February 2024 - ruby-core - ml.ruby-lang.org

[ruby-core:116938] [Ruby master Feature#20298] Introduce `Time()` type-cast / constructor.
by ioquatix (Samuel Williams) 12 Mar '24

12 Mar '24

Issue #20298 has been reported by ioquatix (Samuel Williams). ---------------------------------------- Feature #20298: Introduce `Time()` type-cast / constructor. https://bugs.ruby-lang.org/issues/20298 * Author: ioquatix (Samuel Williams) * Status: Open ---------------------------------------- Many Ruby primitive types have constructors, e.g. `Integer(...)`, `String(...)`, `Float(...)`, etc. These usually convert from some subset of types, e.g. `Float(1) -> 1.0` will convert an Integer to a Float, and `Float("1") -> 1.0` will parse a String to a Float, and similar for other type casts/constructors. I'd like to propose we introduce something similar for `Time` (and possibly this extends to `Date`/`DateTime` in a follow up proposal). Suggested implementation could look something like this: ```ruby def Time(value) case value when Time value when Integer Time.at(value) when String Time.parse(value) else value.to_time end end ``` Alternatively, we might like to be a little more specific with the `else` clause/error handling. ## Background In a project, I need to support multiple serialization formats/coders, including MessagePack, Marshal and JSON. While Marshal and MessagePack are capable of serializing `Time` instances, `JSON` is not. The code looks a bit like this: ``` data = fetch_job_data job = @coder.load(data) scheduled_at = Time(job[:scheduled_at]) # Hypothetical type-cast as outlined above ``` ## Additional Observations While some primitive data types accept themselves as arguments and construct by copy, e.g. `Array.new(Array.new)`, others do not, e.g. `Hash` and `Time`. Perhaps `Time.new(Time.new)` should behave similarly to `Array.new(Array.new)` - the outer instance is a copy of the inner. -- https://bugs.ruby-lang.org/

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[ruby-core:116939] [Ruby master Bug#20299] Tracepoint staying enable after a disable
by MaxLap (Maxime Lapointe) 12 Mar '24

12 Mar '24

Issue #20299 has been reported by MaxLap (Maxime Lapointe). ---------------------------------------- Bug #20299: Tracepoint staying enable after a disable https://bugs.ruby-lang.org/issues/20299 * Author: MaxLap (Maxime Lapointe) * Status: Open * ruby -v: 3.3.0 * Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- Problem is present in Ruby 3.2.2, 3.2.3, 3.3.0. Didn't check before. It seems that TracePoint can sometime be "stuck" enabled after using disabled once on it. Here is a reproduction step using a "check speed" method that just does some work and print out how long it takes. This makes it pretty clear when TracePoint was on. Put this in a Ruby file: ``` def check_speed(msg) t1 = Time.now.to_f a = 0 1000000.times { |i| a += 10 } t2 = Time.now.to_f puts "#{t2-t1} - #{msg}" end check_speed("before") # fast trace = TracePoint.new(:line) {} trace.enable check_speed("after enable") # slow trace.enable { check_speed("in block enable") # slow } check_speed("after block enable") # slow trace.disable check_speed("after disable") # slow !!!! trace.disable check_speed("after disable again") # fast !!!! # And yet, using enable multiple time doesn't have a "counter" or similar trace.enable trace.enable trace.enable check_speed("after triple enable") # slow trace.disable check_speed("after single disable") # fast ``` Running the file, we get this: ``` $ ruby -v ruby 3.3.0 (2023-12-25 revision 5124f9ac75) [x86_64-linux] $ ruby local.rb 0.03473854064941406 - before 0.18935227394104004 - after enable 0.17757630348205566 - in block enable 0.18320131301879883 - after block enable 0.1818866729736328 - after disable 0.03412747383117676 - after disable again 0.18405628204345703 - after triple enable 0.033496856689453125 - after single disable ``` The first "after disable" should probably have been fast. If it's possible to have multiple nested enable/disable, then one would instead assume that after the last "single disable", things would still be slow. Note: This code patterns comes directly for a ruby/spec: ctrl+f for "enables trace object on calling with a block if it was already enabled" I note that in Ruby 3.2, the timing are a lot less similar. I don't know why. It would seem like TracePoint got slower in Ruby 3.3.0. Is that worth checking out / making a distincct bug for? ``` $ rvm use 3.2.3 Using /home/max/.rvm/gems/ruby-3.2.3 $ ruby local.rb 0.03246927261352539 - before 0.07910513877868652 - after enable 0.10309600830078125 - in block enable 0.12397646903991699 - after block enable 0.07114601135253906 - after disable 0.028218746185302734 - after disable again 0.12534689903259277 - after triple enable 0.02810525894165039 - after single disable ``` -- https://bugs.ruby-lang.org/

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[ruby-core:113966] [Ruby master Bug#19742] Introduce `Module#anonymous?`
by ioquatix (Samuel Williams) 12 Mar '24

12 Mar '24

Issue #19742 has been reported by ioquatix (Samuel Williams). ---------------------------------------- Bug #19742: Introduce `Module#anonymous?` https://bugs.ruby-lang.org/issues/19742 * Author: ioquatix (Samuel Williams) * Status: Open * Priority: Normal * Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN ---------------------------------------- As a follow-on <from https://bugs.ruby-lang.org/issues/19521>, I'd like propose we introduce `Module#anonymous?`. In some situations, like logging/formatting, serialisation/deserialization, debugging or meta-programming, we might like to know if a class is a proper constant or not. However, this brings about some other issues which might need to be discussed. After assigning a constant, then removing it, the internal state of Ruby still believes that the class name is permanent, even thought it's no longer true. e.g. ``` m = Module.new m.anonymous? # true M = m m.anonyomous # false Object.send(:remove_const, :M) M # uninitialized constant M (NameError) M.anonymous? # false ``` Because RCLASS data structure is not updated after the constant is removed, internally the state still has a "permanent class name". I want to use this proposal to discuss this issue and whether there is anything we should do about such behaviour (or even if it's desirable). Proposed PR: https://github.com/ruby/ruby/pull/7966 cc @fxn -- https://bugs.ruby-lang.org/

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[ruby-core:116829] [Ruby master Bug#20277] Remove stale `String` test conditionals
by nobu (Nobuyoshi Nakada) 12 Mar '24

12 Mar '24

Issue #20277 has been reported by nobu (Nobuyoshi Nakada). ---------------------------------------- Bug #20277: Remove stale `String` test conditionals https://bugs.ruby-lang.org/issues/20277 * Author: nobu (Nobuyoshi Nakada) * Status: Open * Priority: Normal * Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- I found three instance variables in `TestString`. These select assertions: + `@aref_re_nth = true` Enables `String#[regexp, index]` assertions. + `@aref_re_silent = false` Assignment to unmatched region silently fails, if true. + `@aref_slicebang_silent = true` Out of range argument to `String#slice!` returns `nil`, not raising an exception. These instance variables for conditional execution have remained unchanged for nearly twenty years, since YARV merger. It is questionable whether these behaviors can be changed anymore. So I propose to remove these conditionals. -- https://bugs.ruby-lang.org/

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[ruby-core:115925] [Ruby master Bug#20096] Ruby 3.2.2 win32/registry: Junk appended to Windows Registry String Value
by jay4rubydev (Jay M) 07 Mar '24

07 Mar '24

Issue #20096 has been reported by jay4rubydev (Jay M). ---------------------------------------- Bug #20096: Ruby 3.2.2 win32/registry: Junk appended to Windows Registry String Value https://bugs.ruby-lang.org/issues/20096 * Author: jay4rubydev (Jay M) * Status: Open * Priority: Normal * ruby -v: ruby 3.2.2 (2023-03-30 revision e51014f9c0) [x64-mswin64_140] * Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- Ruby Version: ruby 3.2.2 (2023-03-30 revision e51014f9c0) [x64-mswin64_140] Compiler: MSVC 2019 - Microsoft (R) C/C++ Optimizing Compiler Version 19.29.30147 for x64. Issue: win32/registry adds junk to Windows Registry String Value Code: require 'win32/registry' win_oracle_key = "SOFTWARE\\MicroSoft" reg=Win32::Registry::HKEY_LOCAL_MACHINE.open(win_oracle_key, Win32::Registry::KEY_ALL_ACCESS) inst_loc_key = "inst_loc" inv_dir="C:\\Program Files\\Tester\\ModuleInfo" reg[inst_loc_key] = inv_dir Result: Registry contains: C:\Program Files\Tester\ModuleInfo爀 Observation: Looks like memory overread Expected Result - without the junk: C:\Program Files\Tester\ModuleInfo After changing the code in registry.rb: From: def write(name, type, data) termsize = 0 case type when REG_SZ, REG_EXPAND_SZ data = data.encode(WCHAR) termsize = WCHAR_SIZE To: def write(name, type, data) termsize = 0 case type when REG_SZ, REG_EXPAND_SZ enc_data = data.encode(WCHAR) # Add NULL WCHAR for string data and don't set the termsize because # enc_data.bytesize will now include the size of the NULL character. enc_data += WCHAR_NUL # termsize = WCHAR_SIZE ... -- https://bugs.ruby-lang.org/

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[ruby-core:116542] [Ruby master Misc#20232] Document Kernel#require and Module#autoload concurrency guarantees
by fxn (Xavier Noria) 04 Mar '24

04 Mar '24

Issue #20232 has been reported by fxn (Xavier Noria). ---------------------------------------- Misc #20232: Document Kernel#require and Module#autoload concurrency guarantees https://bugs.ruby-lang.org/issues/20232 * Author: fxn (Xavier Noria) * Status: Open * Priority: Normal ---------------------------------------- I'd like to document `Kernel#require` and `Module#autoload` concurrency guarantees. In the case of multiple threads loading the same file concurrently, `Kernel#require` will succeed in just one of them and the rest will wait and return false. If a constant that has an autoload is concurrently referenced, the same can be said. Assuming no errors, only one thread will succeed, and the rest wait. There will be no context switching in the middle of an autoload that will result in a `NameError` in other threads waiting for that constant. Now, I'd like to have a discussion about those guarantees with fibers. In the case of manually managed fibers, users can enter a deadlock by hand: ```ruby # This produces a deadlock. File.write('/tmp/bar.rb', <<~RUBY) Fiber.yield RUBY Fiber.new { require '/tmp/bar.rb' }.resume Fiber.new { require '/tmp/bar.rb' }.resume ``` If this is expected, I guess users should be told this is a possibility in the API dosc? Because from a user perspective, you don't really have elements to anticipate a deadlock there if the docs don't warn you. A similar deadlock can be triggered with an `autoload` instead of a `require`: ```ruby # This produces a deadlock. File.write('/tmp/bar.rb', <<~RUBY) Fiber.yield Bar = 1 RUBY autoload :Bar, '/tmp/bar.rb' Fiber.new { Bar }.resume Fiber.new { Bar }.resume ``` A different matter is fibers managed by fiber schedulers. I have not been able to enter a deadlock with the fiber schedulers I have tried, but from the point of view of the user, doing something like I/O or sleeping at the top-level is not unlike that manual `Fiber.yield` above. The contract for fiber schedulers is mostly an interface, but it does not address this, at least in an explicit way. Do fiber schedulers guarantee anything about this with the current contract? I'd be glad to volunteer docs with the conclusions of this thread. -- https://bugs.ruby-lang.org/

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[ruby-core:115892] [Ruby master Bug#20085] Fiber.new{ }.resume causes Segmentation fault for Ruby 3.3.0 on aarch64-linux
by oleksii (Oleksii Leonov) 29 Feb '24

29 Feb '24

Issue #20085 has been reported by oleksii (Oleksii Leonov). ---------------------------------------- Bug #20085: Fiber.new{ }.resume causes Segmentation fault for Ruby 3.3.0 on aarch64-linux https://bugs.ruby-lang.org/issues/20085 * Author: oleksii (Oleksii Leonov) * Status: Open * Priority: Normal * ruby -v: ruby 3.3.0 (2023-12-25 revision 5124f9ac75) [aarch64-linux] * Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- ``` ruby -e "Fiber.new{}.resume" 0.170 -e:1: [BUG] Segmentation fault at 0x0036ffffb4f110f0 0.170 ruby 3.3.0 (2023-12-25 revision 5124f9ac75) [aarch64-linux] 0.170 0.170 -- Control frame information ----------------------------------------------- 0.170 c:0003 p:---- s:0010 e:000009 CFUNC :resume 0.170 c:0002 p:0007 s:0006 E:0005e0 EVAL -e:1 [FINISH] 0.170 c:0001 p:0000 s:0003 E:000b50 DUMMY [FINISH] 0.170 0.170 -- Ruby level backtrace information ---------------------------------------- 0.170 -e:1:in `<main>' 0.170 -e:1:in `resume' 0.170 0.170 -- Threading information --------------------------------------------------- 0.170 Total ractor count: 1 0.170 Ruby thread count for this ractor: 1 0.170 0.170 -- Machine register context ------------------------------------------------ 0.170 x0: 0x0000aaab11b4f570 x1: 0x0000aaab11de4a40 x2: 0x0000ffffe5571990 0.170 x3: 0x0000ffff9ac5ff60 x4: 0x0000ffff9ac60018 x5: 0x0000ffff9ac80000 0.170 x6: 0x0000ffffb5458b88 x7: 0x0000000000000000 x18: 0x00000000007fffff 0.170 x19: 0x0000000000000000 x20: 0x0000000000000000 x21: 0x0000000000000000 0.170 x22: 0x0000000000000000 x23: 0x0000000000000000 x24: 0x0000000000000000 0.170 x25: 0x0000000000000000 x26: 0x0000000000000000 x27: 0x0000000000000000 0.170 x28: 0x0000000000000000 x29: 0x0000000000000000 sp: 0x0000ffff9ac60000 0.170 fau: 0x0036ffffb4f110f0 0.170 0.170 -- C level backtrace information ------------------------------------------- 0.171 Segmentation fault ``` - Ruby 3.3.0-rc1 and 3.2.2 work without Segmentation fault on both amd64 and arm64. - Ruby 3.3.0 works on amd64, but fails with Segmentation fault on arm64 (aarch64-linux) on Ubuntu 22.04 and Debian Bookworm. Dockerfile to reproduce: ``` FROM debian:bookworm # Set UTF-8 locale by default. ENV RBENV_ROOT=/usr/local/rbenv \ PATH=/usr/local/rbenv/bin:/usr/local/rbenv/shims:$PATH RUN ( \ export DEBIAN_FRONTEND=noninteractive \ && apt-get update \ && apt-get install -y --no-install-recommends \ ca-certificates curl git \ # standard dependencies for rbenv autoconf \ patch \ build-essential \ rustc \ libssl-dev \ libyaml-dev \ libreadline6-dev \ zlib1g-dev \ libgmp-dev \ libncurses5-dev \ libffi-dev \ libgdbm6 \ libgdbm-dev \ libdb-dev \ uuid-dev \ ) ENV RBENV_VERSION=3.3.0 RUN ( \ export DEBIAN_FRONTEND=noninteractive \ # Install rbenv & ruby-build && git clone https://github.com/rbenv/rbenv.git /usr/local/rbenv \ && git clone https://github.com/rbenv/ruby-build.git /usr/local/rbenv/plugins/ruby-build \ && /usr/local/rbenv/plugins/ruby-build/install.sh \ && echo 'export RBENV_ROOT=/usr/local/rbenv' >> /etc/profile.d/rbenv.sh \ && echo 'export PATH=/usr/local/rbenv/bin:$PATH' >> /etc/profile.d/rbenv.sh \ && echo 'eval "$(rbenv init -)"' >> /etc/profile.d/rbenv.sh \ && echo 'export RBENV_ROOT=/usr/local/rbenv' >> /root/.bashrc \ && echo 'export PATH=/usr/local/rbenv/bin:$PATH' >> /root/.bashrc \ && echo 'eval "$(rbenv init -)"' >> /root/.bashrc \ && eval "$(rbenv init -)"; rbenv install $RBENV_VERSION \ && eval "$(rbenv init -)"; rbenv global $RBENV_VERSION \ ) RUN RUN ruby -e "Fiber.new{}.resume" ``` `docker build --platform linux/arm64 .` ---Files-------------------------------- Dockerfile (1.53 KB) -- https://bugs.ruby-lang.org/

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[ruby-core:117014] [Ruby master Bug#20316] Regexp quantifier behavior changes in different syntactic context.
by jirkamarsik (Jirka Marsik) 29 Feb '24

29 Feb '24

Issue #20316 has been reported by jirkamarsik (Jirka Marsik). ---------------------------------------- Bug #20316: Regexp quantifier behavior changes in different syntactic context. https://bugs.ruby-lang.org/issues/20316 * Author: jirkamarsik (Jirka Marsik) * Status: Open * ruby -v: ruby 3.1.2p20 (2022-04-12 revision 4491bb740a) [x86_64-linux-gnu] * Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- In the example below, adding a vertical bar to the end of a regular expression changes what is being matched by the preceding regular expression. ``` irb(main):001:0> /(|a){3}b/.match("aab") => #<MatchData "aab" 1:""> irb(main):002:0> /(|a){3}b|/.match("aab") => #<MatchData "aab" 1:"a"> ``` This is because the `{3}` quantifier is compiled into a `repeat` loop which uses the `OP_NULL_CHECK_END_MEMST` operation to perform a capture-group sensitive null-check after every loop iteration. The logic behind the `OP_NULL_CHECK_END_MEMST` operation is implemented using the `STACK_NULL_CHECK_MEMST` macro in `regexec.c`. The `STACK_NULL_CHECK_MEMST` macro checks whether any capture groups have been updated inside the last loop iteration and it does so by searching the stack for `STK_MEM_START` entries. However, such entries are not used for all capture groups. They are only used by capture groups which are listed in `bt_mem_start`. A capture group is marked as needing such bookkeeping only when it is either referenced by a back-reference or it appears in certain syntactic contexts (see e.g. around line 4096 of `regcomp.c`). This looks like an optimization that tries to avoid polluting the stack with `STK_MEM_START` entries in cases in which they are not needed. However, in this case, not putting `STK_MEM_START` entries on the stack leads to a different match result. In the example above, by adding a vertical bar to the end of the regexp, we have placed the group `(|a)` inside an alternation. This means that a different operation for tracking the state of the capture group is emitted in the compiled bytecode and this leads to a different result. Incidentally, this result should be the correct result, as the null-check ends up respecting the state of capture groups, as it tries to do in Ruby. This is the compilation and execution of `/(|a){3}b/.match("aab")` with ONIG_DEBUG_PARSE_TREE, ONIG_DEBUG_COMPILE and ONIG_DEBUG_MATCH. Note that `mem-start:1` is used for tracking the state of capture group 1. ``` PATTERN: /(|a){3}b/ (US-ASCII) <list:55db929991f0> <quantifier:55db92999230>{3,3} <enclose:55db92999330> memory:1 <alt:55db929991b0> <string:55db929992f0> <string:55db929992b0>a <string:55db929993b0>b optimize: EXACT anchor: [] sub anchor: [] exact: [b]: length: 1 code length: 37 0:[repeat:0:27] 7:[null-check-start:0] 10:[mem-start:1] 13:[push:(+5)] 18:[jump:(+2)] 23:[exact1:a] 25:[mem-end:1] 28:[null-check-end-memst:0] 31:[repeat-inc:0] 34:[exact1:b] 36:[end] match_at: str: 139809364021904 (0x7f27e77a9290), end: 139809364021906 (0x7f27e77a9292), start: 139809364021904 (0x7f27e77a9290), sprev: 0 ((nil)) size: 2, start offset: 0 ofs> str stk:type addr:opcode 0> "ab" 0:Alt 0:[repeat:0:27] 0> "ab" 1:Rep 7:[null-check-start:0] 0> "ab" 2:NulChS 10:[mem-start:1] 0> "ab" 2:NulChS 13:[push:(+5)] 0> "ab" 3:Alt 18:[jump:(+2)] 0> "ab" 3:Alt 25:[mem-end:1] 0> "ab" 3:Alt 28:[null-check-end-memst:0] NULL_CHECK_END_MEMST: skip id:0, s:139809364021904 (0x7f27e77a9290) 0> "ab" 3:Alt 34:[exact1:b] 0> "ab" 2:NulChS 23:[exact1:a] 1> "b" 2:NulChS 25:[mem-end:1] 1> "b" 2:NulChS 28:[null-check-end-memst:0] 1> "b" 2:NulChS 31:[repeat-inc:0] 1> "b" 3:RepInc 7:[null-check-start:0] 1> "b" 4:NulChS 10:[mem-start:1] 1> "b" 4:NulChS 13:[push:(+5)] 1> "b" 5:Alt 18:[jump:(+2)] 1> "b" 5:Alt 25:[mem-end:1] 1> "b" 5:Alt 28:[null-check-end-memst:0] NULL_CHECK_END_MEMST: skip id:0, s:139809364021905 (0x7f27e77a9291) 1> "b" 5:Alt 34:[exact1:b] 2> "" 5:Alt 36:[end] ``` This is the compilation and execution of `/(|a){3}b|/.match("aab")` (where the group `(|a)` appears inside an alternation) with ONIG_DEBUG_PARSE_TREE, ONIG_DEBUG_COMPILE and ONIG_DEBUG_MATCH. Note that `mem-start-push:1` is used for tracking the state of capture group 1, not `mem-start:1`. ``` PATTERN: /(|a){3}b|/ (US-ASCII) <alt:55d9a91cc3c0> <list:55d9a91cc200> <quantifier:55d9a91cc240>{3,3} <enclose:55d9a91cc340> memory:1 <alt:55d9a91cc1c0> <string:55d9a91cc300> <string:55d9a91cc2c0>a <string:55d9a91cc480>b <string:55d9a91cc400> optimize: NONE anchor: [] code length: 47 0:[push:(+41)] 5:[repeat:0:27] 12:[null-check-start:0] 15:[mem-start-push:1] 18:[push:(+5)] 23:[jump:(+2)] 28:[exact1:a] 30:[mem-end:1] 33:[null-check-end-memst:0] 36:[repeat-inc:0] 39:[exact1:b] 41:[jump:(+0)] 46:[end] match_at: str: 140072854131304 (0x7f6540b69268), end: 140072854131306 (0x7f6540b6926a), start: 140072854131304 (0x7f6540b69268), sprev: 0 ((nil)) size: 2, start offset: 0 ofs> str stk:type addr:opcode 0> "ab" 0:Alt 0:[push:(+41)] 0> "ab" 1:Alt 5:[repeat:0:27] 0> "ab" 2:Rep 12:[null-check-start:0] 0> "ab" 3:NulChS 15:[mem-start-push:1] 0> "ab" 4:MemS 18:[push:(+5)] 0> "ab" 5:Alt 23:[jump:(+2)] 0> "ab" 5:Alt 30:[mem-end:1] 0> "ab" 5:Alt 33:[null-check-end-memst:0] 0> "ab" 5:Alt 36:[repeat-inc:0] 0> "ab" 6:RepInc 12:[null-check-start:0] 0> "ab" 7:NulChS 15:[mem-start-push:1] 0> "ab" 8:MemS 18:[push:(+5)] 0> "ab" 9:Alt 23:[jump:(+2)] 0> "ab" 9:Alt 30:[mem-end:1] 0> "ab" 9:Alt 33:[null-check-end-memst:0] NULL_CHECK_END_MEMST: skip id:0, s:140072854131304 (0x7f6540b69268) 0> "ab" 9:Alt 39:[exact1:b] 0> "ab" 8:MemS 28:[exact1:a] 1> "b" 8:MemS 30:[mem-end:1] 1> "b" 8:MemS 33:[null-check-end-memst:0] 1> "b" 8:MemS 36:[repeat-inc:0] 1> "b" 9:RepInc 12:[null-check-start:0] 1> "b" 10:NulChS 15:[mem-start-push:1] 1> "b" 11:MemS 18:[push:(+5)] 1> "b" 12:Alt 23:[jump:(+2)] 1> "b" 12:Alt 30:[mem-end:1] 1> "b" 12:Alt 33:[null-check-end-memst:0] 1> "b" 12:Alt 36:[repeat-inc:0] 1> "b" 13:RepInc 39:[exact1:b] 2> "" 13:RepInc 41:[jump:(+0)] 2> "" 13:RepInc 46:[end] ``` -- https://bugs.ruby-lang.org/

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[ruby-core:117013] [Ruby master Bug#20315] Quantifier expansion leads to different results in Regexp.
by jirkamarsik (Jirka Marsik) 29 Feb '24

29 Feb '24

Issue #20315 has been reported by jirkamarsik (Jirka Marsik). ---------------------------------------- Bug #20315: Quantifier expansion leads to different results in Regexp. https://bugs.ruby-lang.org/issues/20315 * Author: jirkamarsik (Jirka Marsik) * Status: Open * ruby -v: ruby 3.1.2p20 (2022-04-12 revision 4491bb740a) [x86_64-linux-gnu] * Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- Consider the following series of regular expression matches: ``` irb(main):001:0> /(|a)(|a)(|a)(|a)(|a)b/.match("aaaab") => #<MatchData "aaaab" 1:"" 2:"a" 3:"a" 4:"a" 5:"a"> irb(main):002:0> /(|a)(|a)(|a)(|a)b/.match("aaab") => #<MatchData "aaab" 1:"" 2:"a" 3:"a" 4:"a"> irb(main):003:0> /(|a)(|a)(|a)b/.match("aab") => #<MatchData "aab" 1:"" 2:"a" 3:"a"> irb(main):004:0> /(|a)(|a)b/.match("ab") => #<MatchData "ab" 1:"" 2:"a"> ``` Let `X^{N}` mean `N` concatenated repetitions of `X`. When matching the pattern `/(|a)^{N}b/` against `a^{N-1}b`, the first group will match the empty string and the last `N-1` groups will match `a`. Now, let's look at this series of similar expressions, in which `(|a)^{N}` is replaced with `(|a){N}`, i.e. a counted quantifier. ``` irb(main):001:0> /(|a){5}b/.match("aaaab") => #<MatchData "aaaab" 1:""> irb(main):002:0> /(|a){4}b/.match("aaab") => #<MatchData "aaab" 1:""> irb(main):003:0> /(|a){3}b/.match("aab") => #<MatchData "aab" 1:""> irb(main):004:0> /(|a){2}b/.match("ab") => #<MatchData "ab" 1:"a"> ``` When matching the pattern `/(|a){N}b/` against `a^{N-1}b`, the first `N-1` iterations will match `a` and the `N`-th iteration will match the empty string (compare this with the behavior of the first series of expressions). However, something strange happens when `N` is 2. We end up getting a result which is not consistent with this series, but looks like a result that belongs to the first series discussed above. This is due to quantifier expansion done by the regexp compiler (see usages of `QUANTIFIER_EXPAND_LIMIT_SIZE` in `regcomp.c`). This is an optimization that tries to remove the overhead of managing a counted repetition during regex execution at the cost of increasing the size of the compiled regex bytecode. The source of the inconsistency is caused by the fact that this optimization can actually change the semantics of the regular expression, because as we have seen above, `X^{N}` (`X` repeated `N` times) can have different semantics from `X{N}` (a single `X` with an `{N}` quantifier). Compilation and execution of `/(|a){3}b/.match("aab")` with `ONIG_DEBUG_PARSE_TREE`, `ONIG_DEBUG_COMPILE` and `ONIG_DEBUG_MATCH`: ``` PATTERN: /(|a){3}b/ (US-ASCII) <list:556161bb11f0> <quantifier:556161bb1230>{3,3} <enclose:556161bb1330> memory:1 <alt:556161bb11b0> <string:556161bb12f0> <string:556161bb12b0>a <string:556161bb13b0>b optimize: EXACT anchor: [] sub anchor: [] exact: [b]: length: 1 code length: 37 0:[repeat:0:27] 7:[null-check-start:0] 10:[mem-start:1] 13:[push:(+5)] 18:[jump:(+2)] 23:[exact1:a] 25:[mem-end:1] 28:[null-check-end-memst:0] 31:[repeat-inc:0] 34:[exact1:b] 36:[end] match_at: str: 140607416406704 (0x7fe1b71b92b0), end: 140607416406706 (0x7fe1b71b92b2), start: 140607416406704 (0x7fe1b71b92b0), sprev: 0 ((nil)) size: 2, start offset: 0 ofs> str stk:type addr:opcode 0> "ab" 0:Alt 0:[repeat:0:27] 0> "ab" 1:Rep 7:[null-check-start:0] 0> "ab" 2:NulChS 10:[mem-start:1] 0> "ab" 2:NulChS 13:[push:(+5)] 0> "ab" 3:Alt 18:[jump:(+2)] 0> "ab" 3:Alt 25:[mem-end:1] 0> "ab" 3:Alt 28:[null-check-end-memst:0] NULL_CHECK_END_MEMST: skip id:0, s:140607416406704 (0x7fe1b71b92b0) 0> "ab" 3:Alt 34:[exact1:b] 0> "ab" 2:NulChS 23:[exact1:a] 1> "b" 2:NulChS 25:[mem-end:1] 1> "b" 2:NulChS 28:[null-check-end-memst:0] 1> "b" 2:NulChS 31:[repeat-inc:0] 1> "b" 3:RepInc 7:[null-check-start:0] 1> "b" 4:NulChS 10:[mem-start:1] 1> "b" 4:NulChS 13:[push:(+5)] 1> "b" 5:Alt 18:[jump:(+2)] 1> "b" 5:Alt 25:[mem-end:1] 1> "b" 5:Alt 28:[null-check-end-memst:0] NULL_CHECK_END_MEMST: skip id:0, s:140607416406705 (0x7fe1b71b92b1) 1> "b" 5:Alt 34:[exact1:b] 2> "" 5:Alt 36:[end] ``` Compilation and execution of `/(|a){2}b/.match("ab")` with `ONIG_DEBUG_PARSE_TREE`, `ONIG_DEBUG_COMPILE` and `ONIG_DEBUG_MATCH`: ``` PATTERN: /(|a){2}b/ (US-ASCII) <list:55bbc826c1f0> <quantifier:55bbc826c230>{2,2} <enclose:55bbc826c330> memory:1 <alt:55bbc826c1b0> <string:55bbc826c2f0> <string:55bbc826c2b0>a <string:55bbc826c3b0>b optimize: EXACT anchor: [] sub anchor: [] exact: [b]: length: 1 code length: 39 0:[mem-start:1] 3:[push:(+5)] 8:[jump:(+2)] 13:[exact1:a] 15:[mem-end:1] 18:[mem-start:1] 21:[push:(+5)] 26:[jump:(+2)] 31:[exact1:a] 33:[mem-end:1] 36:[exact1:b] 38:[end] match_at: str: 140139875963504 (0x7f74db869270), end: 140139875963506 (0x7f74db869272), start: 140139875963504 (0x7f74db869270), sprev: 0 ((nil)) size: 2, start offset: 0 ofs> str stk:type addr:opcode 0> "ab" 0:Alt 0:[mem-start:1] 0> "ab" 0:Alt 3:[push:(+5)] 0> "ab" 1:Alt 8:[jump:(+2)] 0> "ab" 1:Alt 15:[mem-end:1] 0> "ab" 1:Alt 18:[mem-start:1] 0> "ab" 1:Alt 21:[push:(+5)] 0> "ab" 2:Alt 26:[jump:(+2)] 0> "ab" 2:Alt 33:[mem-end:1] 0> "ab" 2:Alt 36:[exact1:b] 0> "ab" 1:Alt 31:[exact1:a] 1> "b" 1:Alt 33:[mem-end:1] 1> "b" 1:Alt 36:[exact1:b] 2> "" 1:Alt 38:[end] ``` -- https://bugs.ruby-lang.org/

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[ruby-core:116995] [Ruby master Bug#20312] Memory leak with BigDecimal::EXCEPTION_OVERFLOW
by MaxLap (Maxime Lapointe) 29 Feb '24

29 Feb '24

Issue #20312 has been reported by MaxLap (Maxime Lapointe). ---------------------------------------- Bug #20312: Memory leak with BigDecimal::EXCEPTION_OVERFLOW https://bugs.ruby-lang.org/issues/20312 * Author: MaxLap (Maxime Lapointe) * Status: Open * ruby -v: 3.3.0 * Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- The following causes a memory leak. I left a commented line, both trigger an memory leak. I assume it's the same bug ``` require 'bigdecimal' BigDecimal.mode(BigDecimal::EXCEPTION_OVERFLOW, true) 10.times do |j| 100000.times do |i| begin BigDecimal("1E11111111111111111111") #BigDecimal("1E1000000000000000000")**10 # Also leaks rescue end end GC.start puts `ps -o rss= -p #{$$}`.to_i end ``` ``` $ ruby local.rb 28652 34988 41060 47396 53732 59804 66140 72476 78548 84884 ``` Happens in 3.2.3, 3.3.0, 3.3-head, ruby-head (of a few days ago). -- https://bugs.ruby-lang.org/

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