auto merge of #10676 : eddyb/rust/ast-box-in-enums, r=cmr

**Note**: I only tested on top of my #10670 PR, size reductions come from both change sets.

With this, [more enums are shrinked](https://gist.github.com/eddyb/08fef0dfc6ff54e890bc), the most significant one being `ast_node`, from 104 bytes (master) to 96 (#10670) and now to 32 bytes.

My own testcase requires **200MB** less when compiling (not including the other **200MB** gained in #10670), and rustc-stage2 is down by about **130MB**.

I believe there is more to gain by fiddling with the enums' layouts.

Author: bors

src/librustc/front/config.rs

@@ -27,7 +27,7 @@ impl<'self> fold::ast_fold for Context<'self> {
     fn fold_mod(&self, module: &ast::_mod) -> ast::_mod {
         fold_mod(self, module)
     }
-    fn fold_block(&self, block: &ast::Block) -> ast::Block {
+    fn fold_block(&self, block: ast::P<ast::Block>) -> ast::P<ast::Block> {
         fold_block(self, block)
     }
     fn fold_foreign_mod(&self, foreign_module: &ast::foreign_mod)
@@ -97,10 +97,10 @@ fn fold_foreign_mod(cx: &Context, nm: &ast::foreign_mod) -> ast::foreign_mod {
 
 fn fold_item_underscore(cx: &Context, item: &ast::item_) -> ast::item_ {
     let item = match *item {
-        ast::item_impl(ref a, ref b, ref c, ref methods) => {
+        ast::item_impl(ref a, ref b, c, ref methods) => {
             let methods = methods.iter().filter(|m| method_in_cfg(cx, **m))
                 .map(|x| *x).collect();
-            ast::item_impl((*a).clone(), (*b).clone(), (*c).clone(), methods)
+            ast::item_impl((*a).clone(), (*b).clone(), c, methods)
         }
         ast::item_trait(ref a, ref b, ref methods) => {
             let methods = methods.iter()
@@ -129,22 +129,22 @@ fn retain_stmt(cx: &Context, stmt: @ast::Stmt) -> bool {
     }
 }
 
-fn fold_block(cx: &Context, b: &ast::Block) -> ast::Block {
+fn fold_block(cx: &Context, b: ast::P<ast::Block>) -> ast::P<ast::Block> {
     let resulting_stmts = b.stmts.iter()
             .filter(|&a| retain_stmt(cx, *a))
             .flat_map(|&stmt| cx.fold_stmt(stmt).move_iter())
             .collect();
     let filtered_view_items = b.view_items.iter().filter_map(|a| {
         filter_view_item(cx, a).map(|x| cx.fold_view_item(x))
     }).collect();
-    ast::Block {
+    ast::P(ast::Block {
         view_items: filtered_view_items,
         stmts: resulting_stmts,
         expr: b.expr.map(|x| cx.fold_expr(x)),
         id: b.id,
         rules: b.rules,
         span: b.span,
-    }
+    })
 }
 
 fn item_in_cfg(cx: &Context, item: @ast::item) -> bool {

src/librustc/metadata/encoder.rs

@@ -352,7 +352,7 @@ fn encode_struct_fields(ecx: &EncodeContext,
 fn encode_enum_variant_info(ecx: &EncodeContext,
                             ebml_w: &mut writer::Encoder,
                             id: NodeId,
-                            variants: &[variant],
+                            variants: &[P<variant>],
                             path: &[ast_map::path_elt],
                             index: @mut ~[entry<i64>],
                             generics: &ast::Generics) {
@@ -1081,7 +1081,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
                                         def_id.node);
         }
       }
-      item_impl(_, ref opt_trait, ref ty, ref ast_methods) => {
+      item_impl(_, ref opt_trait, ty, ref ast_methods) => {
         // We need to encode information about the default methods we
         // have inherited, so we drive this based on the impl structure.
         let imp = tcx.impls.get(&def_id);

src/librustc/middle/astencode.rs

@@ -301,7 +301,7 @@ struct NestedItemsDropper {
 }
 
 impl fold::ast_fold for NestedItemsDropper {
-    fn fold_block(&self, blk: &ast::Block) -> ast::Block {
+    fn fold_block(&self, blk: ast::P<ast::Block>) -> ast::P<ast::Block> {
         let stmts_sans_items = blk.stmts.iter().filter_map(|stmt| {
             match stmt.node {
                 ast::StmtExpr(_, _) | ast::StmtSemi(_, _) |
@@ -316,16 +316,16 @@ impl fold::ast_fold for NestedItemsDropper {
                 ast::StmtMac(..) => fail!("unexpanded macro in astencode")
             }
         }).collect();
-        let blk_sans_items = ast::Block {
+        let blk_sans_items = ast::P(ast::Block {
             view_items: ~[], // I don't know if we need the view_items here,
                              // but it doesn't break tests!
             stmts: stmts_sans_items,
             expr: blk.expr,
             id: blk.id,
             rules: blk.rules,
             span: blk.span,
-        };
-        fold::noop_fold_block(&blk_sans_items, self)
+        });
+        fold::noop_fold_block(blk_sans_items, self)
     }
 }
 

src/librustc/middle/borrowck/check_loans.rs

@@ -48,14 +48,14 @@ impl<'self> Visitor<()> for CheckLoanCtxt<'self> {
     fn visit_local(&mut self, l:@ast::Local, _:()) {
         check_loans_in_local(self, l);
     }
-    fn visit_block(&mut self, b:&ast::Block, _:()) {
+    fn visit_block(&mut self, b:ast::P<ast::Block>, _:()) {
         check_loans_in_block(self, b);
     }
     fn visit_pat(&mut self, p:&ast::Pat, _:()) {
         check_loans_in_pat(self, p);
     }
     fn visit_fn(&mut self, fk:&visit::fn_kind, fd:&ast::fn_decl,
-                b:&ast::Block, s:Span, n:ast::NodeId, _:()) {
+                b:ast::P<ast::Block>, s:Span, n:ast::NodeId, _:()) {
         check_loans_in_fn(self, fk, fd, b, s, n);
     }
 }
@@ -64,7 +64,7 @@ pub fn check_loans(bccx: &BorrowckCtxt,
                    dfcx_loans: &LoanDataFlow,
                    move_data: move_data::FlowedMoveData,
                    all_loans: &[Loan],
-                   body: &ast::Block) {
+                   body: ast::P<ast::Block>) {
     debug!("check_loans(body id={:?})", body.id);
 
     let mut clcx = CheckLoanCtxt {
@@ -724,7 +724,7 @@ impl<'self> CheckLoanCtxt<'self> {
 fn check_loans_in_fn<'a>(this: &mut CheckLoanCtxt<'a>,
                          fk: &visit::fn_kind,
                          decl: &ast::fn_decl,
-                         body: &ast::Block,
+                         body: ast::P<ast::Block>,
                          sp: Span,
                          id: ast::NodeId) {
     match *fk {
@@ -855,7 +855,7 @@ fn check_loans_in_pat<'a>(this: &mut CheckLoanCtxt<'a>,
 }
 
 fn check_loans_in_block<'a>(this: &mut CheckLoanCtxt<'a>,
-                            blk: &ast::Block)
+                            blk: ast::P<ast::Block>)
 {
     visit::walk_block(this, blk, ());
     this.check_for_conflicting_loans(blk.id);

src/librustc/middle/borrowck/gather_loans/mod.rs

@@ -32,7 +32,7 @@ use syntax::codemap::Span;
 use syntax::print::pprust;
 use syntax::visit;
 use syntax::visit::{Visitor, fn_kind};
-use syntax::ast::{Expr, fn_decl, Block, NodeId, Stmt, Pat, Local};
+use syntax::ast::{P, Expr, fn_decl, Block, NodeId, Stmt, Pat, Local};
 
 mod lifetime;
 mod restrictions;
@@ -77,10 +77,10 @@ impl<'self> visit::Visitor<()> for GatherLoanCtxt<'self> {
     fn visit_expr(&mut self, ex:@Expr, _:()) {
         gather_loans_in_expr(self, ex);
     }
-    fn visit_block(&mut self, b:&Block, _:()) {
+    fn visit_block(&mut self, b:P<Block>, _:()) {
         gather_loans_in_block(self, b);
     }
-    fn visit_fn(&mut self, fk:&fn_kind, fd:&fn_decl, b:&Block,
+    fn visit_fn(&mut self, fk:&fn_kind, fd:&fn_decl, b:P<Block>,
                 s:Span, n:NodeId, _:()) {
         gather_loans_in_fn(self, fk, fd, b, s, n);
     }
@@ -102,7 +102,7 @@ impl<'self> visit::Visitor<()> for GatherLoanCtxt<'self> {
 
 pub fn gather_loans(bccx: &BorrowckCtxt,
                     decl: &ast::fn_decl,
-                    body: &ast::Block)
+                    body: ast::P<ast::Block>)
                     -> (id_range, @mut ~[Loan], @mut move_data::MoveData) {
     let mut glcx = GatherLoanCtxt {
         bccx: bccx,
@@ -131,7 +131,7 @@ fn add_pat_to_id_range(this: &mut GatherLoanCtxt,
 fn gather_loans_in_fn(this: &mut GatherLoanCtxt,
                       fk: &fn_kind,
                       decl: &ast::fn_decl,
-                      body: &ast::Block,
+                      body: ast::P<ast::Block>,
                       sp: Span,
                       id: ast::NodeId) {
     match fk {
@@ -150,7 +150,7 @@ fn gather_loans_in_fn(this: &mut GatherLoanCtxt,
 }
 
 fn gather_loans_in_block(this: &mut GatherLoanCtxt,
-                         blk: &ast::Block) {
+                         blk: ast::P<ast::Block>) {
     this.id_range.add(blk.id);
     visit::walk_block(this, blk, ());
 }
@@ -286,7 +286,7 @@ fn gather_loans_in_expr(this: &mut GatherLoanCtxt,
       }
 
       // see explanation attached to the `root_ub` field:
-      ast::ExprWhile(cond, ref body) => {
+      ast::ExprWhile(cond, body) => {
           // during the condition, can only root for the condition
           this.push_repeating_id(cond.id);
           this.visit_expr(cond, ());
@@ -299,7 +299,7 @@ fn gather_loans_in_expr(this: &mut GatherLoanCtxt,
       }
 
       // see explanation attached to the `root_ub` field:
-      ast::ExprLoop(ref body, _) => {
+      ast::ExprLoop(body, _) => {
           this.push_repeating_id(body.id);
           visit::walk_expr(this, ex, ());
           this.pop_repeating_id(body.id);

src/librustc/middle/borrowck/mod.rs

@@ -29,7 +29,7 @@ use syntax::codemap::Span;
 use syntax::parse::token;
 use syntax::visit;
 use syntax::visit::{Visitor,fn_kind};
-use syntax::ast::{fn_decl,Block,NodeId};
+use syntax::ast::{P,fn_decl,Block,NodeId};
 
 macro_rules! if_ok(
     ($inp: expr) => (
@@ -62,7 +62,7 @@ pub type LoanDataFlow = DataFlowContext<LoanDataFlowOperator>;
 
 impl Visitor<()> for BorrowckCtxt {
     fn visit_fn(&mut self, fk:&fn_kind, fd:&fn_decl,
-                b:&Block, s:Span, n:NodeId, _:()) {
+                b:P<Block>, s:Span, n:NodeId, _:()) {
         borrowck_fn(self, fk, fd, b, s, n);
     }
 }
@@ -123,7 +123,7 @@ pub fn check_crate(
 fn borrowck_fn(this: &mut BorrowckCtxt,
                fk: &visit::fn_kind,
                decl: &ast::fn_decl,
-               body: &ast::Block,
+               body: ast::P<ast::Block>,
                sp: Span,
                id: ast::NodeId) {
     match fk {

src/librustc/middle/cfg/construct.rs

@@ -161,12 +161,12 @@ impl CFGBuilder {
 
     fn expr(&mut self, expr: @ast::Expr, pred: CFGIndex) -> CFGIndex {
         match expr.node {
-            ast::ExprBlock(ref blk) => {
+            ast::ExprBlock(blk) => {
                 let blk_exit = self.block(blk, pred);
                 self.add_node(expr.id, [blk_exit])
             }
 
-            ast::ExprIf(cond, ref then, None) => {
+            ast::ExprIf(cond, then, None) => {
                 //
                 //     [pred]
                 //       |
@@ -186,7 +186,7 @@ impl CFGBuilder {
                 self.add_node(expr.id, [cond_exit, then_exit])        // 3,4
             }
 
-            ast::ExprIf(cond, ref then, Some(otherwise)) => {
+            ast::ExprIf(cond, then, Some(otherwise)) => {
                 //
                 //     [pred]
                 //       |
@@ -207,7 +207,7 @@ impl CFGBuilder {
                 self.add_node(expr.id, [then_exit, else_exit])        // 4, 5
             }
 
-            ast::ExprWhile(cond, ref body) => {
+            ast::ExprWhile(cond, body) => {
                 //
                 //         [pred]
                 //           |
@@ -241,7 +241,7 @@ impl CFGBuilder {
 
             ast::ExprForLoop(..) => fail!("non-desugared expr_for_loop"),
 
-            ast::ExprLoop(ref body, _) => {
+            ast::ExprLoop(body, _) => {
                 //
                 //     [pred]
                 //       |
@@ -300,7 +300,7 @@ impl CFGBuilder {
                 for arm in arms.iter() {
                     guard_exit = self.opt_expr(arm.guard, guard_exit); // 2
                     let pats_exit = self.pats_any(arm.pats, guard_exit); // 3
-                    let body_exit = self.block(&arm.body, pats_exit);    // 4
+                    let body_exit = self.block(arm.body, pats_exit);    // 4
                     self.add_contained_edge(body_exit, expr_exit);       // 5
                 }
                 expr_exit

src/librustc/middle/check_loop.rs

@@ -35,14 +35,14 @@ impl Visitor<Context> for CheckLoopVisitor {
 
     fn visit_expr(&mut self, e: @ast::Expr, cx:Context) {
         match e.node {
-            ast::ExprWhile(e, ref b) => {
+            ast::ExprWhile(e, b) => {
                 self.visit_expr(e, cx);
                 self.visit_block(b, Loop);
             }
-            ast::ExprLoop(ref b, _) => {
+            ast::ExprLoop(b, _) => {
                 self.visit_block(b, Loop);
             }
-            ast::ExprFnBlock(_, ref b) | ast::ExprProc(_, ref b) => {
+            ast::ExprFnBlock(_, b) | ast::ExprProc(_, b) => {
                 self.visit_block(b, Closure);
             }
             ast::ExprBreak(_) => self.require_loop("break", cx, e.span),

src/librustc/middle/check_match.rs

@@ -45,7 +45,7 @@ impl Visitor<()> for CheckMatchVisitor {
     fn visit_local(&mut self, l:@Local, e:()) {
         check_local(self, self.cx, l, e);
     }
-    fn visit_fn(&mut self, fk:&fn_kind, fd:&fn_decl, b:&Block, s:Span, n:NodeId, e:()) {
+    fn visit_fn(&mut self, fk:&fn_kind, fd:&fn_decl, b:P<Block>, s:Span, n:NodeId, e:()) {
         check_fn(self, self.cx, fk, fd, b, s, n, e);
     }
 }
@@ -827,7 +827,7 @@ fn check_fn(v: &mut CheckMatchVisitor,
                 cx: &MatchCheckCtxt,
                 kind: &visit::fn_kind,
                 decl: &fn_decl,
-                body: &Block,
+                body: P<Block>,
                 sp: Span,
                 id: NodeId,
                 s: ()) {

src/librustc/middle/const_eval.rs

@@ -90,7 +90,7 @@ pub fn lookup_variant_by_id(tcx: ty::ctxt,
                             enum_def: ast::DefId,
                             variant_def: ast::DefId)
                        -> Option<@Expr> {
-    fn variant_expr(variants: &[ast::variant], id: ast::NodeId) -> Option<@Expr> {
+    fn variant_expr(variants: &[ast::P<ast::variant>], id: ast::NodeId) -> Option<@Expr> {
         for variant in variants.iter() {
             if variant.node.id == id {
                 return variant.node.disr_expr;

src/librustc/middle/dataflow.rs

@@ -429,8 +429,8 @@ impl<'self, O:DataFlowOperator> PropagationContext<'self, O> {
         self.merge_with_entry_set(expr.id, in_out);
 
         match expr.node {
-            ast::ExprFnBlock(ref decl, ref body) |
-            ast::ExprProc(ref decl, ref body) => {
+            ast::ExprFnBlock(ref decl, body) |
+            ast::ExprProc(ref decl, body) => {
                 if self.dfcx.oper.walk_closures() {
                     // In the absence of once fns, we must assume that
                     // every function body will execute more than
@@ -519,7 +519,7 @@ impl<'self, O:DataFlowOperator> PropagationContext<'self, O> {
                 }
             }
 
-            ast::ExprIf(cond, ref then, els) => {
+            ast::ExprIf(cond, then, els) => {
                 //
                 //     (cond)
                 //       |
@@ -542,7 +542,7 @@ impl<'self, O:DataFlowOperator> PropagationContext<'self, O> {
                 join_bits(&self.dfcx.oper, then_bits, in_out);
             }
 
-            ast::ExprWhile(cond, ref blk) => {
+            ast::ExprWhile(cond, blk) => {
                 //
                 //     (expr) <--+
                 //       |       |
@@ -570,7 +570,7 @@ impl<'self, O:DataFlowOperator> PropagationContext<'self, O> {
 
             ast::ExprForLoop(..) => fail!("non-desugared expr_for_loop"),
 
-            ast::ExprLoop(ref blk, _) => {
+            ast::ExprLoop(blk, _) => {
                 //
                 //     (expr) <--+
                 //       |       |
@@ -623,7 +623,7 @@ impl<'self, O:DataFlowOperator> PropagationContext<'self, O> {
                     // them into `in_out`, which reflects all bodies to date
                     let mut body = reslice(guards).to_owned();
                     self.walk_pat_alternatives(arm.pats, body, loop_scopes);
-                    self.walk_block(&arm.body, body, loop_scopes);
+                    self.walk_block(arm.body, body, loop_scopes);
                     join_bits(&self.dfcx.oper, body, in_out);
                 }
             }
@@ -730,7 +730,7 @@ impl<'self, O:DataFlowOperator> PropagationContext<'self, O> {
                 }
             }
 
-            ast::ExprBlock(ref blk) => {
+            ast::ExprBlock(blk) => {
                 self.walk_block(blk, in_out, loop_scopes);
             }