Auto merge of #137517 - nnethercote:rm-NtPat-NtItem-NtStmt, r=petrochenkov

Remove `NtPat`, `NtMeta`, and `NtPath`

Another part of #124141.

r? `@petrochenkov`

compiler/rustc_ast/src/ast_traits.rs

@@ -202,9 +202,6 @@ impl HasTokens for Nonterminal {
             Nonterminal::NtItem(item) => item.tokens(),
             Nonterminal::NtStmt(stmt) => stmt.tokens(),
             Nonterminal::NtExpr(expr) | Nonterminal::NtLiteral(expr) => expr.tokens(),
-            Nonterminal::NtPat(pat) => pat.tokens(),
-            Nonterminal::NtMeta(attr_item) => attr_item.tokens(),
-            Nonterminal::NtPath(path) => path.tokens(),
             Nonterminal::NtBlock(block) => block.tokens(),
         }
     }
@@ -213,9 +210,6 @@ impl HasTokens for Nonterminal {
             Nonterminal::NtItem(item) => item.tokens_mut(),
             Nonterminal::NtStmt(stmt) => stmt.tokens_mut(),
             Nonterminal::NtExpr(expr) | Nonterminal::NtLiteral(expr) => expr.tokens_mut(),
-            Nonterminal::NtPat(pat) => pat.tokens_mut(),
-            Nonterminal::NtMeta(attr_item) => attr_item.tokens_mut(),
-            Nonterminal::NtPath(path) => path.tokens_mut(),
             Nonterminal::NtBlock(block) => block.tokens_mut(),
         }
     }

compiler/rustc_ast/src/attr/mod.rs

@@ -14,7 +14,7 @@ use crate::ast::{
     PathSegment, Safety,
 };
 use crate::ptr::P;
-use crate::token::{self, CommentKind, Delimiter, Token};
+use crate::token::{self, CommentKind, Delimiter, InvisibleOrigin, MetaVarKind, Token};
 use crate::tokenstream::{
     DelimSpan, LazyAttrTokenStream, Spacing, TokenStream, TokenStreamIter, TokenTree,
 };
@@ -405,11 +405,17 @@ impl MetaItem {
                 let span = span.with_hi(segments.last().unwrap().ident.span.hi());
                 Path { span, segments, tokens: None }
             }
-            Some(TokenTree::Token(Token { kind: token::Interpolated(nt), .. }, _)) => match &**nt {
+            Some(TokenTree::Delimited(
-                token::Nonterminal::NtMeta(item) => return item.meta(item.path.span),
+                _span,
-                token::Nonterminal::NtPath(path) => (**path).clone(),
+                _spacing,
-                _ => return None,
+                Delimiter::Invisible(InvisibleOrigin::MetaVar(
-            },
+                    MetaVarKind::Meta { .. } | MetaVarKind::Path,
+                )),
+                _stream,
+            )) => {
+                // This path is currently unreachable in the test suite.
+                unreachable!()
+            }
             Some(TokenTree::Token(
                 Token { kind: token::OpenDelim(_) | token::CloseDelim(_), .. },
                 _,

compiler/rustc_ast/src/mut_visit.rs

@@ -905,16 +905,8 @@ fn visit_nonterminal<T: MutVisitor>(vis: &mut T, nt: &mut token::Nonterminal) {
                 vis.flat_map_stmt(stmt).expect_one("expected visitor to produce exactly one item")
             })
         }),
-        token::NtPat(pat) => vis.visit_pat(pat),
         token::NtExpr(expr) => vis.visit_expr(expr),
         token::NtLiteral(expr) => vis.visit_expr(expr),
-        token::NtMeta(item) => {
-            let AttrItem { unsafety: _, path, args, tokens } = item.deref_mut();
-            vis.visit_path(path);
-            visit_attr_args(vis, args);
-            visit_lazy_tts(vis, tokens);
-        }
-        token::NtPath(path) => vis.visit_path(path),
     }
 }
 

compiler/rustc_ast/src/token.rs

@@ -90,7 +90,10 @@ pub enum MetaVarKind {
     Ident,
     Lifetime,
     Literal,
-    Meta,
+    Meta {
+        /// Will `AttrItem::meta` succeed on this, if reparsed?
+        has_meta_form: bool,
+    },
     Path,
     Vis,
     TT,
@@ -110,7 +113,7 @@ impl fmt::Display for MetaVarKind {
             MetaVarKind::Ident => sym::ident,
             MetaVarKind::Lifetime => sym::lifetime,
             MetaVarKind::Literal => sym::literal,
-            MetaVarKind::Meta => sym::meta,
+            MetaVarKind::Meta { .. } => sym::meta,
             MetaVarKind::Path => sym::path,
             MetaVarKind::Vis => sym::vis,
             MetaVarKind::TT => sym::tt,
@@ -621,8 +624,7 @@ impl Token {
                 matches!(&**nt,
                     NtBlock(..)   |
                     NtExpr(..)    |
-                    NtLiteral(..) |
+                    NtLiteral(..)
-                    NtPath(..)
                 ),
             OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(
                 MetaVarKind::Block |
@@ -658,14 +660,11 @@ impl Token {
                 matches!(&**nt,
                     | NtExpr(..)
                     | NtLiteral(..)
-                    | NtMeta(..)
-                    | NtPat(..)
-                    | NtPath(..)
                 ),
             OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(
                 MetaVarKind::Expr { .. } |
                 MetaVarKind::Literal |
-                MetaVarKind::Meta |
+                MetaVarKind::Meta { .. } |
                 MetaVarKind::Pat(_) |
                 MetaVarKind::Path |
                 MetaVarKind::Ty { .. }
@@ -689,7 +688,6 @@ impl Token {
             Lifetime(..)                | // lifetime bound in trait object
             Lt | BinOp(Shl)             | // associated path
             PathSep                      => true, // global path
-            Interpolated(ref nt) => matches!(&**nt, NtPath(..)),
             OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(
                 MetaVarKind::Ty { .. } |
                 MetaVarKind::Path
@@ -848,27 +846,16 @@ impl Token {
         self.ident().is_some_and(|(ident, _)| ident.name == name)
     }
 
-    /// Returns `true` if the token is an interpolated path.
-    fn is_whole_path(&self) -> bool {
-        if let Interpolated(nt) = &self.kind
-            && let NtPath(..) = &**nt
-        {
-            return true;
-        }
-
-        false
-    }
-
     /// Is this a pre-parsed expression dropped into the token stream
     /// (which happens while parsing the result of macro expansion)?
     pub fn is_whole_expr(&self) -> bool {
         if let Interpolated(nt) = &self.kind
-            && let NtExpr(_) | NtLiteral(_) | NtPath(_) | NtBlock(_) = &**nt
+            && let NtExpr(_) | NtLiteral(_) | NtBlock(_) = &**nt
         {
-            return true;
+            true
+        } else {
+            matches!(self.is_metavar_seq(), Some(MetaVarKind::Path))
         }
-
-        false
     }
 
     /// Is the token an interpolated block (`$b:block`)?
@@ -894,7 +881,7 @@ impl Token {
     pub fn is_path_start(&self) -> bool {
         self == &PathSep
             || self.is_qpath_start()
-            || self.is_whole_path()
+            || matches!(self.is_metavar_seq(), Some(MetaVarKind::Path))
             || self.is_path_segment_keyword()
             || self.is_ident() && !self.is_reserved_ident()
     }
@@ -1075,12 +1062,8 @@ pub enum Nonterminal {
     NtItem(P<ast::Item>),
     NtBlock(P<ast::Block>),
     NtStmt(P<ast::Stmt>),
-    NtPat(P<ast::Pat>),
     NtExpr(P<ast::Expr>),
     NtLiteral(P<ast::Expr>),
-    /// Stuff inside brackets for attributes
-    NtMeta(P<ast::AttrItem>),
-    NtPath(P<ast::Path>),
 }
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Encodable, Decodable, Hash, HashStable_Generic)]
@@ -1172,10 +1155,7 @@ impl Nonterminal {
             NtItem(item) => item.span,
             NtBlock(block) => block.span,
             NtStmt(stmt) => stmt.span,
-            NtPat(pat) => pat.span,
             NtExpr(expr) | NtLiteral(expr) => expr.span,
-            NtMeta(attr_item) => attr_item.span(),
-            NtPath(path) => path.span,
         }
     }
 
@@ -1184,11 +1164,8 @@ impl Nonterminal {
             NtItem(..) => "item",
             NtBlock(..) => "block",
             NtStmt(..) => "statement",
-            NtPat(..) => "pattern",
             NtExpr(..) => "expression",
             NtLiteral(..) => "literal",
-            NtMeta(..) => "attribute",
-            NtPath(..) => "path",
         }
     }
 }
@@ -1209,11 +1186,8 @@ impl fmt::Debug for Nonterminal {
             NtItem(..) => f.pad("NtItem(..)"),
             NtBlock(..) => f.pad("NtBlock(..)"),
             NtStmt(..) => f.pad("NtStmt(..)"),
-            NtPat(..) => f.pad("NtPat(..)"),
             NtExpr(..) => f.pad("NtExpr(..)"),
             NtLiteral(..) => f.pad("NtLiteral(..)"),
-            NtMeta(..) => f.pad("NtMeta(..)"),
-            NtPath(..) => f.pad("NtPath(..)"),
         }
     }
 }

compiler/rustc_ast/src/tokenstream.rs

@@ -468,9 +468,6 @@ impl TokenStream {
                 TokenStream::token_alone(token::Semi, stmt.span)
             }
             Nonterminal::NtStmt(stmt) => TokenStream::from_ast(stmt),
-            Nonterminal::NtPat(pat) => TokenStream::from_ast(pat),
-            Nonterminal::NtMeta(attr) => TokenStream::from_ast(attr),
-            Nonterminal::NtPath(path) => TokenStream::from_ast(path),
             Nonterminal::NtExpr(expr) | Nonterminal::NtLiteral(expr) => TokenStream::from_ast(expr),
         }
     }

compiler/rustc_attr_parsing/src/parser.rs

@@ -477,41 +477,21 @@ impl<'a> MetaItemListParserContext<'a> {
 
         // or a path.
         let path =
-            if let Some(TokenTree::Token(Token { kind: token::Interpolated(nt), span, .. }, _)) =
+            if let Some(TokenTree::Token(Token { kind: token::Interpolated(_), span, .. }, _)) =
                 self.inside_delimiters.peek()
             {
-                match &**nt {
+                self.inside_delimiters.next();
-                    // or maybe a full nt meta including the path but we return immediately
+                // We go into this path if an expr ended up in an attribute that
-                    token::Nonterminal::NtMeta(item) => {
+                // expansion did not turn into a literal. Say, `#[repr(align(macro!()))]`
-                        self.inside_delimiters.next();
+                // where the macro didn't expand to a literal. An error is already given
+                // for this at this point, and then we do continue. This makes this path
+                // reachable...
+                let e = self.dcx.span_delayed_bug(
+                    *span,
+                    "expr in place where literal is expected (builtin attr parsing)",
+                );
 
-                        return Some(MetaItemOrLitParser::MetaItemParser(MetaItemParser {
+                return Some(MetaItemOrLitParser::Err(*span, e));
-                            path: PathParser::Ast(&item.path),
-                            args: ArgParser::from_attr_args(&item.args, self.dcx),
-                        }));
-                    }
-                    // an already interpolated path from a macro expansion is a path, no need to parse
-                    // one from tokens
-                    token::Nonterminal::NtPath(path) => {
-                        self.inside_delimiters.next();
-
-                        AttrPath::from_ast(path)
-                    }
-                    _ => {
-                        self.inside_delimiters.next();
-                        // we go into this path if an expr ended up in an attribute that
-                        // expansion did not turn into a literal. Say, `#[repr(align(macro!()))]`
-                        // where the macro didn't expand to a literal. An error is already given
-                        // for this at this point, and then we do continue. This makes this path
-                        // reachable...
-                        let e = self.dcx.span_delayed_bug(
-                            *span,
-                            "expr in place where literal is expected (builtin attr parsing)",
-                        );
-
-                        return Some(MetaItemOrLitParser::Err(*span, e));
-                    }
-                }
             } else {
                 self.next_path()?
             };

compiler/rustc_expand/src/mbe/transcribe.rs

@@ -279,9 +279,9 @@ pub(super) fn transcribe<'a>(
                 if let Some(cur_matched) = lookup_cur_matched(ident, interp, &repeats) {
                     // We wrap the tokens in invisible delimiters, unless they are already wrapped
                     // in invisible delimiters with the same `MetaVarKind`. Because some proc
-                    // macros can't multiple layers of invisible delimiters of the same
+                    // macros can't handle multiple layers of invisible delimiters of the same
                     // `MetaVarKind`. This loses some span info, though it hopefully won't matter.
-                    let mut mk_delimited = |mv_kind, mut stream: TokenStream| {
+                    let mut mk_delimited = |mk_span, mv_kind, mut stream: TokenStream| {
                         if stream.len() == 1 {
                             let tree = stream.iter().next().unwrap();
                             if let TokenTree::Delimited(_, _, delim, inner) = tree
@@ -295,6 +295,7 @@ pub(super) fn transcribe<'a>(
                         // Emit as a token stream within `Delimiter::Invisible` to maintain
                         // parsing priorities.
                         marker.visit_span(&mut sp);
+                        with_metavar_spans(|mspans| mspans.insert(mk_span, sp));
                         // Both the open delim and close delim get the same span, which covers the
                         // `$foo` in the decl macro RHS.
                         TokenTree::Delimited(
@@ -322,12 +323,32 @@ pub(super) fn transcribe<'a>(
                             let kind = token::NtLifetime(*ident, *is_raw);
                             TokenTree::token_alone(kind, sp)
                         }
+                        MatchedSingle(ParseNtResult::Pat(pat, pat_kind)) => mk_delimited(
+                            pat.span,
+                            MetaVarKind::Pat(*pat_kind),
+                            TokenStream::from_ast(pat),
+                        ),
                         MatchedSingle(ParseNtResult::Ty(ty)) => {
                             let is_path = matches!(&ty.kind, TyKind::Path(None, _path));
-                            mk_delimited(MetaVarKind::Ty { is_path }, TokenStream::from_ast(ty))
+                            mk_delimited(
+                                ty.span,
+                                MetaVarKind::Ty { is_path },
+                                TokenStream::from_ast(ty),
+                            )
+                        }
+                        MatchedSingle(ParseNtResult::Meta(attr_item)) => {
+                            let has_meta_form = attr_item.meta_kind().is_some();
+                            mk_delimited(
+                                attr_item.span(),
+                                MetaVarKind::Meta { has_meta_form },
+                                TokenStream::from_ast(attr_item),
+                            )
+                        }
+                        MatchedSingle(ParseNtResult::Path(path)) => {
+                            mk_delimited(path.span, MetaVarKind::Path, TokenStream::from_ast(path))
                         }
                         MatchedSingle(ParseNtResult::Vis(vis)) => {
-                            mk_delimited(MetaVarKind::Vis, TokenStream::from_ast(vis))
+                            mk_delimited(vis.span, MetaVarKind::Vis, TokenStream::from_ast(vis))
                         }
                         MatchedSingle(ParseNtResult::Nt(nt)) => {
                             // Other variables are emitted into the output stream as groups with

compiler/rustc_parse/messages.ftl

@@ -424,7 +424,7 @@ parse_invalid_logical_operator = `{$incorrect}` is not a logical operator
     .use_amp_amp_for_conjunction = use `&&` to perform logical conjunction
     .use_pipe_pipe_for_disjunction = use `||` to perform logical disjunction
 
-parse_invalid_meta_item = expected unsuffixed literal, found `{$token}`
+parse_invalid_meta_item = expected unsuffixed literal, found {$descr}
     .quote_ident_sugg = surround the identifier with quotation marks to make it into a string literal
 
 parse_invalid_offset_of = offset_of expects dot-separated field and variant names

compiler/rustc_parse/src/errors.rs

@@ -1024,7 +1024,7 @@ pub(crate) struct SuffixedLiteralInAttribute {
 pub(crate) struct InvalidMetaItem {
     #[primary_span]
     pub span: Span,
-    pub token: Token,
+    pub descr: String,
     #[subdiagnostic]
     pub quote_ident_sugg: Option<InvalidMetaItemQuoteIdentSugg>,
 }

compiler/rustc_parse/src/parser/attr.rs

@@ -1,4 +1,6 @@
-use rustc_ast::{self as ast, Attribute, attr, token};
+use rustc_ast as ast;
+use rustc_ast::token::{self, MetaVarKind};
+use rustc_ast::{Attribute, attr};
 use rustc_errors::codes::*;
 use rustc_errors::{Diag, PResult};
 use rustc_span::{BytePos, Span};
@@ -9,7 +11,7 @@ use super::{
     AttrWrapper, Capturing, FnParseMode, ForceCollect, Parser, ParserRange, PathStyle, Trailing,
     UsePreAttrPos,
 };
-use crate::{errors, exp, fluent_generated as fluent, maybe_whole};
+use crate::{errors, exp, fluent_generated as fluent};
 
 // Public for rustfmt usage
 #[derive(Debug)]
@@ -269,7 +271,12 @@ impl<'a> Parser<'a> {
     ///     PATH `=` UNSUFFIXED_LIT
     /// The delimiters or `=` are still put into the resulting token stream.
     pub fn parse_attr_item(&mut self, force_collect: ForceCollect) -> PResult<'a, ast::AttrItem> {
-        maybe_whole!(self, NtMeta, |attr| attr.into_inner());
+        if let Some(item) = self.eat_metavar_seq_with_matcher(
+            |mv_kind| matches!(mv_kind, MetaVarKind::Meta { .. }),
+            |this| this.parse_attr_item(force_collect),
+        ) {
+            return Ok(item);
+        }
 
         // Attr items don't have attributes.
         self.collect_tokens(None, AttrWrapper::empty(), force_collect, |this, _empty_attrs| {
@@ -396,18 +403,17 @@ impl<'a> Parser<'a> {
         &mut self,
         unsafe_allowed: AllowLeadingUnsafe,
     ) -> PResult<'a, ast::MetaItem> {
-        // We can't use `maybe_whole` here because it would bump in the `None`
+        if let Some(MetaVarKind::Meta { has_meta_form }) = self.token.is_metavar_seq() {
-        // case, which we don't want.
+            return if has_meta_form {
-        if let token::Interpolated(nt) = &self.token.kind
+                let attr_item = self
-            && let token::NtMeta(attr_item) = &**nt
+                    .eat_metavar_seq(MetaVarKind::Meta { has_meta_form: true }, |this| {
-        {
+                        this.parse_attr_item(ForceCollect::No)
-            match attr_item.meta(attr_item.path.span) {
+                    })
-                Some(meta) => {
+                    .unwrap();
-                    self.bump();
+                Ok(attr_item.meta(attr_item.path.span).unwrap())
-                    return Ok(meta);
+            } else {
-                }
+                self.unexpected_any()
-                None => self.unexpected()?,
+            };
-            }
         }
 
         let lo = self.token.span;
@@ -464,7 +470,7 @@ impl<'a> Parser<'a> {
 
         let mut err = errors::InvalidMetaItem {
             span: self.token.span,
-            token: self.token.clone(),
+            descr: super::token_descr(&self.token),
             quote_ident_sugg: None,
         };
 

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -1,17 +1,15 @@
 use std::mem::take;
 use std::ops::{Deref, DerefMut};
-use std::sync::Arc;
 
 use ast::token::IdentIsRaw;
 use rustc_ast as ast;
 use rustc_ast::ptr::P;
 use rustc_ast::token::{self, Delimiter, Lit, LitKind, Token, TokenKind};
-use rustc_ast::tokenstream::AttrTokenTree;
 use rustc_ast::util::parser::AssocOp;
 use rustc_ast::{
     AngleBracketedArg, AngleBracketedArgs, AnonConst, AttrVec, BinOpKind, BindingMode, Block,
-    BlockCheckMode, Expr, ExprKind, GenericArg, Generics, HasTokens, Item, ItemKind, Param, Pat,
+    BlockCheckMode, Expr, ExprKind, GenericArg, Generics, Item, ItemKind, Param, Pat, PatKind,
-    PatKind, Path, PathSegment, QSelf, Recovered, Ty, TyKind,
+    Path, PathSegment, QSelf, Recovered, Ty, TyKind,
 };
 use rustc_ast_pretty::pprust;
 use rustc_data_structures::fx::FxHashSet;
@@ -2406,52 +2404,6 @@ impl<'a> Parser<'a> {
             err.subdiagnostic(ExprParenthesesNeeded::surrounding(*sp));
         }
         err.span_label(span, "expected expression");
-
-        // Walk the chain of macro expansions for the current token to point at how the original
-        // code was interpreted. This helps the user realize when a macro argument of one type is
-        // later reinterpreted as a different type, like `$x:expr` being reinterpreted as `$x:pat`
-        // in a subsequent macro invocation (#71039).
-        let mut tok = self.token.clone();
-        let mut labels = vec![];
-        while let TokenKind::Interpolated(nt) = &tok.kind {
-            let tokens = nt.tokens();
-            labels.push(Arc::clone(nt));
-            if let Some(tokens) = tokens
-                && let tokens = tokens.to_attr_token_stream()
-                && let tokens = tokens.0.deref()
-                && let [AttrTokenTree::Token(token, _)] = &tokens[..]
-            {
-                tok = token.clone();
-            } else {
-                break;
-            }
-        }
-        let mut iter = labels.into_iter().peekable();
-        let mut show_link = false;
-        while let Some(nt) = iter.next() {
-            let descr = nt.descr();
-            if let Some(next) = iter.peek() {
-                let next_descr = next.descr();
-                if next_descr != descr {
-                    err.span_label(next.use_span(), format!("this is expected to be {next_descr}"));
-                    err.span_label(
-                        nt.use_span(),
-                        format!(
-                            "this is interpreted as {}, but it is expected to be {}",
-                            next_descr, descr,
-                        ),
-                    );
-                    show_link = true;
-                }
-            }
-        }
-        if show_link {
-            err.note(
-                "when forwarding a matched fragment to another macro-by-example, matchers in the \
-                 second macro will see an opaque AST of the fragment type, not the underlying \
-                 tokens",
-            );
-        }
         err
     }
 

compiler/rustc_parse/src/parser/expr.rs

@@ -4,7 +4,7 @@ use core::mem;
 use core::ops::{Bound, ControlFlow};
 
 use ast::mut_visit::{self, MutVisitor};
-use ast::token::IdentIsRaw;
+use ast::token::{IdentIsRaw, MetaVarKind};
 use ast::{CoroutineKind, ForLoopKind, GenBlockKind, MatchKind, Pat, Path, PathSegment, Recovered};
 use rustc_ast::ptr::P;
 use rustc_ast::token::{self, Delimiter, Token, TokenKind};
@@ -1344,6 +1344,7 @@ impl<'a> Parser<'a> {
     fn parse_expr_bottom(&mut self) -> PResult<'a, P<Expr>> {
         maybe_recover_from_interpolated_ty_qpath!(self, true);
 
+        let span = self.token.span;
         if let token::Interpolated(nt) = &self.token.kind {
             match &**nt {
                 token::NtExpr(e) | token::NtLiteral(e) => {
@@ -1351,11 +1352,6 @@ impl<'a> Parser<'a> {
                     self.bump();
                     return Ok(e);
                 }
-                token::NtPath(path) => {
-                    let path = (**path).clone();
-                    self.bump();
-                    return Ok(self.mk_expr(self.prev_token.span, ExprKind::Path(None, path)));
-                }
                 token::NtBlock(block) => {
                     let block = block.clone();
                     self.bump();
@@ -1363,6 +1359,10 @@ impl<'a> Parser<'a> {
                 }
                 _ => {}
             };
+        } else if let Some(path) = self.eat_metavar_seq(MetaVarKind::Path, |this| {
+            this.collect_tokens_no_attrs(|this| this.parse_path(PathStyle::Type))
+        }) {
+            return Ok(self.mk_expr(span, ExprKind::Path(None, path)));
         }
 
         // Outer attributes are already parsed and will be

compiler/rustc_parse/src/parser/item.rs

@@ -4,7 +4,7 @@ use std::mem;
 use ast::token::IdentIsRaw;
 use rustc_ast::ast::*;
 use rustc_ast::ptr::P;
-use rustc_ast::token::{self, Delimiter, TokenKind};
+use rustc_ast::token::{self, Delimiter, InvisibleOrigin, MetaVarKind, TokenKind};
 use rustc_ast::tokenstream::{DelimSpan, TokenStream, TokenTree};
 use rustc_ast::util::case::Case;
 use rustc_ast::{self as ast};
@@ -3071,8 +3071,10 @@ impl<'a> Parser<'a> {
 
     fn is_named_param(&self) -> bool {
         let offset = match &self.token.kind {
-            token::Interpolated(nt) => match &**nt {
+            token::OpenDelim(Delimiter::Invisible(origin)) => match origin {
-                token::NtPat(..) => return self.look_ahead(1, |t| t == &token::Colon),
+                InvisibleOrigin::MetaVar(MetaVarKind::Pat(_)) => {
+                    return self.check_noexpect_past_close_delim(&token::Colon);
+                }
                 _ => 0,
             },
             token::BinOp(token::And) | token::AndAnd => 1,

compiler/rustc_parse/src/parser/mod.rs

@@ -24,7 +24,8 @@ pub use pat::{CommaRecoveryMode, RecoverColon, RecoverComma};
 use path::PathStyle;
 use rustc_ast::ptr::P;
 use rustc_ast::token::{
-    self, Delimiter, IdentIsRaw, InvisibleOrigin, MetaVarKind, Nonterminal, Token, TokenKind,
+    self, Delimiter, IdentIsRaw, InvisibleOrigin, MetaVarKind, Nonterminal, NtPatKind, Token,
+    TokenKind,
 };
 use rustc_ast::tokenstream::{AttrsTarget, Spacing, TokenStream, TokenTree};
 use rustc_ast::util::case::Case;
@@ -1745,7 +1746,10 @@ pub enum ParseNtResult {
     Tt(TokenTree),
     Ident(Ident, IdentIsRaw),
     Lifetime(Ident, IdentIsRaw),
+    Pat(P<ast::Pat>, NtPatKind),
     Ty(P<ast::Ty>),
+    Meta(P<ast::AttrItem>),
+    Path(P<ast::Path>),
     Vis(P<ast::Visibility>),
 
     /// This variant will eventually be removed, along with `Token::Interpolate`.

compiler/rustc_parse/src/parser/nonterminal.rs

@@ -32,7 +32,7 @@ impl<'a> Parser<'a> {
                 | MetaVarKind::Expr { .. }
                 | MetaVarKind::Ty { .. }
                 | MetaVarKind::Literal // `true`, `false`
-                | MetaVarKind::Meta
+                | MetaVarKind::Meta { .. }
                 | MetaVarKind::Path => true,
 
                 MetaVarKind::Item
@@ -49,11 +49,9 @@ impl<'a> Parser<'a> {
         fn nt_may_be_ident(nt: &Nonterminal) -> bool {
             match nt {
                 NtStmt(_)
-                | NtPat(_)
                 | NtExpr(_)
                 | NtLiteral(_) // `true`, `false`
-                | NtMeta(_)
+                => true,
-                | NtPath(_) => true,
 
                 NtItem(_) | NtBlock(_) => false,
             }
@@ -99,7 +97,7 @@ impl<'a> Parser<'a> {
                 token::NtLifetime(..) => true,
                 token::Interpolated(nt) => match &**nt {
                     NtBlock(_) | NtStmt(_) | NtExpr(_) | NtLiteral(_) => true,
-                    NtItem(_) | NtPat(_) | NtMeta(_) | NtPath(_) => false,
+                    NtItem(_) => false,
                 },
                 token::OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(k))) => match k {
                     MetaVarKind::Block
@@ -109,7 +107,7 @@ impl<'a> Parser<'a> {
                     MetaVarKind::Item
                     | MetaVarKind::Pat(_)
                     | MetaVarKind::Ty { .. }
-                    | MetaVarKind::Meta
+                    | MetaVarKind::Meta { .. }
                     | MetaVarKind::Path
                     | MetaVarKind::Vis => false,
                     MetaVarKind::Lifetime | MetaVarKind::Ident | MetaVarKind::TT => {
@@ -170,15 +168,18 @@ impl<'a> Parser<'a> {
                 }
             },
             NonterminalKind::Pat(pat_kind) => {
-                NtPat(self.collect_tokens_no_attrs(|this| match pat_kind {
+                return Ok(ParseNtResult::Pat(
-                    PatParam { .. } => this.parse_pat_no_top_alt(None, None),
+                    self.collect_tokens_no_attrs(|this| match pat_kind {
-                    PatWithOr => this.parse_pat_no_top_guard(
+                        PatParam { .. } => this.parse_pat_no_top_alt(None, None),
-                        None,
+                        PatWithOr => this.parse_pat_no_top_guard(
-                        RecoverComma::No,
+                            None,
-                        RecoverColon::No,
+                            RecoverComma::No,
-                        CommaRecoveryMode::EitherTupleOrPipe,
+                            RecoverColon::No,
-                    ),
+                            CommaRecoveryMode::EitherTupleOrPipe,
-                })?)
+                        ),
+                    })?,
+                    pat_kind,
+                ));
             }
             NonterminalKind::Expr(_) => NtExpr(self.parse_expr_force_collect()?),
             NonterminalKind::Literal => {
@@ -203,9 +204,13 @@ impl<'a> Parser<'a> {
                 };
             }
             NonterminalKind::Path => {
-                NtPath(P(self.collect_tokens_no_attrs(|this| this.parse_path(PathStyle::Type))?))
+                return Ok(ParseNtResult::Path(P(
+                    self.collect_tokens_no_attrs(|this| this.parse_path(PathStyle::Type))?
+                )));
+            }
+            NonterminalKind::Meta => {
+                return Ok(ParseNtResult::Meta(P(self.parse_attr_item(ForceCollect::Yes)?)));
             }
-            NonterminalKind::Meta => NtMeta(P(self.parse_attr_item(ForceCollect::Yes)?)),
             NonterminalKind::Vis => {
                 return Ok(ParseNtResult::Vis(P(self.collect_tokens_no_attrs(|this| {
                     this.parse_visibility(FollowedByType::Yes)

compiler/rustc_parse/src/parser/pat.rs

@@ -2,7 +2,8 @@ use std::ops::Bound;
 
 use rustc_ast::mut_visit::{self, MutVisitor};
 use rustc_ast::ptr::P;
-use rustc_ast::token::{self, BinOpToken, Delimiter, IdentIsRaw, Token};
+use rustc_ast::token::NtPatKind::*;
+use rustc_ast::token::{self, BinOpToken, Delimiter, IdentIsRaw, MetaVarKind, Token};
 use rustc_ast::util::parser::ExprPrecedence;
 use rustc_ast::visit::{self, Visitor};
 use rustc_ast::{
@@ -30,7 +31,7 @@ use crate::errors::{
     UnexpectedVertVertInPattern, WrapInParens,
 };
 use crate::parser::expr::{DestructuredFloat, could_be_unclosed_char_literal};
-use crate::{exp, maybe_recover_from_interpolated_ty_qpath, maybe_whole};
+use crate::{exp, maybe_recover_from_interpolated_ty_qpath};
 
 #[derive(PartialEq, Copy, Clone)]
 pub enum Expected {
@@ -689,6 +690,27 @@ impl<'a> Parser<'a> {
         PatVisitor { parser: self, stmt, arm: None, field: None }.visit_stmt(stmt);
     }
 
+    fn eat_metavar_pat(&mut self) -> Option<P<Pat>> {
+        // Must try both kinds of pattern nonterminals.
+        if let Some(pat) = self.eat_metavar_seq_with_matcher(
+            |mv_kind| matches!(mv_kind, MetaVarKind::Pat(PatParam { .. })),
+            |this| this.parse_pat_no_top_alt(None, None),
+        ) {
+            Some(pat)
+        } else if let Some(pat) = self.eat_metavar_seq(MetaVarKind::Pat(PatWithOr), |this| {
+            this.parse_pat_no_top_guard(
+                None,
+                RecoverComma::No,
+                RecoverColon::No,
+                CommaRecoveryMode::EitherTupleOrPipe,
+            )
+        }) {
+            Some(pat)
+        } else {
+            None
+        }
+    }
+
     /// Parses a pattern, with a setting whether modern range patterns (e.g., `a..=b`, `a..b` are
     /// allowed).
     fn parse_pat_with_range_pat(
@@ -698,7 +720,10 @@ impl<'a> Parser<'a> {
         syntax_loc: Option<PatternLocation>,
     ) -> PResult<'a, P<Pat>> {
         maybe_recover_from_interpolated_ty_qpath!(self, true);
-        maybe_whole!(self, NtPat, |pat| pat);
+
+        if let Some(pat) = self.eat_metavar_pat() {
+            return Ok(pat);
+        }
 
         let mut lo = self.token.span;
 
@@ -1043,10 +1068,8 @@ impl<'a> Parser<'a> {
         self.recover_additional_muts();
 
         // Make sure we don't allow e.g. `let mut $p;` where `$p:pat`.
-        if let token::Interpolated(nt) = &self.token.kind {
+        if let Some(MetaVarKind::Pat(_)) = self.token.is_metavar_seq() {
-            if let token::NtPat(..) = &**nt {
+            self.expected_ident_found_err().emit();
-                self.expected_ident_found_err().emit();
-            }
         }
 
         // Parse the pattern we hope to be an identifier.

compiler/rustc_parse/src/parser/path.rs

@@ -15,9 +15,9 @@ use tracing::debug;
 
 use super::ty::{AllowPlus, RecoverQPath, RecoverReturnSign};
 use super::{Parser, Restrictions, TokenType};
-use crate::errors::{PathSingleColon, PathTripleColon};
+use crate::errors::{self, PathSingleColon, PathTripleColon};
+use crate::exp;
 use crate::parser::{CommaRecoveryMode, RecoverColon, RecoverComma};
-use crate::{errors, exp, maybe_whole};
 
 /// Specifies how to parse a path.
 #[derive(Copy, Clone, PartialEq)]
@@ -194,7 +194,11 @@ impl<'a> Parser<'a> {
             }
         };
 
-        maybe_whole!(self, NtPath, |path| reject_generics_if_mod_style(self, path.into_inner()));
+        if let Some(path) =
+            self.eat_metavar_seq(MetaVarKind::Path, |this| this.parse_path(PathStyle::Type))
+        {
+            return Ok(reject_generics_if_mod_style(self, path));
+        }
 
         // If we have a `ty` metavar in the form of a path, reparse it directly as a path, instead
         // of reparsing it as a `ty` and then extracting the path.

tests/ui/attributes/nonterminal-expansion.rs

@@ -5,7 +5,7 @@
 macro_rules! pass_nonterminal {
     ($n:expr) => {
         #[repr(align($n))]
-        //~^ ERROR expected unsuffixed literal, found `n!()`
+        //~^ ERROR expected unsuffixed literal, found expression `n!()`
         //~^^ ERROR incorrect `repr(align)` attribute format: `align` expects a literal integer as argument [E0693]
         struct S;
     };

tests/ui/attributes/nonterminal-expansion.stderr

@@ -1,4 +1,4 @@
-error: expected unsuffixed literal, found `n!()`
+error: expected unsuffixed literal, found expression `n!()`
   --> $DIR/nonterminal-expansion.rs:7:22
    |
 LL |         #[repr(align($n))]

tests/ui/conditional-compilation/cfg-attr-syntax-validation.rs

@@ -28,8 +28,8 @@ struct S9;
 macro_rules! generate_s10 {
     ($expr: expr) => {
         #[cfg(feature = $expr)]
-        //~^ ERROR expected unsuffixed literal, found `concat!("nonexistent")`
+        //~^ ERROR expected unsuffixed literal, found expression `concat!("nonexistent")`
-        //~| ERROR expected unsuffixed literal, found `concat!("nonexistent")`
+        //~| ERROR expected unsuffixed literal, found expression `concat!("nonexistent")`
         struct S10;
     }
 }

tests/ui/conditional-compilation/cfg-attr-syntax-validation.stderr

@@ -54,7 +54,7 @@ LL | #[cfg(a = b"hi")]
    |           |
    |           help: consider removing the prefix
 
-error: expected unsuffixed literal, found `concat!("nonexistent")`
+error: expected unsuffixed literal, found expression `concat!("nonexistent")`
   --> $DIR/cfg-attr-syntax-validation.rs:30:25
    |
 LL |         #[cfg(feature = $expr)]
@@ -65,7 +65,7 @@ LL | generate_s10!(concat!("nonexistent"));
    |
    = note: this error originates in the macro `generate_s10` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: expected unsuffixed literal, found `concat!("nonexistent")`
+error: expected unsuffixed literal, found expression `concat!("nonexistent")`
   --> $DIR/cfg-attr-syntax-validation.rs:30:25
    |
 LL |         #[cfg(feature = $expr)]

tests/ui/imports/import-prefix-macro-2.rs

@@ -8,7 +8,7 @@ mod a {
 }
 
 macro_rules! import {
-    ($p: path) => (use ::$p {S, Z}); //~ERROR  expected identifier, found `a::b::c`
+    ($p: path) => (use ::$p {S, Z}); //~ERROR expected identifier, found metavariable
 }
 
 import! { a::b::c }

tests/ui/imports/import-prefix-macro-2.stderr

@@ -1,8 +1,8 @@
-error: expected identifier, found `a::b::c`
+error: expected identifier, found metavariable
   --> $DIR/import-prefix-macro-2.rs:11:26
    |
 LL |     ($p: path) => (use ::$p {S, Z});
-   |                          ^^ expected identifier
+   |                          ^^ expected identifier, found metavariable
 ...
 LL | import! { a::b::c }
    | ------------------- in this macro invocation

tests/ui/macros/nonterminal-matching.rs

@@ -31,7 +31,7 @@ macro_rules! foo {
     (tt $x:tt) => { bar!(tt $x); };
     (expr $x:expr) => { bar!(expr $x); }; //~ ERROR: no rules expected expression `3`
     (literal $x:literal) => { bar!(literal $x); }; //~ ERROR: no rules expected literal `4`
-    (path $x:path) => { bar!(path $x); }; //~ ERROR: no rules expected path `a::b::c`
+    (path $x:path) => { bar!(path $x); }; //~ ERROR: no rules expected `path` metavariable
     (stmt $x:stmt) => { bar!(stmt $x); }; //~ ERROR: no rules expected statement `let abc = 0`
 }
 

tests/ui/macros/nonterminal-matching.stderr

@@ -67,7 +67,7 @@ LL |     (literal 4) => {};
    = help: try using `:tt` instead in the macro definition
    = note: this error originates in the macro `foo` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: no rules expected path `a::b::c`
+error: no rules expected `path` metavariable
   --> $DIR/nonterminal-matching.rs:34:35
    |
 LL |     (path $x:path) => { bar!(path $x); };

tests/ui/macros/trace_faulty_macros.rs

@@ -46,7 +46,7 @@ macro_rules! test {
     (let $p:pat = $e:expr) => {test!(($p,$e))};
     // this should be expr
     //           vvv
-    (($p:pat, $e:pat)) => {let $p = $e;}; //~ ERROR expected expression, found pattern `1+1`
+    (($p:pat, $e:pat)) => {let $p = $e;}; //~ ERROR expected expression, found `pat` metavariable
 }
 
 fn foo() {

tests/ui/macros/trace_faulty_macros.stderr

@@ -50,7 +50,7 @@ LL |     my_recursive_macro!();
    = note: expanding `my_recursive_macro! {  }`
    = note: to `my_recursive_macro! ();`
 
-error: expected expression, found pattern `A { a : a, b : 0, c : _, .. }`
+error: expected expression, found `pat` metavariable
   --> $DIR/trace_faulty_macros.rs:16:9
    |
 LL |         $a
@@ -69,22 +69,15 @@ LL | #[derive(Debug)]
 LL | fn use_derive_macro_as_attr() {}
    | -------------------------------- not a `struct`, `enum` or `union`
 
-error: expected expression, found pattern `1+1`
+error: expected expression, found `pat` metavariable
   --> $DIR/trace_faulty_macros.rs:49:37
    |
-LL |     (let $p:pat = $e:expr) => {test!(($p,$e))};
-   |                                          -- this is interpreted as expression, but it is expected to be pattern
-...
 LL |     (($p:pat, $e:pat)) => {let $p = $e;};
    |                                     ^^ expected expression
 ...
 LL |     test!(let x = 1+1);
-   |     ------------------
+   |     ------------------ in this macro invocation
-   |     |             |
-   |     |             this is expected to be expression
-   |     in this macro invocation
    |
-   = note: when forwarding a matched fragment to another macro-by-example, matchers in the second macro will see an opaque AST of the fragment type, not the underlying tokens
    = note: this error originates in the macro `test` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 note: trace_macro

tests/ui/parser/attribute/attr-bad-meta-4.rs

@@ -1,8 +1,8 @@
 macro_rules! mac {
     ($attr_item: meta) => {
         #[cfg($attr_item)]
-        //~^ ERROR expected unsuffixed literal, found `an(arbitrary token stream)`
+        //~^ ERROR expected unsuffixed literal, found `meta` metavariable
-        //~| ERROR expected unsuffixed literal, found `an(arbitrary token stream)`
+        //~| ERROR expected unsuffixed literal, found `meta` metavariable
         struct S;
     }
 }

tests/ui/parser/attribute/attr-bad-meta-4.stderr

@@ -4,7 +4,7 @@ error: expected unsuffixed literal, found `-`
 LL | #[cfg(feature = -1)]
    |                 ^
 
-error: expected unsuffixed literal, found `an(arbitrary token stream)`
+error: expected unsuffixed literal, found `meta` metavariable
   --> $DIR/attr-bad-meta-4.rs:3:15
    |
 LL |         #[cfg($attr_item)]
@@ -15,7 +15,7 @@ LL | mac!(an(arbitrary token stream));
    |
    = note: this error originates in the macro `mac` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: expected unsuffixed literal, found `an(arbitrary token stream)`
+error: expected unsuffixed literal, found `meta` metavariable
   --> $DIR/attr-bad-meta-4.rs:3:15
    |
 LL |         #[cfg($attr_item)]

tests/ui/parser/attribute/attr-unquoted-ident.rs

@@ -19,7 +19,7 @@ fn main() {
 
 macro_rules! make {
     ($name:ident) => { #[doc(alias = $name)] pub struct S; }
-    //~^ ERROR expected unsuffixed literal, found `nickname`
+    //~^ ERROR expected unsuffixed literal, found identifier `nickname`
 }
 
 make!(nickname); //~ NOTE in this expansion

tests/ui/parser/attribute/attr-unquoted-ident.stderr

@@ -20,7 +20,7 @@ help: surround the identifier with quotation marks to make it into a string lite
 LL |     #[cfg(key="foo bar baz")]
    |               +           +
 
-error: expected unsuffixed literal, found `nickname`
+error: expected unsuffixed literal, found identifier `nickname`
   --> $DIR/attr-unquoted-ident.rs:21:38
    |
 LL |     ($name:ident) => { #[doc(alias = $name)] pub struct S; }

tests/ui/parser/issues/issue-65122-mac-invoc-in-mut-patterns.rs

@@ -12,7 +12,7 @@ macro_rules! mac2 {
     ($eval:pat) => {
         let mut $eval = ();
         //~^ ERROR `mut` must be followed by a named binding
-        //~| ERROR expected identifier, found `does_not_exist!()`
+        //~| ERROR expected identifier, found metavariable
     };
 }
 

tests/ui/parser/issues/issue-65122-mac-invoc-in-mut-patterns.stderr

@@ -15,11 +15,11 @@ LL -         let mut $eval = ();
 LL +         let $eval = ();
    |
 
-error: expected identifier, found `does_not_exist!()`
+error: expected identifier, found metavariable
   --> $DIR/issue-65122-mac-invoc-in-mut-patterns.rs:13:17
    |
 LL |         let mut $eval = ();
-   |                 ^^^^^ expected identifier
+   |                 ^^^^^ expected identifier, found metavariable
 ...
 LL |     mac2! { does_not_exist!() }
    |     --------------------------- in this macro invocation

tests/ui/parser/mut-patterns.rs

@@ -45,7 +45,7 @@ pub fn main() {
     // Make sure we don't accidentally allow `mut $p` where `$p:pat`.
     macro_rules! foo {
         ($p:pat) => {
-            let mut $p = 0; //~ ERROR expected identifier, found `x`
+            let mut $p = 0; //~ ERROR expected identifier, found metavariable
         }
     }
     foo!(x);

tests/ui/parser/mut-patterns.stderr

@@ -158,11 +158,11 @@ LL -     let mut W(mut a, W(b, W(ref c, W(d, B { box f }))))
 LL +     let W(mut a, W(mut b, W(ref c, W(mut d, B { box mut f }))))
    |
 
-error: expected identifier, found `x`
+error: expected identifier, found metavariable
   --> $DIR/mut-patterns.rs:48:21
    |
 LL |             let mut $p = 0;
-   |                     ^^ expected identifier
+   |                     ^^ expected identifier, found metavariable
 ...
 LL |     foo!(x);
    |     ------- in this macro invocation