Remove hir::StmtKind::Decl.

It's a level of indirection that hurts far more than it helps. The code is simpler without it. (This commit cuts more than 120 lines of code.) In particular, this commit removes some unnecessary `Span`s within `DeclKind` that were always identical to those in the enclosing `Stmt`, and some unnecessary allocations via `P`.
rust-lang · Jan 17, 2019 · afbd004 · afbd004
1 parent b2ce5a9
commit afbd004
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Showing 16 changed files with 150 additions and 272 deletions.
diff --git a/src/librustc/cfg/construct.rs b/src/librustc/cfg/construct.rs
@@ -100,29 +100,20 @@ impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
 
     fn stmt(&mut self, stmt: &hir::Stmt, pred: CFGIndex) -> CFGIndex {
         let hir_id = self.tcx.hir().node_to_hir_id(stmt.id);
-        match stmt.node {
-            hir::StmtKind::Decl(ref decl) => {
-                let exit = self.decl(&decl, pred);
-                self.add_ast_node(hir_id.local_id, &[exit])
+        let exit = match stmt.node {
+            hir::StmtKind::Local(ref local) => {
+                let init_exit = self.opt_expr(&local.init, pred);
+                self.pat(&local.pat, init_exit)
+            }
+            hir::StmtKind::Item(_) => {
+                pred
             }
-
             hir::StmtKind::Expr(ref expr) |
             hir::StmtKind::Semi(ref expr) => {
-                let exit = self.expr(&expr, pred);
-                self.add_ast_node(hir_id.local_id, &[exit])
+                self.expr(&expr, pred)
             }
-        }
-    }
-
-    fn decl(&mut self, decl: &hir::Decl, pred: CFGIndex) -> CFGIndex {
-        match decl.node {
-            hir::DeclKind::Local(ref local) => {
-                let init_exit = self.opt_expr(&local.init, pred);
-                self.pat(&local.pat, init_exit)
-            }
-
-            hir::DeclKind::Item(_) => pred,
-        }
+        };
+        self.add_ast_node(hir_id.local_id, &[exit])
     }
 
     fn pat(&mut self, pat: &hir::Pat, pred: CFGIndex) -> CFGIndex {

diff --git a/src/librustc/hir/check_attr.rs b/src/librustc/hir/check_attr.rs
@@ -298,8 +298,8 @@ impl<'a, 'tcx> CheckAttrVisitor<'a, 'tcx> {
 
     fn check_stmt_attributes(&self, stmt: &hir::Stmt) {
         // When checking statements ignore expressions, they will be checked later
-        if let hir::StmtKind::Decl(..) = stmt.node {
-            for attr in stmt.node.attrs() {
+        if let hir::StmtKind::Local(ref l) = stmt.node {
+            for attr in l.attrs.iter() {
                 if attr.check_name("inline") {
                     self.check_inline(attr, &stmt.span, Target::Statement);
                 }

diff --git a/src/librustc/hir/intravisit.rs b/src/librustc/hir/intravisit.rs
@@ -260,9 +260,6 @@ pub trait Visitor<'v> : Sized {
     fn visit_pat(&mut self, p: &'v Pat) {
         walk_pat(self, p)
     }
-    fn visit_decl(&mut self, d: &'v Decl) {
-        walk_decl(self, d)
-    }
     fn visit_anon_const(&mut self, c: &'v AnonConst) {
         walk_anon_const(self, c)
     }
@@ -955,23 +952,15 @@ pub fn walk_block<'v, V: Visitor<'v>>(visitor: &mut V, block: &'v Block) {
 pub fn walk_stmt<'v, V: Visitor<'v>>(visitor: &mut V, statement: &'v Stmt) {
     visitor.visit_id(statement.id);
     match statement.node {
-        StmtKind::Decl(ref declaration) => {
-            visitor.visit_decl(declaration)
-        }
+        StmtKind::Local(ref local) => visitor.visit_local(local),
+        StmtKind::Item(ref item) => visitor.visit_nested_item(**item),
         StmtKind::Expr(ref expression) |
         StmtKind::Semi(ref expression) => {
             visitor.visit_expr(expression)
         }
     }
 }
 
-pub fn walk_decl<'v, V: Visitor<'v>>(visitor: &mut V, declaration: &'v Decl) {
-    match declaration.node {
-        DeclKind::Local(ref local) => visitor.visit_local(local),
-        DeclKind::Item(item) => visitor.visit_nested_item(item),
-    }
-}
-
 pub fn walk_anon_const<'v, V: Visitor<'v>>(visitor: &mut V, constant: &'v AnonConst) {
     visitor.visit_id(constant.id);
     visitor.visit_nested_body(constant.body);

diff --git a/src/librustc/hir/lowering.rs b/src/librustc/hir/lowering.rs
@@ -1957,7 +1957,7 @@ impl<'a> LoweringContext<'a> {
         )
     }
 
-    fn lower_local(&mut self, l: &Local) -> (P<hir::Local>, SmallVec<[hir::ItemId; 1]>) {
+    fn lower_local(&mut self, l: &Local) -> (hir::Local, SmallVec<[hir::ItemId; 1]>) {
         let LoweredNodeId { node_id, hir_id } = self.lower_node_id(l.id);
         let mut ids = SmallVec::<[hir::ItemId; 1]>::new();
         if self.sess.features_untracked().impl_trait_in_bindings {
@@ -1967,7 +1967,7 @@ impl<'a> LoweringContext<'a> {
             }
         }
         let parent_def_id = DefId::local(self.current_hir_id_owner.last().unwrap().0);
-        (P(hir::Local {
+        (hir::Local {
             id: node_id,
             hir_id,
             ty: l.ty
@@ -1984,7 +1984,7 @@ impl<'a> LoweringContext<'a> {
             span: l.span,
             attrs: l.attrs.clone(),
             source: hir::LocalSource::Normal,
-        }), ids)
+        }, ids)
     }
 
     fn lower_mutability(&mut self, m: Mutability) -> hir::Mutability {
@@ -4537,23 +4537,13 @@ impl<'a> LoweringContext<'a> {
                     .into_iter()
                     .map(|item_id| hir::Stmt {
                         id: self.next_id().node_id,
-                        node: hir::StmtKind::Decl(
-                            P(Spanned {
-                                node: hir::DeclKind::Item(item_id),
-                                span: s.span,
-                            }),
-                        ),
+                        node: hir::StmtKind::Item(P(item_id)),
                         span: s.span,
                     })
                     .collect();
                 ids.push(hir::Stmt {
                     id: self.lower_node_id(s.id).node_id,
-                    node: hir::StmtKind::Decl(
-                        P(Spanned {
-                            node: hir::DeclKind::Local(l),
-                            span: s.span,
-                        }),
-                    ),
+                    node: hir::StmtKind::Local(P(l)),
                     span: s.span,
                 });
                 return ids;
@@ -4567,12 +4557,7 @@ impl<'a> LoweringContext<'a> {
                         id: id.take()
                               .map(|id| self.lower_node_id(id).node_id)
                               .unwrap_or_else(|| self.next_id().node_id),
-                        node: hir::StmtKind::Decl(
-                            P(Spanned {
-                                node: hir::DeclKind::Item(item_id),
-                                span: s.span,
-                            }),
-                        ),
+                        node: hir::StmtKind::Item(P(item_id)),
                         span: s.span,
                     })
                     .collect();
@@ -4799,7 +4784,7 @@ impl<'a> LoweringContext<'a> {
     ) -> hir::Stmt {
         let LoweredNodeId { node_id, hir_id } = self.next_id();
 
-        let local = P(hir::Local {
+        let local = hir::Local {
             pat,
             ty: None,
             init: ex,
@@ -4808,11 +4793,10 @@ impl<'a> LoweringContext<'a> {
             span: sp,
             attrs: ThinVec::new(),
             source,
-        });
-        let decl = respan(sp, hir::DeclKind::Local(local));
+        };
         hir::Stmt {
             id: self.next_id().node_id,
-            node: hir::StmtKind::Decl(P(decl)),
+            node: hir::StmtKind::Local(P(local)),
             span: sp
         }
     }

diff --git a/src/librustc/hir/mod.rs b/src/librustc/hir/mod.rs
@@ -1160,8 +1160,10 @@ impl fmt::Debug for Stmt {
 
 #[derive(Clone, RustcEncodable, RustcDecodable)]
 pub enum StmtKind {
-    /// Could be an item or a local (let) binding:
-    Decl(P<Decl>),
+    /// A local (let) binding:
+    Local(P<Local>),
+    /// An item binding:
+    Item(P<ItemId>),
 
     /// Expr without trailing semi-colon (must have unit type):
     Expr(P<Expr>),
@@ -1173,7 +1175,8 @@ pub enum StmtKind {
 impl StmtKind {
     pub fn attrs(&self) -> &[Attribute] {
         match *self {
-            StmtKind::Decl(ref d) => d.node.attrs(),
+            StmtKind::Local(ref l) => &l.attrs,
+            StmtKind::Item(_) => &[],
             StmtKind::Expr(ref e) |
             StmtKind::Semi(ref e) => &e.attrs,
         }
@@ -1194,32 +1197,6 @@ pub struct Local {
     pub source: LocalSource,
 }
 
-pub type Decl = Spanned<DeclKind>;
-
-#[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
-pub enum DeclKind {
-    /// A local (let) binding:
-    Local(P<Local>),
-    /// An item binding:
-    Item(ItemId),
-}
-
-impl DeclKind {
-    pub fn attrs(&self) -> &[Attribute] {
-        match *self {
-            DeclKind::Local(ref l) => &l.attrs,
-            DeclKind::Item(_) => &[]
-        }
-    }
-
-    pub fn is_local(&self) -> bool {
-        match *self {
-            DeclKind::Local(_) => true,
-            _ => false,
-        }
-    }
-}
-
 /// represents one arm of a 'match'
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct Arm {

diff --git a/src/librustc/hir/print.rs b/src/librustc/hir/print.rs
@@ -992,8 +992,23 @@ impl<'a> State<'a> {
     pub fn print_stmt(&mut self, st: &hir::Stmt) -> io::Result<()> {
         self.maybe_print_comment(st.span.lo())?;
         match st.node {
-            hir::StmtKind::Decl(ref decl) => {
-                self.print_decl(&decl)?;
+            hir::StmtKind::Local(ref loc) => {
+                self.space_if_not_bol()?;
+                self.ibox(indent_unit)?;
+                self.word_nbsp("let")?;
+
+                self.ibox(indent_unit)?;
+                self.print_local_decl(&loc)?;
+                self.end()?;
+                if let Some(ref init) = loc.init {
+                    self.nbsp()?;
+                    self.word_space("=")?;
+                    self.print_expr(&init)?;
+                }
+                self.end()?
+            }
+            hir::StmtKind::Item(ref item) => {
+                self.ann.nested(self, Nested::Item(**item))?
             }
             hir::StmtKind::Expr(ref expr) => {
                 self.space_if_not_bol()?;
@@ -1562,30 +1577,6 @@ impl<'a> State<'a> {
         Ok(())
     }
 
-    pub fn print_decl(&mut self, decl: &hir::Decl) -> io::Result<()> {
-        self.maybe_print_comment(decl.span.lo())?;
-        match decl.node {
-            hir::DeclKind::Local(ref loc) => {
-                self.space_if_not_bol()?;
-                self.ibox(indent_unit)?;
-                self.word_nbsp("let")?;
-
-                self.ibox(indent_unit)?;
-                self.print_local_decl(&loc)?;
-                self.end()?;
-                if let Some(ref init) = loc.init {
-                    self.nbsp()?;
-                    self.word_space("=")?;
-                    self.print_expr(&init)?;
-                }
-                self.end()
-            }
-            hir::DeclKind::Item(item) => {
-                self.ann.nested(self, Nested::Item(item))
-            }
-        }
-    }
-
     pub fn print_usize(&mut self, i: usize) -> io::Result<()> {
         self.s.word(i.to_string())
     }
@@ -2401,18 +2392,10 @@ fn expr_requires_semi_to_be_stmt(e: &hir::Expr) -> bool {
 /// seen the semicolon, and thus don't need another.
 fn stmt_ends_with_semi(stmt: &hir::StmtKind) -> bool {
     match *stmt {
-        hir::StmtKind::Decl(ref d) => {
-            match d.node {
-                hir::DeclKind::Local(_) => true,
-                hir::DeclKind::Item(_) => false,
-            }
-        }
-        hir::StmtKind::Expr(ref e) => {
-            expr_requires_semi_to_be_stmt(&e)
-        }
-        hir::StmtKind::Semi(..) => {
-            false
-        }
+        hir::StmtKind::Local(_) => true,
+        hir::StmtKind::Item(_) => false,
+        hir::StmtKind::Expr(ref e) => expr_requires_semi_to_be_stmt(&e),
+        hir::StmtKind::Semi(..) => false,
     }
 }
 

diff --git a/src/librustc/ich/impls_hir.rs b/src/librustc/ich/impls_hir.rs
@@ -501,12 +501,6 @@ impl_stable_hash_for!(struct hir::Local {
     source
 });
 
-impl_stable_hash_for_spanned!(hir::DeclKind);
-impl_stable_hash_for!(enum hir::DeclKind {
-    Local(local),
-    Item(item_id)
-});
-
 impl_stable_hash_for!(struct hir::Arm {
     attrs,
     pats,
@@ -946,7 +940,8 @@ impl_stable_hash_for!(enum hir::ForeignItemKind {
 });
 
 impl_stable_hash_for!(enum hir::StmtKind {
-    Decl(decl),
+    Local(local),
+    Item(item_id),
     Expr(expr),
     Semi(expr)
 });

diff --git a/src/librustc/lint/context.rs b/src/librustc/lint/context.rs
@@ -941,11 +941,6 @@ impl<'a, 'tcx> hir_visit::Visitor<'tcx> for LateContext<'a, 'tcx> {
         hir_visit::walk_arm(self, a);
     }
 
-    fn visit_decl(&mut self, d: &'tcx hir::Decl) {
-        run_lints!(self, check_decl, d);
-        hir_visit::walk_decl(self, d);
-    }
-
     fn visit_generic_param(&mut self, p: &'tcx hir::GenericParam) {
         run_lints!(self, check_generic_param, p);
         hir_visit::walk_generic_param(self, p);

diff --git a/src/librustc/lint/mod.rs b/src/librustc/lint/mod.rs
@@ -191,7 +191,6 @@ macro_rules! late_lint_methods {
             fn check_stmt(a: &$hir hir::Stmt);
             fn check_arm(a: &$hir hir::Arm);
             fn check_pat(a: &$hir hir::Pat);
-            fn check_decl(a: &$hir hir::Decl);
             fn check_expr(a: &$hir hir::Expr);
             fn check_expr_post(a: &$hir hir::Expr);
             fn check_ty(a: &$hir hir::Ty);

diff --git a/src/librustc/middle/expr_use_visitor.rs b/src/librustc/middle/expr_use_visitor.rs
@@ -589,17 +589,13 @@ impl<'a, 'gcx, 'tcx> ExprUseVisitor<'a, 'gcx, 'tcx> {
 
     fn walk_stmt(&mut self, stmt: &hir::Stmt) {
         match stmt.node {
-            hir::StmtKind::Decl(ref decl) => {
-                match decl.node {
-                    hir::DeclKind::Local(ref local) => {
-                        self.walk_local(&local);
-                    }
+            hir::StmtKind::Local(ref local) => {
+                self.walk_local(&local);
+            }
 
-                    hir::DeclKind::Item(_) => {
-                        // we don't visit nested items in this visitor,
-                        // only the fn body we were given.
-                    }
-                }
+            hir::StmtKind::Item(_) => {
+                // we don't visit nested items in this visitor,
+                // only the fn body we were given.
             }
 
             hir::StmtKind::Expr(ref expr) |