Obliterate the callee_id hack

Exprs that could be applications of overloaded operators
(expr_unary, expr_binary, expr_index) relied on the previous node ID
being "reserved" to carry extra typechecking info. This was
incredibly error-prone. Fixed it; now all exprs have two node IDs
(which will be wasted in some cases; future work could make this
an option instead if the extra int field ends up being a performance
problem).

Closes #2804

Author: catamorphism

src/fuzzer/fuzzer.rs

@@ -34,7 +34,7 @@ fn find_rust_files(&files: ~[str], path: str) {
 
 fn common_exprs() -> ~[ast::expr] {
     fn dse(e: ast::expr_) -> ast::expr {
-        { id: 0, node: e, span: ast_util::dummy_sp() }
+        { id: 0, callee_id: -1, node: e, span: ast_util::dummy_sp() }
     }
 
     fn dsl(l: ast::lit_) -> ast::lit {

src/libsyntax/ast.rs

@@ -288,7 +288,8 @@ enum blk_check_mode { default_blk, unchecked_blk, unsafe_blk, }
 enum expr_check_mode { claimed_expr, checked_expr, }
 
 #[auto_serialize]
-type expr = {id: node_id, node: expr_, span: span};
+type expr = {id: node_id, callee_id: node_id, node: expr_, span: span};
+// Extra node ID is only used for index, assign_op, unary, binary
 
 #[auto_serialize]
 enum alt_mode { alt_check, alt_exhaustive, }

src/libsyntax/ast_util.rs

@@ -272,11 +272,6 @@ pure fn unguarded_pat(a: arm) -> option<~[@pat]> {
     if is_unguarded(a) { some(/* FIXME (#2543) */ copy a.pats) } else { none }
 }
 
-// Provides an extra node_id to hang callee information on, in case the
-// operator is deferred to a user-supplied method. The parser is responsible
-// for reserving this id.
-fn op_expr_callee_id(e: @expr) -> node_id { e.id - 1 }
-
 pure fn class_item_ident(ci: @class_member) -> ident {
     alt ci.node {
       instance_var(i,_,_,_,_) { /* FIXME (#2543) */ copy i }
@@ -455,14 +450,8 @@ fn id_visitor(vfn: fn@(node_id)) -> visit::vt<()> {
         },
 
         visit_expr: fn@(e: @expr) {
+            vfn(e.callee_id);
             vfn(e.id);
-            alt e.node {
-              expr_index(*) | expr_assign_op(*) |
-              expr_unary(*) | expr_binary(*) {
-                vfn(ast_util::op_expr_callee_id(e));
-              }
-              _ { /* fallthrough */ }
-            }
         },
 
         visit_ty: fn@(t: @ty) {

src/libsyntax/ext/auto_serialize.rs

@@ -172,7 +172,8 @@ impl helpers for ext_ctxt {
     }
 
     fn expr(span: span, node: ast::expr_) -> @ast::expr {
-        @{id: self.next_id(), node: node, span: span}
+        @{id: self.next_id(), callee_id: self.next_id(),
+          node: node, span: span}
     }
 
     fn var_ref(span: span, name: ast::ident) -> @ast::expr {

src/libsyntax/ext/build.rs

@@ -3,12 +3,13 @@ import base::ext_ctxt;
 
 fn mk_expr(cx: ext_ctxt, sp: codemap::span, expr: ast::expr_) ->
     @ast::expr {
-    ret @{id: cx.next_id(), node: expr, span: sp};
+    ret @{id: cx.next_id(), callee_id: cx.next_id(),
+          node: expr, span: sp};
 }
 
 fn mk_lit(cx: ext_ctxt, sp: span, lit: ast::lit_) -> @ast::expr {
     let sp_lit = @{node: lit, span: sp};
-    ret @{id: cx.next_id(), node: ast::expr_lit(sp_lit), span: sp};
+    mk_expr(cx, sp, ast::expr_lit(sp_lit))
 }
 fn mk_str(cx: ext_ctxt, sp: span, s: str) -> @ast::expr {
     let lit = ast::lit_str(@s);
@@ -62,7 +63,7 @@ fn mk_call(cx: ext_ctxt, sp: span, fn_path: ~[ast::ident],
 fn mk_base_vec_e(cx: ext_ctxt, sp: span, exprs: ~[@ast::expr]) ->
    @ast::expr {
     let vecexpr = ast::expr_vec(exprs, ast::m_imm);
-    ret @{id: cx.next_id(), node: vecexpr, span: sp};
+    mk_expr(cx, sp, vecexpr)
 }
 fn mk_vstore_e(cx: ext_ctxt, sp: span, expr: @ast::expr, vst: ast::vstore) ->
    @ast::expr {

src/libsyntax/ext/concat_idents.rs

@@ -9,6 +9,7 @@ fn expand_syntax_ext(cx: ext_ctxt, sp: codemap::span, arg: ast::mac_arg,
     }
 
     ret @{id: cx.next_id(),
+          callee_id: cx.next_id(),
           node: ast::expr_path(@{span: sp, global: false, idents: ~[@res],
                                  rp: none, types: ~[]}),
           span: sp};

src/libsyntax/ext/log_syntax.rs

@@ -11,6 +11,6 @@ fn expand_syntax_ext(cx: ext_ctxt, sp: codemap::span, arg: ast::mac_arg,
     );
 
     //trivial expression
-    ret @{id: cx.next_id(), node: ast::expr_rec(~[], option::none),
-          span: sp};
+    ret @{id: cx.next_id(), callee_id: cx.next_id(),
+          node: ast::expr_rec(~[], option::none), span: sp};
 }

src/libsyntax/ext/simplext.rs

@@ -7,7 +7,7 @@ import base::*;
 import fold::*;
 import ast_util::respan;
 import ast::{ident, path, ty, blk_, expr, expr_path,
-             expr_vec, expr_mac, mac_invoc, node_id};
+             expr_vec, expr_mac, mac_invoc, node_id, expr_index};
 
 export add_new_extension;
 

src/libsyntax/fold.rs

@@ -688,6 +688,7 @@ impl of ast_fold for ast_fold_precursor {
     fn fold_expr(&&x: @expr) -> @expr {
         let (n, s) = self.fold_expr(x.node, x.span, self as ast_fold);
         ret @{id: self.new_id(x.id),
+              callee_id: self.new_id(x.callee_id),
               node: n,
               span: self.new_span(s)};
     }

src/libsyntax/parse/parser.rs

@@ -1,3 +1,5 @@
+import print::pprust::expr_to_str;
+
 import result::result;
 import either::{either, left, right};
 import std::map::{hashmap, str_hash};
@@ -758,11 +760,13 @@ class parser {
     }
 
     fn mk_expr(lo: uint, hi: uint, +node: expr_) -> @expr {
-        ret @{id: self.get_id(), node: node, span: mk_sp(lo, hi)};
+        ret @{id: self.get_id(), callee_id: self.get_id(),
+              node: node, span: mk_sp(lo, hi)};
     }
 
     fn mk_mac_expr(lo: uint, hi: uint, m: mac_) -> @expr {
         ret @{id: self.get_id(),
+              callee_id: self.get_id(),
               node: expr_mac({node: m, span: mk_sp(lo, hi)}),
               span: mk_sp(lo, hi)};
     }
@@ -772,7 +776,8 @@ class parser {
         let lv_lit = @{node: lit_uint(i as u64, ty_u32),
                        span: span};
 
-        ret @{id: self.get_id(), node: expr_lit(lv_lit), span: span};
+        ret @{id: self.get_id(), callee_id: self.get_id(),
+              node: expr_lit(lv_lit), span: span};
     }
 
     fn mk_pexpr(lo: uint, hi: uint, node: expr_) -> pexpr {
@@ -1112,7 +1117,6 @@ class parser {
                 let ix = self.parse_expr();
                 hi = ix.span.hi;
                 self.expect(token::RBRACKET);
-                self.get_id(); // see ast_util::op_expr_callee_id
                 e = self.mk_pexpr(lo, hi, expr_index(self.to_expr(e), ix));
               }