Grammar changes:
* allow 'for _ in 1..i {}' (fixes#20241)
* allow 'for _ in 1.. {}' as infinite loop
* prevent use of range notation in contexts where only operators of high
precedence are expected (fixes#20811)
Parser code cleanup:
* remove RESTRICTION_NO_DOTS
* make AS_PREC const and follow naming convention
* make min_prec inclusive
This commit is an implementation of [RFC 565][rfc] which is a stabilization of
the `std::fmt` module and the implementations of various formatting traits.
Specifically, the following changes were performed:
[rfc]: https://github.com/rust-lang/rfcs/blob/master/text/0565-show-string-guidelines.md
* The `Show` trait is now deprecated, it was renamed to `Debug`
* The `String` trait is now deprecated, it was renamed to `Display`
* Many `Debug` and `Display` implementations were audited in accordance with the
RFC and audited implementations now have the `#[stable]` attribute
* Integers and floats no longer print a suffix
* Smart pointers no longer print details that they are a smart pointer
* Paths with `Debug` are now quoted and escape characters
* The `unwrap` methods on `Result` now require `Display` instead of `Debug`
* The `Error` trait no longer has a `detail` method and now requires that
`Display` must be implemented. With the loss of `String`, this has moved into
libcore.
* `impl<E: Error> FromError<E> for Box<Error>` now exists
* `derive(Show)` has been renamed to `derive(Debug)`. This is not currently
warned about due to warnings being emitted on stage1+
While backwards compatibility is attempted to be maintained with a blanket
implementation of `Display` for the old `String` trait (and the same for
`Show`/`Debug`) this is still a breaking change due to primitives no longer
implementing `String` as well as modifications such as `unwrap` and the `Error`
trait. Most code is fairly straightforward to update with a rename or tweaks of
method calls.
[breaking-change]
Closes#21436
Closes#21033. The new strategy for parsing a field pattern is to look 1 token ahead and if it's a colon, parse as "fieldname: pat", otherwise parse the shorthand form "(box) (ref) (mut) fieldname)". The previous strategy was to parse "(ref) (mut) fieldname" then if we encounter a colon, throw an error if either "ref" or "mut" were encountered.
* add `Token::AndAnd` (double borrow)
* add `Token::DotDot` (range notation)
* remove `Token::Pound` and `Token::At`
This fixes a syntax error when parsing `fn f() -> RangeTo<i32> { return ..1; }`.
Also, remove `fn_expr_lookahead`.
It's from the `fn~` days and seems to no longer be necessary.
* add Token::AndAnd (double borrow)
* add Token::DotDot (range notation)
* remove Token::Pound and Token::At
Fixes a syntax error when parsing "fn f() -> RangeTo<i32> { return ..1; }".
Also, remove "fn_expr_lookahead".
It's from the fn~ days and seems to no longer be necessary.
