable_declaration)]
 pub struct InvalidVariableDeclaration {
     #[primary_span]
@@ -343,7 +342,7 @@ pub struct InvalidVariableDeclaration {
     pub sub: InvalidVariableDeclarationSub,
 }
 
-#[derive(SessionSubdiagnostic)]
+#[derive(Subdiagnostic)]
 pub enum InvalidVariableDeclarationSub {
     #[suggestion(
         parser::switch_mut_let_order,
@@ -363,7 +362,7 @@ pub enum InvalidVariableDeclarationSub {
     UseLetNotVar(#[primary_span] Span),
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::invalid_comparison_operator)]
 pub(crate) struct InvalidComparisonOperator {
     #[primary_span]
@@ -373,7 +372,7 @@ pub(crate) struct InvalidComparisonOperator {
     pub sub: InvalidComparisonOperatorSub,
 }
 
-#[derive(SessionSubdiagnostic)]
+#[derive(Subdiagnostic)]
 pub(crate) enum InvalidComparisonOperatorSub {
     #[suggestion_short(
         parser::use_instead,
@@ -390,7 +389,7 @@ pub(crate) enum InvalidComparisonOperatorSub {
     Spaceship(#[primary_span] Span),
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::invalid_logical_operator)]
 #[note]
 pub(crate) struct InvalidLogicalOperator {
@@ -401,7 +400,7 @@ pub(crate) struct InvalidLogicalOperator {
     pub sub: InvalidLogicalOperatorSub,
 }
 
-#[derive(SessionSubdiagnostic)]
+#[derive(Subdiagnostic)]
 pub(crate) enum InvalidLogicalOperatorSub {
     #[suggestion_short(
         parser::use_amp_amp_for_conjunction,
@@ -417,7 +416,7 @@ pub(crate) enum InvalidLogicalOperatorSub {
     Disjunction(#[primary_span] Span),
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::tilde_is_not_unary_operator)]
 pub(crate) struct TildeAsUnaryOperator(
     #[primary_span]
@@ -425,17 +424,41 @@ pub(crate) struct TildeAsUnaryOperator(
     pub Span,
 );
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::unexpected_token_after_not)]
 pub(crate) struct NotAsNegationOperator {
     #[primary_span]
     pub negated: Span,
     pub negated_desc: String,
-    #[suggestion_short(applicability = "machine-applicable", code = "!")]
-    pub not: Span,
+    #[subdiagnostic]
+    pub sub: NotAsNegationOperatorSub,
+}
+
+#[derive(Subdiagnostic)]
+pub enum NotAsNegationOperatorSub {
+    #[suggestion_short(
+        parser::unexpected_token_after_not_default,
+        applicability = "machine-applicable",
+        code = "!"
+    )]
+    SuggestNotDefault(#[primary_span] Span),
+
+    #[suggestion_short(
+        parser::unexpected_token_after_not_bitwise,
+        applicability = "machine-applicable",
+        code = "!"
+    )]
+    SuggestNotBitwise(#[primary_span] Span),
+
+    #[suggestion_short(
+        parser::unexpected_token_after_not_logical,
+        applicability = "machine-applicable",
+        code = "!"
+    )]
+    SuggestNotLogical(#[primary_span] Span),
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::malformed_loop_label)]
 pub(crate) struct MalformedLoopLabel {
     #[primary_span]
@@ -444,7 +467,7 @@ pub(crate) struct MalformedLoopLabel {
     pub correct_label: Ident,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::lifetime_in_borrow_expression)]
 pub(crate) struct LifetimeInBorrowExpression {
     #[primary_span]
@@ -454,15 +477,15 @@ pub(crate) struct LifetimeInBorrowExpression {
     pub lifetime_span: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::field_expression_with_generic)]
 pub(crate) struct FieldExpressionWithGeneric(#[primary_span] pub Span);
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::macro_invocation_with_qualified_path)]
 pub(crate) struct MacroInvocationWithQualifiedPath(#[primary_span] pub Span);
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::unexpected_token_after_label)]
 pub(crate) struct UnexpectedTokenAfterLabel(
     #[primary_span]
@@ -470,7 +493,7 @@ pub(crate) struct UnexpectedTokenAfterLabel(
     pub Span,
 );
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::require_colon_after_labeled_expression)]
 #[note]
 pub(crate) struct RequireColonAfterLabeledExpression {
@@ -482,7 +505,7 @@ pub(crate) struct RequireColonAfterLabeledExpression {
     pub label_end: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::do_catch_syntax_removed)]
 #[note]
 pub(crate) struct DoCatchSyntaxRemoved {
@@ -491,7 +514,7 @@ pub(crate) struct DoCatchSyntaxRemoved {
     pub span: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::float_literal_requires_integer_part)]
 pub(crate) struct FloatLiteralRequiresIntegerPart {
     #[primary_span]
@@ -500,7 +523,7 @@ pub(crate) struct FloatLiteralRequiresIntegerPart {
     pub correct: String,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::invalid_int_literal_width)]
 #[help]
 pub(crate) struct InvalidIntLiteralWidth {
@@ -509,7 +532,7 @@ pub(crate) struct InvalidIntLiteralWidth {
     pub width: String,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::invalid_num_literal_base_prefix)]
 #[note]
 pub(crate) struct InvalidNumLiteralBasePrefix {
@@ -519,7 +542,7 @@ pub(crate) struct InvalidNumLiteralBasePrefix {
     pub fixed: String,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::invalid_num_literal_suffix)]
 #[help]
 pub(crate) struct InvalidNumLiteralSuffix {
@@ -529,7 +552,7 @@ pub(crate) struct InvalidNumLiteralSuffix {
     pub suffix: String,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::invalid_float_literal_width)]
 #[help]
 pub(crate) struct InvalidFloatLiteralWidth {
@@ -538,7 +561,7 @@ pub(crate) struct InvalidFloatLiteralWidth {
     pub width: String,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::invalid_float_literal_suffix)]
 #[help]
 pub(crate) struct InvalidFloatLiteralSuffix {
@@ -548,14 +571,14 @@ pub(crate) struct InvalidFloatLiteralSuffix {
     pub suffix: String,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::int_literal_too_large)]
 pub(crate) struct IntLiteralTooLarge {
     #[primary_span]
     pub span: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::missing_semicolon_before_array)]
 pub(crate) struct MissingSemicolonBeforeArray {
     #[primary_span]
@@ -564,7 +587,7 @@ pub(crate) struct MissingSemicolonBeforeArray {
     pub semicolon: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::invalid_block_macro_segment)]
 pub(crate) struct InvalidBlockMacroSegment {
     #[primary_span]
@@ -573,7 +596,7 @@ pub(crate) struct InvalidBlockMacroSegment {
     pub context: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::if_expression_missing_then_block)]
 pub(crate) struct IfExpressionMissingThenBlock {
     #[primary_span]
@@ -582,7 +605,7 @@ pub(crate) struct IfExpressionMissingThenBlock {
     pub sub: IfExpressionMissingThenBlockSub,
 }
 
-#[derive(SessionSubdiagnostic)]
+#[derive(Subdiagnostic)]
 pub(crate) enum IfExpressionMissingThenBlockSub {
     #[help(parser::condition_possibly_unfinished)]
     UnfinishedCondition(#[primary_span] Span),
@@ -590,7 +613,7 @@ pub(crate) enum IfExpressionMissingThenBlockSub {
     AddThenBlock(#[primary_span] Span),
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::if_expression_missing_condition)]
 pub(crate) struct IfExpressionMissingCondition {
     #[primary_span]
@@ -600,14 +623,14 @@ pub(crate) struct IfExpressionMissingCondition {
     pub block_span: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::expected_expression_found_let)]
 pub(crate) struct ExpectedExpressionFoundLet {
     #[primary_span]
     pub span: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::expected_else_block)]
 pub(crate) struct ExpectedElseBlock {
     #[primary_span]
@@ -619,7 +642,7 @@ pub(crate) struct ExpectedElseBlock {
     pub condition_start: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::outer_attribute_not_allowed_on_if_else)]
 pub(crate) struct OuterAttributeNotAllowedOnIfElse {
     #[primary_span]
@@ -636,7 +659,7 @@ pub(crate) struct OuterAttributeNotAllowedOnIfElse {
     pub attributes: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::missing_in_in_for_loop)]
 pub(crate) struct MissingInInForLoop {
     #[primary_span]
@@ -645,7 +668,7 @@ pub(crate) struct MissingInInForLoop {
     pub sub: MissingInInForLoopSub,
 }
 
-#[derive(SessionSubdiagnostic)]
+#[derive(Subdiagnostic)]
 pub(crate) enum MissingInInForLoopSub {
     // Has been misleading, at least in the past (closed Issue #48492), thus maybe-incorrect
     #[suggestion_short(parser::use_in_not_of, applicability = "maybe-incorrect", code = "in")]
@@ -654,7 +677,7 @@ pub(crate) enum MissingInInForLoopSub {
     AddIn(#[primary_span] Span),
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::missing_comma_after_match_arm)]
 pub(crate) struct MissingCommaAfterMatchArm {
     #[primary_span]
@@ -662,7 +685,7 @@ pub(crate) struct MissingCommaAfterMatchArm {
     pub span: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::catch_after_try)]
 #[help]
 pub(crate) struct CatchAfterTry {
@@ -670,7 +693,7 @@ pub(crate) struct CatchAfterTry {
     pub span: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::comma_after_base_struct)]
 #[note]
 pub(crate) struct CommaAfterBaseStruct {
@@ -680,7 +703,7 @@ pub(crate) struct CommaAfterBaseStruct {
     pub comma: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::eq_field_init)]
 pub(crate) struct EqFieldInit {
     #[primary_span]
@@ -689,7 +712,7 @@ pub(crate) struct EqFieldInit {
     pub eq: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::dotdotdot)]
 pub(crate) struct DotDotDot {
     #[primary_span]
@@ -698,7 +721,7 @@ pub(crate) struct DotDotDot {
     pub span: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::left_arrow_operator)]
 pub(crate) struct LeftArrowOperator {
     #[primary_span]
@@ -706,6 +729,30 @@ pub(crate) struct LeftArrowOperator {
     pub span: Span,
 }
 
+#[derive(Diagnostic)]
+#[diag(parser::remove_let)]
+pub(crate) struct RemoveLet {
+    #[primary_span]
+    #[suggestion(applicability = "machine-applicable", code = "")]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(parser::use_eq_instead)]
+pub(crate) struct UseEqInstead {
+    #[primary_span]
+    #[suggestion_short(applicability = "machine-applicable", code = "=")]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(parser::use_empty_block_not_semi)]
+pub(crate) struct UseEmptyBlockNotSemi {
+    #[primary_span]
+    #[suggestion_hidden(applicability = "machine-applicable", code = "{{}}")]
+    pub span: Span,
+}
+
 // SnapshotParser is used to create a snapshot of the parser
 // without causing duplicate errors being emitted when the `Parser`
 // is dropped.
@@ -950,6 +997,14 @@ impl<'a> Parser<'a> {
             }
         }
 
+        if self.token.kind == TokenKind::EqEq
+            && self.prev_token.is_ident()
+            && expected.iter().any(|tok| matches!(tok, TokenType::Token(TokenKind::Eq)))
+        {
+            // Likely typo: `=` → `==` in let expr or enum item
+            return Err(self.sess.create_err(UseEqInstead { span: self.token.span }));
+        }
+
         let expect = tokens_to_string(&expected);
         let actual = super::token_descr(&self.token);
         let (msg_exp, (label_sp, label_exp)) = if expected.len() > 1 {
@@ -2962,7 +3017,7 @@ impl<'a> Parser<'a> {
                                 }
                                 _ => {}
                             },
-                            PatKind::Ident(BindingMode::ByValue(Mutability::Not), ident, None) => {
+                            PatKind::Ident(BindingAnnotation::NONE, ident, None) => {
                                 match &first_pat.kind {
                                     PatKind::Ident(_, old_ident, _) => {
                                         let path = PatKind::Path(
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index c8541609514..ae77961b7bc 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -6,8 +6,9 @@ use super::diagnostics::{
     InvalidComparisonOperatorSub, InvalidLogicalOperator, InvalidLogicalOperatorSub,
     LeftArrowOperator, LifetimeInBorrowExpression, MacroInvocationWithQualifiedPath,
     MalformedLoopLabel, MissingInInForLoop, MissingInInForLoopSub, MissingSemicolonBeforeArray,
-    NotAsNegationOperator, OuterAttributeNotAllowedOnIfElse, RequireColonAfterLabeledExpression,
-    SnapshotParser, TildeAsUnaryOperator, UnexpectedTokenAfterLabel,
+    NotAsNegationOperator, NotAsNegationOperatorSub, OuterAttributeNotAllowedOnIfElse,
+    RequireColonAfterLabeledExpression, SnapshotParser, TildeAsUnaryOperator,
+    UnexpectedTokenAfterLabel,
 };
 use super::pat::{CommaRecoveryMode, RecoverColon, RecoverComma, PARAM_EXPECTED};
 use super::ty::{AllowPlus, RecoverQPath, RecoverReturnSign};
@@ -35,10 +36,10 @@ use rustc_ast::{AnonConst, BinOp, BinOpKind, FnDecl, FnRetTy, MacCall, Param, Ty
 use rustc_ast::{Arm, Async, BlockCheckMode, Expr, ExprKind, Label, Movability, RangeLimits};
 use rustc_ast::{ClosureBinder, StmtKind};
 use rustc_ast_pretty::pprust;
+use rustc_errors::IntoDiagnostic;
 use rustc_errors::{Applicability, Diagnostic, PResult};
 use rustc_session::lint::builtin::BREAK_WITH_LABEL_AND_LOOP;
 use rustc_session::lint::BuiltinLintDiagnostics;
-use rustc_session::SessionDiagnostic;
 use rustc_span::source_map::{self, Span, Spanned};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{BytePos, Pos};
@@ -660,12 +661,23 @@ impl<'a> Parser<'a> {
     fn recover_not_expr(&mut self, lo: Span) -> PResult<'a, (Span, ExprKind)> {
         // Emit the error...
         let negated_token = self.look_ahead(1, |t| t.clone());
+
+        let sub_diag = if negated_token.is_numeric_lit() {
+            NotAsNegationOperatorSub::SuggestNotBitwise
+        } else if negated_token.is_bool_lit() {
+            NotAsNegationOperatorSub::SuggestNotLogical
+        } else {
+            NotAsNegationOperatorSub::SuggestNotDefault
+        };
+
         self.sess.emit_err(NotAsNegationOperator {
             negated: negated_token.span,
             negated_desc: super::token_descr(&negated_token),
             // Span the `not` plus trailing whitespace to avoid
             // trailing whitespace after the `!` in our suggestion
-            not: self.sess.source_map().span_until_non_whitespace(lo.to(negated_token.span)),
+            sub: sub_diag(
+                self.sess.source_map().span_until_non_whitespace(lo.to(negated_token.span)),
+            ),
         });
 
         // ...and recover!
@@ -944,13 +956,18 @@ impl<'a> Parser<'a> {
         // Stitch the list of outer attributes onto the return value.
         // A little bit ugly, but the best way given the current code
         // structure
-        self.parse_dot_or_call_expr_with_(e0, lo).map(|expr| {
-            expr.map(|mut expr| {
-                attrs.extend(expr.attrs);
-                expr.attrs = attrs;
-                expr
+        let res = self.parse_dot_or_call_expr_with_(e0, lo);
+        if attrs.is_empty() {
+            res
+        } else {
+            res.map(|expr| {
+                expr.map(|mut expr| {
+                    attrs.extend(expr.attrs);
+                    expr.attrs = attrs;
+                    expr
+                })
             })
-        })
+        }
     }
 
     fn parse_dot_or_call_expr_with_(&mut self, mut e: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
@@ -1578,7 +1595,7 @@ impl<'a> Parser<'a> {
                     Applicability::MachineApplicable,
                 );
 
-                // Replace `'label: non_block_expr` with `'label: {non_block_expr}` in order to supress future errors about `break 'label`.
+                // Replace `'label: non_block_expr` with `'label: {non_block_expr}` in order to suppress future errors about `break 'label`.
                 let stmt = self.mk_stmt(span, StmtKind::Expr(expr));
                 let blk = self.mk_block(vec![stmt], BlockCheckMode::Default, span);
                 self.mk_expr(span, ExprKind::Block(blk, label))
@@ -1972,6 +1989,9 @@ impl<'a> Parser<'a> {
         open_delim_span: Span,
     ) -> PResult<'a, ()> {
         if self.token.kind == token::Comma {
+            if !self.sess.source_map().is_multiline(prev_span.until(self.token.span)) {
+                return Ok(());
+            }
             let mut snapshot = self.create_snapshot_for_diagnostic();
             snapshot.bump();
             match snapshot.parse_seq_to_before_end(
@@ -1992,7 +2012,7 @@ impl<'a> Parser<'a> {
                     return Err(MissingSemicolonBeforeArray {
                         open_delim: open_delim_span,
                         semicolon: prev_span.shrink_to_hi(),
-                    }.into_diagnostic(self.sess));
+                    }.into_diagnostic(&self.sess.span_diagnostic));
                 }
                 Ok(_) => (),
                 Err(err) => err.cancel(),
@@ -2578,7 +2598,7 @@ impl<'a> Parser<'a> {
     }
 
     pub(super) fn parse_arm(&mut self) -> PResult<'a, Arm> {
-        // Used to check the `let_chains` and `if_let_guard` features mostly by scaning
+        // Used to check the `let_chains` and `if_let_guard` features mostly by scanning
         // `&&` tokens.
         fn check_let_expr(expr: &Expr) -> (bool, bool) {
             match expr.kind {
@@ -2740,7 +2760,8 @@ impl<'a> Parser<'a> {
     fn parse_try_block(&mut self, span_lo: Span) -> PResult<'a, P<Expr>> {
         let (attrs, body) = self.parse_inner_attrs_and_block()?;
         if self.eat_keyword(kw::Catch) {
-            Err(CatchAfterTry { span: self.prev_token.span }.into_diagnostic(self.sess))
+            Err(CatchAfterTry { span: self.prev_token.span }
+                .into_diagnostic(&self.sess.span_diagnostic))
         } else {
             let span = span_lo.to(body.span);
             self.sess.gated_spans.gate(sym::try_blocks, span);
diff --git a/compiler/rustc_parse/src/parser/item.rs b/compiler/rustc_parse/src/parser/item.rs
index b743162a7e4..34f25bd0716 100644
--- a/compiler/rustc_parse/src/parser/item.rs
+++ b/compiler/rustc_parse/src/parser/item.rs
@@ -1,4 +1,4 @@
-use super::diagnostics::{dummy_arg, ConsumeClosingDelim, Error};
+use super::diagnostics::{dummy_arg, ConsumeClosingDelim, Error, UseEmptyBlockNotSemi};
 use super::ty::{AllowPlus, RecoverQPath, RecoverReturnSign};
 use super::{AttrWrapper, FollowedByType, ForceCollect, Parser, PathStyle, TrailingToken};
 
@@ -8,7 +8,7 @@ use rustc_ast::token::{self, Delimiter, TokenKind};
 use rustc_ast::tokenstream::{DelimSpan, TokenStream, TokenTree};
 use rustc_ast::{self as ast, AttrVec, Attribute, DUMMY_NODE_ID};
 use rustc_ast::{Async, Const, Defaultness, IsAuto, Mutability, Unsafe, UseTree, UseTreeKind};
-use rustc_ast::{BindingMode, Block, FnDecl, FnSig, Param, SelfKind};
+use rustc_ast::{BindingAnnotation, Block, FnDecl, FnSig, Param, SelfKind};
 use rustc_ast::{EnumDef, FieldDef, Generics, TraitRef, Ty, TyKind, Variant, VariantData};
 use rustc_ast::{FnHeader, ForeignItem, Path, PathSegment, Visibility, VisibilityKind};
 use rustc_ast::{MacArgs, MacCall, MacDelimiter};
@@ -22,7 +22,6 @@ use rustc_span::DUMMY_SP;
 
 use std::convert::TryFrom;
 use std::mem;
-use tracing::debug;
 
 impl<'a> Parser<'a> {
     /// Parses a source module as a crate. This is the main entry point for the parser.
@@ -665,6 +664,14 @@ impl<'a> Parser<'a> {
         mut parse_item: impl FnMut(&mut Parser<'a>) -> PResult<'a, Option<Option<T>>>,
     ) -> PResult<'a, Vec<T>> {
         let open_brace_span = self.token.span;
+
+        // Recover `impl Ty;` instead of `impl Ty {}`
+        if self.token == TokenKind::Semi {
+            self.sess.emit_err(UseEmptyBlockNotSemi { span: self.token.span });
+            self.bump();
+            return Ok(vec![]);
+        }
+
         self.expect(&token::OpenDelim(Delimiter::Brace))?;
         attrs.extend(self.parse_inner_attributes()?);
 
@@ -699,11 +706,22 @@ impl<'a> Parser<'a> {
                     let semicolon_span = self.token.span;
                     // We have to bail or we'll potentially never make progress.
                     let non_item_span = self.token.span;
-                    self.consume_block(Delimiter::Brace, ConsumeClosingDelim::Yes);
+                    let is_let = self.token.is_keyword(kw::Let);
+
                     let mut err = self.struct_span_err(non_item_span, "non-item in item list");
-                    err.span_label(open_brace_span, "item list starts here")
-                        .span_label(non_item_span, "non-item starts here")
-                        .span_label(self.prev_token.span, "item list ends here");
+                    self.consume_block(Delimiter::Brace, ConsumeClosingDelim::Yes);
+                    if is_let {
+                        err.span_suggestion(
+                            non_item_span,
+                            "consider using `const` instead of `let` for associated const",
+                            "const",
+                            Applicability::MachineApplicable,
+                        );
+                    } else {
+                        err.span_label(open_brace_span, "item list starts here")
+                            .span_label(non_item_span, "non-item starts here")
+                            .span_label(self.prev_token.span, "item list ends here");
+                    }
                     if is_unnecessary_semicolon {
                         err.span_suggestion(
                             semicolon_span,
@@ -1295,12 +1313,19 @@ impl<'a> Parser<'a> {
         let mut generics = self.parse_generics()?;
         generics.where_clause = self.parse_where_clause()?;
 
-        let (variants, _) = self
-            .parse_delim_comma_seq(Delimiter::Brace, |p| p.parse_enum_variant())
-            .map_err(|e| {
-                self.recover_stmt();
-                e
-            })?;
+        // Possibly recover `enum Foo;` instead of `enum Foo {}`
+        let (variants, _) = if self.token == TokenKind::Semi {
+            self.sess.emit_err(UseEmptyBlockNotSemi { span: self.token.span });
+            self.bump();
+            (vec![], false)
+        } else {
+            self.parse_delim_comma_seq(Delimiter::Brace, |p| p.parse_enum_variant()).map_err(
+                |e| {
+                    self.recover_stmt();
+                    e
+                },
+            )?
+        };
 
         let enum_definition = EnumDef { variants: variants.into_iter().flatten().collect() };
         Ok((id, ItemKind::Enum(enum_definition, generics)))
@@ -1527,6 +1552,17 @@ impl<'a> Parser<'a> {
         if self.token == token::Comma {
             seen_comma = true;
         }
+        if self.eat(&token::Semi) {
+            let sp = self.prev_token.span;
+            let mut err = self.struct_span_err(sp, format!("{adt_ty} fields are separated by `,`"));
+            err.span_suggestion_short(
+                sp,
+                "replace `;` with `,`",
+                ",",
+                Applicability::MachineApplicable,
+            );
+            return Err(err);
+        }
         match self.token.kind {
             token::Comma => {
                 self.bump();
@@ -1694,6 +1730,7 @@ impl<'a> Parser<'a> {
     fn parse_field_ident(&mut self, adt_ty: &str, lo: Span) -> PResult<'a, Ident> {
         let (ident, is_raw) = self.ident_or_err()?;
         if !is_raw && ident.is_reserved() {
+            let snapshot = self.create_snapshot_for_diagnostic();
             let err = if self.check_fn_front_matter(false) {
                 let inherited_vis = Visibility {
                     span: rustc_span::DUMMY_SP,
@@ -1714,6 +1751,22 @@ impl<'a> Parser<'a> {
                 err.help("unlike in C++, Java, and C#, functions are declared in `impl` blocks");
                 err.help("see https://doc.rust-lang.org/book/ch05-03-method-syntax.html for more information");
                 err
+            } else if self.eat_keyword(kw::Struct) {
+                match self.parse_item_struct() {
+                    Ok((ident, _)) => {
+                        let mut err = self.struct_span_err(
+                            lo.with_hi(ident.span.hi()),
+                            &format!("structs are not allowed in {adt_ty} definitions"),
+                        );
+                        err.help("consider creating a new `struct` definition instead of nesting");
+                        err
+                    }
+                    Err(err) => {
+                        err.cancel();
+                        self.restore_snapshot(snapshot);
+                        self.expected_ident_found()
+                    }
+                }
             } else {
                 self.expected_ident_found()
             };
@@ -2323,7 +2376,7 @@ impl<'a> Parser<'a> {
                 match ty {
                     Ok(ty) => {
                         let ident = Ident::new(kw::Empty, this.prev_token.span);
-                        let bm = BindingMode::ByValue(Mutability::Not);
+                        let bm = BindingAnnotation::NONE;
                         let pat = this.mk_pat_ident(ty.span, bm, ident);
                         (pat, ty)
                     }
diff --git a/compiler/rustc_parse/src/parser/mod.rs b/compiler/rustc_parse/src/parser/mod.rs
index f6516d3bd45..4cb198561e0 100644
--- a/compiler/rustc_parse/src/parser/mod.rs
+++ b/compiler/rustc_parse/src/parser/mod.rs
@@ -37,7 +37,6 @@ use rustc_errors::{
 use rustc_session::parse::ParseSess;
 use rustc_span::source_map::{Span, DUMMY_SP};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
-use tracing::debug;
 
 use std::ops::Range;
 use std::{cmp, mem, slice};
@@ -171,7 +170,7 @@ pub struct ClosureSpans {
 /// attribute, we parse a nested AST node that has `#[cfg]` or `#[cfg_attr]`
 /// In this case, we use a `ReplaceRange` to replace the entire inner AST node
 /// with `FlatToken::AttrTarget`, allowing us to perform eager cfg-expansion
-/// on an `AttrAnnotatedTokenStream`
+/// on an `AttrTokenStream`.
 ///
 /// 2. When we parse an inner attribute while collecting tokens. We
 /// remove inner attributes from the token stream entirely, and
@@ -184,7 +183,7 @@ pub type ReplaceRange = (Range<u32>, Vec<(FlatToken, Spacing)>);
 
 /// Controls how we capture tokens. Capturing can be expensive,
 /// so we try to avoid performing capturing in cases where
-/// we will never need an `AttrAnnotatedTokenStream`
+/// we will never need an `AttrTokenStream`.
 #[derive(Copy, Clone)]
 pub enum Capturing {
     /// We aren't performing any capturing - this is the default mode.
@@ -238,7 +237,7 @@ struct TokenCursor {
     // the trailing `>>` token. The `break_last_token`
     // field is used to track this token - it gets
     // appended to the captured stream when
-    // we evaluate a `LazyTokenStream`
+    // we evaluate a `LazyAttrTokenStream`.
     break_last_token: bool,
 }
 
@@ -281,7 +280,7 @@ impl TokenCursor {
                         if delim != Delimiter::Invisible {
                             return (Token::new(token::OpenDelim(delim), sp.open), Spacing::Alone);
                         }
-                        // No open delimeter to return; continue on to the next iteration.
+                        // No open delimiter to return; continue on to the next iteration.
                     }
                 };
             } else if let Some(frame) = self.stack.pop() {
@@ -1465,11 +1464,11 @@ pub fn emit_unclosed_delims(unclosed_delims: &mut Vec<UnmatchedBrace>, sess: &Pa
     }
 }
 
-/// A helper struct used when building an `AttrAnnotatedTokenStream` from
-/// a `LazyTokenStream`. Both delimiter and non-delimited tokens
+/// A helper struct used when building an `AttrTokenStream` from
+/// a `LazyAttrTokenStream`. Both delimiter and non-delimited tokens
 /// are stored as `FlatToken::Token`. A vector of `FlatToken`s
-/// is then 'parsed' to build up an `AttrAnnotatedTokenStream` with nested
-/// `AttrAnnotatedTokenTree::Delimited` tokens
+/// is then 'parsed' to build up an `AttrTokenStream` with nested
+/// `AttrTokenTree::Delimited` tokens.
 #[derive(Debug, Clone)]
 pub enum FlatToken {
     /// A token - this holds both delimiter (e.g. '{' and '}')
@@ -1477,11 +1476,11 @@ pub enum FlatToken {
     Token(Token),
     /// Holds the `AttributesData` for an AST node. The
     /// `AttributesData` is inserted directly into the
-    /// constructed `AttrAnnotatedTokenStream` as
-    /// an `AttrAnnotatedTokenTree::Attributes`
+    /// constructed `AttrTokenStream` as
+    /// an `AttrTokenTree::Attributes`.
     AttrTarget(AttributesData),
     /// A special 'empty' token that is ignored during the conversion
-    /// to an `AttrAnnotatedTokenStream`. This is used to simplify the
+    /// to an `AttrTokenStream`. This is used to simplify the
     /// handling of replace ranges.
     Empty,
 }
diff --git a/compiler/rustc_parse/src/parser/nonterminal.rs b/compiler/rustc_parse/src/parser/nonterminal.rs
index e215b6872bf..103dd801257 100644
--- a/compiler/rustc_parse/src/parser/nonterminal.rs
+++ b/compiler/rustc_parse/src/parser/nonterminal.rs
@@ -66,18 +66,18 @@ impl<'a> Parser<'a> {
             },
             NonterminalKind::PatParam { .. } | NonterminalKind::PatWithOr { .. } => {
                 match token.kind {
-                token::Ident(..) |                  // box, ref, mut, and other identifiers (can stricten)
-                token::OpenDelim(Delimiter::Parenthesis) |    // tuple pattern
-                token::OpenDelim(Delimiter::Bracket) |  // slice pattern
-                token::BinOp(token::And) |          // reference
-                token::BinOp(token::Minus) |        // negative literal
-                token::AndAnd |                     // double reference
-                token::Literal(..) |                // literal
-                token::DotDot |                     // range pattern (future compat)
-                token::DotDotDot |                  // range pattern (future compat)
-                token::ModSep |                     // path
-                token::Lt |                         // path (UFCS constant)
-                token::BinOp(token::Shl) => true,   // path (double UFCS)
+                token::Ident(..) |                          // box, ref, mut, and other identifiers (can stricten)
+                token::OpenDelim(Delimiter::Parenthesis) |  // tuple pattern
+                token::OpenDelim(Delimiter::Bracket) |      // slice pattern
+                token::BinOp(token::And) |                  // reference
+                token::BinOp(token::Minus) |                // negative literal
+                token::AndAnd |                             // double reference
+                token::Literal(..) |                        // literal
+                token::DotDot |                             // range pattern (future compat)
+                token::DotDotDot |                          // range pattern (future compat)
+                token::ModSep |                             // path
+                token::Lt |                                 // path (UFCS constant)
+                token::BinOp(token::Shl) => true,           // path (double UFCS)
                 // leading vert `|` or-pattern
                 token::BinOp(token::Or) =>  matches!(kind, NonterminalKind::PatWithOr {..}),
                 token::Interpolated(ref nt) => may_be_ident(nt),
diff --git a/compiler/rustc_parse/src/parser/pat.rs b/compiler/rustc_parse/src/parser/pat.rs
index 8b3200d45fc..120a3c267f1 100644
--- a/compiler/rustc_parse/src/parser/pat.rs
+++ b/compiler/rustc_parse/src/parser/pat.rs
@@ -1,11 +1,12 @@
 use super::{ForceCollect, Parser, PathStyle, TrailingToken};
+use crate::parser::diagnostics::RemoveLet;
 use crate::{maybe_recover_from_interpolated_ty_qpath, maybe_whole};
 use rustc_ast::mut_visit::{noop_visit_pat, MutVisitor};
 use rustc_ast::ptr::P;
 use rustc_ast::token::{self, Delimiter};
 use rustc_ast::{
-    self as ast, AttrVec, BindingMode, Expr, ExprKind, MacCall, Mutability, Pat, PatField, PatKind,
-    Path, QSelf, RangeEnd, RangeSyntax,
+    self as ast, AttrVec, BindingAnnotation, ByRef, Expr, ExprKind, MacCall, Mutability, Pat,
+    PatField, PatKind, Path, QSelf, RangeEnd, RangeSyntax,
 };
 use rustc_ast_pretty::pprust;
 use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder, ErrorGuaranteed, PResult};
@@ -320,7 +321,13 @@ impl<'a> Parser<'a> {
         maybe_recover_from_interpolated_ty_qpath!(self, true);
         maybe_whole!(self, NtPat, |x| x);
 
-        let lo = self.token.span;
+        let mut lo = self.token.span;
+
+        if self.token.is_keyword(kw::Let) && self.look_ahead(1, |tok| tok.can_begin_pattern()) {
+            self.bump();
+            self.sess.emit_err(RemoveLet { span: lo });
+            lo = self.token.span;
+        }
 
         let pat = if self.check(&token::BinOp(token::And)) || self.token.kind == token::AndAnd {
             self.parse_pat_deref(expected)?
@@ -353,7 +360,7 @@ impl<'a> Parser<'a> {
         } else if self.eat_keyword(kw::Ref) {
             // Parse ref ident @ pat / ref mut ident @ pat
             let mutbl = self.parse_mutability();
-            self.parse_pat_ident(BindingMode::ByRef(mutbl))?
+            self.parse_pat_ident(BindingAnnotation(ByRef::Yes, mutbl))?
         } else if self.eat_keyword(kw::Box) {
             self.parse_pat_box()?
         } else if self.check_inline_const(0) {
@@ -369,7 +376,7 @@ impl<'a> Parser<'a> {
             // Parse `ident @ pat`
             // This can give false positives and parse nullary enums,
             // they are dealt with later in resolve.
-            self.parse_pat_ident(BindingMode::ByValue(Mutability::Not))?
+            self.parse_pat_ident(BindingAnnotation::NONE)?
         } else if self.is_start_of_pat_with_path() {
             // Parse pattern starting with a path
             let (qself, path) = if self.eat_lt() {
@@ -578,7 +585,8 @@ impl<'a> Parser<'a> {
         let mut pat = self.parse_pat_no_top_alt(Some("identifier"))?;
 
         // If we don't have `mut $ident (@ pat)?`, error.
-        if let PatKind::Ident(BindingMode::ByValue(m @ Mutability::Not), ..) = &mut pat.kind {
+        if let PatKind::Ident(BindingAnnotation(ByRef::No, m @ Mutability::Not), ..) = &mut pat.kind
+        {
             // Don't recurse into the subpattern.
             // `mut` on the outer binding doesn't affect the inner bindings.
             *m = Mutability::Mut;
@@ -604,7 +612,7 @@ impl<'a> Parser<'a> {
             )
             .emit();
 
-        self.parse_pat_ident(BindingMode::ByRef(Mutability::Mut))
+        self.parse_pat_ident(BindingAnnotation::REF_MUT)
     }
 
     /// Turn all by-value immutable bindings in a pattern into mutable bindings.
@@ -613,7 +621,8 @@ impl<'a> Parser<'a> {
         struct AddMut(bool);
         impl MutVisitor for AddMut {
             fn visit_pat(&mut self, pat: &mut P<Pat>) {
-                if let PatKind::Ident(BindingMode::ByValue(m @ Mutability::Not), ..) = &mut pat.kind
+                if let PatKind::Ident(BindingAnnotation(ByRef::No, m @ Mutability::Not), ..) =
+                    &mut pat.kind
                 {
                     self.0 = true;
                     *m = Mutability::Mut;
@@ -838,7 +847,7 @@ impl<'a> Parser<'a> {
     /// Parses `ident` or `ident @ pat`.
     /// Used by the copy foo and ref foo patterns to give a good
     /// error message when parsing mistakes like `ref foo(a, b)`.
-    fn parse_pat_ident(&mut self, binding_mode: BindingMode) -> PResult<'a, PatKind> {
+    fn parse_pat_ident(&mut self, binding_annotation: BindingAnnotation) -> PResult<'a, PatKind> {
         let ident = self.parse_ident()?;
         let sub = if self.eat(&token::At) {
             Some(self.parse_pat_no_top_alt(Some("binding pattern"))?)
@@ -856,7 +865,7 @@ impl<'a> Parser<'a> {
                 .struct_span_err(self.prev_token.span, "expected identifier, found enum pattern"));
         }
 
-        Ok(PatKind::Ident(binding_mode, ident, sub))
+        Ok(PatKind::Ident(binding_annotation, ident, sub))
     }
 
     /// Parse a struct ("record") pattern (e.g. `Foo { ... }` or `Foo::Bar { ... }`).
@@ -936,11 +945,7 @@ impl<'a> Parser<'a> {
                 None
             };
 
-            Ok(PatKind::Ident(
-                BindingMode::ByValue(Mutability::Not),
-                Ident::new(kw::Box, box_span),
-                sub,
-            ))
+            Ok(PatKind::Ident(BindingAnnotation::NONE, Ident::new(kw::Box, box_span), sub))
         } else {
             let pat = self.parse_pat_with_range_pat(false, None)?;
             self.sess.gated_spans.gate(sym::box_patterns, box_span.to(self.prev_token.span));
@@ -1117,14 +1122,12 @@ impl<'a> Parser<'a> {
             let fieldname = self.parse_field_name()?;
             hi = self.prev_token.span;
 
-            let bind_type = match (is_ref, is_mut) {
-                (true, true) => BindingMode::ByRef(Mutability::Mut),
-                (true, false) => BindingMode::ByRef(Mutability::Not),
-                (false, true) => BindingMode::ByValue(Mutability::Mut),
-                (false, false) => BindingMode::ByValue(Mutability::Not),
+            let mutability = match is_mut {
+                false => Mutability::Not,
+                true => Mutability::Mut,
             };
-
-            let fieldpat = self.mk_pat_ident(boxed_span.to(hi), bind_type, fieldname);
+            let ann = BindingAnnotation(ByRef::from(is_ref), mutability);
+            let fieldpat = self.mk_pat_ident(boxed_span.to(hi), ann, fieldname);
             let subpat =
                 if is_box { self.mk_pat(lo.to(hi), PatKind::Box(fieldpat)) } else { fieldpat };
             (subpat, fieldname, true)
@@ -1141,8 +1144,8 @@ impl<'a> Parser<'a> {
         })
     }
 
-    pub(super) fn mk_pat_ident(&self, span: Span, bm: BindingMode, ident: Ident) -> P<Pat> {
-        self.mk_pat(span, PatKind::Ident(bm, ident, None))
+    pub(super) fn mk_pat_ident(&self, span: Span, ann: BindingAnnotation, ident: Ident) -> P<Pat> {
+        self.mk_pat(span, PatKind::Ident(ann, ident, None))
     }
 
     pub(super) fn mk_pat(&self, span: Span, kind: PatKind) -> P<Pat> {
diff --git a/compiler/rustc_parse/src/parser/path.rs b/compiler/rustc_parse/src/parser/path.rs
index fc7fb866f11..fdc1af27f82 100644
--- a/compiler/rustc_parse/src/parser/path.rs
+++ b/compiler/rustc_parse/src/parser/path.rs
@@ -13,7 +13,6 @@ use rustc_span::source_map::{BytePos, Span};
 use rustc_span::symbol::{kw, sym, Ident};
 
 use std::mem;
-use tracing::debug;
 
 /// Specifies how to parse a path.
 #[derive(Copy, Clone, PartialEq)]
diff --git a/compiler/rustc_parse/src/parser/ty.rs b/compiler/rustc_parse/src/parser/ty.rs
index 4a2cf74905b..b47f0c09783 100644
--- a/compiler/rustc_parse/src/parser/ty.rs
+++ b/compiler/rustc_parse/src/parser/ty.rs
@@ -567,7 +567,8 @@ impl<'a> Parser<'a> {
         self.check_keyword(kw::Dyn)
             && (!self.token.uninterpolated_span().rust_2015()
                 || self.look_ahead(1, |t| {
-                    t.can_begin_bound() && !can_continue_type_after_non_fn_ident(t)
+                    (t.can_begin_bound() || t.kind == TokenKind::BinOp(token::Star))
+                        && !can_continue_type_after_non_fn_ident(t)
                 }))
     }
 
@@ -576,10 +577,18 @@ impl<'a> Parser<'a> {
     /// Note that this does *not* parse bare trait objects.
     fn parse_dyn_ty(&mut self, impl_dyn_multi: &mut bool) -> PResult<'a, TyKind> {
         self.bump(); // `dyn`
+
+        // parse dyn* types
+        let syntax = if self.eat(&TokenKind::BinOp(token::Star)) {
+            TraitObjectSyntax::DynStar
+        } else {
+            TraitObjectSyntax::Dyn
+        };
+
         // Always parse bounds greedily for better error recovery.
         let bounds = self.parse_generic_bounds(None)?;
         *impl_dyn_multi = bounds.len() > 1 || self.prev_token.kind == TokenKind::BinOp(token::Plus);
-        Ok(TyKind::TraitObject(bounds, TraitObjectSyntax::Dyn))
+        Ok(TyKind::TraitObject(bounds, syntax))
     }
 
     /// Parses a type starting with a path.