1 files changed, 49 insertions, 40 deletions

diff --git a/compiler/rustc_ast/src/token.rs b/compiler/rustc_ast/src/token.rs
index a74464937c8..90bfb01d6c7 100644
--- a/compiler/rustc_ast/src/token.rs
+++ b/compiler/rustc_ast/src/token.rs
@@ -15,7 +15,7 @@ use rustc_span::hygiene::ExpnKind;
 use rustc_span::source_map::SourceMap;
 use rustc_span::symbol::{kw, sym};
 use rustc_span::symbol::{Ident, Symbol};
-use rustc_span::{self, FileName, RealFileName, Span, DUMMY_SP};
+use rustc_span::{self, edition::Edition, FileName, RealFileName, Span, DUMMY_SP};
 use std::borrow::Cow;
 use std::{fmt, mem};
 
@@ -130,10 +130,7 @@ impl LitKind {
     }
 
     crate fn may_have_suffix(self) -> bool {
-        match self {
-            Integer | Float | Err => true,
-            _ => false,
-        }
+        matches!(self, Integer | Float | Err)
     }
 }
 
@@ -305,10 +302,7 @@ impl TokenKind {
     }
 
     pub fn should_end_const_arg(&self) -> bool {
-        match self {
-            Gt | Ge | BinOp(Shr) | BinOpEq(Shr) => true,
-            _ => false,
-        }
+        matches!(self, Gt | Ge | BinOp(Shr) | BinOpEq(Shr))
     }
 }
 
@@ -346,18 +340,21 @@ impl Token {
     }
 
     pub fn is_op(&self) -> bool {
-        match self.kind {
-            OpenDelim(..) | CloseDelim(..) | Literal(..) | DocComment(..) | Ident(..)
-            | Lifetime(..) | Interpolated(..) | Eof => false,
-            _ => true,
-        }
+        !matches!(
+            self.kind,
+            OpenDelim(..)
+                | CloseDelim(..)
+                | Literal(..)
+                | DocComment(..)
+                | Ident(..)
+                | Lifetime(..)
+                | Interpolated(..)
+                | Eof
+        )
     }
 
     pub fn is_like_plus(&self) -> bool {
-        match self.kind {
-            BinOp(Plus) | BinOpEq(Plus) => true,
-            _ => false,
-        }
+        matches!(self.kind, BinOp(Plus) | BinOpEq(Plus))
     }
 
     /// Returns `true` if the token can appear at the start of an expression.
@@ -379,13 +376,10 @@ impl Token {
             ModSep                            | // global path
             Lifetime(..)                      | // labeled loop
             Pound                             => true, // expression attributes
-            Interpolated(ref nt) => match **nt {
-                NtLiteral(..) |
+            Interpolated(ref nt) => matches!(**nt, NtLiteral(..) |
                 NtExpr(..)    |
                 NtBlock(..)   |
-                NtPath(..) => true,
-                _ => false,
-            },
+                NtPath(..)),
             _ => false,
         }
     }
@@ -405,10 +399,7 @@ impl Token {
             Lifetime(..)                | // lifetime bound in trait object
             Lt | BinOp(Shl)             | // associated path
             ModSep                      => true, // global path
-            Interpolated(ref nt) => match **nt {
-                NtTy(..) | NtPath(..) => true,
-                _ => false,
-            },
+            Interpolated(ref nt) => matches!(**nt, NtTy(..) | NtPath(..)),
             _ => false,
         }
     }
@@ -417,10 +408,7 @@ impl Token {
     pub fn can_begin_const_arg(&self) -> bool {
         match self.kind {
             OpenDelim(Brace) => true,
-            Interpolated(ref nt) => match **nt {
-                NtExpr(..) | NtBlock(..) | NtLiteral(..) => true,
-                _ => false,
-            },
+            Interpolated(ref nt) => matches!(**nt, NtExpr(..) | NtBlock(..) | NtLiteral(..)),
             _ => self.can_begin_literal_maybe_minus(),
         }
     }
@@ -436,10 +424,7 @@ impl Token {
 
     /// Returns `true` if the token is any literal.
     pub fn is_lit(&self) -> bool {
-        match self.kind {
-            Literal(..) => true,
-            _ => false,
-        }
+        matches!(self.kind, Literal(..))
     }
 
     /// Returns `true` if the token is any literal, a minus (which can prefix a literal,
@@ -705,7 +690,16 @@ pub enum NonterminalKind {
     Item,
     Block,
     Stmt,
-    Pat,
+    Pat2018 {
+        /// Keep track of whether the user used `:pat2018` or `:pat` and we inferred it from the
+        /// edition of the span. This is used for diagnostics.
+        inferred: bool,
+    },
+    Pat2021 {
+        /// Keep track of whether the user used `:pat2018` or `:pat` and we inferred it from the
+        /// edition of the span. This is used for diagnostics.
+        inferred: bool,
+    },
     Expr,
     Ty,
     Ident,
@@ -718,12 +712,24 @@ pub enum NonterminalKind {
 }
 
 impl NonterminalKind {
-    pub fn from_symbol(symbol: Symbol) -> Option<NonterminalKind> {
+    /// The `edition` closure is used to get the edition for the given symbol. Doing
+    /// `span.edition()` is expensive, so we do it lazily.
+    pub fn from_symbol(
+        symbol: Symbol,
+        edition: impl FnOnce() -> Edition,
+    ) -> Option<NonterminalKind> {
         Some(match symbol {
             sym::item => NonterminalKind::Item,
             sym::block => NonterminalKind::Block,
             sym::stmt => NonterminalKind::Stmt,
-            sym::pat => NonterminalKind::Pat,
+            sym::pat => match edition() {
+                Edition::Edition2015 | Edition::Edition2018 => {
+                    NonterminalKind::Pat2018 { inferred: true }
+                }
+                Edition::Edition2021 => NonterminalKind::Pat2021 { inferred: true },
+            },
+            sym::pat2018 => NonterminalKind::Pat2018 { inferred: false },
+            sym::pat2021 => NonterminalKind::Pat2021 { inferred: false },
             sym::expr => NonterminalKind::Expr,
             sym::ty => NonterminalKind::Ty,
             sym::ident => NonterminalKind::Ident,
@@ -741,7 +747,10 @@ impl NonterminalKind {
             NonterminalKind::Item => sym::item,
             NonterminalKind::Block => sym::block,
             NonterminalKind::Stmt => sym::stmt,
-            NonterminalKind::Pat => sym::pat,
+            NonterminalKind::Pat2018 { inferred: false } => sym::pat2018,
+            NonterminalKind::Pat2021 { inferred: false } => sym::pat2021,
+            NonterminalKind::Pat2018 { inferred: true }
+            | NonterminalKind::Pat2021 { inferred: true } => sym::pat,
             NonterminalKind::Expr => sym::expr,
             NonterminalKind::Ty => sym::ty,
             NonterminalKind::Ident => sym::ident,
@@ -762,7 +771,7 @@ impl fmt::Display for NonterminalKind {
 }
 
 impl Nonterminal {
-    fn span(&self) -> Span {
+    pub fn span(&self) -> Span {
         match self {
             NtItem(item) => item.span,
             NtBlock(block) => block.span,