Remove boxes from ast list elements

compiler/rustc_ast/src/ast.rs

@@ -869,11 +869,11 @@ pub enum PatKind {
     Struct(Option<Box<QSelf>>, Path, ThinVec<PatField>, PatFieldsRest),
 
     /// A tuple struct/variant pattern (`Variant(x, y, .., z)`).
-    TupleStruct(Option<Box<QSelf>>, Path, ThinVec<Box<Pat>>),
+    TupleStruct(Option<Box<QSelf>>, Path, ThinVec<Pat>),
 
     /// An or-pattern `A | B | C`.
     /// Invariant: `pats.len() >= 2`.
-    Or(ThinVec<Box<Pat>>),
+    Or(ThinVec<Pat>),
 
     /// A possibly qualified path pattern.
     /// Unqualified path patterns `A::B::C` can legally refer to variants, structs, constants
@@ -882,7 +882,7 @@ pub enum PatKind {
     Path(Option<Box<QSelf>>, Path),
 
     /// A tuple pattern (`(a, b)`).
-    Tuple(ThinVec<Box<Pat>>),
+    Tuple(ThinVec<Pat>),
 
     /// A `box` pattern.
     Box(Box<Pat>),
@@ -900,7 +900,7 @@ pub enum PatKind {
     Range(Option<Box<Expr>>, Option<Box<Expr>>, Spanned<RangeEnd>),
 
     /// A slice pattern `[a, b, c]`.
-    Slice(ThinVec<Box<Pat>>),
+    Slice(ThinVec<Pat>),
 
     /// A rest pattern `..`.
     ///
@@ -2579,7 +2579,7 @@ pub enum TyPatKind {
     /// A range pattern (e.g., `1...2`, `1..2`, `1..`, `..2`, `1..=2`, `..=2`).
     Range(Option<Box<AnonConst>>, Option<Box<AnonConst>>, Spanned<RangeEnd>),
 
-    Or(ThinVec<Box<TyPat>>),
+    Or(ThinVec<TyPat>),
 
     /// Placeholder for a pattern that wasn't syntactically well formed in some way.
     Err(ErrorGuaranteed),

compiler/rustc_ast/src/visit.rs

@@ -389,9 +389,9 @@ macro_rules! common_visitor_and_walkers {
             ThinVec<(NodeId, Path)>,
             ThinVec<PathSegment>,
             ThinVec<PreciseCapturingArg>,
-            ThinVec<Box<Pat>>,
+            ThinVec<Pat>,
             ThinVec<Box<Ty>>,
-            ThinVec<Box<TyPat>>,
+            ThinVec<TyPat>,
         );
 
         // This macro generates `impl Visitable` and `impl MutVisitable` that forward to `Walkable`

compiler/rustc_ast_lowering/src/pat.rs

@@ -154,7 +154,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
 
     fn lower_pat_tuple(
         &mut self,
-        pats: &[Box<Pat>],
+        pats: &[Pat],
         ctx: &str,
     ) -> (&'hir [hir::Pat<'hir>], hir::DotDotPos) {
         let mut elems = Vec::with_capacity(pats.len());
@@ -209,7 +209,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     /// When encountering `($binding_mode $ident @)? ..` (`slice`),
     /// this is interpreted as a sub-slice pattern semantically.
     /// Patterns that follow, which are not like `slice` -- or an error occurs, are in `after`.
-    fn lower_pat_slice(&mut self, pats: &[Box<Pat>]) -> hir::PatKind<'hir> {
+    fn lower_pat_slice(&mut self, pats: &[Pat]) -> hir::PatKind<'hir> {
         let mut before = Vec::new();
         let mut after = Vec::new();
         let mut slice = None;

compiler/rustc_builtin_macros/src/deriving/generic/mod.rs

@@ -1507,7 +1507,7 @@ impl<'a> TraitDef<'a> {
         struct_def: &'a VariantData,
         prefixes: &[String],
         by_ref: ByRef,
-    ) -> ThinVec<Box<ast::Pat>> {
+    ) -> ThinVec<ast::Pat> {
         prefixes
             .iter()
             .map(|prefix| {
@@ -1543,7 +1543,7 @@ impl<'a> TraitDef<'a> {
                                     attrs: ast::AttrVec::new(),
                                     id: ast::DUMMY_NODE_ID,
                                     span: pat.span.with_ctxt(self.span.ctxt()),
-                                    pat,
+                                    pat: Box::new(pat),
                                     is_placeholder: false,
                                 }
                             })

compiler/rustc_builtin_macros/src/pattern_type.rs

@@ -32,7 +32,7 @@ fn parse_pat_ty<'a>(
 
     let pat = pat_to_ty_pat(
         cx,
-        *parser.parse_pat_no_top_guard(
+        parser.parse_pat_no_top_guard(
             None,
             RecoverComma::No,
             RecoverColon::No,
@@ -44,22 +44,22 @@ fn parse_pat_ty<'a>(
         parser.unexpected()?;
     }
 
-    Ok((ty, pat))
+    Ok((ty, Box::new(pat)))
 }
 
-fn ty_pat(kind: TyPatKind, span: Span) -> Box<TyPat> {
-    Box::new(TyPat { id: DUMMY_NODE_ID, kind, span, tokens: None })
+fn ty_pat(kind: TyPatKind, span: Span) -> TyPat {
+    TyPat { id: DUMMY_NODE_ID, kind, span, tokens: None }
 }
 
-fn pat_to_ty_pat(cx: &mut ExtCtxt<'_>, pat: ast::Pat) -> Box<TyPat> {
+fn pat_to_ty_pat(cx: &mut ExtCtxt<'_>, pat: ast::Pat) -> TyPat {
     let kind = match pat.kind {
         ast::PatKind::Range(start, end, include_end) => TyPatKind::Range(
             start.map(|value| Box::new(AnonConst { id: DUMMY_NODE_ID, value })),
             end.map(|value| Box::new(AnonConst { id: DUMMY_NODE_ID, value })),
             include_end,
         ),
         ast::PatKind::Or(variants) => {
-            TyPatKind::Or(variants.into_iter().map(|pat| pat_to_ty_pat(cx, *pat)).collect())
+            TyPatKind::Or(variants.into_iter().map(|pat| pat_to_ty_pat(cx, pat)).collect())
         }
         ast::PatKind::Err(guar) => TyPatKind::Err(guar),
         _ => TyPatKind::Err(cx.dcx().span_err(pat.span, "pattern not supported in pattern types")),

compiler/rustc_expand/src/build.rs

@@ -233,7 +233,7 @@ impl<'a> ExtCtxt<'a> {
         };
         let local = Box::new(ast::Local {
             super_: None,
-            pat,
+            pat: Box::new(pat),
             ty,
             id: ast::DUMMY_NODE_ID,
             kind: LocalKind::Init(ex),
@@ -249,7 +249,7 @@ impl<'a> ExtCtxt<'a> {
     pub fn stmt_let_type_only(&self, span: Span, ty: Box<ast::Ty>) -> ast::Stmt {
         let local = Box::new(ast::Local {
             super_: None,
-            pat: self.pat_wild(span),
+            pat: Box::new(self.pat_wild(span)),
             ty: Some(ty),
             id: ast::DUMMY_NODE_ID,
             kind: LocalKind::Decl,
@@ -528,16 +528,16 @@ impl<'a> ExtCtxt<'a> {
         self.expr_match(sp, head, thin_vec![ok_arm, err_arm])
     }
 
-    pub fn pat(&self, span: Span, kind: PatKind) -> Box<ast::Pat> {
-        Box::new(ast::Pat { id: ast::DUMMY_NODE_ID, kind, span, tokens: None })
+    pub fn pat(&self, span: Span, kind: PatKind) -> ast::Pat {
+        ast::Pat { id: ast::DUMMY_NODE_ID, kind, span, tokens: None }
     }
-    pub fn pat_wild(&self, span: Span) -> Box<ast::Pat> {
+    pub fn pat_wild(&self, span: Span) -> ast::Pat {
         self.pat(span, PatKind::Wild)
     }
-    pub fn pat_lit(&self, span: Span, expr: Box<ast::Expr>) -> Box<ast::Pat> {
+    pub fn pat_lit(&self, span: Span, expr: Box<ast::Expr>) -> ast::Pat {
         self.pat(span, PatKind::Expr(expr))
     }
-    pub fn pat_ident(&self, span: Span, ident: Ident) -> Box<ast::Pat> {
+    pub fn pat_ident(&self, span: Span, ident: Ident) -> ast::Pat {
         self.pat_ident_binding_mode(span, ident, ast::BindingMode::NONE)
     }
 
@@ -546,43 +546,43 @@ impl<'a> ExtCtxt<'a> {
         span: Span,
         ident: Ident,
         ann: ast::BindingMode,
-    ) -> Box<ast::Pat> {
+    ) -> ast::Pat {
         let pat = PatKind::Ident(ann, ident.with_span_pos(span), None);
         self.pat(span, pat)
     }
-    pub fn pat_path(&self, span: Span, path: ast::Path) -> Box<ast::Pat> {
+    pub fn pat_path(&self, span: Span, path: ast::Path) -> ast::Pat {
         self.pat(span, PatKind::Path(None, path))
     }
     pub fn pat_tuple_struct(
         &self,
         span: Span,
         path: ast::Path,
-        subpats: ThinVec<Box<ast::Pat>>,
-    ) -> Box<ast::Pat> {
+        subpats: ThinVec<ast::Pat>,
+    ) -> ast::Pat {
         self.pat(span, PatKind::TupleStruct(None, path, subpats))
     }
     pub fn pat_struct(
         &self,
         span: Span,
         path: ast::Path,
         field_pats: ThinVec<ast::PatField>,
-    ) -> Box<ast::Pat> {
+    ) -> ast::Pat {
         self.pat(span, PatKind::Struct(None, path, field_pats, ast::PatFieldsRest::None))
     }
-    pub fn pat_tuple(&self, span: Span, pats: ThinVec<Box<ast::Pat>>) -> Box<ast::Pat> {
+    pub fn pat_tuple(&self, span: Span, pats: ThinVec<ast::Pat>) -> ast::Pat {
         self.pat(span, PatKind::Tuple(pats))
     }
 
-    pub fn pat_some(&self, span: Span, pat: Box<ast::Pat>) -> Box<ast::Pat> {
+    pub fn pat_some(&self, span: Span, pat: ast::Pat) -> ast::Pat {
         let some = self.std_path(&[sym::option, sym::Option, sym::Some]);
         let path = self.path_global(span, some);
         self.pat_tuple_struct(span, path, thin_vec![pat])
     }
 
-    pub fn arm(&self, span: Span, pat: Box<ast::Pat>, expr: Box<ast::Expr>) -> ast::Arm {
+    pub fn arm(&self, span: Span, pat: ast::Pat, expr: Box<ast::Expr>) -> ast::Arm {
         ast::Arm {
             attrs: AttrVec::new(),
-            pat,
+            pat: Box::new(pat),
             guard: None,
             body: Some(expr),
             span,
@@ -661,11 +661,11 @@ impl<'a> ExtCtxt<'a> {
     }
 
     pub fn param(&self, span: Span, ident: Ident, ty: Box<ast::Ty>) -> ast::Param {
-        let arg_pat = self.pat_ident(span, ident);
+        let pat = Box::new(self.pat_ident(span, ident));
         ast::Param {
             attrs: AttrVec::default(),
             id: ast::DUMMY_NODE_ID,
-            pat: arg_pat,
+            pat,
             span,
             ty,
             is_placeholder: false,

compiler/rustc_expand/src/expand.rs

@@ -1152,12 +1152,12 @@ pub fn parse_ast_fragment<'a>(
             }
         }
         AstFragmentKind::Ty => AstFragment::Ty(this.parse_ty()?),
-        AstFragmentKind::Pat => AstFragment::Pat(this.parse_pat_allow_top_guard(
+        AstFragmentKind::Pat => AstFragment::Pat(Box::new(this.parse_pat_allow_top_guard(
             None,
             RecoverComma::No,
             RecoverColon::Yes,
             CommaRecoveryMode::LikelyTuple,
-        )?),
+        )?)),
         AstFragmentKind::Crate => AstFragment::Crate(this.parse_crate_mod()?),
         AstFragmentKind::Arms
         | AstFragmentKind::ExprFields

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -73,6 +73,16 @@ pub(super) trait RecoverQPath: Sized + 'static {
     fn recovered(qself: Option<Box<QSelf>>, path: ast::Path) -> Self;
 }
 
+impl<T: RecoverQPath> RecoverQPath for Box<T> {
+    const PATH_STYLE: PathStyle = T::PATH_STYLE;
+    fn to_ty(&self) -> Option<Box<Ty>> {
+        T::to_ty(self)
+    }
+    fn recovered(qself: Option<Box<QSelf>>, path: ast::Path) -> Self {
+        Box::new(T::recovered(qself, path))
+    }
+}
+
 impl RecoverQPath for Ty {
     const PATH_STYLE: PathStyle = PathStyle::Type;
     fn to_ty(&self) -> Option<Box<Ty>> {
@@ -1833,17 +1843,19 @@ impl<'a> Parser<'a> {
     /// tail, and combines them into a `<Ty>::AssocItem` expression/pattern/type.
     pub(super) fn maybe_recover_from_bad_qpath<T: RecoverQPath>(
         &mut self,
-        base: Box<T>,
-    ) -> PResult<'a, Box<T>> {
-        if !self.may_recover() {
-            return Ok(base);
+        base: T,
+    ) -> PResult<'a, T> {
+        // Do not add `::` to expected tokens.
+        if self.may_recover() && self.token == token::PathSep {
+            return self.recover_from_bad_qpath(base);
         }
+        Ok(base)
+    }
 
-        // Do not add `::` to expected tokens.
-        if self.token == token::PathSep {
-            if let Some(ty) = base.to_ty() {
-                return self.maybe_recover_from_bad_qpath_stage_2(ty.span, ty);
-            }
+    #[cold]
+    fn recover_from_bad_qpath<T: RecoverQPath>(&mut self, base: T) -> PResult<'a, T> {
+        if let Some(ty) = base.to_ty() {
+            return self.maybe_recover_from_bad_qpath_stage_2(ty.span, ty);
         }
         Ok(base)
     }
@@ -1854,7 +1866,7 @@ impl<'a> Parser<'a> {
         &mut self,
         ty_span: Span,
         ty: Box<Ty>,
-    ) -> PResult<'a, Box<T>> {
+    ) -> PResult<'a, T> {
         self.expect(exp!(PathSep))?;
 
         let mut path = ast::Path { segments: ThinVec::new(), span: DUMMY_SP, tokens: None };
@@ -1867,7 +1879,7 @@ impl<'a> Parser<'a> {
         });
 
         let path_span = ty_span.shrink_to_hi(); // Use an empty path since `position == 0`.
-        Ok(Box::new(T::recovered(Some(Box::new(QSelf { ty, path_span, position: 0 })), path)))
+        Ok(T::recovered(Some(Box::new(QSelf { ty, path_span, position: 0 })), path))
     }
 
     /// This function gets called in places where a semicolon is NOT expected and if there's a
@@ -2360,6 +2372,7 @@ impl<'a> Parser<'a> {
         None
     }
 
+    #[cold]
     pub(super) fn recover_arg_parse(&mut self) -> PResult<'a, (Box<ast::Pat>, Box<ast::Ty>)> {
         let pat = self.parse_pat_no_top_alt(Some(Expected::ArgumentName), None)?;
         self.expect(exp!(Colon))?;
@@ -2740,11 +2753,12 @@ impl<'a> Parser<'a> {
 
     /// Some special error handling for the "top-level" patterns in a match arm,
     /// `for` loop, `let`, &c. (in contrast to subpatterns within such).
-    pub(crate) fn maybe_recover_colon_colon_in_pat_typo(
+    #[cold]
+    pub(crate) fn recover_colon_colon_in_pat_typo(
         &mut self,
-        mut first_pat: Box<Pat>,
+        mut first_pat: Pat,
         expected: Option<Expected>,
-    ) -> Box<Pat> {
+    ) -> Pat {
         if token::Colon != self.token.kind {
             return first_pat;
         }
@@ -2925,7 +2939,11 @@ impl<'a> Parser<'a> {
         if self.token != token::Comma {
             return Ok(());
         }
+        self.recover_unexpected_comma(lo, rt)
+    }
 
+    #[cold]
+    fn recover_unexpected_comma(&mut self, lo: Span, rt: CommaRecoveryMode) -> PResult<'a, ()> {
         // An unexpected comma after a top-level pattern is a clue that the
         // user (perhaps more accustomed to some other language) forgot the
         // parentheses in what should have been a tuple pattern; return a