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Added support for parsing in PLACE { BLOCK_CONTENT }.

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This commit is contained in:
Felix S. Klock II 2015-07-21 18:31:37 +02:00
parent e0b44797ce
commit 9f6f35bef4
1 changed files with 33 additions and 8 deletions
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41
src/libsyntax/parse/parser.rs
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@ -2612,18 +2612,43 @@ impl<'a> Parser<'a> {
ex = ExprAddrOf(m, e);
}
token::Ident(_, _) => {
if !self.check_keyword(keywords::Box) {
if !self.check_keyword(keywords::Box) && !self.check_keyword(keywords::In) {
return self.parse_dot_or_call_expr();
}
let lo = self.span.lo;
let box_hi = self.span.hi;
let keyword_hi = self.span.hi;
let is_in = self.token.is_keyword(keywords::In);
try!(self.bump());
// Check for a place: `box(PLACE) EXPR`.
if is_in {
let place = try!(self.parse_expr_res(Restrictions::RESTRICTION_NO_STRUCT_LITERAL));
let blk = try!(self.parse_block());
hi = blk.span.hi;
let blk_expr = self.mk_expr(blk.span.lo, blk.span.hi, ExprBlock(blk));
ex = ExprBox(Some(place), blk_expr);
return Ok(self.mk_expr(lo, hi, ex));
}
// FIXME (#22181) Remove `box (PLACE) EXPR` support
// entirely after next release (enabling `(box (EXPR))`),
// since it will be replaced by `in PLACE { EXPR }`, ...
//
// ... but for now: check for a place: `box(PLACE) EXPR`.
if try!(self.eat(&token::OpenDelim(token::Paren)) ){
// Support `box() EXPR` as the default.
// SNAP ba0e1cd
// Enable this warning after snapshot ...
//
// let box_span = mk_sp(lo, self.last_span.hi);
// self.span_warn(
// box_span,
// "deprecated syntax; use the `in` keyword now \
// (e.g. change `box (<expr>) <expr>` to \
// `in <expr> { <expr> }`)");
// Continue supporting `box () EXPR` (temporarily)
if !try!(self.eat(&token::CloseDelim(token::Paren)) ){
let place = try!(self.parse_expr_nopanic());
try!(self.expect(&token::CloseDelim(token::Paren)));
@ -2634,10 +2659,9 @@ impl<'a> Parser<'a> {
self.span_err(span,
&format!("expected expression, found `{}`",
this_token_to_string));
let box_span = mk_sp(lo, box_hi);
self.span_suggestion(box_span,
"try using `box()` instead:",
"box()".to_string());
let box_span = mk_sp(lo, keyword_hi);
let new_expr = format!("box () {}", pprust::expr_to_string(&place));
self.span_suggestion(box_span, "try using `box ()` instead:", new_expr);
self.abort_if_errors();
}
let subexpression = try!(self.parse_prefix_expr());
@ -2650,6 +2674,7 @@ impl<'a> Parser<'a> {
// Otherwise, we use the unique pointer default.
let subexpression = try!(self.parse_prefix_expr());
hi = subexpression.span.hi;
// FIXME (pnkfelix): After working out kinks with box
// desugaring, should be `ExprBox(None, subexpression)`
// instead.