Different Identifiers and Names can have identical textual representations, but different internal representations, due to the macro hygiene machinery (syntax contexts and gensyms). This provides a way to see these internals by compiling with `--pretty expanded,hygiene`.
This is useful for debugging & hacking on macros (e.g. diagnosing https://github.com/rust-lang/rust/issues/15750/https://github.com/rust-lang/rust/issues/15962 likely would've been faster with this functionality).
E.g.
```rust
#![feature(macro_rules)]
// minimal junk
#![no_std]
macro_rules! foo {
($x: ident) => { y + $x }
}
fn bar() {
foo!(x)
}
```
```rust
#![feature(macro_rules)]
// minimal junk
#![no_std]
fn bar /* 61#0 */() { y /* 60#2 */ + x /* 58#3 */ }
```
Fixes#12643
> Say!
> I like labelled breaks/continues!
I will use them with a `for` loop.
And I will use with a `loop` loop.
Say! I will use them ANYWHERE!
… _even_ in a `while` loop.
Because they're now supported there.
`--pretty expanded,hygiene` is helpful with debugging macro issues,
since two identifiers/names can be textually the same, but different
internally (resulting in weird "undefined variable" errors).
This unifies the `non_snake_case_functions` and `uppercase_variables` lints into one lint, `non_snake_case`. It also now checks for non-snake-case modules. This also extends the non-camel-case types lint to check type parameters, and merges the `non_uppercase_pattern_statics` lint into the `non_uppercase_statics` lint.
Because the `uppercase_variables` lint is now part of the `non_snake_case` lint, all non-snake-case variables that start with lowercase characters (such as `fooBar`) will now trigger the `non_snake_case` lint.
New code should be updated to use the new `non_snake_case` lint instead of the previous `non_snake_case_functions` and `uppercase_variables` lints. All use of the `non_uppercase_pattern_statics` should be replaced with the `non_uppercase_statics` lint. Any code that previously contained non-snake-case module or variable names should be updated to use snake case names or disable the `non_snake_case` lint. Any code with non-camel-case type parameters should be changed to use camel case or disable the `non_camel_case_types` lint.
This also adds support for lint groups to the compiler. Lint groups are a way of grouping a number of lints together under one name. For example, this also defines a default lint for naming conventions, named `bad_style`. Writing `#[allow(bad_style)]` is equivalent to writing `#[allow(non_camel_case_types, non_snake_case, non_uppercase_statics)]`. These lint groups can also be defined as a compiler plugin using the new `Registry::register_lint_group` method.
This also adds two built-in lint groups, `bad_style` and `unused`. The contents of these groups can be seen by running `rustc -W help`.
[breaking-change]
This adds support for lint groups to the compiler. Lint groups are a way of
grouping a number of lints together under one name. For example, this also
defines a default lint for naming conventions, named `bad_style`. Writing
`#[allow(bad_style)]` is equivalent to writing
`#[allow(non_camel_case_types, non_snake_case, non_uppercase_statics)]`. These
lint groups can also be defined as a compiler plugin using the new
`Registry::register_lint_group` method.
This also adds two built-in lint groups, `bad_style` and `unused`. The contents
of these groups can be seen by running `rustc -W help`.
This unifies the `non_snake_case_functions` and `uppercase_variables` lints
into one lint, `non_snake_case`. It also now checks for non-snake-case modules.
This also extends the non-camel-case types lint to check type parameters, and
merges the `non_uppercase_pattern_statics` lint into the
`non_uppercase_statics` lint.
Because the `uppercase_variables` lint is now part of the `non_snake_case`
lint, all non-snake-case variables that start with lowercase characters (such
as `fooBar`) will now trigger the `non_snake_case` lint.
New code should be updated to use the new `non_snake_case` lint instead of the
previous `non_snake_case_functions` and `uppercase_variables` lints. All use of
the `non_uppercase_pattern_statics` should be replaced with the
`non_uppercase_statics` lint. Any code that previously contained non-snake-case
module or variable names should be updated to use snake case names or disable
the `non_snake_case` lint. Any code with non-camel-case type parameters should
be changed to use camel case or disable the `non_camel_case_types` lint.
[breaking-change]
The inference scheme proposed in <http://smallcultfollowing.com/babysteps/blog/2014/07/09/an-experimental-new-type-inference-scheme-for-rust/>.
This is theoretically a [breaking-change]. It is possible that you may encounter type checking errors, particularly related to closures or functions with higher-ranked lifetimes or object types. Adding more explicit type annotations should help the problem. However, I have not been able to make an example that *actually* successfully compiles with the older scheme and fails with the newer scheme.
f? @pcwalton, @pnkfelix
Previously, this caused methods of re-exported types to not be inserted into
the search index. This fix may introduce some false positives, but in my
testing they appear as orphaned methods and end up not being inserted into the
final search index at a later stage.
Fixes issue #11943
This squashes the
> `for` loop expression has type `[type error]` which does not implement
> the `Iterator` trait
message that one received when writing `for ... in x` where was
previously found to have a type error.
Fixes#16042.
Per API meeting
https://github.com/rust-lang/meeting-minutes/blob/master/Meeting-API-review-2014-08-13.md
# Changes to `core::option`
Most of the module is marked as stable or unstable; most of the unstable items are awaiting resolution of conventions issues.
However, a few methods have been deprecated, either due to lack of use or redundancy:
* `take_unwrap`, `get_ref` and `get_mut_ref` (redundant, and we prefer for this functionality to go through an explicit .unwrap)
* `filtered` and `while`
* `mutate` and `mutate_or_set`
* `collect`: this functionality is being moved to a new `FromIterator` impl.
# Changes to `core::result`
Most of the module is marked as stable or unstable; most of the unstable items are awaiting resolution of conventions issues.
* `collect`: this functionality is being moved to a new `FromIterator` impl.
* `fold_` is deprecated due to lack of use
* Several methods found in `core::option` are added here, including `iter`, `as_slice`, and variants.
Due to deprecations, this is a:
[breaking-change]
This changes the internal representation of `Duration` from
days: i32,
secs: i32,
nanos: u32
to
secs: i64,
nanos: i32
This resolves#16466. Note that `nanos` is an `i32` and not `u32` as suggested, because `i32` is easier to deal with, and it is not exposed anyway. Some methods now take `i64` instead of `i32` due to the increased range. Some methods, like `num_milliseconds`, now return an `Option<i64>` instead of `i64`, because the range of `Duration` is now larger than e.g. 2^63 milliseconds.
A few remarks:
- Negating `MIN` is impossible. I chose to return `MAX` as `-MIN`, but it is one nanosecond less than the actual negation. Is this the desired behaviour?
- In `std::io::timer`, some functions accept a `Duration`, which is internally converted into a number of milliseconds. However, the range of `Duration` is now larger than 2^64 milliseconds. There is already a FIXME in the file that this should be addressed (without a ticket number though). I chose to silently use 0 ms if the duration is too long. Is that right, as long as the backend still uses milliseconds?
- Negative durations are not formatted correctly, but they were not formatted correctly before either.
The implemented fix rounds half-way cases away from zero as described in
the original comments.
This rounding algorithm is sometimes called arithmetic rounding. It is
described further here:
http://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero
I also added several new tests to prevent regressions.
