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Jeremy Evans 67d1dd2ebd Avoid array allocation for *nil, by not calling nil.to_a
The following method call:

```ruby
a(*nil)
```

A method call such as `a(*nil)` previously allocated an array, because
it calls `nil.to_a`, but I have determined this array allocation is
unnecessary.  The instructions in this case are:

```
0000 putself                                                          (   1)[Li]
0001 putnil
0002 splatarray                             false
0004 opt_send_without_block                 <calldata!mid:a, argc:1, ARGS_SPLAT|FCALL>
0006 leave
```

The method call uses `ARGS_SPLAT` without `ARGS_SPLAT_MUT`, so the
returned array doesn't need to be mutable.  I believe all cases where
`splatarray false` are used allow the returned object to be frozen,
since the `false` means to not duplicate the array.  The optimization
in this case is to have `splatarray false` push a shared empty frozen
array, instead of calling `nil.to_a` to return a newly allocated array.

There is a slightly backwards incompatibility with this optimization,
in that `nil.to_a` is not called.  However, I believe the new behavior
of `*nil` not calling `nil.to_a` is more consistent with how `**nil`
does not call `nil.to_hash`.  Also, so much Ruby code would break if
`nil.to_a` returned something different from the empty hash, that it's
difficult to imagine anyone actually doing that in real code, though
we have a few tests/specs for that.

I think it would be bad for consistency if `*nil` called `nil.to_a`
in some cases and not others, so this changes other cases to not
call `nil.to_a`:

For `[*nil]`, this uses `splatarray true`, which now allocates a
new array for a `nil` argument without calling `nil.to_a`.

For `[1, *nil]`, this uses `concattoarray`, which now returns
the first array if the second array is `nil`.

This updates the allocation tests to check that the array allocations
are avoided where possible.

Implements [Feature #21047]
2025-03-27 11:17:40 -07:00
.github Do not run ruby/spec on CI on Ruby 3.0 2025-03-27 11:09:24 +01:00
basictest Ensure test suite is compatible with --frozen-string-literal 2024-03-14 17:56:15 +01:00
benchmark Avoid array allocation for *nil, by not calling nil.to_a 2025-03-27 11:17:40 -07:00
bin
bootstraptest Avoid array allocation for *nil, by not calling nil.to_a 2025-03-27 11:17:40 -07:00
ccan Initialize loop variable of ccan_list_for_each 2023-12-24 19:34:25 +09:00
coroutine coroutine/ppc64le: fix conditional registers got clobbered unexpectedly 2025-01-10 00:07:20 +09:00
coverage
cygwin Win32: Remove win32 directory if empty 2024-12-27 14:25:07 +09:00
defs Revert "[Bug #20965] Define it like an ordinary argument" (#12418) 2024-12-23 04:46:50 +00:00
doc Escape Binding reference in pattern matching docs 2025-03-21 10:36:13 +09:00
enc [Feature #19908] Update Unicode headers to 15.1.0 2025-03-18 21:18:12 +09:00
ext [ruby/psych] Format Date in ISO-8601 explicitly 2025-03-27 14:56:49 +00:00
gc Prefer FL_TEST_RAW() in GC on known on-heap objects 2025-03-25 18:16:31 -04:00
gems Update bundled gems list as of 2025-03-12 2025-03-13 07:01:36 +00:00
include Suppress sign-conversion warning [ci skip] 2025-03-18 16:22:49 +09:00
internal Freeze $/ and make it ractor safe 2025-03-27 17:54:56 +01:00
lib [rubygems/rubygems] Bump up connection_pool-2.5.0 with rake vendor:install 2025-03-27 16:57:10 +09:00
libexec Removed executables of bundled gems 2025-01-30 09:40:12 +09:00
man [DOC] Fix minor miscalculation of stack size 2025-03-07 16:18:25 -05:00
misc Fix .vscode/settings.json for the latest extension 2025-02-12 16:17:08 -08:00
missing [Bug #20705] Update strtod implementation 2024-10-05 23:29:42 +09:00
prism [ruby/prism] Update Ruby deps 2025-03-23 22:16:45 +00:00
sample Migrate win32ole as bundled gems 2025-01-16 12:35:21 +09:00
spec Avoid array allocation for *nil, by not calling nil.to_a 2025-03-27 11:17:40 -07:00
template Remove obsoleted insn_may_depend_on_sp_or_pc() 2025-03-05 16:23:31 -08:00
test Avoid array allocation for *nil, by not calling nil.to_a 2025-03-27 11:17:40 -07:00
tool Update the all of gemfile deps 2025-03-27 16:56:59 +09:00
wasm [wasm] Stop using mprotect(PROT_NONE) on WASI 2025-02-19 11:46:12 +09:00
win32 fix rb_w32_strerror when errno < 0 2025-03-19 01:28:59 +09:00
yjit YJIT: Add Counter::invalidate_everything 2025-03-07 20:23:32 -05:00
.dir-locals.el
.document [Feature #21116] Extract RJIT as a third-party gem 2025-02-13 18:01:03 +09:00
.editorconfig
.gdbinit .gdbinit: Fix T_HASH printing [ci skip] 2025-03-03 18:54:08 -05:00
.git-blame-ignore-revs Add commit 2da9238 to .git-blame-ignore-revs [ci skip] 2024-11-28 11:35:24 -05:00
.gitattributes
.gitignore [Feature #21116] Extract RJIT as a third-party gem 2025-02-13 18:01:03 +09:00
.indent.pro
.mailmap Parenthesized SVN IDs in .mailmap look too verbose [ci skip] 2024-04-12 18:22:04 +09:00
.rdoc_options [DOC] Fix exclude: as regexps 2025-01-07 13:29:35 +09:00
.rspec_parallel
.travis.yml .travis.yml: Drop arm64 case. 2025-01-20 15:48:08 +01:00
aclocal.m4
addr2line.c [Bug #21150] macOS: Temporary workaround at unwinding coroutine 2025-02-21 17:53:16 +09:00
addr2line.h
array.c [DOC] Reference to the idiom from Array#sort 2025-02-27 13:07:43 +09:00
array.rb [DOC] Tweaks for Array doc 2025-01-03 11:42:53 -05:00
ast.c Implement CLASS NODE locations 2025-03-08 18:26:40 +09:00
ast.rb [DOC] Fix typo in related class reference 2024-12-22 15:07:56 +09:00
autogen.sh
bignum.c bignum nogvl is offload safe. (#12132) 2024-11-21 13:46:27 +13:00
BSDL
builtin.c Gather code for builtin loading to miniinit.c 2024-09-08 23:16:46 +09:00
builtin.h YJIT: Replace Array#each only when YJIT is enabled (#11955) 2024-11-04 11:14:28 -05:00
class.c Trigger inherited and const_set callbacks after const has been defined 2025-03-20 18:18:11 +01:00
common.mk Use release version of turbo_tests 2025-03-26 19:37:22 +09:00
compar.c [DOC] Exclude 'Class' and 'Module' from RDoc's autolinking 2025-01-02 12:36:06 +09:00
compile.c Remove leading nop from block when we don't need it 2025-03-20 11:49:13 -07:00
complex.c [DOC] Exclude 'Class' and 'Module' from RDoc's autolinking 2025-01-02 12:36:06 +09:00
configure.ac Check programs for CC in the same path 2025-02-17 13:19:08 +09:00
constant.h
cont.c [wasm] Stop using mprotect(PROT_NONE) on WASI 2025-02-19 11:46:12 +09:00
CONTRIBUTING.md
COPYING
COPYING.ja
darray.h Create rb_darray_realloc_mul_add 2025-01-02 11:03:04 -05:00
debug.c Fix setting GC stress at boot when objspace not available 2024-03-27 09:39:23 -04:00
debug_counter.c
debug_counter.h Use real filename instead of __FILE__ 2024-06-02 22:12:05 +09:00
dir.c [Bug #21128] Include fcntl.h before checking for O_CLOEXEC 2025-02-17 13:05:18 +09:00
dir.rb [DOC] Exclude 'Class' and 'Module' from RDoc's autolinking 2025-01-02 12:36:06 +09:00
dln.c Avoid dangling pointer on cygwin 2024-10-25 20:52:32 +09:00
dln.h Revert all changes to dln.c, dmydln.c, dln.h for the shared GC 2024-07-10 14:28:10 -04:00
dln_find.c Make dln_warning a variadic macro 2024-04-07 16:44:42 +09:00
dmydln.c Revert all changes to dln.c, dmydln.c, dln.h for the shared GC 2024-07-10 14:28:10 -04:00
dmyenc.c Separate miniruby from dmyext.c 2024-02-21 23:37:20 +09:00
dmyext.c Separate miniruby from dmyext.c 2024-02-21 23:37:20 +09:00
encindex.h
encoding.c string.c: Directly create strings with the correct encoding 2024-11-13 13:32:32 +01:00
enum.c [DOC] Fix grep_v description 2025-01-31 15:41:56 +09:00
enumerator.c Remove write barrier for non-Ruby object 2024-09-23 15:51:16 -04:00
error.c [DOC] Improve Errno and SystemCallError.new 2025-01-31 21:30:07 +09:00
eval.c [Feature #21116] Extract RJIT as a third-party gem 2025-02-13 18:01:03 +09:00
eval_error.c Do not include a backtick in error messages and backtraces 2024-02-15 18:42:31 +09:00
eval_intern.h [Bug #21127] Thread deadlock does not display backtraces (#12721) 2025-02-14 16:31:58 +09:00
eval_jump.c With ASAN EC_REPUSH_TAG doesn't work 2024-06-24 16:50:09 +09:00
file.c [Feature #20971] Deprecate rb_path_check 2025-03-13 18:43:48 +09:00
gc.c Re-use objspace variable instead of calling rb_gc_get_objspace() 2025-03-26 09:35:51 -04:00
gc.rb [DOC] Fix description comment typo 2025-02-13 08:53:02 +09:00
gem_prelude.rb
golf_prelude.rb
goruby.c Initialize goruby only when executing 2024-09-08 23:40:18 +09:00
GPL
hash.c [DOC] Doc for Hash#transform_keys! (#12942) 2025-03-25 15:26:51 -04:00
hash.rb [DOC] Tweaks for Hash.new 2025-01-24 10:44:24 -05:00
hrtime.h use of stdckdint.h 2024-04-27 21:55:28 +09:00
id_table.c Replace assert with RUBY_ASSERT in id_table.c 2024-02-12 15:07:47 -05:00
id_table.h
imemo.c Only mark cc->cme_ on valid imemo_callcache 2025-03-16 16:00:08 -04:00
inits.c [Feature #21116] Extract RJIT as a third-party gem 2025-02-13 18:01:03 +09:00
insns.def Adjust style [ci skip] 2025-03-18 16:22:34 +09:00
internal.h [Feature #20265] Remove rb_newobj_of and RB_NEWOBJ_OF 2024-03-14 12:53:04 -04:00
io.c Freeze $/ and make it ractor safe 2025-03-27 17:54:56 +01:00
io.rb
io_buffer.c [Bug #20933] Fix IO::Buffer overlap calculation 2024-12-09 11:52:02 -05:00
iseq.c Avoid pinning storage_head in iseq_mark_and_move (#12880) 2025-03-17 10:42:48 -04:00
iseq.h Avoid pinning storage_head in iseq_mark_and_move (#12880) 2025-03-17 10:42:48 -04:00
kernel.rb Move Kernel#with_yjit to Module#with_yjit 2024-11-27 09:04:07 -08:00
KNOWNBUGS.rb
LEGAL Use release version of turbo_tests 2025-03-26 19:37:22 +09:00
lex.c.blt Use gperf 3.1 to generate ANSI-C code 2024-06-24 23:43:45 +09:00
load.c Add a document to autoload 2025-03-13 22:08:01 +09:00
loadpath.c
localeinit.c
main.c Make wrapper of main for wasm more generic 2025-03-16 17:33:58 +09:00
marshal.c Manage skipping instance variable IDs in one place 2025-03-17 23:42:16 +09:00
marshal.rb
math.c
memory_view.c Refactor VM root modules 2024-03-06 15:33:43 -05:00
method.h Use atomic for method reference count [Bug #20934] 2025-03-20 13:09:40 -07:00
mini_builtin.c Fix memory leak in prism when syntax error in iseq compilation 2024-11-08 15:43:41 -05:00
miniinit.c Gather code for builtin loading to miniinit.c 2024-09-08 23:16:46 +09:00
NEWS.md Avoid array allocation for *nil, by not calling nil.to_a 2025-03-27 11:17:40 -07:00
nilclass.rb
node.c Add rb_node_get_type for debuggers 2025-01-09 19:24:27 +09:00
node.h Make node line macros inline functions 2025-01-30 18:19:53 +09:00
node_dump.c Implement CLASS NODE locations 2025-03-08 18:26:40 +09:00
numeric.c [DOC] Fix indentation 2025-02-27 13:00:34 +09:00
numeric.rb Fix the method name in a comment [ci skip] 2024-11-14 09:24:00 +09:00
object.c [Bug #21163] Fix hexadecimal float conversion 2025-03-07 12:14:48 +09:00
pack.c Expand buffer at once then fill it at once 2024-09-29 18:55:15 +09:00
pack.rb [DOC] Mention block mode of String#unpack 2024-09-29 19:09:59 +09:00
parse.y [Bug #21026] no singleton method on pseudo variable literal 2025-03-20 17:32:26 +09:00
parser_bits.h
parser_node.h
parser_st.c Fix extra semicolon outside of a function in NO_SANITIZE 2024-10-08 23:29:49 +09:00
parser_st.h
parser_value.h
prelude.rb Allow arguments to be passed through Binding#irb (#12796) 2025-03-18 02:19:43 +09:00
prism_compile.c Handle void expressions in defined? 2025-03-18 14:44:28 -04:00
prism_compile.h [PRISM] Handle forwarding inside eval 2025-01-14 18:41:50 -05:00
prism_init.c
probes.d
probes_helper.h
proc.c Fix enums in comparisons 2025-03-16 12:27:56 +09:00
process.c [Feature #21116] Extract RJIT as a third-party gem 2025-02-13 18:01:03 +09:00
ractor.c Ractor.make_shareable(proc_obj) makes inner structure shareable 2025-03-26 16:05:02 -07:00
ractor.rb [DOC] Exclude 'Class' and 'Module' from RDoc's autolinking 2025-01-02 12:36:06 +09:00
ractor_core.h Ractor.set_if_absent(key) 2024-12-13 06:22:13 +09:00
random.c Remove a useless condition expression 2024-11-30 00:03:07 +09:00
range.c [DOC] beginless and endless ranges inspect returns "nil..nil" always 2025-03-21 10:30:40 +09:00
rational.c [DOC] Exclude 'Method' from RDoc's autolinking 2025-01-02 12:23:49 +09:00
re.c Fix memory leak in rb_reg_search_set_match 2025-03-11 21:55:03 -04:00
README.EXT
README.EXT.ja
README.ja.md [Feature #21116] Extract RJIT as a third-party gem 2025-02-13 18:01:03 +09:00
README.md [Feature #21116] Extract RJIT as a third-party gem 2025-02-13 18:01:03 +09:00
regcomp.c Fix [Bug #20246]: Don't set next_head_exact if a capture is called (#9897) 2024-02-13 09:53:03 +09:00
regenc.c [Bug #20239] Fix overflow at down-casting 2024-02-07 15:14:26 +09:00
regenc.h
regerror.c
regexec.c Fix regex timeout double-free after stack_double 2024-11-11 23:33:21 -08:00
regint.h Fix memory leak in String#start_with? when regexp times out 2024-07-26 08:42:38 -04:00
regparse.c Do not break within certain combinations with Indic_Conjunct_Break (InCB)=Linker. 2025-03-18 21:18:12 +09:00
regparse.h
regsyntax.c
ruby-runner.c Do not overwrite GEM_PATH if already set 2025-02-10 18:04:25 +09:00
ruby.c Freeze $/ and make it ractor safe 2025-03-27 17:54:56 +01:00
ruby_assert.h
ruby_atomic.h
ruby_parser.c Remove rb_enc_associate for Parser 2025-02-15 15:37:09 +09:00
rubyparser.h Implement CLASS NODE locations 2025-03-08 18:26:40 +09:00
rubystub.c
scheduler.c Prefer 0.000001 over 0.000001f for timeout calculations. (#12803) 2025-02-25 16:37:21 +13:00
shape.c [DOC] Hide RubyVM::Shape that is for debug from RDoc totally 2024-12-24 21:31:52 +09:00
shape.h Rename size_pool -> heap 2024-10-03 21:20:09 +01:00
signal.c Use rb_gc_enable/rb_gc_disable_no_rest instead of ruby_disable_gc 2024-12-05 16:21:37 -05:00
siphash.c
siphash.h
sparc.c
sprintf.c Fix benign off-by-one 2024-11-08 17:39:19 -08:00
st.c Replace tombstone when converting AR to ST hash 2025-03-05 14:05:24 -08:00
strftime.c Remove unused or wrong conversions 2024-10-20 19:33:21 +09:00
string.c Freeze $/ and make it ractor safe 2025-03-27 17:54:56 +01:00
string.rb [DOC] Exclude 'Class' and 'Module' from RDoc's autolinking 2025-01-02 12:36:06 +09:00
struct.c [DOC] Show NONE within Measure namespace (#12274) 2025-01-09 13:53:49 +09:00
symbol.c Move global symbol reference updating to rb_sym_global_symbols_update_references 2025-02-10 08:47:44 -05:00
symbol.h Use dllexport as RUBY_FUNC_EXPORTED on Windows 2024-06-09 16:55:27 +09:00
symbol.rb Move Symbol#name into symbol.rb 2024-11-13 10:29:07 +01:00
thread.c Reset thread interrupt lock on fork 2025-03-25 19:14:26 -07:00
thread_none.c Add an environment variable for controlling the default Thread quantum 2024-12-12 16:04:49 -08:00
thread_none.h
thread_pthread.c Clear VM_CHECK lock info on fork 2025-03-25 19:14:26 -07:00
thread_pthread.h Use no-inline version rb_current_ec on Arm64 2025-01-17 22:48:10 +09:00
thread_pthread_mn.c [Bug #21150] macOS: Temporary workaround at unwinding coroutine 2025-02-21 17:53:16 +09:00
thread_sync.c Ensure fiber scheduler re-acquires mutex when interrupted from sleep. (#12158) 2024-11-23 23:54:12 +00:00
thread_sync.rb
thread_win32.c Proof of Concept: Allow to prevent fork from happening in known fork unsafe API 2024-09-05 11:43:46 +02:00
thread_win32.h
time.c [Bug #21141] [DOC] Fix indentation 2025-03-24 15:49:41 +09:00
timev.h
timev.rb [doc] update Time document. 2025-02-23 10:37:36 +09:00
trace_point.rb [DOC] Fix grammar errors, typos, and improve readability of trace_point.rb (#12150) 2024-12-12 16:44:15 -05:00
transcode.c Fix constant documents (#12357) 2024-12-17 11:58:00 +09:00
transcode_data.h
universal_parser.c Remove rb_enc_associate for Parser 2025-02-15 15:37:09 +09:00
util.c Fix double free when getcwd does not allocate buffer 2024-07-17 15:16:21 +09:00
variable.c Trigger inherited and const_set callbacks after const has been defined 2025-03-20 18:18:11 +01:00
variable.h Free everything at shutdown 2023-12-07 15:52:35 -05:00
vcpkg.json Revert "Temporary removed gmp because vcpkg package is broken." 2025-02-17 18:08:37 +09:00
version.c [Feature #21116] Extract RJIT as a third-party gem 2025-02-13 18:01:03 +09:00
version.h
vm.c Ractor.make_shareable(proc_obj) makes inner structure shareable 2025-03-26 16:05:02 -07:00
vm_args.c FCALL shouldn't be forwarded from caller 2025-03-21 12:25:02 -07:00
vm_backtrace.c [Bug #21127] Thread deadlock does not display backtraces (#12721) 2025-02-14 16:31:58 +09:00
vm_callinfo.h Remove dead vm_cc_valid_p 2025-01-24 11:07:20 -05:00
vm_core.h reject numbered parameters from Binding#local_variables 2025-02-18 16:23:24 +09:00
vm_debug.h Add ruby_debug_print functions to vm_debug.h 2024-01-06 09:32:45 +09:00
vm_dump.c [Bug #21150] macOS: Temporary workaround at unwinding coroutine 2025-02-21 17:53:16 +09:00
vm_eval.c reject numbered parameters from Binding#local_variables 2025-02-18 16:23:24 +09:00
vm_exec.c Only count VM instructions in YJIT stats builds 2025-02-14 14:39:35 -05:00
vm_exec.h Use UNDEF_P 2024-01-30 14:48:59 +09:00
vm_insnhelper.c Avoid array allocation for *nil, by not calling nil.to_a 2025-03-27 11:17:40 -07:00
vm_insnhelper.h Only count VM instructions in YJIT stats builds 2025-02-14 14:39:35 -05:00
vm_method.c Use atomic for method reference count [Bug #20934] 2025-03-20 13:09:40 -07:00
vm_opts.h Implement chilled strings 2024-03-19 09:26:49 +01:00
vm_sync.c VM barrier needs to store GC root 2024-07-05 21:20:54 +09:00
vm_sync.h specify NOINLINE for LTO 2024-11-08 18:02:46 +09:00
vm_trace.c [Feature #21116] Extract RJIT as a third-party gem 2025-02-13 18:01:03 +09:00
vsnprintf.c Use free with ruby_dtoa 2023-12-07 09:23:02 -08:00
warning.rb Kernel#warn: don't call Warning.warn unless the category is enabled 2024-06-12 20:57:31 +02:00
weakmap.c Fix a typo in WeakKeyMap argument error 2025-02-04 22:25:17 +01:00
yjit.c Allow YJIT mem-size and call-threshold to be set at runtime via YJIT.enable() (#12505) 2025-03-03 15:45:39 -05:00
yjit.h Fix false-positive memory leak using Valgrind in YJIT (#12057) 2024-11-11 20:45:11 +00:00
yjit.rb yjit.rb: Fix parameter name in documentation 2025-03-05 10:19:31 -05:00
yjit_hook.rb Move Kernel#with_yjit to Module#with_yjit 2024-11-27 09:04:07 -08:00

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What is Ruby?

Ruby is an interpreted object-oriented programming language often used for web development. It also offers many scripting features to process plain text and serialized files, or manage system tasks. It is simple, straightforward, and extensible.

Features of Ruby

  • Simple Syntax
  • Normal Object-oriented Features (e.g. class, method calls)
  • Advanced Object-oriented Features (e.g. mix-in, singleton-method)
  • Operator Overloading
  • Exception Handling
  • Iterators and Closures
  • Garbage Collection
  • Dynamic Loading of Object Files (on some architectures)
  • Highly Portable (works on many Unix-like/POSIX compatible platforms as well as Windows, macOS, etc.) cf. https://docs.ruby-lang.org/en/master/maintainers_md.html#label-Platform+Maintainers

How to get Ruby

For a complete list of ways to install Ruby, including using third-party tools like rvm, see:

https://www.ruby-lang.org/en/downloads/

You can download release packages and the snapshot of the repository. If you want to download whole versions of Ruby, please visit https://www.ruby-lang.org/en/downloads/releases/.

Download with Git

The mirror of the Ruby source tree can be checked out with the following command:

$ git clone https://github.com/ruby/ruby.git

There are some other branches under development. Try the following command to see the list of branches:

$ git ls-remote https://github.com/ruby/ruby.git

You may also want to use https://git.ruby-lang.org/ruby.git (actual master of Ruby source) if you are a committer.

How to build

See Building Ruby

Ruby home page

https://www.ruby-lang.org/

Documentation

Mailing list

There is a mailing list to discuss Ruby. To subscribe to this list, please send the following phrase:

join

in the mail subject (not body) to the address ruby-talk-request@ml.ruby-lang.org.

Copying

See the file COPYING.

Feedback

Questions about the Ruby language can be asked on the Ruby-Talk mailing list or on websites like https://stackoverflow.com.

Bugs should be reported at https://bugs.ruby-lang.org. Read "Reporting Issues" for more information.

Contributing

See "Contributing to Ruby", which includes setup and build instructions.

The Author

Ruby was originally designed and developed by Yukihiro Matsumoto (Matz) in 1995.

matz@ruby-lang.org