make it illegal to implicitly capture mutable variables

this is the final part of #1273

Author: nikomatsakis

src/librustsyntax/ast.rs

@@ -362,7 +362,7 @@ type capture_item = {
 };
 
 #[auto_serialize]
-type capture_clause = [capture_item];
+type capture_clause = @[capture_item];
 
 /*
 // Says whether this is a block the user marked as

src/librustsyntax/parse/parser.rs

@@ -1187,7 +1187,8 @@ fn parse_fn_expr(p: parser, proto: ast::proto) -> @ast::expr {
 
     let body = parse_block(p);
     ret mk_expr(p, lo, body.span.hi,
-                ast::expr_fn(proto, decl, body, capture_clause + cc_old));
+                ast::expr_fn(proto, decl, body,
+                             @(*capture_clause + cc_old)));
 }
 
 fn parse_fn_block_expr(p: parser) -> @ast::expr {
@@ -1679,7 +1680,7 @@ fn parse_ty_params(p: parser) -> [ast::ty_param] {
 }
 
 // FIXME Remove after snapshot
-fn parse_old_skool_capture_clause(p: parser) -> ast::capture_clause {
+fn parse_old_skool_capture_clause(p: parser) -> [ast::capture_item] {
     fn expect_opt_trailing_semi(p: parser) {
         if !eat(p, token::SEMI) {
             if p.token != token::RBRACKET {
@@ -1739,7 +1740,7 @@ fn parse_fn_decl(p: parser, purity: ast::purity,
                   parse_arg_fn, p).node;
 
     let inputs = either::lefts(args_or_capture_items);
-    let capture_clause = either::rights(args_or_capture_items);
+    let capture_clause = @either::rights(args_or_capture_items);
 
     // Use the args list to translate each bound variable
     // mentioned in a constraint to an arg index.
@@ -1778,7 +1779,7 @@ fn parse_fn_block_decl(p: parser) -> (ast::fn_decl, ast::capture_clause) {
           purity: ast::impure_fn,
           cf: ast::return_val,
           constraints: []},
-         either::rights(inputs_captures));
+         @either::rights(inputs_captures));
 }
 
 fn parse_fn_header(p: parser) -> {ident: ast::ident, tps: [ast::ty_param]} {

src/librustsyntax/print/pprust.rs

@@ -1018,7 +1018,7 @@ fn print_expr(s: ps, &&expr: @ast::expr) {
         // head-box, will be closed by print-block at start
         ibox(s, 0u);
         word(s.s, proto_to_str(proto));
-        print_fn_args_and_ret(s, decl, cap_clause);
+        print_fn_args_and_ret(s, decl, *cap_clause);
         space(s.s);
         print_block(s, body);
       }
@@ -1028,7 +1028,7 @@ fn print_expr(s: ps, &&expr: @ast::expr) {
         // head-box, will be closed by print-block at start
         ibox(s, 0u);
         word(s.s, "{");
-        print_fn_block_args(s, decl, cap_clause);
+        print_fn_block_args(s, decl, *cap_clause);
         print_possibly_embedded_block(s, body, block_block_fn, indent_unit);
       }
       ast::expr_loop_body(body) {

src/librustsyntax/visit.rs

@@ -16,8 +16,8 @@ enum fn_kind {
     fk_item_fn(ident, [ty_param]), //< an item declared with fn()
     fk_method(ident, [ty_param], @method),
     fk_res(ident, [ty_param], region_param),
-    fk_anon(proto),  //< an anonymous function like fn@(...)
-    fk_fn_block,     //< a block {||...}
+    fk_anon(proto, capture_clause),  //< an anonymous function like fn@(...)
+    fk_fn_block(capture_clause),     //< a block {||...}
     fk_ctor(ident, [ty_param], node_id /* self id */,
             def_id /* parent class id */) // class constructor
 }
@@ -26,15 +26,15 @@ fn name_of_fn(fk: fn_kind) -> ident {
     alt fk {
       fk_item_fn(name, _) | fk_method(name, _, _) | fk_res(name, _, _)
           | fk_ctor(name, _, _, _) { name }
-      fk_anon(_) | fk_fn_block { "anon" }
+      fk_anon(*) | fk_fn_block(*) { "anon" }
     }
 }
 
 fn tps_of_fn(fk: fn_kind) -> [ty_param] {
     alt fk {
       fk_item_fn(_, tps) | fk_method(_, tps, _) | fk_res(_, tps, _)
           | fk_ctor(_, tps, _, _) { tps }
-      fk_anon(_) | fk_fn_block { [] }
+      fk_anon(*) | fk_fn_block(*) { [] }
     }
 }
 
@@ -381,11 +381,13 @@ fn visit_expr<E>(ex: @expr, e: E, v: vt<E>) {
         v.visit_expr(x, e, v);
         for arms.each {|a| v.visit_arm(a, e, v); }
       }
-      expr_fn(proto, decl, body, _) {
-        v.visit_fn(fk_anon(proto), decl, body, ex.span, ex.id, e, v);
+      expr_fn(proto, decl, body, cap_clause) {
+        v.visit_fn(fk_anon(proto, cap_clause), decl, body,
+                   ex.span, ex.id, e, v);
       }
-      expr_fn_block(decl, body, _) {
-        v.visit_fn(fk_fn_block, decl, body, ex.span, ex.id, e, v);
+      expr_fn_block(decl, body, cap_clause) {
+        v.visit_fn(fk_fn_block(cap_clause), decl, body,
+                   ex.span, ex.id, e, v);
       }
       expr_block(b) { v.visit_block(b, e, v); }
       expr_assign(a, b) { v.visit_expr(b, e, v); v.visit_expr(a, e, v); }

src/rustc/front/test.rs

@@ -368,7 +368,7 @@ fn mk_test_wrapper(cx: test_ctxt,
     let wrapper_expr: ast::expr = {
         id: cx.sess.next_node_id(),
         node: ast::expr_fn(ast::proto_bare, wrapper_decl,
-                           wrapper_body, []),
+                           wrapper_body, @[]),
         span: span
     };
 

src/rustc/metadata/astencode.rs

@@ -223,8 +223,7 @@ fn visit_ids(item: ast::inlined_item, vfn: fn@(ast::node_id)) {
                 vfn(m.self_id);
                 vec::iter(tps) {|tp| vfn(tp.id)}
               }
-              visit::fk_anon(_) |
-              visit::fk_fn_block {
+              visit::fk_anon(*) | visit::fk_fn_block(*) {
               }
             }
 

src/rustc/middle/capture.rs

@@ -31,12 +31,11 @@ type capture_map = map::hashmap<ast::def_id, capture_var>;
 // errors for any irregularities which we identify.
 fn check_capture_clause(tcx: ty::ctxt,
                         fn_expr_id: ast::node_id,
-                        fn_proto: ast::proto,
                         cap_clause: ast::capture_clause) {
     let freevars = freevars::get_freevars(tcx, fn_expr_id);
     let seen_defs = map::int_hash();
 
-    let check_capture_item = fn@(cap_item: ast::capture_item) {
+    for (*cap_clause).each { |cap_item|
         let cap_def = tcx.def_map.get(cap_item.id);
         if !vec::any(*freevars, {|fv| fv.def == cap_def}) {
             tcx.sess.span_warn(
@@ -52,22 +51,6 @@ fn check_capture_clause(tcx: ty::ctxt,
                 #fmt("variable '%s' captured more than once",
                      cap_item.name));
         }
-    };
-
-    alt fn_proto {
-      ast::proto_any | ast::proto_block {
-        if vec::is_not_empty(cap_clause) {
-            let cap_item0 = vec::head(cap_clause);
-            tcx.sess.span_err(
-                cap_item0.span,
-                "cannot capture values explicitly with a block closure");
-        }
-      }
-      ast::proto_bare | ast::proto_box | ast::proto_uniq {
-        for cap_clause.each { |cap_item|
-            check_capture_item(cap_item);
-        }
-      }
     }
 }
 
@@ -80,7 +63,7 @@ fn compute_capture_vars(tcx: ty::ctxt,
 
     // first add entries for anything explicitly named in the cap clause
 
-    for cap_clause.each { |cap_item|
+    for (*cap_clause).each { |cap_item|
         let cap_def = tcx.def_map.get(cap_item.id);
         let cap_def_id = ast_util::def_id_of_def(cap_def).node;
         if cap_item.is_move {