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For #2229, recognize 'again' in place of 'cont', final change pending snapshot.
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doc/rust.md
16
doc/rust.md
@ -209,9 +209,9 @@ import export use mod
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The keywords in [source files](#source-files) are the following strings:
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~~~~~~~~ {.keyword}
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alt assert
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alt again assert
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break
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check claim class const cont copy
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check claim class const copy
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drop
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else enum export extern
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fail false fn for
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@ -2034,19 +2034,19 @@ break_expr : "break" ;
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Executing a `break` expression immediately terminates the innermost loop
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enclosing it. It is only permitted in the body of a loop.
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### Continue expressions
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### Again expressions
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~~~~~~~~{.ebnf .gram}
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break_expr : "cont" ;
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again_expr : "again" ;
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~~~~~~~~
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Evaluating a `cont` expression immediately terminates the current iteration of
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Evaluating an `again` expression immediately terminates the current iteration of
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the innermost loop enclosing it, returning control to the loop *head*. In the
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case of a `while` loop, the head is the conditional expression controlling the
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loop. In the case of a `for` loop, the head is the vector-element increment
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controlling the loop.
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loop. In the case of a `for` loop, the head is the call-expression controlling
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the loop.
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A `cont` expression is only permitted in the body of a loop.
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An `again` expression is only permitted in the body of a loop.
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### For expressions
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@ -783,7 +783,7 @@ a specific value, are not allowed.
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`while` produces a loop that runs as long as its given condition
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(which must have type `bool`) evaluates to true. Inside a loop, the
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keyword `break` can be used to abort the loop, and `cont` can be used
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keyword `break` can be used to abort the loop, and `again` can be used
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to abort the current iteration and continue with the next.
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~~~~
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@ -1187,7 +1187,7 @@ Empty argument lists can be omitted from `do` expressions.
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Most iteration in Rust is done with `for` loops. Like `do`,
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`for` is a nice syntax for doing control flow with closures.
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Additionally, within a `for` loop, `break, `cont`, and `ret`
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Additionally, within a `for` loop, `break, `again`, and `ret`
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work just as they do with `while` and `loop`.
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Consider again our `each` function, this time improved to
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@ -1221,8 +1221,8 @@ each(~[2, 4, 8, 5, 16], |n| {
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With `for`, functions like `each` can be treated more
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like builtin looping structures. When calling `each`
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in a `for` loop, instead of returning `false` to break
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out of the loop, you just write `break`. To continue
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to the next iteration, write `cont`.
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out of the loop, you just write `break`. To skip ahead
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to the next iteration, write `again`.
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~~~~
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# import each = vec::each;
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@ -56,9 +56,9 @@
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"trait" "fn" "enum" "iface"
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"impl"))
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(puthash word 'def table))
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(dolist (word '("assert"
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(dolist (word '("again" "assert"
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"break"
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"check" "claim" "cont" "copy"
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"check" "claim" "copy"
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"do" "drop"
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"else" "export" "extern"
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"fail" "for"
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@ -42,7 +42,7 @@ fn common_exprs() -> ~[ast::expr] {
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}
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~[dse(ast::expr_break),
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dse(ast::expr_cont),
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dse(ast::expr_again),
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dse(ast::expr_fail(option::none)),
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dse(ast::expr_fail(option::some(
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@dse(ast::expr_lit(@dsl(ast::lit_str(@"boo"))))))),
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@ -336,7 +336,7 @@ enum expr_ {
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expr_addr_of(mutability, @expr),
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expr_fail(option<@expr>),
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expr_break,
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expr_cont,
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expr_again,
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expr_ret(option<@expr>),
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expr_log(int, @expr, @expr),
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@ -464,7 +464,7 @@ fn noop_fold_expr(e: expr_, fld: ast_fold) -> expr_ {
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}
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expr_path(pth) { expr_path(fld.fold_path(pth)) }
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expr_fail(e) { expr_fail(option::map(e, fld.fold_expr)) }
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expr_break | expr_cont { copy e }
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expr_break | expr_again { copy e }
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expr_ret(e) { expr_ret(option::map(e, fld.fold_expr)) }
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expr_log(i, lv, e) { expr_log(i, fld.fold_expr(lv),
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fld.fold_expr(e)) }
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@ -966,8 +966,9 @@ class parser {
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} else if self.eat_keyword("break") {
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ex = expr_break;
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hi = self.span.hi;
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} else if self.eat_keyword("cont") {
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ex = expr_cont;
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} else if self.eat_keyword("cont") ||
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self.eat_keyword("again") {
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ex = expr_again;
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hi = self.span.hi;
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} else if self.eat_keyword("copy") {
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let e = self.parse_expr();
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@ -304,8 +304,7 @@ fn contextual_keyword_table() -> hashmap<str, ()> {
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fn restricted_keyword_table() -> hashmap<str, ()> {
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let words = str_hash();
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let keys = ~[
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"alt",
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"assert",
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"alt", "again", "assert",
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"break",
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"check", "claim", "class", "const", "cont", "copy",
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"do", "drop",
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@ -1063,7 +1063,7 @@ fn print_expr(s: ps, &&expr: @ast::expr) {
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}
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}
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ast::expr_break { word(s.s, "break"); }
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ast::expr_cont { word(s.s, "cont"); }
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ast::expr_again { word(s.s, "again"); }
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ast::expr_ret(result) {
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word(s.s, "ret");
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alt result {
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@ -421,7 +421,7 @@ fn visit_expr<E>(ex: @expr, e: E, v: vt<E>) {
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expr_path(p) { visit_path(p, e, v); }
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expr_fail(eo) { visit_expr_opt(eo, e, v); }
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expr_break { }
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expr_cont { }
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expr_again { }
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expr_ret(eo) { visit_expr_opt(eo, e, v); }
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expr_log(_, lv, x) {
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v.visit_expr(lv, e, v);
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@ -176,7 +176,7 @@ impl public_methods for borrowck_ctxt {
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ast::expr_new(*) | ast::expr_binary(*) | ast::expr_while(*) |
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ast::expr_block(*) | ast::expr_loop(*) | ast::expr_alt(*) |
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ast::expr_lit(*) | ast::expr_break | ast::expr_mac(*) |
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ast::expr_cont | ast::expr_rec(*) {
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ast::expr_again | ast::expr_rec(*) {
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ret self.cat_rvalue(expr, expr_ty);
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}
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}
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@ -33,7 +33,7 @@ fn check_crate(tcx: ty::ctxt, crate: @crate) {
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tcx.sess.span_err(e.span, "`break` outside of loop");
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}
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}
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expr_cont {
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expr_again {
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if !cx.in_loop {
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tcx.sess.span_err(e.span, "`cont` outside of loop");
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}
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@ -470,7 +470,7 @@ fn visit_expr(expr: @expr, &&self: @ir_maps, vt: vt<@ir_maps>) {
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expr_assert(*) | expr_check(*) | expr_addr_of(*) | expr_copy(*) |
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expr_loop_body(*) | expr_do_body(*) | expr_cast(*) |
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expr_unary(*) | expr_fail(*) |
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expr_break | expr_cont | expr_lit(_) | expr_ret(*) |
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expr_break | expr_again | expr_lit(_) | expr_ret(*) |
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expr_block(*) | expr_move(*) | expr_assign(*) | expr_swap(*) |
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expr_assign_op(*) | expr_mac(*) {
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visit::visit_expr(expr, self, vt);
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@ -1009,7 +1009,7 @@ class liveness {
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self.break_ln
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}
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expr_cont {
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expr_again {
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if !self.cont_ln.is_valid() {
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self.tcx.sess.span_bug(
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expr.span, "cont with invalid cont_ln");
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@ -1457,7 +1457,7 @@ fn check_expr(expr: @expr, &&self: @liveness, vt: vt<@liveness>) {
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expr_assert(*) | expr_check(*) | expr_copy(*) |
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expr_loop_body(*) | expr_do_body(*) |
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expr_cast(*) | expr_unary(*) | expr_fail(*) |
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expr_ret(*) | expr_break | expr_cont | expr_lit(_) |
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expr_ret(*) | expr_break | expr_again | expr_lit(_) |
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expr_block(*) | expr_swap(*) | expr_mac(*) | expr_addr_of(*) {
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visit::visit_expr(expr, self, vt);
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}
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@ -3644,7 +3644,7 @@ fn trans_expr(bcx: block, e: @ast::expr, dest: dest) -> block {
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assert dest == ignore;
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ret trans_break(bcx);
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}
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ast::expr_cont {
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ast::expr_again {
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assert dest == ignore;
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ret trans_cont(bcx);
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}
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@ -242,7 +242,7 @@ fn mark_for_expr(cx: ctx, e: @expr) {
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})
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}
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expr_alt(_, _, _) | expr_block(_) | expr_if(_, _, _) |
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expr_while(_, _) | expr_fail(_) | expr_break | expr_cont |
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expr_while(_, _) | expr_fail(_) | expr_break | expr_again |
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expr_unary(_, _) | expr_lit(_) | expr_assert(_) | expr_check(_, _) |
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expr_if_check(_, _, _) | expr_mac(_) | expr_addr_of(_, _) |
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expr_ret(_) | expr_loop(_) |
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@ -446,7 +446,7 @@ fn find_pre_post_expr(fcx: fn_ctxt, e: @expr) {
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join_then_else(fcx, p, conseq, maybe_alt, e.id, if_check);
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}
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expr_break { clear_pp(expr_pp(fcx.ccx, e)); }
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expr_cont { clear_pp(expr_pp(fcx.ccx, e)); }
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expr_again { clear_pp(expr_pp(fcx.ccx, e)); }
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expr_mac(_) { fcx.ccx.tcx.sess.bug("unexpanded macro"); }
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}
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}
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@ -498,7 +498,7 @@ fn find_pre_post_state_expr(fcx: fn_ctxt, pres: prestate, e: @expr) -> bool {
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ret join_then_else(fcx, p, conseq, maybe_alt, e.id, if_check, pres);
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}
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expr_break { ret pure_exp(fcx.ccx, e.id, pres); }
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expr_cont { ret pure_exp(fcx.ccx, e.id, pres); }
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expr_again { ret pure_exp(fcx.ccx, e.id, pres); }
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}
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}
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@ -1220,7 +1220,7 @@ fn check_expr_with_unifier(fcx: @fn_ctxt,
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fcx.write_bot(id);
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}
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ast::expr_break { fcx.write_bot(id); bot = true; }
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ast::expr_cont { fcx.write_bot(id); bot = true; }
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ast::expr_again { fcx.write_bot(id); bot = true; }
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ast::expr_ret(expr_opt) {
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bot = true;
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let ret_ty = alt fcx.indirect_ret_ty {
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@ -57,7 +57,7 @@ fn loop_query(b: ast::blk, p: fn@(ast::expr_) -> bool) -> bool {
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fn has_nonlocal_exits(b: ast::blk) -> bool {
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do loop_query(b) |e| { alt e {
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ast::expr_break | ast::expr_cont { true }
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ast::expr_break | ast::expr_again { true }
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_ { false }}}
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}
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