This isn't ready to merge yet.
The 'containers and iterators' guide is basically just a collection of stuff that should be in the module definitions. So I'm moving the guide to just an 'iterators' guide, and moved the info that was there into the right places.
So, is this a good path forward, and is all of the information still correct?
Based on an observation that strings and arguments are always interleaved, thanks to #15832. Additionally optimize invocations where formatting parameters are unspecified for all arguments, e.g. `"{} {:?} {:x}"`, by emptying the `__STATIC_FMTARGS` array. Next, `Arguments::new` replaces an empty slice with `None` so that passing empty `__STATIC_FMTARGS` generates slightly less machine code when `Arguments::new` is inlined. Furthermore, formatting itself treats these cases separately without making redundant copies of formatting parameters.
All in all, this adds a single mov instruction per `write!` in most cases. That's why code size has increased.
Format specs are ignored and not stored in case they're all default.
Restore default formatting parameters during iteration.
Pass `None` instead of empty slices of format specs to take advantage
of non-nullable pointer optimization.
Generate a call to one of two functions of `fmt::Argument`.
Use '^' to specify center alignment in format strings.
fmt!( "[{:^5s}]", "Hi" ) -> "[ Hi ]"
fmt!( "[{:^5s}]", "H" ) -> "[ H ]"
fmt!( "[{:^5d}]", 1i ) -> "[ 1 ]"
fmt!( "[{:^5d}]", -1i ) -> "[ -1 ]"
fmt!( "[{:^6d}]", 1i ) -> "[ 1 ]"
fmt!( "[{:^6d}]", -1i ) -> "[ -1 ]"
If the padding is odd then the padding on the right will be one
character longer than the padding on the left.
Tuples squashed
As outlined in
https://aturon.github.io/style/naming/conversions.html
`to_` functions names should only be used for expensive operations.
Thus `to_option` is better named `as_option`. Also, putting type
names into method names is considered bad style; what the user is
really trying to get is a reference. This `as_ref` is even better.
Also, we are missing a mutable version of this method.
Finally, there is a bug in the signature of `to_option` which has
been around since lifetime elision: originally the returned reference
had 'static lifetime, but since the elision changes this become
the lifetime of the raw pointer (which does not make sense, since
the pointer lifetime and referent lifetime are unrelated). We fix
the bug to return a reference with a fresh lifetime which will be
inferred from the calling context.
[breaking-change]
As outlined in
https://aturon.github.io/style/naming/conversions.html
`to_` functions names should only be used for expensive operations.
Thus `to_option` is better named `as_option`. Also, putting type
names into method names is considered bad style; what the user is
really trying to get is a reference. This `as_ref` is even better.
Also, we are missing a mutable version of this method. So add a
new trait `RawMutPtr` with a corresponding `as_mut` methode.
Finally, there is a bug in the signature of `to_option` which has
been around since lifetime elision: originally the returned reference
had 'static lifetime, but since the elision changes this become
the lifetime of the raw pointer (which does not make sense, since
the pointer lifetime and referent lifetime are unrelated). Fix
the bug to return a reference with a fresh lifetime (which will
be inferred from the calling context).
[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]
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]
Per API meeting
https://github.com/rust-lang/meeting-minutes/blob/master/Meeting-API-review-2014-08-13.md
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]
Per API meeting
https://github.com/rust-lang/meeting-minutes/blob/master/Meeting-API-review-2014-08-13.md
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.
Due to deprecations, this is a:
[breaking-change]
[breaking-change]
1. The internal layout for traits has changed from (vtable, data) to (data, vtable). If you were relying on this in unsafe transmutes, you might get some very weird and apparently unrelated errors. You should not be doing this! Prefer not to do this at all, but if you must, you should use raw::TraitObject rather than hardcoding rustc's internal representation into your code.
2. The minimal type of reference-to-vec-literals (e.g., `&[1, 2, 3]`) is now a fixed size vec (e.g., `&[int, ..3]`) where it used to be an unsized vec (e.g., `&[int]`). If you want the unszied type, you must explicitly give the type (e.g., `let x: &[_] = &[1, 2, 3]`). Note in particular where multiple blocks must have the same type (e.g., if and else clauses, vec elements), the compiler will not coerce to the unsized type without a hint. E.g., `[&[1], &[1, 2]]` used to be a valid expression of type '[&[int]]'. It no longer type checks since the first element now has type `&[int, ..1]` and the second has type &[int, ..2]` which are incompatible.
3. The type of blocks (including functions) must be coercible to the expected type (used to be a subtype). Mostly this makes things more flexible and not less (in particular, in the case of coercing function bodies to the return type). However, in some rare cases, this is less flexible. TBH, I'm not exactly sure of the exact effects. I think the change causes us to resolve inferred type variables slightly earlier which might make us slightly more restrictive. Possibly it only affects blocks with unreachable code. E.g., `if ... { fail!(); "Hello" }` used to type check, it no longer does. The fix is to add a semicolon after the string.
Use ExactSize::len() and defer to its decisions about overly defensive
assertions. Remove the length double-check and simply put a failure
case if the Zip finds an uneven end in .next_back().
Fixing this up since I think I wrote this, and it's been known to
confuse rusties (PR #15886).
