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# NEWS for Ruby 3.2.0
2021-12-15 11:24:31 -05:00
This document is a list of user-visible feature changes
since the **3.1.0** release, except for bug fixes.
Note that each entry is kept to a minimum, see links for details.
## Language changes
Evaluate multiple assignment left hand side before right hand side In regular assignment, Ruby evaluates the left hand side before the right hand side. For example: ```ruby foo[0] = bar ``` Calls `foo`, then `bar`, then `[]=` on the result of `foo`. Previously, multiple assignment didn't work this way. If you did: ```ruby abc.def, foo[0] = bar, baz ``` Ruby would previously call `bar`, then `baz`, then `abc`, then `def=` on the result of `abc`, then `foo`, then `[]=` on the result of `foo`. This change makes multiple assignment similar to single assignment, changing the evaluation order of the above multiple assignment code to calling `abc`, then `foo`, then `bar`, then `baz`, then `def=` on the result of `abc`, then `[]=` on the result of `foo`. Implementing this is challenging with the stack-based virtual machine. We need to keep track of all of the left hand side attribute setter receivers and setter arguments, and then keep track of the stack level while handling the assignment processing, so we can issue the appropriate topn instructions to get the receiver. Here's an example of how the multiple assignment is executed, showing the stack and instructions: ``` self # putself abc # send abc, self # putself abc, foo # send abc, foo, 0 # putobject 0 abc, foo, 0, [bar, baz] # evaluate RHS abc, foo, 0, [bar, baz], baz, bar # expandarray abc, foo, 0, [bar, baz], baz, bar, abc # topn 5 abc, foo, 0, [bar, baz], baz, abc, bar # swap abc, foo, 0, [bar, baz], baz, def= # send abc, foo, 0, [bar, baz], baz # pop abc, foo, 0, [bar, baz], baz, foo # topn 3 abc, foo, 0, [bar, baz], baz, foo, 0 # topn 3 abc, foo, 0, [bar, baz], baz, foo, 0, baz # topn 2 abc, foo, 0, [bar, baz], baz, []= # send abc, foo, 0, [bar, baz], baz # pop abc, foo, 0, [bar, baz] # pop [bar, baz], foo, 0, [bar, baz] # setn 3 [bar, baz], foo, 0 # pop [bar, baz], foo # pop [bar, baz] # pop ``` As multiple assignment must deal with splats, post args, and any level of nesting, it gets quite a bit more complex than this in non-trivial cases. To handle this, struct masgn_state is added to keep track of the overall state of the mass assignment, which stores a linked list of struct masgn_attrasgn, one for each assigned attribute. This adds a new optimization that replaces a topn 1/pop instruction combination with a single swap instruction for multiple assignment to non-aref attributes. This new approach isn't compatible with one of the optimizations previously used, in the case where the multiple assignment return value was not needed, there was no lhs splat, and one of the left hand side used an attribute setter. This removes that optimization. Removing the optimization allowed for removing the POP_ELEMENT and adjust_stack functions. This adds a benchmark to measure how much slower multiple assignment is with the correct evaluation order. This benchmark shows: * 4-9% decrease for attribute sets * 14-23% decrease for array member sets * Basically same speed for local variable sets Importantly, it shows no significant difference between the popped (where return value of the multiple assignment is not needed) and !popped (where return value of the multiple assignment is needed) cases for attribute and array member sets. This indicates the previous optimization, which was dropped in the evaluation order fix and only affected the popped case, is not important to performance. Fixes [Bug #4443]
2021-04-21 13:49:19 -04:00
* Anonymous rest and keyword rest arguments can now be passed as
arguments, instead of just used in method parameters.
[[Feature #18351]]
```ruby
def foo(*)
bar(*)
end
def baz(**)
quux(**)
end
```
Fix constant assignment evaluation order Previously, the right hand side was always evaluated before the left hand side for constant assignments. For the following: ```ruby lhs::C = rhs ``` rhs was evaluated before lhs, which is inconsistant with attribute assignment (lhs.m = rhs), and apparently also does not conform to JIS 3017:2013 11.4.2.2.3. Fix this by changing evaluation order. Previously, the above compiled to: ``` 0000 putself ( 1)[Li] 0001 opt_send_without_block <calldata!mid:rhs, argc:0, FCALL|VCALL|ARGS_SIMPLE> 0003 dup 0004 putself 0005 opt_send_without_block <calldata!mid:lhs, argc:0, FCALL|VCALL|ARGS_SIMPLE> 0007 setconstant :C 0009 leave ``` After this change: ``` 0000 putself ( 1)[Li] 0001 opt_send_without_block <calldata!mid:lhs, argc:0, FCALL|VCALL|ARGS_SIMPLE> 0003 putself 0004 opt_send_without_block <calldata!mid:rhs, argc:0, FCALL|VCALL|ARGS_SIMPLE> 0006 swap 0007 topn 1 0009 swap 0010 setconstant :C 0012 leave ``` Note that if expr is not a module/class, then a TypeError is not raised until after the evaluation of rhs. This is because that error is raised by setconstant. If we wanted to raise TypeError before evaluation of rhs, we would have to add a VM instruction for calling vm_check_if_namespace. Changing assignment order for single assignments caused problems in the multiple assignment code, revealing that the issue also affected multiple assignment. Fix the multiple assignment code so left-to-right evaluation also works for constant assignments. Do some refactoring of the multiple assignment code to reduce duplication after adding support for constants. Rename struct masgn_attrasgn to masgn_lhs_node, since it now handles both constants and attributes. Add add_masgn_lhs_node static function for adding data for lhs attribute and constant setting. Fixes [Bug #15928]
2021-04-30 19:01:27 -04:00
* Constant assignment evaluation order for constants set on explicit
objects has been made consistent with single attribute assignment
evaluation order. With this code:
```ruby
foo::BAR = baz
```
`foo` is now called before `baz`. Similarly, for multiple assignment
to constants, left-to-right evaluation order is used. With this
code:
```ruby
foo1::BAR1, foo2::BAR2 = baz1, baz2
```
The following evaluation order is now used:
1. `foo1`
2. `foo2`
3. `baz1`
4. `baz2`
[[Bug #15928]]
## Command line options
## Core classes updates
2021-12-15 11:24:31 -05:00
Note: We're only listing outstanding class updates.
* Hash
* Hash#shift now always returns nil if the hash is
empty, instead of returning the default value or
calling the default proc. [[Bug #16908]]
2022-01-05 02:58:23 -05:00
* Module
* Module.used_refinements has been added. [[Feature #14332]]
* Module#refinements has been added. [[Feature #12737]]
* Module#const_added has been added. [[Feature #17881]]
2022-01-13 03:45:25 -05:00
* Proc
* Proc#dup returns an instance of subclass. [[Bug #17545]]
* Refinement
* Refinement#refined_class has been added. [[Feature #12737]]
2022-01-05 02:58:23 -05:00
* Struct
* A Struct class can also be initialized with keyword arguments
without `keyword_init: true` on `Struct.new` [[Feature #16806]]
## Stdlib updates
* The following default gem are updated.
* RubyGems 3.4.0.dev
* bigdecimal 3.1.2
* bundler 2.4.0.dev
* etc 1.4.0
* io-console 0.5.11
* io-wait 0.2.2
* ipaddr 1.2.4
* reline 0.3.1
* The following bundled gems are updated.
2022-01-06 02:02:37 -05:00
* net-imap 0.2.3
* rbs 2.1.0
2021-12-29 02:02:15 -05:00
* typeprof 0.21.2
* The following default gems are now bundled gems.
## Compatibility issues
2021-12-15 11:24:31 -05:00
Note: Excluding feature bug fixes.
### Removed constants
2021-12-31 09:59:50 -05:00
2022-01-06 19:44:08 -05:00
The following deprecated constants are removed.
2022-01-02 01:05:02 -05:00
* `Fixnum` and `Bignum` [[Feature #12005]]
* `Random::DEFAULT` [[Feature #17351]]
2022-01-02 01:05:02 -05:00
* `Struct::Group`
* `Struct::Passwd`
### Removed methods
2021-12-31 09:59:50 -05:00
The following deprecated methods are removed.
* `Dir.exists?` [[Feature #17391]]
* `File.exists?` [[Feature #17391]]
* `Kernel#=~` [[Feature #15231]]
* `Kernel#taint`, `Kernel#untaint`, `Kernel#tainted?`
[[Feature #16131]]
* `Kernel#trust`, `Kernel#untrust`, `Kernel#untrusted?`
[[Feature #16131]]
2021-12-31 09:59:50 -05:00
## Stdlib compatibility issues
2020-06-18 08:11:19 -04:00
## C API updates
2021-12-31 09:59:04 -05:00
### Removed C APIs
The following deprecated APIs are removed.
* `rb_cData` variable.
* "taintedness" and "trustedness" functions. [[Feature #16131]]
2021-12-31 09:59:04 -05:00
## Implementation improvements
## JIT
### MJIT
2021-10-20 15:51:07 -04:00
### YJIT: New experimental in-process JIT compiler
2020-11-10 12:15:57 -05:00
## Static analysis
2020-10-20 00:16:19 -04:00
### RBS
2020-09-25 04:08:39 -04:00
2020-10-20 00:16:19 -04:00
### TypeProf
2021-10-19 21:18:54 -04:00
## Debugger
2021-10-19 22:05:05 -04:00
## error_highlight
## IRB Autocomplete and Document Display
## Miscellaneous changes
[Feature #12005]: https://bugs.ruby-lang.org/issues/12005
2022-01-06 09:49:27 -05:00
[Feature #12737]: https://bugs.ruby-lang.org/issues/12737
[Feature #14332]: https://bugs.ruby-lang.org/issues/14332
[Feature #15231]: https://bugs.ruby-lang.org/issues/15231
Fix constant assignment evaluation order Previously, the right hand side was always evaluated before the left hand side for constant assignments. For the following: ```ruby lhs::C = rhs ``` rhs was evaluated before lhs, which is inconsistant with attribute assignment (lhs.m = rhs), and apparently also does not conform to JIS 3017:2013 11.4.2.2.3. Fix this by changing evaluation order. Previously, the above compiled to: ``` 0000 putself ( 1)[Li] 0001 opt_send_without_block <calldata!mid:rhs, argc:0, FCALL|VCALL|ARGS_SIMPLE> 0003 dup 0004 putself 0005 opt_send_without_block <calldata!mid:lhs, argc:0, FCALL|VCALL|ARGS_SIMPLE> 0007 setconstant :C 0009 leave ``` After this change: ``` 0000 putself ( 1)[Li] 0001 opt_send_without_block <calldata!mid:lhs, argc:0, FCALL|VCALL|ARGS_SIMPLE> 0003 putself 0004 opt_send_without_block <calldata!mid:rhs, argc:0, FCALL|VCALL|ARGS_SIMPLE> 0006 swap 0007 topn 1 0009 swap 0010 setconstant :C 0012 leave ``` Note that if expr is not a module/class, then a TypeError is not raised until after the evaluation of rhs. This is because that error is raised by setconstant. If we wanted to raise TypeError before evaluation of rhs, we would have to add a VM instruction for calling vm_check_if_namespace. Changing assignment order for single assignments caused problems in the multiple assignment code, revealing that the issue also affected multiple assignment. Fix the multiple assignment code so left-to-right evaluation also works for constant assignments. Do some refactoring of the multiple assignment code to reduce duplication after adding support for constants. Rename struct masgn_attrasgn to masgn_lhs_node, since it now handles both constants and attributes. Add add_masgn_lhs_node static function for adding data for lhs attribute and constant setting. Fixes [Bug #15928]
2021-04-30 19:01:27 -04:00
[Bug #15928]: https://bugs.ruby-lang.org/issues/15928
[Feature #16131]: https://bugs.ruby-lang.org/issues/16131
[Feature #16806]: https://bugs.ruby-lang.org/issues/16806
[Bug #16908]: https://bugs.ruby-lang.org/issues/16908
[Feature #17351]: https://bugs.ruby-lang.org/issues/17351
[Feature #17391]: https://bugs.ruby-lang.org/issues/17391
2022-01-13 03:45:25 -05:00
[Bug #17545]: https://bugs.ruby-lang.org/issues/17545
2022-01-18 08:57:21 -05:00
[Feature #17881]: https://bugs.ruby-lang.org/issues/17881
[Feature #18351]: https://bugs.ruby-lang.org/issues/18351