Auto merge of rust-lang#137517 - nnethercote:rm-NtPat-NtItem-NtStmt, …

…r=<try>

Remove `NtPat`

Another part of rust-lang#124141.

r? `@petrochenkov`

compiler/rustc_ast/src/ast_traits.rs

@@ -202,7 +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(),
@@ -213,7 +212,6 @@ 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/mut_visit.rs

@@ -905,7 +905,6 @@ 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) => {

compiler/rustc_ast/src/token.rs

@@ -659,7 +659,6 @@ impl Token {
                     | NtExpr(..)
                     | NtLiteral(..)
                     | NtMeta(..)
-                    | NtPat(..)
                     | NtPath(..)
                 ),
             OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(
@@ -1075,7 +1074,6 @@ 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
@@ -1172,7 +1170,6 @@ 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,
@@ -1184,7 +1181,6 @@ impl Nonterminal {
             NtItem(..) => "item",
             NtBlock(..) => "block",
             NtStmt(..) => "statement",
-            NtPat(..) => "pattern",
             NtExpr(..) => "expression",
             NtLiteral(..) => "literal",
             NtMeta(..) => "attribute",
@@ -1209,7 +1205,6 @@ 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(..)"),

compiler/rustc_ast/src/tokenstream.rs

@@ -468,7 +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_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 +323,21 @@ 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::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/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,
-    PatKind, Path, PathSegment, QSelf, Recovered, Ty, TyKind,
+    BlockCheckMode, Expr, ExprKind, GenericArg, Generics, Item, ItemKind, Param, Pat, PatKind,
+    Path, PathSegment, QSelf, Recovered, Ty, TyKind,
 };
 use rustc_ast_pretty::pprust;
 use rustc_data_structures::fx::FxHashSet;
@@ -2400,52 +2398,6 @@ 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/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::NtPat(..) => return self.look_ahead(1, |t| t == &token::Colon),
+            token::OpenDelim(Delimiter::Invisible(origin)) => match origin {
+                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;
@@ -1745,6 +1746,7 @@ pub enum ParseNtResult {
     Tt(TokenTree),
     Ident(Ident, IdentIsRaw),
     Lifetime(Ident, IdentIsRaw),
+    Pat(P<ast::Pat>, NtPatKind),
     Ty(P<ast::Ty>),
     Vis(P<ast::Visibility>),
 

compiler/rustc_parse/src/parser/nonterminal.rs

@@ -49,7 +49,6 @@ impl<'a> Parser<'a> {
         fn nt_may_be_ident(nt: &Nonterminal) -> bool {
             match nt {
                 NtStmt(_)
-                | NtPat(_)
                 | NtExpr(_)
                 | NtLiteral(_) // `true`, `false`
                 | NtMeta(_)
@@ -99,7 +98,7 @@ impl<'a> Parser<'a> {
                 token::NtLifetime(..) => true,
                 token::Interpolated(nt) => match &**nt {
                     NtBlock(_) | NtStmt(_) | NtExpr(_) | NtLiteral(_) => true,
-                    NtItem(_) | NtPat(_) | NtMeta(_) | NtPath(_) => false,
+                    NtItem(_) | NtMeta(_) | NtPath(_) => false,
                 },
                 token::OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(k))) => match k {
                     MetaVarKind::Block
@@ -170,15 +169,18 @@ impl<'a> Parser<'a> {
                 }
             },
             NonterminalKind::Pat(pat_kind) => {
-                NtPat(self.collect_tokens_no_attrs(|this| match pat_kind {
-                    PatParam { .. } => this.parse_pat_no_top_alt(None, None),
-                    PatWithOr => this.parse_pat_no_top_guard(
-                        None,
-                        RecoverComma::No,
-                        RecoverColon::No,
-                        CommaRecoveryMode::EitherTupleOrPipe,
-                    ),
-                })?)
+                return Ok(ParseNtResult::Pat(
+                    self.collect_tokens_no_attrs(|this| match pat_kind {
+                        PatParam { .. } => this.parse_pat_no_top_alt(None, None),
+                        PatWithOr => this.parse_pat_no_top_guard(
+                            None,
+                            RecoverComma::No,
+                            RecoverColon::No,
+                            CommaRecoveryMode::EitherTupleOrPipe,
+                        ),
+                    })?,
+                    pat_kind,
+                ));
             }
             NonterminalKind::Expr(_) => NtExpr(self.parse_expr_force_collect()?),
             NonterminalKind::Literal => {

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 token::NtPat(..) = &**nt {
-                self.expected_ident_found_err().emit();
-            }
+        if let Some(MetaVarKind::Pat(_)) = self.token.is_metavar_seq() {
+            self.expected_ident_found_err().emit();
         }
 
         // Parse the pattern we hope to be an identifier.

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);
-   |     ------------------
-   |     |             |
-   |     |             this is expected to be expression
-   |     in this macro invocation
+   |     ------------------ 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/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
     };
 }