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Auto merge of #21947 - bluss:full-range-syntax, r=brson

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Implement step 1 of rust-lang/rfcs#702

Allows the expression `..` (without either endpoint) in general, can be
used in slicing syntax `&expr[..]` where we previously wrote `&expr[]`.

The old syntax &expr[] is not yet removed or warned for.
This commit is contained in:
bors 2015-02-06 03:11:34 +00:00
commit 715f9a5e8d
18 changed files with 51 additions and 51 deletions
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33
src/libsyntax/parse/parser.rs
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@ -2527,16 +2527,7 @@ impl<'a> Parser<'a> {
let bracket_pos = self.span.lo;
self.bump();
let mut found_dotdot = false;
if self.token == token::DotDot &&
self.look_ahead(1, |t| t == &token::CloseDelim(token::Bracket)) {
// Using expr[..], which is a mistake, should be expr[]
self.bump();
self.bump();
found_dotdot = true;
}
if found_dotdot || self.eat(&token::CloseDelim(token::Bracket)) {
if self.eat(&token::CloseDelim(token::Bracket)) {
// No expression, expand to a RangeFull
// FIXME(#20516) It would be better to use a lang item or
// something for RangeFull.
@ -2560,7 +2551,11 @@ impl<'a> Parser<'a> {
let range = ExprStruct(path, vec![], None);
let ix = self.mk_expr(bracket_pos, hi, range);
let index = self.mk_index(e, ix);
e = self.mk_expr(lo, hi, index)
e = self.mk_expr(lo, hi, index);
// Enable after snapshot.
// self.span_warn(e.span, "deprecated slicing syntax: `[]`");
// self.span_note(e.span,
// "use `&expr[..]` to construct a slice of the whole of expr");
} else {
let ix = self.parse_expr();
hi = self.span.hi;
@ -2569,11 +2564,6 @@ impl<'a> Parser<'a> {
e = self.mk_expr(lo, hi, index)
}
if found_dotdot {
self.span_err(e.span, "incorrect slicing expression: `[..]`");
self.span_note(e.span,
"use `&expr[]` to construct a slice of the whole of expr");
}
}
_ => return e
}
@ -2934,9 +2924,14 @@ impl<'a> Parser<'a> {
// with the postfix-form 'expr..'
let lo = self.span.lo;
self.bump();
let rhs = self.parse_binops();
let hi = rhs.span.hi;
let ex = self.mk_range(None, Some(rhs));
let opt_end = if self.is_at_start_of_range_notation_rhs() {
let end = self.parse_binops();
Some(end)
} else {
None
};
let hi = self.span.hi;
let ex = self.mk_range(None, opt_end);
self.mk_expr(lo, hi, ex)
}
_ => {