v10.1.0.0: JRuby 10.1.0.0

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The JRuby community is pleased to announce the release of JRuby 10.1.0.0.

• Homepage: https://www.jruby.org/
• Download: https://www.jruby.org/download

JRuby 10.1.0.x targets Ruby 4.0 compatibility.

Thank you to our contributors this release, you help keep JRuby moving forward!

JRuby 10.1: Experimenting and Evolving

JRuby 10.1.0.0 is our first major release since catching up with Ruby compatibility. We have used this opportunity to explore many experimental optimizations and improvements we have been chasing for many years. Ruby 4.0 compatibility is largely complete, but there will be additional features added in update releases. We also plan to continue with large scale experiments in subsequent updates, and recommend production users continue to use JRuby 10.0 while we work toward stabilization of the 10.1 series.

Here's an overview of the major enhancments already in JRuby 10.1.0.0 and others planned for update releases in the coming months.

Reduced Object Size

In JRuby 10.1 all objects have been reduced in size by 8 bytes, bringing the base object size down from 32 bytes to 24 bytes. This translates into smaller objects across the system, reduced GC load, higher allocation throughput, and better cache locality.

On JVM versions that support Compact Object Headers (JEP 450: "Project Lilliput") the base object size can be further reduced to 16 bytes, 40% smaller than objects in the standard Ruby implememtation.

Evolving Strings, Arrays, and Hashes

During the upcoming JRuby 10.1 update releases, we plan to introduce new versions of String, Array, and Hash that are optimized for memory compactness, concurrency, or integration with other JVM languages. To support these features, we have made the internal implementations RubyArray and RubyHash into abstract classes and deprecated the direct constructors for RubyString. Please test your JRuby extension code and make sure it does not call abstract or deprecated constructors.

Smaller Numeric Representations

JRuby's internal class for representing 64-bit signed Integer values, RubyFixnum, has been split into two versions: LongFixnum and ShortFixnum. Combined with the reduced size of objects overall, this reduces the size of these long and short-ranged Integer objects from 40 bytes to 32 bytes or 24 bytes (24 bytes or 16 bytes if using Compact Object Headers). The size of Float objects have similarly been reduced from 40 bytes to 32 bytes. These size reductions help improve the performance of numeric algorithms and reduce impact to the heap and GC of boxing numeric values.

Cross-platform Prism Parser

JRuby 10.1 ships with support for the Prism Ruby parser, packaged as a set of pre-optimized native builds (for Windows, Linux, and MacOS on x86_64 or arm64) or as a WASM build on other platforms. We're still working out a few remaining features, but we encourage experimenters to enable it by passing -Xparser.prism to JRuby. We plan to make this the default parser once the remaining issues are solved.

Direct Argument Passing

We have also laid the groundwork to start passing all forms of method arguments on the call stack, avoiding boxed collections for most optional and keyword arguments. In upcoming JRuby 10.1 releases, we will begin to connect these call paths up for both pure-Ruby and native (Java) method targets, eliminating box allocation and drastically improving the peformance of such forms. Watch this space for rapid improvements.

New Policy for EOL and LTS Releases

With the release of JRuby 10.1, we are moving JRuby 9.4 into a "soft" EOL status. This means we will no longer be doing regular OSS release updates of JRuby 9.4, but users may get in contact with us to sponsor continued support. JRuby 10.0 will be our stable LTS release until April 2028 and we recommend all users upgrade or get in contact with us for assistance. JRuby 10.1 will be our "tip" release line, with many exciting optimizations and enhancements due to land over the next several months.

Going forward, we will provide a new LTS baseline release every two years, starting in spring of 2027, and alternating years will be considered as edge or development versions without LTS guarantees. This will allow us a free hand to keep bringing you more experimental features while still providing a stable baseline for more conservative users.

Try JRuby Today!

Users can install JRuby 10.1 through the usual means, and we encourage you to give it a try and let us know how it handles your applications and libraries. We have much more planned for the 10.1 updates and hope to move fast and push the edges of what's possible with Ruby on the JVM.

59 Issues and PRs resolved for 10.1.0.0

• #​8716 dup a lot
• #​8747 Launcher script chokes on GraalVM release file
• #​9055 Array experiments
• #​9066 Move Set to a core class [Ruby 4.0]
• #​9069 Implement Ruby 4.0 support
• #​9074 Avoid array allocation for *nil, by not calling nil.to_a
• #​9075 Selective inspect of instance variables
• #​9077 No numbered parameters in Binding#local_variables
• #​9078 Add Math.{expm1,log1p}
• #​9079 Align IO.select timeout logic with CRuby
• #​9083 Implement missing raise features
• #​9085 Specialize Fixnum
• #​9090 Reduce the size of the varTableStamp
• #​9091 Shrink varTableStamp
• #​9095 Eliminate global flags
• #​9096 Cache object ID and hash in low-count immediate values
• #​9102 Add a fast path for hashing numerics and immediates
• #​9113 Performance regression in RubyHash for large hashes (~8-10x slower than JRuby 1.7)
• #​9119 Implement fast-path builtin method flags
• #​9123 Fast builtin validation experiment
• #​9124 Reduce load factor for Hash from 5 to 2
• #​9136 Marshal.load 2.9x regression vs JRuby 1.7
• #​9143 Cache both hash forms for FString
• #​9148 Allow logical ops to begin on beginning of next line
• #​9154 Mask internal Ruby backtrace elements like native masking
• #​9156 Small marshal fixes
• #​9174 Add complete thread-local builtin tracking system (Issues #​9116, #​9119)
• #​9180 Implement implicit param logic for Binding
• #​9181 Fix Data subclasses with ivars
• #​9202 A Data object should be frozen even if it has no members
• #​9209 Add ruby_bug for spec of Data with no members being frozen
• #​9210 Remove Process::Status#& and Process::Status#>>
• #​9233 Load boot scripts from classloader URI
• #​9235 Use capitalized Class and Module for frozen errors
• #​9236 Properly handle keywords in {Kernel|Thread|Fiber}#raise
• #​9238 Cloned class's singleton class has too many classes in hierarchy
• #​9239 Fix for cloned class singleton class has too many ancestors
• #​9250 Update Unicode to Version 17.0.0 and Emoji Version 17.0
• #​9262 Abstract RubyHash
• #​9263 Implicit param fixes for proc and binding
• #​9266 Endless method with modifier method does not parse
• #​9273 Cleanup recursion guards
• #​9277 Use live counts for event hook stats
• #​9279 Move fiddle back to default temporarily for resolv
• #​9286 Proposing RISC-V architecture support
• #​9287 Add riscv64 platform support
• #​9298 Ensure we have a classloader to boot from
• #​9299 Delete methods deprecated prior to JRuby 9.4.0.0
• #​9300 Replace now-deprecated wait_timeout
• #​9313 Time being returned as ASCII-8BIT encoding in JRuby 10
• #​9318 Process.detach raises ArrayIndexOutOfBoundsException if called from a thread that is not the main thread
• #​9325 [fix] NullPointerException from closed IO
• #​9362 Allow endless methods to be an argument to methods like visibity
• #​9365 Marshal load perf
• #​9371 Deprecate all public RubyString constructors
• #​9374 Integrate WASM-based Prism parser into standard build
• #​9383 Disable IntFixnum
• #​9384 Set.new(a_set) throws LocalJumpError
• #​9385 Fixes #​9384. Set.new(a_set) throws LocalJumpError

v10.0.6.0: JRuby 10.0.6.0

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The JRuby community is pleased to announce the release of JRuby 10.0.6.0.

• Homepage: https://www.jruby.org/
• Download: https://www.jruby.org/download

JRuby 10.0.6.x targets Ruby 3.4 compatibility.

Thank you to our contributors this release, you help keep JRuby moving forward! @​chadlwilson, @​kares, @​sampokuokkanen

Notable Changes:

Standard Library

• erb has been updated to 4.0.4.1 to address CVE-2026-41316. (#​9389)
• jruby-openssl has been updated to 0.16.0, fixing many long-standing issues with SSLSocket. (#​6455, #​8935, #​9390)

Java Integration

• Performance and consistency improvements for passing a block or proc as the implementation of a Java interface. (#​1401, #​9401, #​9424)

23 Issues and PRs resolved for 10.0.6.0

• #​1401 Java interface using closure implementaion is slower than mixin implementation
• #​6455 Unhandled IOError --> SSLSocket.java:893:in `sysread_nonblock'
• #​8935 Error during gem push using jruby
• #​9367 review (wrong) asserts
• #​9368 [refactor] remove duplicate fallback in CallableSelector
• #​9372 Crash when AOT compiling rubocop-ast sources
• #​9373 Ensure the initial string has correct size
• #​9389 [10.0] deps(stdlib): bump erb from 4.0.4 to 4.0.4.1 to resolve CVE-2026-41316
• #​9390 [10.0] [deps] bump jruby-openssl to 0.16.0
• #​9401 improve performance for Java "block-to-interface" conversion
• #​9416 Checking out aws-sdk-ruby creates a file with binary data.
• #​9421 Fix missing frozen check in 1 and 2-element Array sort!/reverse!
• #​9424 proc to interface inconsistency with multiple args
• #​9451 [fix] escape shell metachars in chdir: to prevent injection
• #​9457 Deprecate and replace all RubyHash, RubyString, and RubyArray constructors
• #​9458 Support backtrace_locations with Java exceptions
• #​9461 [ji] support java.lang.Throwable#backtrace_locations
• #​9474 Deprecate RubyHash constructors for 10.1 abstraction
• #​9476 Backport extended dist verification to 10.0
• #​9478 [fix] @​JRubyMethod error with required>=1 and var-args
• #​9484 Make JVM bytecode version detection more robust
• #​9489 Deprecate all public String constructors
• #​9490 Deprecate public RubyArray constructors

v10.0.5.0: JRuby 10.0.5.0

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The JRuby community is pleased to announce the release of JRuby 10.0.5.0.

• Homepage: https://www.jruby.org/
• Download: https://www.jruby.org/download

JRuby 10.0.5.x targets Ruby 3.4 compatibility.

Thank you to our contributors this release, you help keep JRuby moving forward! @​evaniainbrooks, @​kares, @​chadlwilson, #jimtng

Compatibility

• Fixed: Two bugs in the JIT compiler that broke certain super calls and defined_method yields. (#​8944, #​8946, #​9310, #​9349)
• Fixed: Fiber#raise left the fiber in an resumable state by not correctly transfering control. (#​9297, #​9356)
• Fixed: Connecting a socket using nonblocking operations failed to complete the establishment of the connection. This affected Redis users, among other cases. (#​9304, #​9305)
• Fixed: Process#detach raised a NullPointerException if called from a non-main thread. (#​9314, #​9311)

JVM Integration

• Java 26 is officially supported. (#​9332)

Platform Integration

• New platform support: The native library backend for JRuby, JNR, has been updated to include support for the RISCv64 architecture.
• Fixed on Windows: File#flock used unsupported native operations on Windows, causing it to raise errors. This affected the "logger" library, among other cases. (#​9347, #​9348)
• Fixed on Windows: IO#popen failed to pass keyword arguments if also given a leading environment hash. (#​9351, #​9352)

Stability

• Fixed: Several memory leaks that affected users running multiple JRuby instances in a single process. (#​9070, #​9092, #​9187, #​9359)

43 Issues and PRs resolved for 10.0.5.0

• #​4213 squiggly heredoc strip space between interpolation and line connector by mistake
• #​8944 Double unresolved super from aliased method when compiled with indy
• #​8946 define_method conversion fails to yield after indy JIT
• #​9070 Memory leak in jruby within openhab
• #​9092 ThreadLocal Memory Leak in JRuby 10.0.2.0 with ScriptingContainer
• #​9187 Memory leak running RubyGems in separate runtimes in a loop
• #​9261 Fix Time subsecond precision loss from floating point arithmetic
• #​9292 Reduce BigInteger construction
• #​9293 Incorrect caller_locations line for multi-line call with unless
• #​9297 Different behaviour than MRI on Fiber#raise
• #​9302 review call-info reset
• #​9304 Socket.tcp does not complete connection
• #​9305 Ensure connectable sockets finish
• #​9307 Time being returned as ASCII-8BIT encoding in JRuby 10
• #​9310 [fix] define_method captured block propagation in JIT mode
• #​9311 Push a frame for thread toplevel
• #​9312 Construct xmlschema string as US-ASCII
• #​9314 Process.detach raises ArrayIndexOutOfBoundsException if called from a thread that is not the main thread
• #​9316 [10.0] build: bump maven from 3.9.11 to 3.9.14 via script-only style
• #​9317 [10.0] build: improve build/maven consistency / bump github actions
• #​9322 Fix prepended module initialize not called for Ruby classes rooted in a Java superclass
• #​9323 [deps] bump jruby-openssl to latest
• #​9324 NPE retrieving IO channel
• #​9326 [fix] NullPointerException from closed IO
• #​9330 Sync with prism update so we can compile jruby-prism using 10.0
• #​9332 Support Java 26
• #​9334 [fix] Exception#dup: copy cause to the duplicated exception
• #​9335 [fix] MatchData#deconstruct_keys: include non-participating captures
• #​9336 [fix] Bignum#eql?: use type-strict comparison (not ==)
• #​9337 [fix] Bignum comparison with Float in <=> and ==
• #​9338 [fix] Bignum: use correct site for coerced comparisons
• #​9339 [fix] IO#reopen: copy encoding from source IO
• #​9340 Hash#rehash corrupts insertion-order when deduplicating keys
• #​9341 [fix] Hash#rehash: fix deduplicating keys (#​9340)
• #​9343 [compat] Thread#native_thread_id: using Java thread-id
• #​9344 [fix] Digest::Base: synchronize MessageDigest mutation
• #​9345 [fix] Encoding.compatible?: check when swapping args
• #​9347 Use JDK for File#flock on Windows
• #​9348 ruby/logger gem broken after version 1.6.3 using JRuby on Windows
• #​9349 Disable AliasMethod direct binding for now
• #​9352 Issue with calling IO.popen(env, cmd, opts) on Windows
• #​9351 Fix non-native IO.popen env + kwargs handling
• #​9354 Update JNR dependencies
• #​9355 Propagate newline from if to bodies
• #​9356 Properly complete Fiber#raise transfer
• #​9359 Leak fixes redux
• #​9364 [fix] TCPServer#initialize: close channel on bind/init failure

v10.0.4.0: JRuby 10.0.4.0

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The JRuby community is pleased to announce the release of JRuby 10.0.4.0.

• Homepage: https://www.jruby.org/
• Download: https://www.jruby.org/download

JRuby 10.0.4.x targets Ruby 3.4 compatibility.

Thank you to our contributors this release, you help keep JRuby moving forward! @​evaniainbrooks, @​katafrakt, @​mrnoname1000

Standard Library

• The syslog library moves to bundled gems. (#​9198)
• The unicode_normalize library is now thread-safely loaded as an internal library (#​9231, #​9232)

43 Issues and PRs resolved for 10.0.4.0

• #​8697 Tracing :call doesn't work if the traced code is running on a different thread
• #​8876 import_methods doesn't allow calling another refined method
• #​9120 File.path doesn't raise Encoding::CompatibilityError for ASCII-incompatible string
• #​9195 Refactor keyword arguments logic
• #​9198 Move syslog to bundled gems
• #​9206 Fix exception message when calling import_methods without a Module
• #​9208 Inconsistency with block parameter default value
• #​9211 Fix block argument destructuring with optional parameters
• #​9212 Fix method owner when using import_methods
• #​9213 Make refine method of Module private
• #​9214 Data.define single-attribute class rejects positional arguments
• #​9215 Ignore empty kwrest in Data subtypes' constructors
• #​9217 Add an error for running jruby.sh from a broken JRUBY_HOME
• #​9218 JavaFX AnimationTimer + Mutex.synchronize triggers “deadlock; lock already owned by another fiber belonging to the same thread” on JRuby 10.0.3.0
• #​9222 String interpolation of BasicObject object raises NameError instead of NoMethodError
• #​9224 ClassCastException handling kwargs in Struct
• #​9225 Expand Data initialize empty kwargs fix to Struct
• #​9226 Narrow deadlock check for sibling fibers locking mutex
• #​9227 Version output may not accurately represent JIT mode
• #​9228 Fix version output to reflect current runtime
• #​9230 Use normal call type error for missing dynamic string to_s
• #​9231 Thread safety of require and implications on stdlib string.normalize()
• #​9232 Internalize and threadsafetify String#unicode_normalize
• #​9237 Fix for import_methods does not allow calling another refined method
• #​9240 Fix for File.path doesn't raise Encoding::CompatibilityError for ASCII incompatible string
• #​9241 Data#to_h and Data#deconstruct return values in wrong order when module overrides initialize in a subclassed Data class
• #​9242 Spurious Struct#initialize keyword argument warning (and crash) with ... forwarding through super
• #​9243 Data#==/Data#eql? and Struct#eql? return false when instances are extended in initialize
• #​9244 Fix for ClassCastException inside Struct#initialize when delegating ... from a prepended module
• #​9247 Fix Array#slice raises a RangeError when the start index is out of range of Fixnum
• #​9248 Additional fixes for import_methods with JIT
• #​9252 Use prepared accessors to retrieve Data fields
• #​9254 Compare "real" classes for Data#== and eql?
• #​9258 Kernel#respond_to? fails if #respond_to_missing? is not defined
• #​9259 Only set locking thread once successful
• #​9260 Restore Cleaner API use for embedding cleanup
• #​9272 Avoid passing bogus -classpath when empty
• #​9280 Check if respond_to_missing? exists before respond_to?
• #​9281 unexpected ArgumentError: wrong number of arguments
• #​9283 Only localize TracePoint to thread if specified
• #​9285 Clear callInfo so it does not taint other calls
• #​9289 Include gem extension stubs in stdlib artifacts
• #​9290 Improve dist verification

v10.0.3.0: JRuby 10.0.3.0

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layout: post
title: JRuby 10.0.3.0 Released

The JRuby community is pleased to announce the release of JRuby 10.0.3.0.

• Homepage: https://www.jruby.org/
• Download: https://www.jruby.org/download

JRuby 10.0.3.x targets Ruby 3.4 compatibility.

Thank you to our contributors this release, you help keep JRuby moving forward! @​mrnoname1000, @​ngr-ilmarh, @​Earlopain, @​philr, @​jotamartos, @​kares, @​aleksandrs-ledovskis, @​trinistr, @​katafrakt, @​chadlwilson, @​khasinski, @​evaniainbrooks

Compatibility

• JRuby now reports RbConfig::CONFIG['arch'] without a version number, as universal-java. This allows using different JDK versions without triggering RubyGems missing extension warnings for installed gems. The host Java version is still available as RbConfig::CONFIG['arch_version']. [#​9107]

Standard Library

• The non-gem standard library is upgraded to Ruby 3.4.5 [#​8967]
• rexml is updated to 3.4.4 to address CVE-2025-58767. [#​9011]
• syslog is moved to a default gem at version 0.4.0. The syslog gem now includes JRuby support. [#​9109], ruby/syslog#1
• strscan is updated to 3.1.7. [#​9159]

Documentation

• Ruby ri documentation for core and standard library are now included in the release distribution. [#​9049], [#​9052]

All Issues/PRs

• #​8707 [WARNING: A terminally deprecated method in sun.misc.Unsafe has been called][#​8707]
• #​8727 [Cannot install latest rubocop][#​8727]
• #​8730 [Launcher: Defensive fixes][#​8730]
• #​8758 [Require is not working for .class file if the class is inside a module since 9.3.0][#​8758]
• #​8810 [Possible fix for 8809][#​8810]
• #​8923 [NameError for autoloaded constant with private_constant][#​8923]
• #​8934 [JRuby under Java 22+ always thinks it's running under a TTY][#​8934]
• #​8940 [Verify to_s is string or fall back on anyToString][#​8940]
• #​8947 [New check for System.console tty on JDK 22+][#​8947]
• #​8955 [Range#count always returns size for Integer bounds][#​8955]
• #​8956 [Handle argument or block passed to Range#count][#​8956]
• #​8958 [Concurrent requires can lead to StringIndexOutOfBoundsException][#​8958]
• #​8960 [Fix index -1 error while searching for feature path][#​8960]
• #​8962 [Upgrade polyglot and remove openssl lib hack][#​8962]
• #​8967 [Update stdlib to 3.4.5 and clean up old files][#​8967]
• #​8975 [Use RuboCop to clean up poms (10.x)][#​8975]
• #​8976 [Regression in keyword argument matching in JRuby v10.0.1.0][#​8976]
• #​8978 [Additional fixes for scheme-based globbing][#​8978]
• #​8984 [glob refactoring][#​8984]
• #​8985 [Fix language spec where error string changed][#​8985]
• #​8987 [InvokeDynamicSupport.findVirtual fails with IllegalAccessException: symbolic reference class is not accessible][#​8987]
• #​8989 [Explicitly request access before Lookup.find*][#​8989]
• #​8994 [autoload + private_constant do not play well together][#​8994]
• #​8995 [private_constant should just update existing autoload][#​8995]
• #​8996 [Avoid binding unreadable modules' classes][#​8996]
• #​8998 [Time#localtime incorrectly treats zero offset as UTC (regression in v10.0.2.0)][#​8998]
• #​9006 [Consider .class a source extension during search][#​9006]
• #​9007 [Handle warn(foo, uplevel: nil)][#​9007]
• #​9009 [Encoding a string with undefined chars fails with NoMethodError][#​9009]
• #​9010 [Fix "+00:00" and 0 being treated as UTC by Time#localtime and Time.at][#​9010]
• #​9011 [Update rexml gem to solve CVE-2025-58767][#​9011]
• #​9016 [[fix] regression calling static hash() method on Java proxy][#​9016]
• #​9017 [can not use Java class with static hash() method][#​9017]
• #​9018 [Parser does not convert newlines reading \r\n on Windows][#​9018]
• #​9019 [We need to remove \r from heredoc strings][#​9019]
• #​9021 [Retire safe double processing utilities][#​9021]
• #​9024 [Move all main classes to org.jruby.main package][#​9024]
• #​9027 [Add "since" to bare Deprecated annotations][#​9027]
• #​9035 [IO#read does not clear code-range for buffer argument][#​9035]
• #​9036 [fix: clear code-range when re-using a string buffer][#​9036]
• #​9038 [Add opens and native access to all jar manifests][#​9038]
• #​9039 [Update all jnr dependencies][#​9039]
• #​9041 [Migrate .java-version contents to .jruby.release][#​9041]
• #​9049 [ri docs are not available for core][#​9049]
• #​9050 [Marshal fails to load an encoding with an encoding ivar][#​9050]
• #​9051 [Ignore encoding when unmarshaling an Encoding][#​9051]
• #​9052 [Download and include in dist CRuby's rdoc data][#​9052]
• #​9058 [Implement efficient unshifting][#​9058]
• #​9059 [Reserve extra space before elements when unshifting][#​9059]
• #​9063 [Hash's compare_by_identity state does not marshal][#​9063]
• #​9065 [Preserve compare_by_identity for marshaled Hash][#​9065]
• #​9068 [Windows CI spec runs][#​9068]
• #​9073 [fix: Permit overriding of JSA file location using ENV variable][#​9073]
• #​9084 [object_id improvements][#​9084]
• #​9094 [Implement GC.config [Ruby 3.4]][#​9094]
• #​9097 [Update jruby-openssl to v0.15.5 to resolve BouncyCastle 1.79 vulnerability (sonatype-2025-001911).][#​9097]
• #​9098 [Fix CoverageData.mergeLines when coverage increases][#​9098]
• #​9101 [Cached fixnums for immediate values][#​9101]
• #​9103 [Update jruby-openssl to 0.15.5][#​9103]
• #​9106 [Use smaller default size for many collections][#​9106]
• #​9107 [Separate Java version out of rbconfig 'arch'][#​9107]
• #​9108 [Tidy up default gems][#​9108]
• #​9109 [Switch to syslog gem][#​9109]
• #​9110 [Calling inspect on proc resets line in source_location][#​9110]
• #​9112 [Prevent modifying state in RubyProc][#​9112]
• #​9117 [Add file path to error message when unlinking non-existing file][#​9117]
• #​9122 [Unexpected jruby.sh error messages on Windows][#​9122]
• #​9127 [fix(launcher): correct parsing of java release files under Bash/msys2 etc on Windows][#​9127]
• #​9138 [Copy Data type's var table manager with new realClass][#​9138]
• #​9141 [refactorings and cleanup motivated by error-prone][#​9141]
• #​9142 [Change GC's methods from module_function to metaclass methods][#​9142]
• #​9145 [Never trust external content for FString][#​9145]
• #​9152

✂ Note

PR body was truncated to here.