make treatment of unchecked/unsafe blocks more uniform

also repair various errors in the parser related to such blocks.
rename checked_blk to default_blk to reflect the fact that it
inherits its purity from the surrounding context.

src/comp/syntax/ast.rs

@@ -174,7 +174,7 @@ type field_ = {mut: mutability, ident: ident, expr: @expr};
 
 type field = spanned<field_>;
 
-tag blk_check_mode { checked_blk; unchecked_blk; unsafe_blk; }
+tag blk_check_mode { default_blk; unchecked_blk; unsafe_blk; }
 
 tag expr_check_mode { claimed_expr; checked_expr; }
 

src/comp/syntax/ast_util.rs

@@ -185,13 +185,13 @@ fn eq_ty(&&a: @ty, &&b: @ty) -> bool { ret std::box::ptr_eq(a, b); }
 fn hash_ty(&&t: @ty) -> uint { ret t.span.lo << 16u + t.span.hi; }
 
 fn block_from_expr(e: @expr) -> blk {
-    let blk_ = checked_block([], option::some::<@expr>(e), e.id);
+    let blk_ = default_block([], option::some::<@expr>(e), e.id);
     ret {node: blk_, span: e.span};
 }
 
-fn checked_block(stmts1: [@stmt], expr1: option::t<@expr>, id1: node_id) ->
+fn default_block(stmts1: [@stmt], expr1: option::t<@expr>, id1: node_id) ->
    blk_ {
-    ret {stmts: stmts1, expr: expr1, id: id1, rules: checked_blk};
+    ret {stmts: stmts1, expr: expr1, id: id1, rules: default_blk};
 }
 
 fn obj_field_from_anon_obj_field(f: anon_obj_field) -> obj_field {

src/comp/syntax/parse/parser.rs

@@ -828,7 +828,7 @@ fn parse_bottom_expr(p: parser) -> @ast::expr {
                       p.peek() == token::OROR {
             ret parse_fn_block_expr(p);
         } else {
-            let blk = parse_block_tail(p, lo, ast::checked_blk);
+            let blk = parse_block_tail(p, lo, ast::default_blk);
             ret mk_expr(p, blk.span.lo, blk.span.hi, ast::expr_block(blk));
         }
     } else if eat_word(p, "if") {
@@ -873,7 +873,7 @@ fn parse_bottom_expr(p: parser) -> @ast::expr {
     } else if p.peek() == token::POUND_LBRACE {
         p.bump();
         let blk = ast::mac_embed_block(
-            parse_block_tail(p, lo, ast::checked_blk));
+            parse_block_tail(p, lo, ast::default_blk));
         ret mk_mac_expr(p, lo, p.get_hi_pos(), blk);
     } else if p.peek() == token::ELLIPSIS {
         p.bump();
@@ -1320,7 +1320,7 @@ fn parse_fn_expr(p: parser, proto: ast::proto) -> @ast::expr {
 fn parse_fn_block_expr(p: parser) -> @ast::expr {
     let lo = p.get_last_lo_pos();
     let decl = parse_fn_block_decl(p);
-    let body = parse_block_tail(p, lo, ast::checked_blk);
+    let body = parse_block_tail(p, lo, ast::default_blk);
     let _fn = {decl: decl, proto: ast::proto_block, body: body};
     ret mk_expr(p, lo, body.span.hi, ast::expr_fn(_fn));
 }
@@ -1684,12 +1684,14 @@ fn stmt_ends_with_semi(stmt: ast::stmt) -> bool {
 fn parse_block(p: parser) -> ast::blk {
     let lo = p.get_lo_pos();
     if eat_word(p, "unchecked") {
+        expect(p, token::LBRACE);
         be parse_block_tail(p, lo, ast::unchecked_blk);
     } else if eat_word(p, "unsafe") {
+        expect(p, token::LBRACE);
         be parse_block_tail(p, lo, ast::unsafe_blk);
     } else {
         expect(p, token::LBRACE);
-        be parse_block_tail(p, lo, ast::checked_blk);
+        be parse_block_tail(p, lo, ast::default_blk);
     }
 }
 

src/comp/syntax/print/pprust.rs

@@ -575,7 +575,7 @@ fn print_possibly_embedded_block(s: ps, blk: ast::blk, embedded: embed_type,
     alt blk.node.rules {
       ast::unchecked_blk. { word(s.s, "unchecked"); }
       ast::unsafe_blk. { word(s.s, "unsafe"); }
-      ast::checked_blk. { }
+      ast::default_blk. { }
     }
 
     maybe_print_comment(s, blk.span.lo);