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628 lines
19 KiB
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628 lines
19 KiB
Markdown
# NEWS for Ruby 3.0.0
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This document is a list of user visible feature changes
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since the **2.7.0** release, except for bug fixes.
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Note that each entry is kept so brief that no reason behind or reference
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information is supplied with. For a full list of changes with all
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sufficient information, see the ChangeLog file or Redmine
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(e.g. `https://bugs.ruby-lang.org/issues/$FEATURE_OR_BUG_NUMBER`).
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## Language changes
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* Keyword arguments are now separated from positional arguments.
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Code that resulted in deprecation warnings in Ruby 2.7 will now
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result in ArgumentError or different behavior. [[Feature #14183]]
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* Arguments forwarding (`...`) now supports leading arguments.
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[[Feature #16378]]
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```ruby
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def method_missing(meth, ...)
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send(:"do_#{meth}", ...)
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end
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```
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* Procs accepting a single rest argument and keywords are no longer
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subject to autosplatting. This now matches the behavior of Procs
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accepting a single rest argument and no keywords.
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[[Feature #16166]]
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```ruby
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pr = proc{|*a, **kw| [a, kw]}
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pr.call([1])
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# 2.7 => [[1], {}]
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# 3.0 => [[[1]], {}]
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pr.call([1, {a: 1}])
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# 2.7 => [[1], {:a=>1}] # and deprecation warning
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# 3.0 => [[[1, {:a=>1}]], {}]
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```
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* $SAFE is now a normal global variable with no special behavior.
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C-API methods related to $SAFE have been removed.
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[[Feature #16131]]
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* $KCODE is now a normal global variable with no special behavior. No
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warnings are emitted by access/assignment to it, and the assigned
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value will be returned. [[Feature #17136]]
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* yield in singleton class definitions in methods is now a SyntaxError
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instead of a warning. yield in a class definition outside of a method
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is now a SyntaxError instead of a LocalJumpError. [[Feature #15575]]
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* Pattern matching is no longer experimental. [[Feature #17260]]
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* One-line pattern matching now uses `=>` instead of `in`. [EXPERIMENTAL]
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[[Feature #17260]]
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```ruby
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# version 3.0
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{a: 0, b: 1} => {a:}
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p a # => 0
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# version 2.7
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{a: 0, b: 1} in {a:}
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p a # => 0
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```
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* Find pattern is added. [EXPERIMENTAL]
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[[Feature #16828]]
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```ruby
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case ["a", 1, "b", "c", 2, "d", "e", "f", 3]
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in [*pre, String => x, String => y, *post]
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p pre #=> ["a", 1]
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p x #=> "b"
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p y #=> "c"
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p post #=> [2, "d", "e", "f", 3]
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end
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```
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* When a class variable is overtaken by the same definition in an
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ancestor class/module, a RuntimeError is now raised (previously,
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it only issued a warning in verbose mode). Additionally, accessing a
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class variable from the toplevel scope is now a RuntimeError.
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[[Bug #14541]]
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* Assigning to a numbered parameter is now a SyntaxError instead of
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a warning.
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* Endless method definition is added. [EXPERIMENTAL]
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[[Feature #16746]]
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```ruby
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def square(x) = x * x
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```
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* Interpolated String literals are no longer frozen when
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`# frozen-string-literal: true` is used. [[Feature #17104]]
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* A static analysis foundation is introduced. See "Static analysis" section in detail.
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* RBS is introduced. It is a type definition language for Ruby programs.
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* TypeProf is experimentally bundled. It is a type analysis tool for Ruby programs.
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## Command line options
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### `--help` option
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When the environment variable `RUBY_PAGER` or `PAGER` is present and has
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non-empty value, and the standard input and output are tty, `--help`
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option shows the help message via the pager designated by the value.
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[[Feature #16754]]
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### `--backtrace-limit` option
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`--backtrace-limit` option limits the maximum length of backtrace.
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[[Feature #8661]]
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## Core classes updates
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Outstanding ones only.
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* Array
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* The following methods now return Array instances instead of
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subclass instances when called on subclass instances:
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[[Bug #6087]]
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* Array#drop
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* Array#drop_while
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* Array#flatten
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* Array#slice!
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* Array#slice / Array#[]
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* Array#take
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* Array#take_while
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* Array#uniq
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* Array#*
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* ConditionVariable
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* ConditionVariable#wait may now invoke the `block`/`unblock` scheduler
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hooks in a non-blocking context. [[Feature #16786]]
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* Dir
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* Dir.glob and Dir.[] now sort the results by default, and
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accept `sort:` keyword option. [[Feature #8709]]
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* ENV
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* ENV.except has been added, which returns a hash excluding the
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given keys and their values. [[Feature #15822]]
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* Encoding
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* Added new encoding IBM720. [[Feature #16233]]
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* Fiber
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* Fiber.new(blocking: true/false) allows you to create non-blocking
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execution contexts. [[Feature #16786]]
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* Fiber#blocking? tells whether the fiber is non-blocking. [[Feature #16786]]
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* Fiber#backtrace & Fiber#backtrace_locations provide per-fiber backtrace.
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[[Feature #16815]]
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* The limitation of Fiber#transfer is relaxed. [[Bug #17221]]
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* GC
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* GC.auto_compact= and GC.auto_compact have been added to control
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when compaction runs. Setting `auto_compact=` to true will cause
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compaction to occur during major collections. At the moment,
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compaction adds significant overhead to major collections, so please
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test first! [[Feature #17176]]
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* Hash
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* Hash#transform_keys now accepts a hash that maps keys to new
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keys. [[Feature #16274]]
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* Hash#except has been added, which returns a hash excluding the
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given keys and their values. [[Feature #15822]]
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* IO
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* IO#nonblock? now defaults to `true`. [[Feature #16786]]
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* IO#wait_readable, IO#wait_writable, IO#read, IO#write and other
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related methods (e.g. IO#puts, IO#gets) may invoke the scheduler hook
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`#io_wait(io, events, timeout)` in a non-blocking execution context.
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[[Feature #16786]]
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* Kernel
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* Kernel#clone when called with `freeze: false` keyword will call
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`#initialize_clone` with the `freeze: false` keyword.
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[[Bug #14266]]
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* Kernel#clone when called with `freeze: true` keyword will call
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`#initialize_clone` with the `freeze: true` keyword, and will
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return a frozen copy even if the receiver is unfrozen.
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[[Feature #16175]]
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* Kernel#eval when called with two arguments will use "(eval)"
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for `__FILE__` and 1 for `__LINE__` in the evaluated code.
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[[Bug #4352]]
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* Kernel#lambda now warns if called without a literal block.
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[[Feature #15973]]
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* Kernel.sleep invokes the scheduler hook `#kernel_sleep(...)` in a
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non-blocking execution context. [[Feature #16786]]
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* Module
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* Module#include and Module#prepend now affect classes and modules
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that have already included or prepended the receiver, mirroring the
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behavior if the arguments were included in the receiver before
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the other modules and classes included or prepended the receiver.
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[[Feature #9573]]
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```ruby
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class C; end
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module M1; end
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module M2; end
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C.include M1
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M1.include M2
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p C.ancestors #=> [C, M1, M2, Object, Kernel, BasicObject]
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```
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* Mutex
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* `Mutex` is now acquired per-`Fiber` instead of per-`Thread`. This change
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should be compatible for essentially all usages and avoids blocking when
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using a scheduler. [[Feature #16792]]
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* Proc
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* Proc#== and Proc#eql? are now defined and will return true for
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separate Proc instances if the procs were created from the same block.
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[[Feature #14267]]
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* Queue / SizedQueue
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* Queue#pop, SizedQueue#push and related methods may now invoke the
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`block`/`unblock` scheduler hooks in a non-blocking context.
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[[Feature #16786]]
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* Ractor
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* New class added to enable parallel execution. See doc/ractor.md for
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more details.
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* String
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* The following methods now return or yield String instances
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instead of subclass instances when called on subclass instances:
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[[Bug #10845]]
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* String#*
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* String#capitalize
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* String#center
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* String#chomp
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* String#chop
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* String#delete
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* String#delete_prefix
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* String#delete_suffix
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* String#downcase
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* String#dump
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* String#each_char
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* String#each_grapheme_cluster
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* String#each_line
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* String#gsub
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* String#ljust
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* String#lstrip
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* String#partition
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* String#reverse
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* String#rjust
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* String#rpartition
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* String#rstrip
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* String#scrub
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* String#slice!
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* String#slice / String#[]
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* String#split
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* String#squeeze
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* String#strip
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* String#sub
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* String#succ / String#next
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* String#swapcase
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* String#tr
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* String#tr_s
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* String#upcase
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* Symbol
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* Symbol#to_proc now returns a lambda Proc. [[Feature #16260]]
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* Symbol#name has been added, which returns the name of the symbol
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if it is named. The returned string is frozen. [[Feature #16150]]
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* Thread
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* Introduce Fiber.set_scheduler for intercepting blocking operations and
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Fiber.scheduler for accessing the current scheduler. See
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doc/scheduler.md for more details. [[Feature #16786]]
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* Fiber.blocking? tells whether the current execution context is
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blocking. [[Feature #16786]]
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* Thread#join invokes the scheduler hooks `block`/`unblock` in a
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non-blocking execution context. [[Feature #16786]]
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* Thread.ignore_deadlock accessor has been added for disabling the
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default deadlock detection, allowing the use of signal handlers to
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break deadlock. [[Bug #13768]]
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* Warning
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* Warning#warn now supports a category keyword argument.
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[[Feature #17122]]
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## Stdlib updates
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Outstanding ones only.
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* Bundler
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* Update to Bundler 2.2.0.rc.1
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* CSV
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* Update to CSV 3.1.9
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* Fiddle
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* Update to Fiddle 1.0.2
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* IRB
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* Update to IRB 1.2.6
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* Net::HTTP
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* Net::HTTP#verify_hostname= and Net::HTTP#verify_hostname have been
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added to skip hostname verification. [[Feature #16555]]
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* Net::HTTP.get, Net::HTTP.get_response, and Net::HTTP.get_print
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can take the request headers as a Hash in the second argument when the
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first argument is a URI. [[Feature #16686]]
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* OpenStruct
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* Initialization no longer lazy [[Bug #12136]]
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* Builtin methods can now be overridden safely. [[Bug #15409]]
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* Implementation uses only methods ending with `!`.
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* Ractor compatible.
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* Improved support for YAML [[Bug #8382]]
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* Use officially discouraged. Read "Caveats" section.
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* Reline
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* Update to Reline 0.1.5
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* RubyGems
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* Update to RubyGems 3.2.0.rc.1
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* Socket
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* TCPSocket.new now supports `resolv_timeout`. [[Feature #17134]]
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```ruby
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# it raises SocketError if name resolution is not finished within resolve_timeout.
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tcp_socket = TCPSocket.new("example.com", 80, resolv_timeout: 10)
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```
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## Compatibility issues
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Excluding feature bug fixes.
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* Regexp literals and all Range objects are frozen [[Feature #8948]] [[Feature #16377]] [[Feature #15504]]
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```ruby
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/foo/.frozen? #=> true
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(42...).frozen? # => true
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```
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* EXPERIMENTAL: Hash#each consistently yields a 2-element array [[Bug #12706]]
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* Now `{ a: 1 }.each(&->(k, v) { })` raises an ArgumentError
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due to lambda's arity check.
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* This is experimental; if it brings a big incompatibility issue,
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it may be reverted until 2.8/3.0 release.
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* When writing to STDOUT redirected to a closed pipe, no broken pipe
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error message will be shown now. [[Feature #14413]]
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* `TRUE`/`FALSE`/`NIL` constants are no longer defined.
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* Integer#zero? overrides Numeric#zero? for optimization. [[Misc #16961]]
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## Stdlib compatibility issues
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* Default gems
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* The following libraries are promoted the default gems from stdlib.
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* English
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* abbrev
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* base64
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* drb
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* debug
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* erb
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* find
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* net-ftp
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* net-http
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* net-imap
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* net-protocol
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* open-uri
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* optparse
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* pp
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* prettyprint
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* resolv-replace
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* resolv
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* rinda
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* set
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* securerandom
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* shellwords
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* tempfile
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* tmpdir
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* time
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* tsort
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* un
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* weakref
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* The following extensions are promoted the default gems from stdlib.
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* digest
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* io-nonblock
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* io-wait
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* nkf
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* pathname
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* syslog
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* win32ole
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* Bundled gems
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* net-telnet and xmlrpc have been removed from the bundled gems.
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If you are interested in maintaining them, please comment on
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your plan to https://github.com/ruby/xmlrpc
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or https://github.com/ruby/net-telnet.
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* SDBM have been removed from ruby standard library. [[Bug #8446]]
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* The issues of sdbm will be handled at https://github.com/ruby/sdbm
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## C API updates
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* C API functions related to $SAFE have been removed.
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[[Feature #16131]]
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* C API header file `ruby/ruby.h` was split. [[GH-2991]] Should have no impact
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on extension libraries, but users might experience slow compilations.
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* Memory view interface [EXPERIMENTAL]
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* The memory view interface is a C-API set to exchange a raw memory area,
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such as a numeric array and a bitmap image, between extension libraries.
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The extension libraries can share also the metadata of the memory area
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that consists of the shape, the element format, and so on.
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Using these kinds of metadata, the extension libraries can share even
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a multidimensional array appropriately.
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This feature is designed by referring to Python's buffer protocol.
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[[Feature #13767]] [[Feature #14722]]
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## Implementation improvements
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* New method cache mechanism for Ractor [[Feature #16614]]
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* Inline method caches pointed from ISeq can be accessed by multiple Ractors
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in parallel and synchronization is needed even for method caches. However,
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such synchronization can be overhead so introducing new inline method cache
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mechanisms, (1) Disposable inline method cache (2) per-Class method cache
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and (3) new invalidation mechanism. (1) can avoid per-method call
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synchronization because it only uses atomic operations.
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See the ticket for more details.
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* The number of hashes allocated when using a keyword splat in
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a method call has been reduced to a maximum of 1, and passing
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a keyword splat to a method that accepts specific keywords
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does not allocate a hash.
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* `super` is optimized when the same type of method is called in the previous call
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if it's not refinements or an attr reader or writer.
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### JIT
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* Native functions shared by multiple methods are deduplicated on JIT compaction.
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* Decrease code size of hot paths by some optimizations and partitioning cold paths.
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* Not only pure Ruby methods but also some C methods skip pushing a method frame.
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* `Kernel#class`, `Integer#zero?`
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* Always generate appropriate code for `==`, `nil?`, and `!` calls depending on
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a receiver class.
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* Optimize instance variable access in some core classes like Hash and their subclasses.
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* Eliminate VM register access on a method return.
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* Optimize C method calls a little.
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## Static analysis
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### RBS
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* RBS is a new language for type definition of Ruby programs.
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It allows writing types of classes and modules with advanced
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types including union types, overloading, generics, and
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_interface types_ for duck typing.
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* Ruby ships with type definitions for core/stdlib classes.
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* `rbs` gem is bundled to load and process RBS files.
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### TypeProf
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* TypeProf is a type analysis tool for Ruby code based on abstract interpretation.
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* It reads non-annotated Ruby code, tries inferring its type signature, and prints
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the analysis result in RBS format.
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* Though it supports only a subset of the Ruby language yet, we will continuously
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improve the coverage of language features, the analysis performance, and usability.
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```ruby
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# test.rb
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def foo(x)
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if x > 10
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x.to_s
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else
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nil
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end
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end
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foo(42)
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```
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```
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$ typeprof test.rb
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# Classes
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class Object
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def foo : (Integer) -> String?
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end
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```
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## Miscellaneous changes
|
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* Methods using `ruby2_keywords` will no longer keep empty keyword
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splats, those are now removed just as they are for methods not
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using `ruby2_keywords`.
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* When an exception is caught in the default handler, the error
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message and backtrace are printed in order from the innermost.
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[[Feature #8661]]
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[Bug #4352]: https://bugs.ruby-lang.org/issues/4352
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[Bug #6087]: https://bugs.ruby-lang.org/issues/6087
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[Bug #8382]: https://bugs.ruby-lang.org/issues/8382
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[Bug #8446]: https://bugs.ruby-lang.org/issues/8446
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[Feature #8661]: https://bugs.ruby-lang.org/issues/8661
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[Feature #8709]: https://bugs.ruby-lang.org/issues/8709
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[Feature #8948]: https://bugs.ruby-lang.org/issues/8948
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[Feature #9573]: https://bugs.ruby-lang.org/issues/9573
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[Bug #10845]: https://bugs.ruby-lang.org/issues/10845
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[Bug #12136]: https://bugs.ruby-lang.org/issues/12136
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[Bug #12706]: https://bugs.ruby-lang.org/issues/12706
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[Feature #13767]: https://bugs.ruby-lang.org/issues/13767
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[Bug #13768]: https://bugs.ruby-lang.org/issues/13768
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[Feature #14183]: https://bugs.ruby-lang.org/issues/14183
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[Bug #14266]: https://bugs.ruby-lang.org/issues/14266
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[Feature #14267]: https://bugs.ruby-lang.org/issues/14267
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[Feature #14413]: https://bugs.ruby-lang.org/issues/14413
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[Bug #14541]: https://bugs.ruby-lang.org/issues/14541
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[Feature #14722]: https://bugs.ruby-lang.org/issues/14722
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[Bug #15409]: https://bugs.ruby-lang.org/issues/15409
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[Feature #15504]: https://bugs.ruby-lang.org/issues/15504
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[Feature #15575]: https://bugs.ruby-lang.org/issues/15575
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[Feature #15822]: https://bugs.ruby-lang.org/issues/15822
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[Feature #15921]: https://bugs.ruby-lang.org/issues/15921
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[Feature #15973]: https://bugs.ruby-lang.org/issues/15973
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[Feature #16131]: https://bugs.ruby-lang.org/issues/16131
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[Feature #16150]: https://bugs.ruby-lang.org/issues/16150
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[Feature #16166]: https://bugs.ruby-lang.org/issues/16166
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[Feature #16175]: https://bugs.ruby-lang.org/issues/16175
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[Feature #16233]: https://bugs.ruby-lang.org/issues/16233
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[Feature #16260]: https://bugs.ruby-lang.org/issues/16260
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[Feature #16274]: https://bugs.ruby-lang.org/issues/16274
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[Feature #16377]: https://bugs.ruby-lang.org/issues/16377
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[Feature #16378]: https://bugs.ruby-lang.org/issues/16378
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[Feature #16555]: https://bugs.ruby-lang.org/issues/16555
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[Feature #16614]: https://bugs.ruby-lang.org/issues/16614
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[Feature #16686]: https://bugs.ruby-lang.org/issues/16686
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[Feature #16746]: https://bugs.ruby-lang.org/issues/16746
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[Feature #16754]: https://bugs.ruby-lang.org/issues/16754
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[Feature #16786]: https://bugs.ruby-lang.org/issues/16786
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[Feature #16792]: https://bugs.ruby-lang.org/issues/16792
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[Feature #16815]: https://bugs.ruby-lang.org/issues/16815
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[Feature #16828]: https://bugs.ruby-lang.org/issues/16828
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[Misc #16961]: https://bugs.ruby-lang.org/issues/16961
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[Feature #17104]: https://bugs.ruby-lang.org/issues/17104
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[Feature #17122]: https://bugs.ruby-lang.org/issues/17122
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[Feature #17134]: https://bugs.ruby-lang.org/issues/17134
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[Feature #17136]: https://bugs.ruby-lang.org/issues/17136
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[Feature #17176]: https://bugs.ruby-lang.org/issues/17176
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[Bug #17221]: https://bugs.ruby-lang.org/issues/17221
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[Feature #17260]: https://bugs.ruby-lang.org/issues/17260
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[GH-2991]: https://github.com/ruby/ruby/pull/2991
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