Update version and release date. (mruby 4.0.0 (2026-04-20))

Co-authored-by: Claude <noreply@anthropic.com>

.github/dependabot.yml

@@ -5,11 +5,29 @@ updates:
     directory: "/"
     schedule:
       interval: "daily"
+    groups:
+      bundler-dependencies:
+        patterns:
+          - "*"
     cooldown:
       default-days: 7
   - package-ecosystem: "github-actions"
     directory: "/"
     schedule:
       interval: "daily"
+    groups:
+      github-actions-dependencies:
+        patterns:
+          - "*"
+    cooldown:
+      default-days: 7
+  - package-ecosystem: "pre-commit"
+    directory: "/"
+    schedule:
+      interval: "daily"
+    groups:
+      pre-commit-hooks:
+        patterns:
+          - "*"
     cooldown:
       default-days: 7

.github/workflows/build.yml

@@ -31,7 +31,9 @@ jobs:
       LD: ${{ matrix.cc }}
     steps:
       - name: "Checkout ${{ github.ref }} ( ${{ github.sha }} )"
-        uses: actions/checkout@v6
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
       - name: Ruby version
         run: ruby -v
       - name: Compiler version
@@ -44,11 +46,13 @@ jobs:
     timeout-minutes: 15
     steps:
       - name: "Checkout ${{ github.ref }} ( ${{ github.sha }} )"
-        uses: actions/checkout@v6
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
       - name: Ruby version
         run: ruby -v
       - name: Cache cosmocc
-        uses: actions/cache@v5
+        uses: actions/cache@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5.0.4
         id: cache-cosmocc
         with:
           path: ~/cosmo
@@ -70,7 +74,9 @@ jobs:
       MRUBY_CONFIG: ci/msvc
     steps:
       - name: "Checkout ${{ github.ref }} ( ${{ github.sha }} )"
-        uses: actions/checkout@v6
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
       - name: Ruby version
         run: ruby -v
       - name: Build and test

.github/workflows/codeql-analysis.yml

@@ -18,7 +18,9 @@ jobs:
         language: ["actions"]
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
       - name: Initialize CodeQL
         uses: github/codeql-action/init@v4
         with:

.github/workflows/coverage.yml

@@ -2,6 +2,9 @@ name: Coverage
 
 on: [push]
 
+permissions:
+  contents: read
+
 jobs:
   coverage:
     name: Coverage
@@ -16,7 +19,9 @@ jobs:
       LDFLAGS: --coverage
     steps:
       - name: "Checkout ${{ github.ref }} ( ${{ github.sha }} )"
-        uses: actions/checkout@v6
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
       - name: Ruby version
         run: ruby -v
       - name: Compiler version
@@ -34,7 +39,7 @@ jobs:
             echo \`\`\`
           } > "$GITHUB_STEP_SUMMARY"
       - name: Upload coverage report
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         with:
           name: coverage-${{ github.sha }}
           path: coverage/

.github/workflows/labeler.yml

@@ -9,7 +9,7 @@ jobs:
       pull-requests: write
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/labeler@v6
+      - uses: actions/labeler@634933edcd8ababfe52f92936142cc22ac488b1b # v6.0.1
         with:
           repo-token: "${{ secrets.GITHUB_TOKEN }}"
           sync-labels: true

.github/workflows/ls-lint.yml

@@ -11,7 +11,9 @@ jobs:
     name: Run ls-lint
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
-      - uses: ls-lint/action@v2.3.1
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
+      - uses: ls-lint/action@02e380fe8733d499cbfc9e22276de5085508a5bd # v2.3.1
         with:
           config: .github/linters/.ls-lint.yml

.github/workflows/oss-fuzz.yml

@@ -20,7 +20,7 @@ jobs:
           fuzz-seconds: 600
           dry-run: false
       - name: Upload Crash
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         if: failure()
         with:
           name: artifacts

.github/workflows/pre-commit-manual.yml

@@ -0,0 +1,22 @@
+# https://github.com/j178/prek
+name: Manual hooks
+
+on: [pull_request]
+
+permissions:
+  contents: read
+
+jobs:
+  pre-commit:
+    name: Run pre-commit
+    runs-on: ubuntu-latest
+    steps:
+      - name: "Checkout ${{ github.ref }} ( ${{ github.sha }} )"
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
+      - uses: j178/prek-action@53276d8b0d10f8b6672aa85b4588c6921d0370cc # v2.0.1
+        with:
+          install-only: true
+      - name: Run manual pre-commit hooks
+        run: prek run --color=always --all-files --hook-stage manual

.github/workflows/pre-commit.yml

@@ -12,9 +12,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: "Checkout ${{ github.ref }} ( ${{ github.sha }} )"
-        uses: actions/checkout@v6
-      - uses: j178/prek-action@v1
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
+      - uses: j178/prek-action@53276d8b0d10f8b6672aa85b4588c6921d0370cc # v2.0.1
         with:
           extra-args: --all-files
-      - name: Run manual pre-commit hooks
-        run: prek run --color=always --all-files --hook-stage manual

.github/workflows/release.yml

@@ -19,7 +19,9 @@ jobs:
       fail-fast: false
     steps:
       - name: "Checkout ${{ github.ref_name }} ( ${{ github.sha }} )"
-        uses: actions/checkout@v6
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
       - name: Builds
         id: builds
         run: |

.github/workflows/super-linter.yml

@@ -15,12 +15,13 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: "Checkout ${{ github.ref }} ( ${{ github.sha }} )"
-        uses: actions/checkout@v6
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
           # Full git history is needed to get a proper list of changed files within `super-linter`
           fetch-depth: 0
+          persist-credentials: false
       - name: Lint Code Base
-        uses: super-linter/super-linter/slim@v8.5.0
+        uses: super-linter/super-linter/slim@9e863354e3ff62e0727d37183162c4a88873df41 # v8.6.0
         env:
           # VALIDATE_BASH_EXEC: true
           VALIDATE_DOCKERFILE_HADOLINT: true

.pre-commit-config.yaml

@@ -3,7 +3,7 @@
 default_stages: [pre-commit, pre-push]
 default_language_version:
   python: python3
-  node: 24.11.1
+  node: 24.14.0
 minimum_pre_commit_version: "3.2.0"
 exclude: "^tools/lrama/"
 repos:
@@ -24,6 +24,7 @@ repos:
         files: \.(md|ya?ml)$
         language: node
         additional_dependencies: ["prettier@3.7.4"]
+        pass_filenames: false
         stages: [manual]
       - id: check-zip-file-is-not-committed
         name: disallow zip files
@@ -34,13 +35,13 @@ repos:
           track and have security implications. Please remove the zip file from the repository.
         files: \.zip$
   - repo: https://github.com/gitleaks/gitleaks
-    rev: v8.30.0
+    rev: v8.30.1
     hooks:
       - id: gitleaks
         name: run gitleaks
         description: detect hardcoded secrets with gitleaks
   - repo: https://github.com/oxipng/oxipng
-    rev: v10.0.0
+    rev: v10.1.0
     hooks:
       - id: oxipng
         name: run oxipng
@@ -72,7 +73,7 @@ repos:
       - id: mixed-line-ending
       - id: trailing-whitespace
   - repo: https://github.com/Lucas-C/pre-commit-hooks
-    rev: v1.5.5
+    rev: v1.5.6
     hooks:
       - id: forbid-tabs
         name: run no-tabs checker
@@ -84,19 +85,19 @@ repos:
         args: [--whitespaces-count, "2"]
         exclude: Makefile$
   - repo: https://github.com/rhysd/actionlint
-    rev: v1.7.9
+    rev: v1.7.12
     hooks:
       - id: actionlint
         name: run actionlint
         description: lint GitHub Actions workflow files
   - repo: https://github.com/codespell-project/codespell
-    rev: v2.4.1
+    rev: v2.4.2
     hooks:
       - id: codespell
         name: run codespell
         description: check spelling with codespell
   - repo: https://github.com/igorshubovych/markdownlint-cli
-    rev: v0.46.0
+    rev: v0.48.0
     hooks:
       - id: markdownlint
         name: run markdownlint
@@ -105,7 +106,7 @@ repos:
         types: [markdown]
         files: \.md$
   - repo: https://github.com/rubocop/rubocop
-    rev: v1.81.7
+    rev: v1.86.0
     hooks:
       - id: rubocop
         name: run rubocop
@@ -119,7 +120,7 @@ repos:
         name: run shellcheck
         description: check shell scripts with a static analysis tool
   - repo: https://github.com/adrienverge/yamllint
-    rev: v1.37.1
+    rev: v1.38.0
     hooks:
       - id: yamllint
         name: run yamllint

.prettierignore

@@ -3,3 +3,4 @@ build
 coverage
 doc/internal/opcode.md
 tools/lrama
+.venv

Doxyfile

@@ -48,7 +48,7 @@ PROJECT_NAME           = mruby
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 3.4.0
+PROJECT_NUMBER         = 4.0.0
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a

NEWS.md

@@ -23,6 +23,8 @@ mruby now supports pattern matching (case/in) syntax:
 - Trailing comma in method definition parameters: `def foo(a, b,)` ([f78334b](https://github.com/mruby/mruby/commit/f78334b))
 - Array/Hash/String subclasses can now override `[]` and `[]=` methods ([#6675](https://github.com/mruby/mruby/pull/6675))
 - `OP_SETIDX` optimization for Array and Hash ([ddd8fe1](https://github.com/mruby/mruby/commit/ddd8fe1))
+- `case`/`in` without `else` now raises `NoMatchingPatternError` ([d8de35b](https://github.com/mruby/mruby/commit/d8de35b))
+- Allow compound statement in parenthesized argument context ([919cbd8](https://github.com/mruby/mruby/commit/919cbd8))
 
 # Changes in C API
 
@@ -37,6 +39,8 @@ mruby now supports pattern matching (case/in) syntax:
 - `mrb_open()` returns mrb_state with exc set on init failure ([05ffe0c](https://github.com/mruby/mruby/commit/05ffe0c))
 - `mrb_utf8_to_buf()` for UTF-8 encoding consolidation ([7e28e68](https://github.com/mruby/mruby/commit/7e28e68))
 - `kh_is_end()` macro for safe khash iteration ([893cc75](https://github.com/mruby/mruby/commit/893cc75))
+- `mrb_bigint_p()` always defined regardless of bigint gem presence ([6c4a8c0](https://github.com/mruby/mruby/commit/6c4a8c0))
+- `RInteger` and `RFloat` added to `RVALUE` union ([13dbca0](https://github.com/mruby/mruby/commit/13dbca0))
 
 # ROM Method Tables
 
@@ -76,6 +80,7 @@ mruby-symbol-ext, mruby-range-ext, mruby-object-ext.
 - Emscripten: use native WASM exception handling ([ca364e3](https://github.com/mruby/mruby/commit/ca364e3))
 - HAL (Hardware Abstraction Layer) for platform abstraction in mruby-io, mruby-socket, mruby-dir, mruby-task ([74ca22f](https://github.com/mruby/mruby/commit/74ca22f))
 - `MRUBY_MIRB_READLINE` environment variable to control readline library selection ([0aafb83](https://github.com/mruby/mruby/commit/0aafb83))
+- MSYS2 drive letter support in build script ([77f6ffe](https://github.com/mruby/mruby/commit/77f6ffe))
 - Inter-gem headers separated from external API headers ([#6671](https://github.com/mruby/mruby/pull/6671))
 
 # Changes in mrbgems
@@ -110,6 +115,7 @@ mruby-symbol-ext, mruby-range-ext, mruby-object-ext.
 ## Other Gem Changes
 
 - **_NOTE_**: `Hash#deconstruct_keys` removed for CRuby compatibility ([34b9412](https://github.com/mruby/mruby/commit/34b9412))
+- **mruby-enum-lazy**: Fix `Lazy#flat_map` to handle non-enumerable block return values ([#6765](https://github.com/mruby/mruby/pull/6765))
 - **mruby-array-ext**: Add `Array#find` and `Array#rfind` methods
 - **mruby-io**: Add `IO#putc` and `Kernel#putc` ([baff6e6](https://github.com/mruby/mruby/commit/baff6e6))
 - **mruby-random**: Replace xoshiro with PCG for better memory efficiency ([f1bab01](https://github.com/mruby/mruby/commit/f1bab01))
@@ -125,6 +131,8 @@ mruby-symbol-ext, mruby-range-ext, mruby-object-ext.
 - Optimized masgn to generate literals directly into target registers ([fb5d966](https://github.com/mruby/mruby/commit/fb5d966))
 - Optimized splat of literal arrays in args/literals ([1cb8d73](https://github.com/mruby/mruby/commit/1cb8d73))
 - Early termination after too many parse errors ([510ebd7](https://github.com/mruby/mruby/commit/510ebd7))
+- Chunk array literals at 64 elements to reduce register pressure ([f98d641](https://github.com/mruby/mruby/commit/f98d641))
+- Chunk `%w()` and `%i()` literals to reduce register pressure ([62cf0dc](https://github.com/mruby/mruby/commit/62cf0dc))
 
 # VM Optimizations
 
@@ -185,6 +193,10 @@ Other optimizations:
 - [#6705](https://github.com/mruby/mruby/issues/6705) Can't get outer class of an object in C
 - [#6713](https://github.com/mruby/mruby/issues/6713) mruby-polarssl not work
 - [#6720](https://github.com/mruby/mruby/issues/6720) Random float range: different behavior from CRuby
+- [#6722](https://github.com/mruby/mruby/issues/6722) RBreak size overflow on 32-bit platforms with MRB_NO_BOXING
+- [#6740](https://github.com/mruby/mruby/issues/6740) `%w()`/`%i()` register pressure with large literals
+- [#6741](https://github.com/mruby/mruby/issues/6741) `case`/`in` without `else` should raise `NoMatchingPatternError`
+- [#6760](https://github.com/mruby/mruby/issues/6760) `mrb_gc_unregister()` not removing all matching entries
 
 # Merged Pull Requests
 
@@ -260,6 +272,7 @@ Other optimizations:
 - [#6589](https://github.com/mruby/mruby/pull/6589) Add pre-commit hook `check-zip-file-is-not-committed`
 - [#6591](https://github.com/mruby/mruby/pull/6591) mruby-eval fix license link in README
 - [#6593](https://github.com/mruby/mruby/pull/6593) README: Add Contributors Avatars, Star History, Table of Contents
+- [#6598](https://github.com/mruby/mruby/pull/6598) Fix heap buffer overflow in `#method_missing`
 - [#6599](https://github.com/mruby/mruby/pull/6599) pre-commit: run `markdown-link-check`, `oxipng`, `prettier` manually
 - [#6600](https://github.com/mruby/mruby/pull/6600) `dreamcast_shelf build config`: update to use KallistiOS wrappers
 - [#6601](https://github.com/mruby/mruby/pull/6601) fix: skip local build_config.rb when working in MRUBY_ROOT
@@ -303,6 +316,33 @@ Other optimizations:
 - [#6716](https://github.com/mruby/mruby/pull/6716) Fixes identity for proc object
 - [#6717](https://github.com/mruby/mruby/pull/6717) Fix mruby-task: wrapping by critical section and setting initial task receiver
 - [#6718](https://github.com/mruby/mruby/pull/6718) Add installation instructions for conda and Homebrew
+- [#6723](https://github.com/mruby/mruby/pull/6723) Add `RInteger` and `RFloat` to `RVALUE`
+- [#6727](https://github.com/mruby/mruby/pull/6727) Language documentation: update wording of "overloading" section
+- [#6729](https://github.com/mruby/mruby/pull/6729) Simplifying dependency addition for gensym task
+- [#6730](https://github.com/mruby/mruby/pull/6730) Simplifying presym file generation actions
+- [#6733](https://github.com/mruby/mruby/pull/6733) Include `mruby/presym.h` for all source files
+- [#6734](https://github.com/mruby/mruby/pull/6734) Chunk array literals at 64 elements to reduce register pressure
+- [#6735](https://github.com/mruby/mruby/pull/6735) Prevent full recompilation without changes to presym file
+- [#6739](https://github.com/mruby/mruby/pull/6739) Fix MSYS2 build error with drive letters
+- [#6743](https://github.com/mruby/mruby/pull/6743) Chunk `%w()` and `%i()` literals to reduce register pressure
+- [#6744](https://github.com/mruby/mruby/pull/6744) Raise `NoMatchingPatternError` in `case`/`in` without `else`
+- [#6747](https://github.com/mruby/mruby/pull/6747) Correctly handle empty hash as default named argument
+- [#6749](https://github.com/mruby/mruby/pull/6749) Fix microcontroller profile
+- [#6750](https://github.com/mruby/mruby/pull/6750) Fix out-of-bounds read and divide-by-zero in `Array#product`
+- [#6752](https://github.com/mruby/mruby/pull/6752) Fix `attr_reader`-generated methods accepting extra arguments
+- [#6753](https://github.com/mruby/mruby/pull/6753) Further optimize `Array#product`
+- [#6754](https://github.com/mruby/mruby/pull/6754) Mark `attr_reader` procs as noarg
+- [#6755](https://github.com/mruby/mruby/pull/6755) Reload `ci` after `mrb_hash_delete_key()` in keyword argument handling
+- [#6756](https://github.com/mruby/mruby/pull/6756) Avoid impact of object modifications caused by `mrb_vm_exec()` calls
+- [#6758](https://github.com/mruby/mruby/pull/6758) Don't assign result of `mrb_funcall()` directly to `regs`
+- [#6759](https://github.com/mruby/mruby/pull/6759) Define `mrb_bigint_p()` always
+- [#6761](https://github.com/mruby/mruby/pull/6761) Fix `mrb_gc_unregister()` to remove all matching entries
+- [#6762](https://github.com/mruby/mruby/pull/6762) Write generated test C files atomically to avoid build race condition
+- [#6765](https://github.com/mruby/mruby/pull/6765) Fix `Lazy#flat_map` to handle non-enumerable block return values
+- [#6767](https://github.com/mruby/mruby/pull/6767) Allow compound statement in parenthesized argument context
+- [#6780](https://github.com/mruby/mruby/pull/6780) Fix `String#prepend` with self-referencing arguments
+- [#6781](https://github.com/mruby/mruby/pull/6781) Protect `sprintf` format string from mutation during callbacks
+- [#6783](https://github.com/mruby/mruby/pull/6783) Pin GitHub Actions workflows to commit hashes
 
 # Security Fixes
 
@@ -320,4 +360,8 @@ Other optimizations:
 - Heap-use-after-free in insertion_sort ([099d2c47](https://github.com/mruby/mruby/commit/099d2c47))
 - Integer overflow in str_check_length ([6afff1c3](https://github.com/mruby/mruby/commit/6afff1c3))
 - Integer overflow in Integer#lcm ([070bef24](https://github.com/mruby/mruby/commit/070bef24))
+- Heap buffer overflow in `#method_missing` ([550d10a](https://github.com/mruby/mruby/commit/550d10a))
+- Out-of-bounds read and divide-by-zero in `Array#product` ([8441eaf](https://github.com/mruby/mruby/commit/8441eaf))
+- Heap buffer overflow in `String#prepend` with self-referencing arguments ([18ba026](https://github.com/mruby/mruby/commit/18ba026))
+- Use-after-free in `sprintf` via `to_s` callback mutating format string ([48fc422](https://github.com/mruby/mruby/commit/48fc422))
 - Multiple memory leak fixes in bigint, Set, Array, and Task gems

README.md

@@ -51,6 +51,8 @@ To get mruby, you can download the stable version 4.0.0 from the official mruby
 GitHub repository or clone the trunk of the mruby source tree with the "git
 clone" command. You can also install and compile mruby using [ruby-install](https://github.com/postmodern/ruby-install), [ruby-build](https://github.com/rbenv/ruby-build), [rvm](https://github.com/rvm/rvm), [conda](https://anaconda.org/channels/conda-forge/packages/mruby/overview) or [Homebrew](https://formulae.brew.sh/formula/mruby).
 
+The release candidate version 4.0.0 of mruby can be downloaded via the following URL: [https://github.com/mruby/mruby/archive/4.0.0-rc3.zip](https://github.com/mruby/mruby/archive/4.0.0-rc3.zip)
+
 The latest development version of mruby can be downloaded via the following URL: [https://github.com/mruby/mruby/zipball/master](https://github.com/mruby/mruby/zipball/master)
 
 The trunk of the mruby source tree can be checked out with the

build_config/ArduinoDue.rb

@@ -30,7 +30,7 @@ MRuby::CrossBuild.new("ArduinoDue") do |conf|
 
     #configuration for low memory environment
     cc.defines << %w(MRB_HEAP_PAGE_SIZE=64)
-    cc.defines << %w(KHASH_DEFAULT_SIZE=8)
+    cc.defines << %w(KHASH_INITIAL_SIZE=8)
     cc.defines << %w(MRB_GC_STRESS)
     #cc.defines << %w(MRB_NO_STDIO) #if you don't need stdio.
     #cc.defines << %w(POOL_PAGE_SIZE=1000) #effective only for use with mruby-eval

build_config/RX630.rb

@@ -16,7 +16,7 @@ MRuby::CrossBuild.new("RX630") do |conf|
     #configuration for low memory environment
     cc.defines << %w(MRB_USE_FLOAT32)
     cc.defines << %w(MRB_HEAP_PAGE_SIZE=64)
-    cc.defines << %w(KHASH_DEFAULT_SIZE=8)
+    cc.defines << %w(KHASH_INITIAL_SIZE=8)
     cc.defines << %w(MRB_GC_STRESS)
     cc.defines << %w(MRB_NO_STDIO) #if you don't need stdio.
     #cc.defines << %w(POOL_PAGE_SIZE=1000) #effective only for use with mruby-eval

build_config/chipKITMax32.rb

@@ -27,7 +27,7 @@ MRuby::CrossBuild.new("chipKITMax32") do |conf|
 
     #configuration for low memory environment
     cc.defines << %w(MRB_HEAP_PAGE_SIZE=64)
-    cc.defines << %w(KHASH_DEFAULT_SIZE=8)
+    cc.defines << %w(KHASH_INITIAL_SIZE=8)
     cc.defines << %w(MRB_GC_STRESS)
     #cc.defines << %w(MRB_NO_STDIO) #if you don't need stdio.
     #cc.defines << %w(POOL_PAGE_SIZE=1000) #effective only for use with mruby-eval

doc/README.md

@@ -4,44 +4,44 @@
 
 New to mruby? Start here:
 
-| Document | Description |
-| -------- | ----------- |
+| Document                                     | Description                            |
+| -------------------------------------------- | -------------------------------------- |
 | [Getting Started](guides/getting-started.md) | Build mruby and run your first program |
-| [Language Features](guides/language.md) | Ruby subset supported by mruby |
-| [Limitations](limitations.md) | Behavioral differences from CRuby |
+| [Language Features](guides/language.md)      | Ruby subset supported by mruby         |
+| [Limitations](limitations.md)                | Behavioral differences from CRuby      |
 
 ## Guides (for embedders and gem authors)
 
 ### Embedding mruby in C
 
-| Document | Description |
-| -------- | ----------- |
-| [C API Reference](guides/capi.md) | Values, classes, methods, error handling, fibers |
-| [GC Arena](guides/gc-arena-howto.md) | Managing temporary objects in C extensions |
-| [Linking](guides/link.md) | Linking with `libmruby` |
-| [Amalgamation](guides/amalgamation.md) | Single-file build for easy integration |
-| [Precompiled Symbols](guides/symbol.md) | Compile-time symbol allocation |
+| Document                                | Description                                      |
+| --------------------------------------- | ------------------------------------------------ |
+| [C API Reference](guides/capi.md)       | Values, classes, methods, error handling, fibers |
+| [GC Arena](guides/gc-arena-howto.md)    | Managing temporary objects in C extensions       |
+| [Linking](guides/link.md)               | Linking with `libmruby`                          |
+| [Amalgamation](guides/amalgamation.md)  | Single-file build for easy integration           |
+| [Precompiled Symbols](guides/symbol.md) | Compile-time symbol allocation                   |
 
 ### Building and Configuring
 
-| Document | Description |
-| -------- | ----------- |
-| [Compilation](guides/compile.md) | Build system, cross-compilation, toolchains |
-| [Build Configuration](guides/mrbconf.md) | Compile-time macros (`MRB_*` flags) |
-| [mrbgems](guides/mrbgems.md) | Creating and managing gems |
-| [Memory](guides/memory.md) | Allocator customization and heap regions |
+| Document                                 | Description                                 |
+| ---------------------------------------- | ------------------------------------------- |
+| [Compilation](guides/compile.md)         | Build system, cross-compilation, toolchains |
+| [Build Configuration](guides/mrbconf.md) | Compile-time macros (`MRB_*` flags)         |
+| [mrbgems](guides/mrbgems.md)             | Creating and managing gems                  |
+| [Memory](guides/memory.md)               | Allocator customization and heap regions    |
 
 ### Tools
 
-| Document | Description |
-| -------- | ----------- |
-| [Debugger](guides/debugger.md) | Using `mrdb` for debugging |
+| Document                                        | Description                                     |
+| ----------------------------------------------- | ----------------------------------------------- |
+| [Debugger](guides/debugger.md)                  | Using `mrdb` for debugging                      |
 | [ROM Method Tables](guides/rom-method-table.md) | Read-only method tables for constrained devices |
 
 ### Reference
 
-| Document | Description |
-| -------- | ----------- |
+| Document                              | Description        |
+| ------------------------------------- | ------------------ |
 | [Directory Structure](guides/hier.md) | Source tree layout |
 
 ## Internals (for mruby contributors)
@@ -49,14 +49,14 @@ New to mruby? Start here:
 Start with [Architecture](internal/architecture.md) for an overview,
 then dive into the subsystem you need:
 
-| Document | Description |
-| -------- | ----------- |
-| [Architecture](internal/architecture.md) | Overview of object model, VM, GC, compiler |
-| [Virtual Machine](internal/vm.md) | Dispatch loop, call frames, method lookup, fibers |
-| [Garbage Collector](internal/gc.md) | Tri-color marking, write barriers, generational GC |
-| [Compiler Pipeline](internal/compiler.md) | Parser, code generator, IRep, binary format |
-| [Opcodes](internal/opcode.md) | VM instruction set reference |
-| [Value Boxing](internal/boxing.md) | How `mrb_value` encodes types |
+| Document                                  | Description                                        |
+| ----------------------------------------- | -------------------------------------------------- |
+| [Architecture](internal/architecture.md)  | Overview of object model, VM, GC, compiler         |
+| [Virtual Machine](internal/vm.md)         | Dispatch loop, call frames, method lookup, fibers  |
+| [Garbage Collector](internal/gc.md)       | Tri-color marking, write barriers, generational GC |
+| [Compiler Pipeline](internal/compiler.md) | Parser, code generator, IRep, binary format        |
+| [Opcodes](internal/opcode.md)             | VM instruction set reference                       |
+| [Value Boxing](internal/boxing.md)        | How `mrb_value` encodes types                      |
 
 ## Release Notes
 

doc/guides/capi.md

@@ -99,23 +99,23 @@ mrb_str_to_cstr(mrb, v)     /* const char* from String value */
 
 ### Value Types
 
-| `mrb_vtype` | Ruby Class | Notes |
-| ----------- | ---------- | ----- |
-| `MRB_TT_FALSE` | FalseClass/NilClass | `nil` has `MRB_TT_FALSE` |
-| `MRB_TT_TRUE` | TrueClass | |
-| `MRB_TT_INTEGER` | Integer | Immediate value |
-| `MRB_TT_FLOAT` | Float | May be immediate |
-| `MRB_TT_SYMBOL` | Symbol | Immediate value |
-| `MRB_TT_STRING` | String | Heap object |
-| `MRB_TT_ARRAY` | Array | Heap object |
-| `MRB_TT_HASH` | Hash | Heap object |
-| `MRB_TT_OBJECT` | Object | User-defined classes |
-| `MRB_TT_CLASS` | Class | |
-| `MRB_TT_MODULE` | Module | |
-| `MRB_TT_PROC` | Proc | |
-| `MRB_TT_CDATA` | (C data) | Wrapped C structs |
-| `MRB_TT_EXCEPTION` | Exception | |
-| `MRB_TT_FIBER` | Fiber | |
+| `mrb_vtype`        | Ruby Class          | Notes                    |
+| ------------------ | ------------------- | ------------------------ |
+| `MRB_TT_FALSE`     | FalseClass/NilClass | `nil` has `MRB_TT_FALSE` |
+| `MRB_TT_TRUE`      | TrueClass           |                          |
+| `MRB_TT_INTEGER`   | Integer             | Immediate value          |
+| `MRB_TT_FLOAT`     | Float               | May be immediate         |
+| `MRB_TT_SYMBOL`    | Symbol              | Immediate value          |
+| `MRB_TT_STRING`    | String              | Heap object              |
+| `MRB_TT_ARRAY`     | Array               | Heap object              |
+| `MRB_TT_HASH`      | Hash                | Heap object              |
+| `MRB_TT_OBJECT`    | Object              | User-defined classes     |
+| `MRB_TT_CLASS`     | Class               |                          |
+| `MRB_TT_MODULE`    | Module              |                          |
+| `MRB_TT_PROC`      | Proc                |                          |
+| `MRB_TT_CDATA`     | (C data)            | Wrapped C structs        |
+| `MRB_TT_EXCEPTION` | Exception           |                          |
+| `MRB_TT_FIBER`     | Fiber               |                          |
 
 ## Defining Classes and Modules
 
@@ -165,15 +165,15 @@ mrb_define_module_function(mrb, mod, "name", my_method, MRB_ARGS_ANY());
 
 ### Argument Specifiers
 
-| Macro | Meaning |
-| ----- | ------- |
-| `MRB_ARGS_NONE()` | No arguments |
-| `MRB_ARGS_REQ(n)` | `n` required arguments |
-| `MRB_ARGS_OPT(n)` | `n` optional arguments |
-| `MRB_ARGS_ARG(r,o)` | `r` required + `o` optional |
-| `MRB_ARGS_REST()` | Splat (`*args`) |
-| `MRB_ARGS_BLOCK()` | Block (`&block`) |
-| `MRB_ARGS_ANY()` | Any number (same as REST) |
+| Macro                  | Meaning                               |
+| ---------------------- | ------------------------------------- |
+| `MRB_ARGS_NONE()`      | No arguments                          |
+| `MRB_ARGS_REQ(n)`      | `n` required arguments                |
+| `MRB_ARGS_OPT(n)`      | `n` optional arguments                |
+| `MRB_ARGS_ARG(r,o)`    | `r` required + `o` optional           |
+| `MRB_ARGS_REST()`      | Splat (`*args`)                       |
+| `MRB_ARGS_BLOCK()`     | Block (`&block`)                      |
+| `MRB_ARGS_ANY()`       | Any number (same as REST)             |
 | `MRB_ARGS_KEY(n,rest)` | `n` keyword args, `rest`=1 for `**kw` |
 
 These can be combined with `|`:
@@ -192,27 +192,27 @@ mrb_int mrb_get_args(mrb_state *mrb, const char *format, ...);
 
 ### Format Specifiers
 
-| Spec | Ruby Type | C Type(s) | Notes |
-| ---- | --------- | --------- | ----- |
-| `o` | any | `mrb_value` | No type check |
-| `i` | Numeric | `mrb_int` | Coerces to integer |
-| `f` | Numeric | `mrb_float` | Coerces to float |
-| `b` | any | `mrb_bool` | Truthiness |
-| `n` | String/Symbol | `mrb_sym` | Converts to symbol |
-| `s` | String | `const char*, mrb_int` | Pointer + length |
-| `z` | String | `const char*` | Null-terminated |
-| `S` | String | `mrb_value` | String value |
-| `A` | Array | `mrb_value` | Array value |
-| `H` | Hash | `mrb_value` | Hash value |
-| `C` | Class | `mrb_value` | Class/Module value |
-| `c` | Class | `struct RClass*` | Class pointer |
-| `a` | Array | `const mrb_value*, mrb_int` | Array pointer + length |
-| `d` | C Data | `void*` | Requires `mrb_data_type*` |
-| `&` | Block | `mrb_value` | Block argument |
-| `*` | rest | `const mrb_value*, mrb_int` | Rest arguments |
-| `\|` | — | — | Following args are optional |
-| `?` | — | `mrb_bool` | Was previous optional arg given? |
-| `:` | keywords | `mrb_kwargs` | Keyword arguments |
+| Spec | Ruby Type     | C Type(s)                   | Notes                            |
+| ---- | ------------- | --------------------------- | -------------------------------- |
+| `o`  | any           | `mrb_value`                 | No type check                    |
+| `i`  | Numeric       | `mrb_int`                   | Coerces to integer               |
+| `f`  | Numeric       | `mrb_float`                 | Coerces to float                 |
+| `b`  | any           | `mrb_bool`                  | Truthiness                       |
+| `n`  | String/Symbol | `mrb_sym`                   | Converts to symbol               |
+| `s`  | String        | `const char*, mrb_int`      | Pointer + length                 |
+| `z`  | String        | `const char*`               | Null-terminated                  |
+| `S`  | String        | `mrb_value`                 | String value                     |
+| `A`  | Array         | `mrb_value`                 | Array value                      |
+| `H`  | Hash          | `mrb_value`                 | Hash value                       |
+| `C`  | Class         | `mrb_value`                 | Class/Module value               |
+| `c`  | Class         | `struct RClass*`            | Class pointer                    |
+| `a`  | Array         | `const mrb_value*, mrb_int` | Array pointer + length           |
+| `d`  | C Data        | `void*`                     | Requires `mrb_data_type*`        |
+| `&`  | Block         | `mrb_value`                 | Block argument                   |
+| `*`  | rest          | `const mrb_value*, mrb_int` | Rest arguments                   |
+| `\|` | —             | —                           | Following args are optional      |
+| `?`  | —             | `mrb_bool`                  | Was previous optional arg given? |
+| `:`  | keywords      | `mrb_kwargs`                | Keyword arguments                |
 
 Adding `!` to `S`, `A`, `H`, `C`, `c`, `s`, `z`, `a`, `d` allows `nil`
 (returns NULL/zero for nil).
@@ -608,14 +608,14 @@ my_yield_method(mrb_state *mrb, mrb_value self)
 
 ### Fiber States
 
-| State | Meaning |
-| ----- | ------- |
-| `MRB_FIBER_CREATED` | Created but not yet resumed |
-| `MRB_FIBER_RUNNING` | Currently executing |
-| `MRB_FIBER_RESUMED` | Resumed another fiber |
-| `MRB_FIBER_SUSPENDED` | Yielded, waiting to resume |
+| State                   | Meaning                          |
+| ----------------------- | -------------------------------- |
+| `MRB_FIBER_CREATED`     | Created but not yet resumed      |
+| `MRB_FIBER_RUNNING`     | Currently executing              |
+| `MRB_FIBER_RESUMED`     | Resumed another fiber            |
+| `MRB_FIBER_SUSPENDED`   | Yielded, waiting to resume       |
 | `MRB_FIBER_TRANSFERRED` | Transferred via `Fiber#transfer` |
-| `MRB_FIBER_TERMINATED` | Finished execution |
+| `MRB_FIBER_TERMINATED`  | Finished execution               |
 
 **Limitation:** fibers cannot yield across C function boundaries.
 You cannot call `mrb_fiber_yield` from within a C-implemented
@@ -644,13 +644,13 @@ mrb_ccontext_free(mrb, cxt);
 
 The `mrb_ccontext` structure provides several flags:
 
-| Field | Purpose |
-| ----- | ------- |
+| Field            | Purpose                                 |
+| ---------------- | --------------------------------------- |
 | `capture_errors` | Collect parse errors instead of raising |
-| `no_exec` | Compile without executing (get RProc) |
-| `no_optimize` | Disable peephole optimizations |
-| `no_ext_ops` | Disable extended operand instructions |
-| `keep_lv` | Preserve local variables across loads |
+| `no_exec`        | Compile without executing (get RProc)   |
+| `no_optimize`    | Disable peephole optimizations          |
+| `no_ext_ops`     | Disable extended operand instructions   |
+| `keep_lv`        | Preserve local variables across loads   |
 
 ### Loading with Context
 
@@ -843,14 +843,14 @@ $ build/host/bin/mruby-config --libs      # libraries
 
 Key macros that affect ABI:
 
-| Macro | Effect |
-| ----- | ------ |
-| `MRB_NO_BOXING` | Struct-based values (larger, debuggable) |
-| `MRB_WORD_BOXING` | Single-word values (fast, 32-bit safe) |
-| `MRB_NAN_BOXING` | NaN-tagged values (default on 32-bit) |
-| `MRB_NO_FLOAT` | Disable Float support |
-| `MRB_INT64` | 64-bit integers |
-| `MRB_USE_FLOAT32` | 32-bit floats |
+| Macro             | Effect                                   |
+| ----------------- | ---------------------------------------- |
+| `MRB_NO_BOXING`   | Struct-based values (larger, debuggable) |
+| `MRB_WORD_BOXING` | Single-word values (fast, 32-bit safe)   |
+| `MRB_NAN_BOXING`  | NaN-tagged values (default on 32-bit)    |
+| `MRB_NO_FLOAT`    | Disable Float support                    |
+| `MRB_INT64`       | 64-bit integers                          |
+| `MRB_USE_FLOAT32` | 32-bit floats                            |
 
 Mismatching these between library and application causes silent
 data corruption.

doc/guides/debugger.md

@@ -40,7 +40,7 @@ To confirm mrdb was installed properly, run mrdb with the `--version` option:
 
 ```bash
 $ mrdb --version
-mruby 3.4.0 (2025-04-20)
+mruby 4.0.0 (2026-04-20)
 ```
 
 ## 2.2 Basic Operation

doc/guides/language.md

@@ -205,11 +205,11 @@ mruby's numeric type sizes depend on the boxing mode and platform.
 
 ### Integer
 
-| Configuration | Range |
-| ------------- | ----- |
+| Configuration                          | Range            |
+| -------------------------------------- | ---------------- |
 | 64-bit word boxing (default on 64-bit) | roughly +/- 2^62 |
 | 32-bit word boxing (default on 32-bit) | roughly +/- 2^30 |
-| NaN boxing (64-bit only) | -2^31 to 2^31-1 |
+| NaN boxing (64-bit only)               | -2^31 to 2^31-1  |
 
 Integer overflow raises a `RangeError` unless the `mruby-bigint` gem
 is included, in which case integers automatically promote to
@@ -235,32 +235,32 @@ With word boxing on 64-bit, many float values are stored inline
 
 These classes are always available in mruby (no gem required):
 
-| Class | Notes |
-| ----- | ----- |
-| Object | Base class for all objects |
-| Module | Module definition and mixin |
-| Class | Class definition and instantiation |
-| NilClass | Singleton `nil` |
-| TrueClass | Singleton `true` |
-| FalseClass | Singleton `false` |
-| Integer | Fixed-precision integer |
-| Float | Floating-point (unless `MRB_NO_FLOAT`) |
-| Symbol | Interned identifier |
-| String | Mutable byte string |
-| Array | Ordered collection |
-| Hash | Key-value mapping |
-| Range | Interval representation |
-| Proc | Closure / callable object |
-| Exception | Exception hierarchy root |
-| StandardError | Common error base |
+| Class         | Notes                                  |
+| ------------- | -------------------------------------- |
+| Object        | Base class for all objects             |
+| Module        | Module definition and mixin            |
+| Class         | Class definition and instantiation     |
+| NilClass      | Singleton `nil`                        |
+| TrueClass     | Singleton `true`                       |
+| FalseClass    | Singleton `false`                      |
+| Integer       | Fixed-precision integer                |
+| Float         | Floating-point (unless `MRB_NO_FLOAT`) |
+| Symbol        | Interned identifier                    |
+| String        | Mutable byte string                    |
+| Array         | Ordered collection                     |
+| Hash          | Key-value mapping                      |
+| Range         | Interval representation                |
+| Proc          | Closure / callable object              |
+| Exception     | Exception hierarchy root               |
+| StandardError | Common error base                      |
 
 ### Core Modules
 
-| Module | Notes |
-| ------ | ----- |
-| Kernel | Core methods (`puts`, `p`, `raise`, etc.) |
-| Comparable | Comparison operators via `<=>` |
-| Enumerable | Collection iteration methods |
+| Module     | Notes                                     |
+| ---------- | ----------------------------------------- |
+| Kernel     | Core methods (`puts`, `p`, `raise`, etc.) |
+| Comparable | Comparison operators via `<=>`            |
+| Enumerable | Collection iteration methods              |
 
 ## Standard Library (via gemboxes)
 
@@ -270,70 +270,70 @@ gembox provides the class or feature you need:
 
 ### Classes and Modules
 
-| Class/Module | Gembox | Gem |
-| ------------ | ------ | --- |
-| Fiber | stdlib | mruby-fiber |
-| Enumerator | stdlib | mruby-enumerator |
-| Enumerator::Lazy | stdlib | mruby-enum-lazy |
-| Set | stdlib | mruby-set |
-| ObjectSpace | stdlib | mruby-objectspace |
-| Time | stdlib-ext | mruby-time |
-| Struct | stdlib-ext | mruby-struct |
-| Data | stdlib-ext | mruby-data |
-| Random | stdlib-ext | mruby-random |
-| IO, File | stdlib-io | mruby-io |
-| Socket | stdlib-io | mruby-socket |
-| Dir | stdlib-io | mruby-dir |
-| Errno | stdlib-io | mruby-errno |
-| Math | math | mruby-math |
-| Rational | math | mruby-rational |
-| Complex | math | mruby-complex |
-| Bigint | math | mruby-bigint |
-| Method, UnboundMethod | metaprog | mruby-method |
+| Class/Module          | Gembox     | Gem               |
+| --------------------- | ---------- | ----------------- |
+| Fiber                 | stdlib     | mruby-fiber       |
+| Enumerator            | stdlib     | mruby-enumerator  |
+| Enumerator::Lazy      | stdlib     | mruby-enum-lazy   |
+| Set                   | stdlib     | mruby-set         |
+| ObjectSpace           | stdlib     | mruby-objectspace |
+| Time                  | stdlib-ext | mruby-time        |
+| Struct                | stdlib-ext | mruby-struct      |
+| Data                  | stdlib-ext | mruby-data        |
+| Random                | stdlib-ext | mruby-random      |
+| IO, File              | stdlib-io  | mruby-io          |
+| Socket                | stdlib-io  | mruby-socket      |
+| Dir                   | stdlib-io  | mruby-dir         |
+| Errno                 | stdlib-io  | mruby-errno       |
+| Math                  | math       | mruby-math        |
+| Rational              | math       | mruby-rational    |
+| Complex               | math       | mruby-complex     |
+| Bigint                | math       | mruby-bigint      |
+| Method, UnboundMethod | metaprog   | mruby-method      |
 
 ### Methods and Features
 
-| Feature | Gembox | Gem |
-| ------- | ------ | --- |
-| `catch`/`throw` | stdlib | mruby-catch |
-| `Kernel#sprintf`, `String#%` | stdlib-ext | mruby-sprintf |
-| `Array#pack`, `String#unpack` | stdlib-ext | mruby-pack |
-| `Kernel#rand` | stdlib-ext | mruby-random |
-| `Kernel#eval` | metaprog | mruby-eval |
-| `Kernel#binding` | metaprog | mruby-binding |
-| `Proc#binding` | metaprog | mruby-proc-binding |
-| Runtime compiler | metaprog | mruby-compiler |
+| Feature                       | Gembox     | Gem                |
+| ----------------------------- | ---------- | ------------------ |
+| `catch`/`throw`               | stdlib     | mruby-catch        |
+| `Kernel#sprintf`, `String#%`  | stdlib-ext | mruby-sprintf      |
+| `Array#pack`, `String#unpack` | stdlib-ext | mruby-pack         |
+| `Kernel#rand`                 | stdlib-ext | mruby-random       |
+| `Kernel#eval`                 | metaprog   | mruby-eval         |
+| `Kernel#binding`              | metaprog   | mruby-binding      |
+| `Proc#binding`                | metaprog   | mruby-proc-binding |
+| Runtime compiler              | metaprog   | mruby-compiler     |
 
 ### Core Class Extensions
 
 The `stdlib` gembox also extends built-in classes with additional
 methods. These are included by default:
 
-| Extension | Examples |
-| --------- | -------- |
-| Array extensions | `#dig`, `#union`, `#difference` |
-| Hash extensions | `#dig`, `#transform_keys`, `#transform_values` |
-| String extensions | `#encode`, `#bytes`, `#chars` |
-| Numeric extensions | `Integer#digits`, `Integer#pow` |
-| Comparable extensions | `#clamp` |
-| Enumerable extensions | `#sort_by`, `#min_by`, `#max_by`, `#tally` |
-| Range extensions | `#size`, `#cover?` |
-| Proc extensions | `#<<`, `#>>` (composition) |
-| Symbol extensions | `#to_proc` |
-| Object extensions | `#then`, `#yield_self` |
-| Kernel extensions | `#__method__` |
-| Class/Module extensions | `Module#name` |
+| Extension               | Examples                                       |
+| ----------------------- | ---------------------------------------------- |
+| Array extensions        | `#dig`, `#union`, `#difference`                |
+| Hash extensions         | `#dig`, `#transform_keys`, `#transform_values` |
+| String extensions       | `#encode`, `#bytes`, `#chars`                  |
+| Numeric extensions      | `Integer#digits`, `Integer#pow`                |
+| Comparable extensions   | `#clamp`                                       |
+| Enumerable extensions   | `#sort_by`, `#min_by`, `#max_by`, `#tally`     |
+| Range extensions        | `#size`, `#cover?`                             |
+| Proc extensions         | `#<<`, `#>>` (composition)                     |
+| Symbol extensions       | `#to_proc`                                     |
+| Object extensions       | `#then`, `#yield_self`                         |
+| Kernel extensions       | `#__method__`                                  |
+| Class/Module extensions | `Module#name`                                  |
 
 ### Gembox Summary
 
-| Gembox | Contents | Notes |
-| ------ | -------- | ----- |
-| `stdlib` | Core class extensions, Fiber, Enumerator, Set | Works with `MRB_NO_STDIO` and `MRB_NO_FLOAT` |
-| `stdlib-ext` | Time, Struct, Data, Random, sprintf, pack | Works with `MRB_NO_STDIO` and `MRB_NO_FLOAT` |
-| `stdlib-io` | IO, File, Dir, Socket, Errno | Requires stdio |
-| `math` | Math, Rational, Complex, Bigint | Works with `MRB_NO_STDIO` |
-| `metaprog` | eval, binding, Method, compiler | Works with `MRB_NO_STDIO` and `MRB_NO_FLOAT` |
-| `default` | All of the above + CLI tools | Full installation |
+| Gembox       | Contents                                      | Notes                                        |
+| ------------ | --------------------------------------------- | -------------------------------------------- |
+| `stdlib`     | Core class extensions, Fiber, Enumerator, Set | Works with `MRB_NO_STDIO` and `MRB_NO_FLOAT` |
+| `stdlib-ext` | Time, Struct, Data, Random, sprintf, pack     | Works with `MRB_NO_STDIO` and `MRB_NO_FLOAT` |
+| `stdlib-io`  | IO, File, Dir, Socket, Errno                  | Requires stdio                               |
+| `math`       | Math, Rational, Complex, Bigint               | Works with `MRB_NO_STDIO`                    |
+| `metaprog`   | eval, binding, Method, compiler               | Works with `MRB_NO_STDIO` and `MRB_NO_FLOAT` |
+| `default`    | All of the above + CLI tools                  | Full installation                            |
 
 ## Key Differences from CRuby
 
@@ -416,15 +416,15 @@ differently on 32-bit or NaN boxing configurations.
 
 Key compile-time macros that affect language behavior:
 
-| Macro | Effect |
-| ----- | ------ |
-| `MRB_NO_FLOAT` | Remove all float support |
-| `MRB_USE_FLOAT32` | Use 32-bit float instead of double |
-| `MRB_UTF8_STRING` | Enable UTF-8 string handling |
-| `MRB_INT32` | Force 32-bit integer |
-| `MRB_INT64` | Force 64-bit integer |
-| `MRB_STR_LENGTH_MAX` | Max string length (default 1MB) |
-| `MRB_ARY_LENGTH_MAX` | Max array length (default 2^17) |
+| Macro                | Effect                             |
+| -------------------- | ---------------------------------- |
+| `MRB_NO_FLOAT`       | Remove all float support           |
+| `MRB_USE_FLOAT32`    | Use 32-bit float instead of double |
+| `MRB_UTF8_STRING`    | Enable UTF-8 string handling       |
+| `MRB_INT32`          | Force 32-bit integer               |
+| `MRB_INT64`          | Force 64-bit integer               |
+| `MRB_STR_LENGTH_MAX` | Max string length (default 1MB)    |
+| `MRB_ARY_LENGTH_MAX` | Max array length (default 2^17)    |
 
 See [mrbconf.md](mrbconf.md) for the complete list of configuration
 macros.

doc/guides/memory.md

@@ -202,10 +202,10 @@ any other heap page. The only differences are:
 The page size is controlled by `MRB_HEAP_PAGE_SIZE` (default: 1024 slots).
 Each page occupies:
 
-| Platform | Slot size | Page size (approx)  |
-|----------|-----------|---------------------|
-| 64-bit   | 40 bytes  | ~41 KB              |
-| 32-bit   | 24 bytes  | ~25 KB              |
+| Platform | Slot size | Page size (approx) |
+| -------- | --------- | ------------------ |
+| 64-bit   | 40 bytes  | ~41 KB             |
+| 32-bit   | 24 bytes  | ~25 KB             |
 
 To estimate pages for a given buffer: `pages = buffer_size / sizeof(mrb_heap_page)`.
 Each page provides `MRB_HEAP_PAGE_SIZE` object slots.

doc/guides/mrbconf.md

@@ -233,10 +233,10 @@ end
 - Specifies 4th argument(`argc`) max value of `mrb_funcall`.
 - Raises `ArgumentError` when the `argc` argument is bigger then this value `mrb_funcall`.
 
-`KHASH_DEFAULT_SIZE`
+`KHASH_INITIAL_SIZE`
 
 - Default value is `32`.
-- Specifies default size of khash table bucket.
+- Specifies initial size of khash table bucket.
 - Used in `kh_init_ ## name` function.
 
 `MRB_NO_METHOD_CACHE`
@@ -272,7 +272,7 @@ deployment targets. Define one of the following:
 `MRB_CONSTRAINED_BASELINE_PROFILE`
 
 - For micro controllers.
-- Enables `MRB_NO_METHOD_CACHE`, reduces `KHASH_DEFAULT_SIZE` to `16`,
+- Enables `MRB_NO_METHOD_CACHE`, reduces `KHASH_INITIAL_SIZE` to `16`,
   and `MRB_HEAP_PAGE_SIZE` to `256`.
 
 `MRB_BASELINE_PROFILE`

doc/internal/architecture.md

@@ -31,17 +31,17 @@ struct RBasic (8 bytes on 64-bit)
 
 All object structs embed this header via `MRB_OBJECT_HEADER`:
 
-| Struct | Ruby Type | Extra Fields |
-| ------ | --------- | ------------ |
-| `RObject` | Object instances | `iv` (instance variables) |
-| `RClass` | Class/Module | `iv`, `mt` (method table), `super` |
-| `RString` | String | embedded or heap buffer, length |
-| `RArray` | Array | embedded or heap buffer, length |
-| `RHash` | Hash | hash table or k-v array |
-| `RProc` | Proc/Lambda | `irep` or C function, environment |
-| `RData` | C data wrapper | `void *data`, `mrb_data_type` |
-| `RFiber` | Fiber | `mrb_context` |
-| `RException` | Exception | `iv` |
+| Struct       | Ruby Type        | Extra Fields                       |
+| ------------ | ---------------- | ---------------------------------- |
+| `RObject`    | Object instances | `iv` (instance variables)          |
+| `RClass`     | Class/Module     | `iv`, `mt` (method table), `super` |
+| `RString`    | String           | embedded or heap buffer, length    |
+| `RArray`     | Array            | embedded or heap buffer, length    |
+| `RHash`      | Hash             | hash table or k-v array            |
+| `RProc`      | Proc/Lambda      | `irep` or C function, environment  |
+| `RData`      | C data wrapper   | `void *data`, `mrb_data_type`      |
+| `RFiber`     | Fiber            | `mrb_context`                      |
+| `RException` | Exception        | `iv`                               |
 
 Immediate values (Integer, Symbol, `true`, `false`, `nil`) are encoded
 directly in `mrb_value` without heap allocation. The encoding depends on
@@ -111,52 +111,52 @@ See [compiler.md](compiler.md) for detailed compiler internals,
 
 ### Core (`src/`)
 
-| File | Responsibility |
-| ---- | -------------- |
-| `vm.c` | Bytecode dispatch loop, method invocation |
-| `state.c` | `mrb_state` init/close, irep management |
-| `gc.c` | Garbage collector (mark-sweep, incremental) |
-| `class.c` | Class/module definition, method tables |
-| `object.c` | Core object operations |
-| `variable.c` | Instance/class/global variables, object shapes |
-| `proc.c` | Proc/Lambda/closure handling |
-| `array.c` | Array implementation |
-| `string.c` | String implementation (embedded, shared, heap) |
-| `hash.c` | Hash implementation (open addressing) |
-| `numeric.c` | Integer/Float arithmetic |
-| `symbol.c` | Symbol table and interning |
-| `range.c` | Range implementation |
-| `error.c` | Exception creation, raise, backtrace |
-| `kernel.c` | Kernel module methods |
-| `load.c` | `.mrb` bytecode loading |
-| `dump.c` | Bytecode serialization (write `.mrb`) |
-| `print.c` | Print/puts/p output |
-| `backtrace.c` | Stack trace generation |
+| File          | Responsibility                                 |
+| ------------- | ---------------------------------------------- |
+| `vm.c`        | Bytecode dispatch loop, method invocation      |
+| `state.c`     | `mrb_state` init/close, irep management        |
+| `gc.c`        | Garbage collector (mark-sweep, incremental)    |
+| `class.c`     | Class/module definition, method tables         |
+| `object.c`    | Core object operations                         |
+| `variable.c`  | Instance/class/global variables, object shapes |
+| `proc.c`      | Proc/Lambda/closure handling                   |
+| `array.c`     | Array implementation                           |
+| `string.c`    | String implementation (embedded, shared, heap) |
+| `hash.c`      | Hash implementation (open addressing)          |
+| `numeric.c`   | Integer/Float arithmetic                       |
+| `symbol.c`    | Symbol table and interning                     |
+| `range.c`     | Range implementation                           |
+| `error.c`     | Exception creation, raise, backtrace           |
+| `kernel.c`    | Kernel module methods                          |
+| `load.c`      | `.mrb` bytecode loading                        |
+| `dump.c`      | Bytecode serialization (write `.mrb`)          |
+| `print.c`     | Print/puts/p output                            |
+| `backtrace.c` | Stack trace generation                         |
 
 ### Compiler (`mrbgems/mruby-compiler/core/`)
 
-| File | Responsibility |
-| ---- | -------------- |
-| `parse.y` | Yacc grammar → AST |
-| `y.tab.c` | Generated parser (from parse.y) |
-| `codegen.c` | AST → bytecode (irep) |
-| `node.h` | AST node type definitions |
+| File        | Responsibility                  |
+| ----------- | ------------------------------- |
+| `parse.y`   | Yacc grammar → AST              |
+| `y.tab.c`   | Generated parser (from parse.y) |
+| `codegen.c` | AST → bytecode (irep)           |
+| `node.h`    | AST node type definitions       |
 
 ### Key Headers (`include/mruby/`)
 
-| Header | Contents |
-| ------ | -------- |
-| `mruby.h` | `mrb_state`, core API declarations |
-| `value.h` | `mrb_value`, type enums, value macros |
-| `object.h` | `RBasic`, `RObject`, object header |
-| `class.h` | `RClass`, method table types |
-| `string.h` | `RString`, string macros |
-| `array.h` | `RArray`, array macros |
-| `hash.h` | `RHash`, hash API |
-| `data.h` | `RData`, C data wrapping |
-| `irep.h` | `mrb_irep`, bytecode structures |
-| `compile.h` | Compiler context, `mrb_load_string` |
-| `boxing_*.h` | Value boxing implementations |
+| Header       | Contents                              |
+| ------------ | ------------------------------------- |
+| `mruby.h`    | `mrb_state`, core API declarations    |
+| `value.h`    | `mrb_value`, type enums, value macros |
+| `object.h`   | `RBasic`, `RObject`, object header    |
+| `class.h`    | `RClass`, method table types          |
+| `string.h`   | `RString`, string macros              |
+| `array.h`    | `RArray`, array macros                |
+| `hash.h`     | `RHash`, hash API                     |
+| `data.h`     | `RData`, C data wrapping              |
+| `irep.h`     | `mrb_irep`, bytecode structures       |
+| `compile.h`  | Compiler context, `mrb_load_string`   |
+| `boxing_*.h` | Value boxing implementations          |
 
 ## mrbgems System
 

doc/internal/boxing.md

@@ -77,16 +77,16 @@ No boxing represents `mrb_value` by the C struct with `type` and the value union
 
 ## Comparison
 
-| Property               | Word Boxing        | NaN Boxing         | No Boxing            |
-| ---------------------- | ------------------ | ------------------ | -------------------- |
-| `mrb_value` size       | 1 word (4/8 byte)  | 8 bytes            | 2 words (8/16 bytes) |
-| Default on             | most platforms     | (manual opt-in)    | `host-debug`         |
-| Macro                  | `MRB_WORD_BOXING`  | `MRB_NAN_BOXING`   | `MRB_NO_BOXING`      |
-| Inline integers        | yes (31/63 bit)    | yes (32 bit)       | yes (full width)     |
-| Inline floats (64-bit) | yes (rotation)     | yes (native)       | yes (struct field)   |
-| Inline floats (32-bit) | no (heap RFloat)   | yes (native)       | yes (struct field)   |
-| Pointer size limit     | none               | 48 bits            | none                 |
-| Debugger friendly      | no                 | no                 | yes                  |
+| Property               | Word Boxing       | NaN Boxing       | No Boxing            |
+| ---------------------- | ----------------- | ---------------- | -------------------- |
+| `mrb_value` size       | 1 word (4/8 byte) | 8 bytes          | 2 words (8/16 bytes) |
+| Default on             | most platforms    | (manual opt-in)  | `host-debug`         |
+| Macro                  | `MRB_WORD_BOXING` | `MRB_NAN_BOXING` | `MRB_NO_BOXING`      |
+| Inline integers        | yes (31/63 bit)   | yes (32 bit)     | yes (full width)     |
+| Inline floats (64-bit) | yes (rotation)    | yes (native)     | yes (struct field)   |
+| Inline floats (32-bit) | no (heap RFloat)  | yes (native)     | yes (struct field)   |
+| Pointer size limit     | none              | 48 bits          | none                 |
+| Debugger friendly      | no                | no               | yes                  |
 
 ## ABI Compatibility
 

doc/internal/compiler.md

@@ -40,18 +40,18 @@ file: `mrbgems/mruby-compiler/core/parse.y`.
 
 The parser maintains extensive state in `mrb_parser_state`:
 
-- **lstate**: current lexer state (EXPR\_BEG, EXPR\_END, EXPR\_ARG,
-  EXPR\_DOT, EXPR\_FNAME, etc.). Controls how tokens like `+`/`-`
+- **lstate**: current lexer state (EXPR_BEG, EXPR_END, EXPR_ARG,
+  EXPR_DOT, EXPR_FNAME, etc.). Controls how tokens like `+`/`-`
   are interpreted (sign vs operator) and whether newlines are
   significant.
 - **locals**: stack of local variable lists (one per scope), stored
   as cons-lists of symbols.
-- **lex\_strterm**: string/heredoc parsing state for handling nested
+- **lex_strterm**: string/heredoc parsing state for handling nested
   interpolation.
-- **cond\_stack**, **cmdarg\_stack**: bit stacks tracking
+- **cond_stack**, **cmdarg_stack**: bit stacks tracking
   conditional and command argument contexts.
 - **tree**: root AST node after successful parse.
-- **error\_buffer**: accumulated parse errors.
+- **error_buffer**: accumulated parse errors.
 
 ### AST Nodes
 
@@ -123,10 +123,10 @@ reuse temporaries within an expression.
 Instructions are emitted via helper functions:
 
 - `genop_0(opcode)`: no operands
-- `genop_1(opcode, a)`: one operand (auto-extends with OP\_EXT1
+- `genop_1(opcode, a)`: one operand (auto-extends with OP_EXT1
   if a > 255)
 - `genop_2(opcode, a, b)`: two operands (auto-extends with
-  OP\_EXT1/2/3 as needed)
+  OP_EXT1/2/3 as needed)
 - `genop_3(opcode, a, b, c)`: three operands
 - `genop_W(opcode, a)`: 24-bit operand
 - `genop_2S(opcode, a, b)`: one 8-bit + one 16-bit operand
@@ -176,14 +176,14 @@ mrb_irep
 
 Pool entries store constants referenced by instructions:
 
-| Type | Tag | Description |
-| ---- | --- | ----------- |
-| `IREP_TT_STR` | 0 | Dynamic string (heap allocated) |
-| `IREP_TT_SSTR` | 2 | Static string (read-only) |
-| `IREP_TT_INT32` | 1 | 32-bit integer |
-| `IREP_TT_INT64` | 3 | 64-bit integer |
-| `IREP_TT_FLOAT` | 5 | Floating-point number |
-| `IREP_TT_BIGINT` | 7 | Arbitrary-precision integer |
+| Type             | Tag | Description                     |
+| ---------------- | --- | ------------------------------- |
+| `IREP_TT_STR`    | 0   | Dynamic string (heap allocated) |
+| `IREP_TT_SSTR`   | 2   | Static string (read-only)       |
+| `IREP_TT_INT32`  | 1   | 32-bit integer                  |
+| `IREP_TT_INT64`  | 3   | 64-bit integer                  |
+| `IREP_TT_FLOAT`  | 5   | Floating-point number           |
+| `IREP_TT_BIGINT` | 7   | Arbitrary-precision integer     |
 
 The code generator deduplicates pool entries: identical strings
 and equal numeric values share the same pool index.
@@ -209,28 +209,28 @@ During exception unwinding, handlers are searched in reverse order
 Standard instructions use 8-bit operands. When a value exceeds
 255, extension prefixes widen operands to 16 bits:
 
-| Prefix | Effect |
-| ------ | ------ |
-| `OP_EXT1` | First operand (a) becomes 16-bit |
+| Prefix    | Effect                            |
+| --------- | --------------------------------- |
+| `OP_EXT1` | First operand (a) becomes 16-bit  |
 | `OP_EXT2` | Second operand (b) becomes 16-bit |
-| `OP_EXT3` | Both a and b become 16-bit |
+| `OP_EXT3` | Both a and b become 16-bit        |
 
 Instruction formats:
 
-| Format | Layout | Size |
-| ------ | ------ | ---- |
-| Z | opcode only | 1 byte |
-| B | opcode + a(8) | 2 bytes |
-| BB | opcode + a(8) + b(8) | 3 bytes |
-| BBB | opcode + a(8) + b(8) + c(8) | 4 bytes |
-| BS | opcode + a(8) + b(16) | 4 bytes |
-| BSS | opcode + a(8) + b(16) + c(16) | 6 bytes |
-| S | opcode + a(16) | 3 bytes |
-| W | opcode + a(24) | 4 bytes |
+| Format | Layout                        | Size    |
+| ------ | ----------------------------- | ------- |
+| Z      | opcode only                   | 1 byte  |
+| B      | opcode + a(8)                 | 2 bytes |
+| BB     | opcode + a(8) + b(8)          | 3 bytes |
+| BBB    | opcode + a(8) + b(8) + c(8)   | 4 bytes |
+| BS     | opcode + a(8) + b(16)         | 4 bytes |
+| BSS    | opcode + a(8) + b(16) + c(16) | 6 bytes |
+| S      | opcode + a(16)                | 3 bytes |
+| W      | opcode + a(24)                | 4 bytes |
 
 See [opcode.md](opcode.md) for the full instruction table.
 
-## OP\_ENTER: Argument Specification
+## OP_ENTER: Argument Specification
 
 `OP_ENTER` encodes a method's argument layout in a 24-bit value
 (W format). The bit fields are defined by the `MRB_ARGS_*` macros:
@@ -258,16 +258,16 @@ string interning for common symbols.
 Generated by `lib/mruby/presym.rb`, the presym table maps symbol
 names to compile-time constants:
 
-| Macro | Example | Symbol |
-| ----- | ------- | ------ |
-| `MRB_SYM(name)` | `MRB_SYM(initialize)` | `:initialize` |
-| `MRB_SYM_B(name)` | `MRB_SYM_B(map)` | `:map!` |
-| `MRB_SYM_Q(name)` | `MRB_SYM_Q(nil)` | `:nil?` |
-| `MRB_SYM_E(name)` | `MRB_SYM_E(name)` | `:name=` |
-| `MRB_OPSYM(op)` | `MRB_OPSYM(add)` | `:+` |
-| `MRB_IVSYM(name)` | `MRB_IVSYM(name)` | `:@name` |
-| `MRB_CVSYM(name)` | `MRB_CVSYM(count)` | `:@@count` |
-| `MRB_GVSYM(name)` | `MRB_GVSYM(stdout)` | `:$stdout` |
+| Macro             | Example               | Symbol        |
+| ----------------- | --------------------- | ------------- |
+| `MRB_SYM(name)`   | `MRB_SYM(initialize)` | `:initialize` |
+| `MRB_SYM_B(name)` | `MRB_SYM_B(map)`      | `:map!`       |
+| `MRB_SYM_Q(name)` | `MRB_SYM_Q(nil)`      | `:nil?`       |
+| `MRB_SYM_E(name)` | `MRB_SYM_E(name)`     | `:name=`      |
+| `MRB_OPSYM(op)`   | `MRB_OPSYM(add)`      | `:+`          |
+| `MRB_IVSYM(name)` | `MRB_IVSYM(name)`     | `:@name`      |
+| `MRB_CVSYM(name)` | `MRB_CVSYM(count)`    | `:@@count`    |
+| `MRB_GVSYM(name)` | `MRB_GVSYM(stdout)`   | `:$stdout`    |
 
 ## Binary Format (.mrb)
 
@@ -299,25 +299,25 @@ mrbc -Boutput source.rb           # C array format
 
 ## Compilation Limits
 
-| Limit | Value |
-| ----- | ----- |
-| Max nesting depth | 256 (`MRB_CODEGEN_LEVEL_MAX`) |
-| Max local variables | 255 (uint16 `nlocals`) |
-| Max symbols per irep | 65535 |
-| Max operand (standard) | 255 (8-bit) |
-| Max operand (extended) | 65535 (16-bit) |
+| Limit                  | Value                         |
+| ---------------------- | ----------------------------- |
+| Max nesting depth      | 256 (`MRB_CODEGEN_LEVEL_MAX`) |
+| Max local variables    | 255 (uint16 `nlocals`)        |
+| Max symbols per irep   | 65535                         |
+| Max operand (standard) | 255 (8-bit)                   |
+| Max operand (extended) | 65535 (16-bit)                |
 
 ## Source Files
 
-| File | Contents |
-| ---- | -------- |
-| `mrbgems/mruby-compiler/core/parse.y` | Lrama/Bison grammar |
-| `mrbgems/mruby-compiler/core/y.tab.c` | Generated parser |
-| `mrbgems/mruby-compiler/core/codegen.c` | Code generator |
-| `mrbgems/mruby-compiler/core/node.h` | AST node types |
-| `include/mruby/irep.h` | IRep structure definition |
-| `include/mruby/compile.h` | Compiler context API |
-| `include/mruby/ops.h` | Opcode definitions |
-| `src/load.c` | Binary format loader |
-| `src/dump.c` | Binary format writer |
-| `lib/mruby/presym.rb` | Presym table generator |
+| File                                    | Contents                  |
+| --------------------------------------- | ------------------------- |
+| `mrbgems/mruby-compiler/core/parse.y`   | Lrama/Bison grammar       |
+| `mrbgems/mruby-compiler/core/y.tab.c`   | Generated parser          |
+| `mrbgems/mruby-compiler/core/codegen.c` | Code generator            |
+| `mrbgems/mruby-compiler/core/node.h`    | AST node types            |
+| `include/mruby/irep.h`                  | IRep structure definition |
+| `include/mruby/compile.h`               | Compiler context API      |
+| `include/mruby/ops.h`                   | Opcode definitions        |
+| `src/load.c`                            | Binary format loader      |
+| `src/dump.c`                            | Binary format writer      |
+| `lib/mruby/presym.rb`                   | Presym table generator    |

doc/internal/gc.md

@@ -26,12 +26,12 @@ pauses.
 Every heap-allocated object has a color stored in
 `RBasic::gc_color` (3 bits):
 
-| Color | Value | Meaning |
-| ----- | ----- | ------- |
-| White (A or B) | 1 or 2 | Unmarked, candidate for collection |
-| Gray | 0 | Marked, but children not yet scanned |
-| Black | 4 | Fully marked and scanned |
-| Red | 7 | Static/ROM object, never collected |
+| Color          | Value  | Meaning                              |
+| -------------- | ------ | ------------------------------------ |
+| White (A or B) | 1 or 2 | Unmarked, candidate for collection   |
+| Gray           | 0      | Marked, but children not yet scanned |
+| Black          | 4      | Fully marked and scanned             |
+| Red            | 7      | Static/ROM object, never collected   |
 
 The GC uses two white types (A and B) in a flip-flop scheme. At the
 start of each GC cycle, the meaning of "current white" is flipped by
@@ -107,7 +107,7 @@ The GC operates as a three-state machine:
 GC_STATE_ROOT --> GC_STATE_MARK --> GC_STATE_SWEEP --> GC_STATE_ROOT
 ```
 
-### Root Scan (GC\_STATE\_ROOT)
+### Root Scan (GC_STATE_ROOT)
 
 Marks objects directly reachable from the VM:
 
@@ -121,7 +121,7 @@ Marks objects directly reachable from the VM:
 
 After root scanning, the white color is flipped.
 
-### Incremental Marking (GC\_STATE\_MARK)
+### Incremental Marking (GC_STATE_MARK)
 
 Gray objects are popped from the gray stack and their children
 marked. Each step processes a limited number of objects:
@@ -137,7 +137,7 @@ When the gray stack is exhausted, the final marking phase re-marks
 the arena and global variables to catch objects created during
 marking, then transitions to sweep.
 
-### Sweep (GC\_STATE\_SWEEP)
+### Sweep (GC_STATE_SWEEP)
 
 Iterates through heap pages. For each object:
 
@@ -325,15 +325,15 @@ From Ruby: `GC.start`.
 
 ### Compile-Time
 
-| Macro | Default | Description |
-| ----- | ------- | ----------- |
-| `MRB_HEAP_PAGE_SIZE` | 1024 | Objects per heap page |
-| `MRB_GRAY_STACK_SIZE` | 1024 | Gray stack capacity |
-| `MRB_GC_ARENA_SIZE` | 100 | Arena size (fixed mode) or initial size |
-| `MRB_GC_FIXED_ARENA` | off | Use fixed-size arena |
-| `MRB_GC_TURN_OFF_GENERATIONAL` | off | Disable generational mode |
-| `MRB_GC_STRESS` | off | Full GC on every allocation (debug) |
-| `MRB_USE_MALLOC_TRIM` | off | Call `malloc_trim()` after full GC |
+| Macro                          | Default | Description                             |
+| ------------------------------ | ------- | --------------------------------------- |
+| `MRB_HEAP_PAGE_SIZE`           | 1024    | Objects per heap page                   |
+| `MRB_GRAY_STACK_SIZE`          | 1024    | Gray stack capacity                     |
+| `MRB_GC_ARENA_SIZE`            | 100     | Arena size (fixed mode) or initial size |
+| `MRB_GC_FIXED_ARENA`           | off     | Use fixed-size arena                    |
+| `MRB_GC_TURN_OFF_GENERATIONAL` | off     | Disable generational mode               |
+| `MRB_GC_STRESS`                | off     | Full GC on every allocation (debug)     |
+| `MRB_USE_MALLOC_TRIM`          | off     | Call `malloc_trim()` after full GC      |
 
 ### Runtime
 
@@ -350,8 +350,8 @@ GC.disable                 # disable GC
 
 ## Source Files
 
-| File | Contents |
-| ---- | -------- |
-| `src/gc.c` | GC implementation (~1400 lines) |
+| File                 | Contents                          |
+| -------------------- | --------------------------------- |
+| `src/gc.c`           | GC implementation (~1400 lines)   |
 | `include/mruby/gc.h` | `mrb_gc` structure, public GC API |
-| `include/mruby.h` | Arena save/restore macros |
+| `include/mruby.h`    | Arena save/restore macros         |

doc/internal/vm.md

@@ -97,12 +97,12 @@ return n + 1 (skip self)
 
 ### Call Context Info (cci)
 
-| Value | Name | Meaning |
-| ----- | ---- | ------- |
-| 0 | `CINFO_NONE` | Normal VM-to-VM call |
-| 1 | `CINFO_DIRECT` | Explicit VM call (block, lambda.call) |
-| 2 | `CINFO_SKIP` | Skip frame in stack traces |
-| 3 | `CINFO_RESUMED` | Fiber resumed (stop execution) |
+| Value | Name            | Meaning                               |
+| ----- | --------------- | ------------------------------------- |
+| 0     | `CINFO_NONE`    | Normal VM-to-VM call                  |
+| 1     | `CINFO_DIRECT`  | Explicit VM call (block, lambda.call) |
+| 2     | `CINFO_SKIP`    | Skip frame in stack traces            |
+| 3     | `CINFO_RESUMED` | Fiber resumed (stop execution)        |
 
 ## Dispatch Loop
 
@@ -241,13 +241,13 @@ correctness.
 
 ### Proc Types
 
-| Flag | Meaning |
-| ---- | ------- |
-| `MRB_PROC_CFUNC_FL` | C function (not irep-based) |
-| `MRB_PROC_STRICT` | Lambda (strict argument check) |
-| `MRB_PROC_ORPHAN` | No environment attachment |
-| `MRB_PROC_ENVSET` | Has captured environment |
-| `MRB_PROC_SCOPE` | Defines a new variable scope |
+| Flag                | Meaning                        |
+| ------------------- | ------------------------------ |
+| `MRB_PROC_CFUNC_FL` | C function (not irep-based)    |
+| `MRB_PROC_STRICT`   | Lambda (strict argument check) |
+| `MRB_PROC_ORPHAN`   | No environment attachment      |
+| `MRB_PROC_ENVSET`   | Has captured environment       |
+| `MRB_PROC_SCOPE`    | Defines a new variable scope   |
 
 ## Fiber Switching
 
@@ -317,9 +317,9 @@ ensuring the incremental GC correctly tracks live references.
 
 ## Source Files
 
-| File | Contents |
-| ---- | -------- |
-| `src/vm.c` | Dispatch loop, method invocation (~1900 lines) |
-| `include/mruby.h` | `mrb_state`, `mrb_callinfo`, `mrb_context` |
-| `include/mruby/proc.h` | `RProc`, `REnv` structures |
-| `include/mruby/throw.h` | `MRB_TRY`/`MRB_CATCH` macros |
+| File                    | Contents                                       |
+| ----------------------- | ---------------------------------------------- |
+| `src/vm.c`              | Dispatch loop, method invocation (~1900 lines) |
+| `include/mruby.h`       | `mrb_state`, `mrb_callinfo`, `mrb_context`     |
+| `include/mruby/proc.h`  | `RProc`, `REnv` structures                     |
+| `include/mruby/throw.h` | `MRB_TRY`/`MRB_CATCH` macros                   |

doc/limitations.md

@@ -274,11 +274,11 @@ enabled with the `MRB_UTF8_STRING` compile flag.
 
 Integer size depends on the value boxing configuration:
 
-| Configuration | Integer range |
-| ------------- | ------------- |
+| Configuration                 | Integer range    |
+| ----------------------------- | ---------------- |
 | Word boxing, 64-bit (default) | roughly +/- 2^62 |
 | Word boxing, 32-bit (default) | roughly +/- 2^30 |
-| NaN boxing (64-bit only) | -2^31 to 2^31-1 |
+| NaN boxing (64-bit only)      | -2^31 to 2^31-1  |
 
 Code relying on 64-bit integer precision may behave differently
 across configurations. The `mruby-bigint` gem provides

doc/mruby4.0.md

@@ -0,0 +1,367 @@
+# User visible changes in `mruby4.0` from `mruby3.4`
+
+"**_NOTE_**:" are changes to be aware of.
+
+# The language
+
+## Pattern Matching
+
+mruby now supports pattern matching (case/in) syntax:
+
+- Basic pattern matching with `case`/`in` syntax ([dadfac6](https://github.com/mruby/mruby/commit/dadfac6))
+- Array pattern matching ([ec67fd9](https://github.com/mruby/mruby/commit/ec67fd9))
+- Hash pattern matching ([2147263](https://github.com/mruby/mruby/commit/2147263))
+- Find pattern matching (`[*pre, target, *post]`) ([6c4d98b](https://github.com/mruby/mruby/commit/6c4d98b))
+- Pin operator (`^variable`) ([1de6340](https://github.com/mruby/mruby/commit/1de6340))
+- Guard clauses (`if`/`unless` conditions) ([07ac110](https://github.com/mruby/mruby/commit/07ac110))
+- One-line pattern matching (`expr in pattern`) ([e76ce24](https://github.com/mruby/mruby/commit/e76ce24))
+- Brace-less hash pattern support ([e8096bf](https://github.com/mruby/mruby/commit/e8096bf))
+
+## Other Language Changes
+
+- `&nil` in formal parameters to explicitly opt out of block arguments ([b07518e](https://github.com/mruby/mruby/commit/b07518e))
+- Trailing comma in method definition parameters: `def foo(a, b,)` ([f78334b](https://github.com/mruby/mruby/commit/f78334b))
+- Array/Hash/String subclasses can now override `[]` and `[]=` methods ([#6675](https://github.com/mruby/mruby/pull/6675))
+- `OP_SETIDX` optimization for Array and Hash ([ddd8fe1](https://github.com/mruby/mruby/commit/ddd8fe1))
+- `case`/`in` without `else` now raises `NoMatchingPatternError` ([d8de35b](https://github.com/mruby/mruby/commit/d8de35b))
+- Allow compound statement in parenthesized argument context ([919cbd8](https://github.com/mruby/mruby/commit/919cbd8))
+
+# Changes in C API
+
+- **_NOTE_**: `mrb_alloca()` renamed to `mrb_temp_alloc()` ([7fe5c2e](https://github.com/mruby/mruby/commit/7fe5c2e))
+- **_NOTE_**: `mruby/ext/io.h` renamed to `mruby/io.h` ([2813f79](https://github.com/mruby/mruby/commit/2813f79))
+- `mrb_gc_add_region()` for contiguous heap region support ([072855a](https://github.com/mruby/mruby/commit/072855a))
+- `mrb_class_outer()` to get the outer class/module ([3a1b771](https://github.com/mruby/mruby/commit/3a1b771))
+- `MRB_ENSURE()` macro for exception-safe cleanup ([3ac682b](https://github.com/mruby/mruby/commit/3ac682b))
+- `mrb_time_get_tm()` for accessing struct tm ([daaaafe](https://github.com/mruby/mruby/commit/daaaafe))
+- `MRB_OPEN_FAILURE()` macro for checking mrb_open result ([40b0cb9](https://github.com/mruby/mruby/commit/40b0cb9))
+- `mrb_print_error()` now handles NULL gracefully ([8e50a45](https://github.com/mruby/mruby/commit/8e50a45))
+- `mrb_open()` returns mrb_state with exc set on init failure ([05ffe0c](https://github.com/mruby/mruby/commit/05ffe0c))
+- `mrb_utf8_to_buf()` for UTF-8 encoding consolidation ([7e28e68](https://github.com/mruby/mruby/commit/7e28e68))
+- `kh_is_end()` macro for safe khash iteration ([893cc75](https://github.com/mruby/mruby/commit/893cc75))
+- `mrb_bigint_p()` always defined regardless of bigint gem presence ([6c4a8c0](https://github.com/mruby/mruby/commit/6c4a8c0))
+- `RInteger` and `RFloat` added to `RVALUE` union ([13dbca0](https://github.com/mruby/mruby/commit/13dbca0))
+
+# ROM Method Tables
+
+All built-in classes and most extension gems now use read-only method
+tables stored in `.rodata` instead of heap-allocated hash tables. Method
+definitions no longer consume heap memory, significantly reducing memory
+footprint for embedded use.
+
+Core classes converted: BasicObject, Object, Module, Class, Kernel,
+String, Array, Hash, Numeric, Integer, Float, NilClass, TrueClass,
+FalseClass, Range, Symbol, Exception, Proc.
+
+Extension gems converted: mruby-string-ext, mruby-array-ext, mruby-set,
+mruby-struct, mruby-class-ext, mruby-numeric-ext, mruby-random,
+mruby-kernel-ext, mruby-complex, mruby-rational, mruby-io, mruby-socket,
+mruby-method, mruby-metaprog, mruby-time, mruby-hash-ext, mruby-proc-ext,
+mruby-symbol-ext, mruby-range-ext, mruby-object-ext.
+
+# GC and Memory
+
+- **_NOTE_**: `MRB_NO_PRESYM` removed; presym is now always enabled ([81689045](https://github.com/mruby/mruby/commit/81689045))
+- Replace `gcnext` gray linked list with fixed-size gray stack, reducing per-object overhead ([31fea170](https://github.com/mruby/mruby/commit/31fea170))
+- `mrb_gc_add_region()` for providing contiguous memory buffers as GC heap pages ([072855a](https://github.com/mruby/mruby/commit/072855a))
+- Chunk-based pool for symbol string allocation ([e05bd8f](https://github.com/mruby/mruby/commit/e05bd8f))
+- Reduce `IV_INITIAL_SIZE` from 4 to 2 ([6bd1f51](https://github.com/mruby/mruby/commit/6bd1f51))
+- Lossless float encoding using rotation in word boxing ([b6148c8](https://github.com/mruby/mruby/commit/b6148c8))
+- Lossless rotation encoding for 32-bit float32 word boxing ([14a5cfb](https://github.com/mruby/mruby/commit/14a5cfb))
+- Consolidated irep allocation for .mrb loading ([74fb045](https://github.com/mruby/mruby/commit/74fb045))
+- Object shapes (hidden classes) for `MRB_TT_OBJECT` IV storage, sharing key layouts across objects with the same instance variable assignment order ([8d10056](https://github.com/mruby/mruby/commit/8d10056))
+
+# Build & Configuration
+
+- **_NOTE_**: `MRB_WORDBOX_NO_FLOAT_TRUNCATE` renamed to `MRB_WORDBOX_NO_INLINE_FLOAT` (old name still works) ([59e1fe2](https://github.com/mruby/mruby/commit/59e1fe2))
+- **_NOTE_**: `MRB_INT64` on 32-bit now requires `MRB_NO_BOXING` (other boxing modes cannot guarantee alignment for heap-allocated 64-bit integers) ([eaaa66b](https://github.com/mruby/mruby/commit/eaaa66b))
+- Amalgamation support via `rake amalgam` task ([d995ca2](https://github.com/mruby/mruby/commit/d995ca2))
+- New Platform: Cosmopolitan Libc ([#6681](https://github.com/mruby/mruby/pull/6681))
+- Emscripten: use native WASM exception handling ([ca364e3](https://github.com/mruby/mruby/commit/ca364e3))
+- HAL (Hardware Abstraction Layer) for platform abstraction in mruby-io, mruby-socket, mruby-dir, mruby-task ([74ca22f](https://github.com/mruby/mruby/commit/74ca22f))
+- `MRUBY_MIRB_READLINE` environment variable to control readline library selection ([0aafb83](https://github.com/mruby/mruby/commit/0aafb83))
+- MSYS2 drive letter support in build script ([77f6ffe](https://github.com/mruby/mruby/commit/77f6ffe))
+- Inter-gem headers separated from external API headers ([#6671](https://github.com/mruby/mruby/pull/6671))
+
+# Changes in mrbgems
+
+## New Gems
+
+- **mruby-task**: Cooperative multitasking with preemptive scheduling ([ae0d7a0](https://github.com/mruby/mruby/commit/ae0d7a0))
+- **mruby-benchmark**: Benchmarking gem ([2f40f3d](https://github.com/mruby/mruby/commit/2f40f3d))
+- **mruby-strftime**: Time#strftime implementation ([b31e22f](https://github.com/mruby/mruby/commit/b31e22f))
+
+## mruby-bin-mirb Improvements
+
+- Custom multi-line editor replacing readline ([527018c](https://github.com/mruby/mruby/commit/527018c))
+- Syntax highlighting for keywords, strings, result values, hash key symbols ([624272b](https://github.com/mruby/mruby/commit/624272b), [1713d4a](https://github.com/mruby/mruby/commit/1713d4a))
+- Automatic light/dark theme detection via OSC 11 ([db4c8d9](https://github.com/mruby/mruby/commit/db4c8d9))
+- Tab completion support ([2f15282](https://github.com/mruby/mruby/commit/2f15282))
+- Colored output for prompts and errors ([b36e0b4](https://github.com/mruby/mruby/commit/b36e0b4))
+- Auto-indentation and auto-dedent ([d52f318](https://github.com/mruby/mruby/commit/d52f318), [e901b6d](https://github.com/mruby/mruby/commit/e901b6d))
+- Command history with Up/Down navigation ([5f85c1b](https://github.com/mruby/mruby/commit/5f85c1b))
+- Line numbers in multi-line prompts ([5a3f0e2](https://github.com/mruby/mruby/commit/5a3f0e2))
+- UTF-8 multibyte character support ([4a97da3](https://github.com/mruby/mruby/commit/4a97da3))
+
+## mruby-bigint Improvements
+
+- Toom-3 multiplication for large numbers ([99620804](https://github.com/mruby/mruby/commit/99620804))
+- Karatsuba multiplication for medium-sized numbers ([85e81072](https://github.com/mruby/mruby/commit/85e81072))
+- Balance multiplication for asymmetric operands ([0220ec2b](https://github.com/mruby/mruby/commit/0220ec2b))
+- Divide-and-conquer optimization for `to_s` ([990ff90f](https://github.com/mruby/mruby/commit/990ff90f))
+- Consolidated mpn layer for low-level limb operations ([9ef3362f](https://github.com/mruby/mruby/commit/9ef3362f))
+- Always use 32-bit limbs by default ([c747c77f](https://github.com/mruby/mruby/commit/c747c77f))
+
+## Other Gem Changes
+
+- **_NOTE_**: `Hash#deconstruct_keys` removed for CRuby compatibility ([34b9412](https://github.com/mruby/mruby/commit/34b9412))
+- **mruby-enum-lazy**: Fix `Lazy#flat_map` to handle non-enumerable block return values ([#6765](https://github.com/mruby/mruby/pull/6765))
+- **mruby-array-ext**: Add `Array#find` and `Array#rfind` methods
+- **mruby-io**: Add `IO#putc` and `Kernel#putc` ([baff6e6](https://github.com/mruby/mruby/commit/baff6e6))
+- **mruby-random**: Replace xoshiro with PCG for better memory efficiency ([f1bab01](https://github.com/mruby/mruby/commit/f1bab01))
+- **mruby-compiler**: Variable-sized AST nodes for reduced memory usage
+- **mruby-compiler**: `no_return_value` context flag for script optimization ([613b03a](https://github.com/mruby/mruby/commit/613b03a))
+- `initialize_copy` and `respond_to_missing?` defined as private ([#6708](https://github.com/mruby/mruby/pull/6708))
+- Struct keyword argument initialization ([#6574](https://github.com/mruby/mruby/pull/6574))
+
+# Compiler Improvements
+
+- Variable-sized AST nodes for reduced memory consumption ([821b989](https://github.com/mruby/mruby/commit/821b989))
+- Pattern matching bytecode optimizations ([21d4135](https://github.com/mruby/mruby/commit/21d4135))
+- Optimized masgn to generate literals directly into target registers ([fb5d966](https://github.com/mruby/mruby/commit/fb5d966))
+- Optimized splat of literal arrays in args/literals ([1cb8d73](https://github.com/mruby/mruby/commit/1cb8d73))
+- Early termination after too many parse errors ([510ebd7](https://github.com/mruby/mruby/commit/510ebd7))
+- Chunk array literals at 64 elements to reduce register pressure ([f98d641](https://github.com/mruby/mruby/commit/f98d641))
+- Chunk `%w()` and `%i()` literals to reduce register pressure ([62cf0dc](https://github.com/mruby/mruby/commit/62cf0dc))
+
+# VM Optimizations
+
+New super-instructions that fuse common opcode sequences to reduce bytecode size and improve performance:
+
+- `OP_SEND0`/`OP_SSEND0`: Zero-argument method call, avoiding argument count setup ([9123ef4](https://github.com/mruby/mruby/commit/9123ef4))
+- `OP_TDEF`/`OP_SDEF`: Fused method definition combining TCLASS/SCLASS+METHOD+DEF into single instruction, saving 4 bytes per method ([8d4f47e](https://github.com/mruby/mruby/commit/8d4f47e))
+- `OP_GETIDX0`: Fast path for `array[0]` and `Array#first` access ([680f7ec](https://github.com/mruby/mruby/commit/680f7ec))
+- `OP_ADDILV`/`OP_SUBILV`: Local variable increment/decrement fusion for `i += n` patterns ([43f64b9](https://github.com/mruby/mruby/commit/43f64b9))
+- `OP_RETSELF`: Single-byte instruction for `return self` pattern ([a71db8c](https://github.com/mruby/mruby/commit/a71db8c))
+- `OP_RETNIL`: Single-byte instruction for `return nil` pattern ([64e30bf](https://github.com/mruby/mruby/commit/64e30bf))
+- `OP_RETTRUE`/`OP_RETFALSE`: Single-byte instructions for `return true`/`return false` patterns ([0b15727](https://github.com/mruby/mruby/commit/0b15727))
+- `OP_MATCHERR`: Pattern matching error with conditional execution ([944168a](https://github.com/mruby/mruby/commit/944168a))
+- `OP_BLKCALL`: Direct block call for `yield`, bypassing method dispatch (13-17% faster) ([3aa2872](https://github.com/mruby/mruby/commit/3aa2872))
+
+Other optimizations:
+
+- 1.5x stack growth instead of linear growth for reduced reallocations ([f7988c93](https://github.com/mruby/mruby/commit/f7988c93))
+- Skip keyword argument hash duplication ([5970e350](https://github.com/mruby/mruby/commit/5970e350))
+
+# Fixed GitHub Issues
+
+- [#5531](https://github.com/mruby/mruby/issues/5531) Hash recursion detection
+- [#6506](https://github.com/mruby/mruby/issues/6506) Constant lookup in singleton class
+- [#6507](https://github.com/mruby/mruby/issues/6507) tally multi-values
+- [#6508](https://github.com/mruby/mruby/issues/6508) Enumerable#sum index
+- [#6509](https://github.com/mruby/mruby/issues/6509) scope_new nregs initialization
+- [#6515](https://github.com/mruby/mruby/issues/6515) y.tab.c in repository
+- [#6516](https://github.com/mruby/mruby/issues/6516) Private backquote
+- [#6554](https://github.com/mruby/mruby/issues/6554) Socket private #initialize
+- [#6570](https://github.com/mruby/mruby/issues/6570) instance_eval crash
+- [#6613](https://github.com/mruby/mruby/issues/6613) const_added hook during bootstrapping
+- [#6635](https://github.com/mruby/mruby/issues/6635), [#6636](https://github.com/mruby/mruby/issues/6636) Colon3 constant lookup
+- [#6637](https://github.com/mruby/mruby/issues/6637) arm64 mingw64 builtin setjmp/longjmp
+- [#6642](https://github.com/mruby/mruby/issues/6642) Task segfault when sleep called from C
+- [#6645](https://github.com/mruby/mruby/issues/6645) Set memory leak from double initialization
+- [#6646](https://github.com/mruby/mruby/issues/6646) IO#gets negative length
+- [#6647](https://github.com/mruby/mruby/issues/6647) IO#ungetc buffer overflow
+- [#6648](https://github.com/mruby/mruby/issues/6648) sprintf buffer overread
+- [#6649](https://github.com/mruby/mruby/issues/6649) Array#sort! use-after-realloc
+- [#6650](https://github.com/mruby/mruby/issues/6650) Array#fill validation
+- [#6652](https://github.com/mruby/mruby/issues/6652) Array comparison use-after-realloc
+- [#6657](https://github.com/mruby/mruby/issues/6657) Exception handling for ||= on class variables
+- [#6659](https://github.com/mruby/mruby/issues/6659) Super with keyword arguments
+- [#6660](https://github.com/mruby/mruby/issues/6660) Regression on struct/array/hash == override with super
+- [#6662](https://github.com/mruby/mruby/issues/6662) Array set operations use-after-free
+- [#6664](https://github.com/mruby/mruby/issues/6664) Set#flatten memory leak
+- [#6666](https://github.com/mruby/mruby/issues/6666) Regexp literal with encoding
+- [#6668](https://github.com/mruby/mruby/issues/6668) Method#== for aliased methods and comparison bug
+- [#6671](https://github.com/mruby/mruby/issues/6671) Separate inter-gem headers from external API headers
+- [#6674](https://github.com/mruby/mruby/issues/6674) Document pattern matching limitations
+- [#6675](https://github.com/mruby/mruby/issues/6675) Allow Hash#[] to be aliased again
+- [#6687](https://github.com/mruby/mruby/issues/6687) Expand MRB_SYM/MRB_GVSYM support for symbols with special characters
+- [#6698](https://github.com/mruby/mruby/issues/6698) Bigint tests fail on architectures other than x86_64 and i386
+- [#6701](https://github.com/mruby/mruby/issues/6701) Heap-use-after-free in mrb_vm_exec involving mruby-rational / mruby-bigint
+- [#6702](https://github.com/mruby/mruby/issues/6702) mruby-bigint doesn't compile in C++ project
+- [#6704](https://github.com/mruby/mruby/issues/6704) Heap-buffer-overflow in mrb_vm_exec via malformed source code
+- [#6705](https://github.com/mruby/mruby/issues/6705) Can't get outer class of an object in C
+- [#6713](https://github.com/mruby/mruby/issues/6713) mruby-polarssl not work
+- [#6720](https://github.com/mruby/mruby/issues/6720) Random float range: different behavior from CRuby
+- [#6722](https://github.com/mruby/mruby/issues/6722) RBreak size overflow on 32-bit platforms with MRB_NO_BOXING
+- [#6740](https://github.com/mruby/mruby/issues/6740) `%w()`/`%i()` register pressure with large literals
+- [#6741](https://github.com/mruby/mruby/issues/6741) `case`/`in` without `else` should raise `NoMatchingPatternError`
+- [#6760](https://github.com/mruby/mruby/issues/6760) `mrb_gc_unregister()` not removing all matching entries
+
+# Merged Pull Requests
+
+- [#6418](https://github.com/mruby/mruby/pull/6418) Add `ls-lint` with GitHub Actions
+- [#6492](https://github.com/mruby/mruby/pull/6492) fix a typo, update specs
+- [#6493](https://github.com/mruby/mruby/pull/6493) Fix TYPO in memory.md
+- [#6495](https://github.com/mruby/mruby/pull/6495) Remove `MRB_ENDIAN_LOHI()` that is no longer in use
+- [#6497](https://github.com/mruby/mruby/pull/6497) gha: update `build.yml` try `windows-2025` image
+- [#6498](https://github.com/mruby/mruby/pull/6498) Clean up and standardize the pre-commit config
+- [#6501](https://github.com/mruby/mruby/pull/6501) Update pre-commit Node.js version to `v22.14.0 LTS`
+- [#6502](https://github.com/mruby/mruby/pull/6502) pre-commit: update prettier to the latest version
+- [#6503](https://github.com/mruby/mruby/pull/6503) misc: fix typos
+- [#6505](https://github.com/mruby/mruby/pull/6505) mrbgems: fix spelling
+- [#6510](https://github.com/mruby/mruby/pull/6510) Fixed class method visibility via `module_function`
+- [#6511](https://github.com/mruby/mruby/pull/6511) Exclude the external project "lrama" from pre-commit
+- [#6513](https://github.com/mruby/mruby/pull/6513) mruby 3.4.0 released
+- [#6517](https://github.com/mruby/mruby/pull/6517) core/codegen.c: remove unneeded duplicate semicolon
+- [#6518](https://github.com/mruby/mruby/pull/6518) Change mrbc_args.flags bit width from 2 to 3
+- [#6519](https://github.com/mruby/mruby/pull/6519) Add `tools/lrama` to `.prettierignore`
+- [#6520](https://github.com/mruby/mruby/pull/6520) pre-commit: autoupdate and update node LTS version
+- [#6521](https://github.com/mruby/mruby/pull/6521) Add codespell config file `.codespellrc`
+- [#6522](https://github.com/mruby/mruby/pull/6522) gha: label more files
+- [#6523](https://github.com/mruby/mruby/pull/6523) add `rand(Range)` and unify implementations of `Random#rand` and `Kernel#rand`
+- [#6524](https://github.com/mruby/mruby/pull/6524) Fix Kernel#p when no argument
+- [#6525](https://github.com/mruby/mruby/pull/6525) Skip adding empty input to mirb history
+- [#6526](https://github.com/mruby/mruby/pull/6526) Add build config for Luckfox Pico embedded SBC
+- [#6528](https://github.com/mruby/mruby/pull/6528) misc: fix spelling
+- [#6530](https://github.com/mruby/mruby/pull/6530) Revert "class.c (find_visibility_scope): when callinfo returns, \*ep == NULL; #6512"
+- [#6531](https://github.com/mruby/mruby/pull/6531) Improve method table performance by rehashing at 75% load factor
+- [#6532](https://github.com/mruby/mruby/pull/6532) Reverted method table optimizations to prioritize memory savings
+- [#6533](https://github.com/mruby/mruby/pull/6533) Fix calling `extended` callback
+- [#6534](https://github.com/mruby/mruby/pull/6534) Add descriptive comment to mrb_read_float function
+- [#6535](https://github.com/mruby/mruby/pull/6535) Added descriptive comments for functions/macros in src/mempool.c
+- [#6536](https://github.com/mruby/mruby/pull/6536) Add descriptive comments to public functions in src/debug.c
+- [#6537](https://github.com/mruby/mruby/pull/6537) Updated comments in `cdump.c` to remove the `@brief` tag
+- [#6539](https://github.com/mruby/mruby/pull/6539) Add descriptive comments for functions in src/load.c
+- [#6540](https://github.com/mruby/mruby/pull/6540) Add descriptive comments to MRB_API functions in object.c
+- [#6541](https://github.com/mruby/mruby/pull/6541) Add descriptive comments for MRB_API functions in src/array.c
+- [#6542](https://github.com/mruby/mruby/pull/6542) Add descriptive comments to MRB_API functions in src/symbol.c
+- [#6543](https://github.com/mruby/mruby/pull/6543) Add descriptive comments to several functions in src/dump.c
+- [#6544](https://github.com/mruby/mruby/pull/6544) Fix build strings that must be mutable
+- [#6545](https://github.com/mruby/mruby/pull/6545) Add descriptive comments for MRB_API functions in src/class.c
+- [#6548](https://github.com/mruby/mruby/pull/6548) Add descriptive comments to MRB_API functions in src/etc.c
+- [#6549](https://github.com/mruby/mruby/pull/6549) Add descriptive comments to kernel functions
+- [#6550](https://github.com/mruby/mruby/pull/6550) Add descriptive comments for MRB_API functions in src/proc.c
+- [#6551](https://github.com/mruby/mruby/pull/6551) Add descriptive comments for MRB_API functions in src/state.c
+- [#6552](https://github.com/mruby/mruby/pull/6552) Fix: Correct placement of comments in src/variable.c
+- [#6553](https://github.com/mruby/mruby/pull/6553) Add descriptive comments for MRB_API functions in src/vm.c
+- [#6555](https://github.com/mruby/mruby/pull/6555) `mrb_mt_foreach()` needs to update the pointer at each loop
+- [#6556](https://github.com/mruby/mruby/pull/6556) `iv_foreach()` needs to update the pointer at each loop
+- [#6560](https://github.com/mruby/mruby/pull/6560) Refactor: Improve Set GC marking and freeing
+- [#6561](https://github.com/mruby/mruby/pull/6561) pre-commit updates and fix prettier entrypoint
+- [#6562](https://github.com/mruby/mruby/pull/6562) misc: fix spelling word case
+- [#6563](https://github.com/mruby/mruby/pull/6563) pre-commit add rubocop with one rule spaces for indentation
+- [#6564](https://github.com/mruby/mruby/pull/6564) Remove jumanjihouse pre-commit hooks no longer maintained
+- [#6565](https://github.com/mruby/mruby/pull/6565) Rubocop: fix target Ruby version; add two more cops; fix lint error
+- [#6566](https://github.com/mruby/mruby/pull/6566) Removed unreferenced variables in `CrossBuild#run_bintest`
+- [#6567](https://github.com/mruby/mruby/pull/6567) Avoid array object creation in `cmd_bin` method in bintest
+- [#6568](https://github.com/mruby/mruby/pull/6568) mruby-bin-debugger depends on mruby-bin-mrbc in bintest
+- [#6569](https://github.com/mruby/mruby/pull/6569) sed s/Mruby/MRuby/g
+- [#6571](https://github.com/mruby/mruby/pull/6571) Update limitations.md to add behavior on small hash
+- [#6572](https://github.com/mruby/mruby/pull/6572) Add Claude Code GitHub Workflow
+- [#6573](https://github.com/mruby/mruby/pull/6573) pre-commit fixes and updates
+- [#6574](https://github.com/mruby/mruby/pull/6574) Support initializing structs via keyword arguments
+- [#6575](https://github.com/mruby/mruby/pull/6575) Fix typo in file time methods
+- [#6581](https://github.com/mruby/mruby/pull/6581) Merge `mrb_obj_iv_inspect()` into `mrb_obj_inspect()`
+- [#6582](https://github.com/mruby/mruby/pull/6582) Stricter type tag in `mrb_obj_alloc()`
+- [#6583](https://github.com/mruby/mruby/pull/6583) Add fallback to local build_config.rb before using default configuration
+- [#6585](https://github.com/mruby/mruby/pull/6585) Fix typo in mruby3.2 docs
+- [#6586](https://github.com/mruby/mruby/pull/6586) Makefile: refactor add docs and add command line `help` target
+- [#6587](https://github.com/mruby/mruby/pull/6587) Add Set#hash tests
+- [#6588](https://github.com/mruby/mruby/pull/6588) Add CodeQL Analysis for GitHub Actions
+- [#6589](https://github.com/mruby/mruby/pull/6589) Add pre-commit hook `check-zip-file-is-not-committed`
+- [#6591](https://github.com/mruby/mruby/pull/6591) mruby-eval fix license link in README
+- [#6593](https://github.com/mruby/mruby/pull/6593) README: Add Contributors Avatars, Star History, Table of Contents
+- [#6598](https://github.com/mruby/mruby/pull/6598) Fix heap buffer overflow in `#method_missing`
+- [#6599](https://github.com/mruby/mruby/pull/6599) pre-commit: run `markdown-link-check`, `oxipng`, `prettier` manually
+- [#6600](https://github.com/mruby/mruby/pull/6600) `dreamcast_shelf build config`: update to use KallistiOS wrappers
+- [#6601](https://github.com/mruby/mruby/pull/6601) fix: skip local build_config.rb when working in MRUBY_ROOT
+- [#6602](https://github.com/mruby/mruby/pull/6602) Improved iseq annotations for `new` and `!=`
+- [#6604](https://github.com/mruby/mruby/pull/6604) pre-commit config updates
+- [#6607](https://github.com/mruby/mruby/pull/6607) fix bigint on raspberry pi
+- [#6610](https://github.com/mruby/mruby/pull/6610) Extract golden ratio prime into constant
+- [#6614](https://github.com/mruby/mruby/pull/6614) Fix uninitialized variable in io_gets causing segmentation fault
+- [#6617](https://github.com/mruby/mruby/pull/6617) Fix various minor problems and speed up build
+- [#6618](https://github.com/mruby/mruby/pull/6618) Stop generating unnecessary C++ files in mruby-bin-mruby
+- [#6621](https://github.com/mruby/mruby/pull/6621) Set up all GEMS before mruby core tasks definition
+- [#6624](https://github.com/mruby/mruby/pull/6624) Fixed wrong `MRuby::Build.current` at the top level of `mrbgem.rake`
+- [#6628](https://github.com/mruby/mruby/pull/6628) Revert `File.absolute_path` logic
+- [#6629](https://github.com/mruby/mruby/pull/6629) pre-commit update
+- [#6631](https://github.com/mruby/mruby/pull/6631) Revert "Rakefile: make the whole thing parallel unless SERIAL=1"
+- [#6633](https://github.com/mruby/mruby/pull/6633) Fix a heap-buffer-overflow in str strip! methods
+- [#6643](https://github.com/mruby/mruby/pull/6643) Fix crash caused by an incorrect node type check in `codegen_masgn`
+- [#6651](https://github.com/mruby/mruby/pull/6651) Address stack-use-after-return in the mruby bigint implementation
+- [#6653](https://github.com/mruby/mruby/pull/6653) Improve HAL-related components for MinGW
+- [#6655](https://github.com/mruby/mruby/pull/6655) Preventing Memory Leaks in `Array#__combination_init`
+- [#6656](https://github.com/mruby/mruby/pull/6656) Fix integer overflow in allocation size calculation
+- [#6663](https://github.com/mruby/mruby/pull/6663) Added the `kh_is_end()` macro function
+- [#6665](https://github.com/mruby/mruby/pull/6665) Fixed use-after-free with `Set#join`
+- [#6670](https://github.com/mruby/mruby/pull/6670) Arranging VM dispatch macros
+- [#6673](https://github.com/mruby/mruby/pull/6673) Adjust broken license links; clean up Markdown
+- [#6677](https://github.com/mruby/mruby/pull/6677) gha: run pre-commit with `--color=always`
+- [#6678](https://github.com/mruby/mruby/pull/6678) Put ls-lint and pre-commit in separate workflow files
+- [#6679](https://github.com/mruby/mruby/pull/6679) pre-commit autoupdate; update node and prettier
+- [#6681](https://github.com/mruby/mruby/pull/6681) Add Cosmopolitan Libc build configuration
+- [#6689](https://github.com/mruby/mruby/pull/6689) docs: fix pre-commit manual hooks; fix link
+- [#6694](https://github.com/mruby/mruby/pull/6694) Fix mirb build under Cosmopolitan
+- [#6695](https://github.com/mruby/mruby/pull/6695) Dependabot: add a cooldown period for new releases
+- [#6696](https://github.com/mruby/mruby/pull/6696) Fix parse error with required kwargs and omitted parens
+- [#6699](https://github.com/mruby/mruby/pull/6699) Fix mruby-task for PicoRuby Integration
+- [#6700](https://github.com/mruby/mruby/pull/6700) Fix float/double pack/unpack on s390x
+- [#6706](https://github.com/mruby/mruby/pull/6706) Refactor task class to use symbol IDs
+- [#6708](https://github.com/mruby/mruby/pull/6708) `initialize_copy` and `respond_to_missing?` defined as private
+- [#6709](https://github.com/mruby/mruby/pull/6709) Add the `MRB_ENSURE()` macro
+- [#6711](https://github.com/mruby/mruby/pull/6711) Fix out of bounds read and write in IO.select
+- [#6714](https://github.com/mruby/mruby/pull/6714) Fix OP_DEBUG operand type and add NULL check for debug_op_hook
+- [#6716](https://github.com/mruby/mruby/pull/6716) Fixes identity for proc object
+- [#6717](https://github.com/mruby/mruby/pull/6717) Fix mruby-task: wrapping by critical section and setting initial task receiver
+- [#6718](https://github.com/mruby/mruby/pull/6718) Add installation instructions for conda and Homebrew
+- [#6723](https://github.com/mruby/mruby/pull/6723) Add `RInteger` and `RFloat` to `RVALUE`
+- [#6727](https://github.com/mruby/mruby/pull/6727) Language documentation: update wording of "overloading" section
+- [#6729](https://github.com/mruby/mruby/pull/6729) Simplifying dependency addition for gensym task
+- [#6730](https://github.com/mruby/mruby/pull/6730) Simplifying presym file generation actions
+- [#6733](https://github.com/mruby/mruby/pull/6733) Include `mruby/presym.h` for all source files
+- [#6734](https://github.com/mruby/mruby/pull/6734) Chunk array literals at 64 elements to reduce register pressure
+- [#6735](https://github.com/mruby/mruby/pull/6735) Prevent full recompilation without changes to presym file
+- [#6739](https://github.com/mruby/mruby/pull/6739) Fix MSYS2 build error with drive letters
+- [#6743](https://github.com/mruby/mruby/pull/6743) Chunk `%w()` and `%i()` literals to reduce register pressure
+- [#6744](https://github.com/mruby/mruby/pull/6744) Raise `NoMatchingPatternError` in `case`/`in` without `else`
+- [#6747](https://github.com/mruby/mruby/pull/6747) Correctly handle empty hash as default named argument
+- [#6749](https://github.com/mruby/mruby/pull/6749) Fix microcontroller profile
+- [#6750](https://github.com/mruby/mruby/pull/6750) Fix out-of-bounds read and divide-by-zero in `Array#product`
+- [#6752](https://github.com/mruby/mruby/pull/6752) Fix `attr_reader`-generated methods accepting extra arguments
+- [#6753](https://github.com/mruby/mruby/pull/6753) Further optimize `Array#product`
+- [#6754](https://github.com/mruby/mruby/pull/6754) Mark `attr_reader` procs as noarg
+- [#6755](https://github.com/mruby/mruby/pull/6755) Reload `ci` after `mrb_hash_delete_key()` in keyword argument handling
+- [#6756](https://github.com/mruby/mruby/pull/6756) Avoid impact of object modifications caused by `mrb_vm_exec()` calls
+- [#6758](https://github.com/mruby/mruby/pull/6758) Don't assign result of `mrb_funcall()` directly to `regs`
+- [#6759](https://github.com/mruby/mruby/pull/6759) Define `mrb_bigint_p()` always
+- [#6761](https://github.com/mruby/mruby/pull/6761) Fix `mrb_gc_unregister()` to remove all matching entries
+- [#6762](https://github.com/mruby/mruby/pull/6762) Write generated test C files atomically to avoid build race condition
+- [#6765](https://github.com/mruby/mruby/pull/6765) Fix `Lazy#flat_map` to handle non-enumerable block return values
+- [#6767](https://github.com/mruby/mruby/pull/6767) Allow compound statement in parenthesized argument context
+- [#6780](https://github.com/mruby/mruby/pull/6780) Fix `String#prepend` with self-referencing arguments
+- [#6781](https://github.com/mruby/mruby/pull/6781) Protect `sprintf` format string from mutation during callbacks
+- [#6783](https://github.com/mruby/mruby/pull/6783) Pin GitHub Actions workflows to commit hashes
+
+# Security Fixes
+
+- Buffer overflow in bigint uadd ([3f2611e](https://github.com/mruby/mruby/commit/3f2611e))
+- Stack buffer overflow in Montgomery reduction ([edce0a3](https://github.com/mruby/mruby/commit/edce0a3))
+- Buffer overflow in pack_uu encoding ([2993302](https://github.com/mruby/mruby/commit/2993302))
+- Buffer overflow in IO#ungetc ([01ab2ff](https://github.com/mruby/mruby/commit/01ab2ff))
+- Heap-buffer-overflow in pattern alternation codegen ([eea9e30](https://github.com/mruby/mruby/commit/eea9e30))
+- Out of bounds read and write in IO.select ([44831711](https://github.com/mruby/mruby/commit/44831711))
+- Off-by-one in bounds check for symbol names and pool strings in load.c ([b3b8c01](https://github.com/mruby/mruby/commit/b3b8c01))
+- Use-after-free in Set operations ([a6b55e7](https://github.com/mruby/mruby/commit/a6b55e7))
+- Use-after-free in Array set operations ([729b84c](https://github.com/mruby/mruby/commit/729b84c))
+- Use-after-free in Set#join ([0e653eb](https://github.com/mruby/mruby/commit/0e653eb))
+- Use-after-realloc in Array#sort! ([eb39897](https://github.com/mruby/mruby/commit/eb39897))
+- Heap-use-after-free in insertion_sort ([099d2c47](https://github.com/mruby/mruby/commit/099d2c47))
+- Integer overflow in str_check_length ([6afff1c3](https://github.com/mruby/mruby/commit/6afff1c3))
+- Integer overflow in Integer#lcm ([070bef24](https://github.com/mruby/mruby/commit/070bef24))
+- Heap buffer overflow in `#method_missing` ([550d10a](https://github.com/mruby/mruby/commit/550d10a))
+- Out-of-bounds read and divide-by-zero in `Array#product` ([8441eaf](https://github.com/mruby/mruby/commit/8441eaf))
+- Heap buffer overflow in `String#prepend` with self-referencing arguments ([18ba026](https://github.com/mruby/mruby/commit/18ba026))
+- Use-after-free in `sprintf` via `to_s` callback mutating format string ([48fc422](https://github.com/mruby/mruby/commit/48fc422))
+- Multiple memory leak fixes in bigint, Set, Array, and Task gems

include/mrbconf.h

@@ -138,8 +138,8 @@
 /* turn off generational GC by default */
 //#define MRB_GC_TURN_OFF_GENERATIONAL
 
-/* default size of khash table bucket */
-//#define KHASH_DEFAULT_SIZE 32
+/* initial size of khash table bucket */
+//#define KHASH_INITIAL_SIZE 32
 
 /* allocated memory address alignment */
 //#define POOL_ALIGNMENT 4
@@ -208,8 +208,8 @@
 #  define MRB_NO_METHOD_CACHE
 # endif
 
-# ifndef KHASH_DEFAULT_SIZE
-#  define KHASH_DEFAULT_SIZE 16
+# ifndef KHASH_INITIAL_SIZE
+#  define KHASH_INITIAL_SIZE 16
 # endif
 
 # ifndef MRB_HEAP_PAGE_SIZE

include/mruby/khash.h

@@ -21,7 +21,7 @@ typedef uint32_t khint_t;
 typedef khint_t khiter_t;
 
 #ifndef KHASH_INITIAL_SIZE
-# define KHASH_INITIAL_SIZE 8
+# define KHASH_INITIAL_SIZE 32
 #endif
 #define KHASH_MIN_SIZE 8
 #define KHASH_SMALL_LIMIT 4

include/mruby/value.h

@@ -316,7 +316,11 @@ struct RCptr {
 #endif
 #define mrb_test(o)   mrb_bool(o)
 #ifndef mrb_bigint_p
+#ifdef MRB_USE_BIGINT
 #define mrb_bigint_p(o) (mrb_type(o) == MRB_TT_BIGINT)
+#else
+#define mrb_bigint_p(o) FALSE
+#endif
 #endif
 
 /**

include/mruby/version.h

@@ -80,7 +80,7 @@ MRB_BEGIN_DECL
 /*
  * Release year.
  */
-#define MRUBY_RELEASE_YEAR 2025
+#define MRUBY_RELEASE_YEAR 2026
 
 /*
  * Release month.

lib/mruby/gem.rb

@@ -109,7 +109,8 @@ module MRuby
         if build.kind_of?(MRuby::CrossBuild)
           return %w(x86_64-w64-mingw32 i686-w64-mingw32).include?(build.host_target)
         elsif build.kind_of?(MRuby::Build)
-          return ('A'..'Z').to_a.any? { |vol| Dir.exist?("#{vol}:") }
+          return ('A'..'Z').to_a.any? { |vol| Dir.exist?("#{vol}:") } ||
+                 ('a'..'z').to_a.any? { |vol| Dir.exist?("/#{vol}/") }
         end
         return false
       end

mrbgems/mruby-array-ext/mrblib/array.rb

@@ -611,37 +611,15 @@ class Array
   #   ary.product(*arys)                  ->   array
   #   ary.product(*arys) { |item| ... }   ->   self
   def product(*arys, &block)
-    size = arys.size
-    i = size
-    while i > 0
-      i -= 1
-      unless arys[i].kind_of?(Array)
-        raise TypeError, "no implicit conversion into Array"
+    gen = __product_generate(arys, &block)
+    return gen unless block
+
+    if gen
+      while group = __product_next(arys, gen)
+        yield group
       end
     end
-
-    i = size
-    total = self.size
-    total *= arys[i -= 1].size while i > 0
-
-    if block
-      i = 0
-      while i < total
-        group = self.__product_group(arys, i, size + 1)
-        block.call(group)
-        i += 1
-      end
-      return self
-    else
-      result = [nil] * total
-      i = 0
-      while i < total
-        group = self.__product_group(arys, i, size + 1)
-        result[i] = group
-        i += 1
-      end
-      return result
-    end
+    self
   end
 
   ##

mrbgems/mruby-array-ext/src/array.c

@@ -6,6 +6,7 @@
 #include <mruby/hash.h>
 #include <mruby/data.h>
 #include <mruby/class.h>
+#include <mruby/numeric.h>
 #include <mruby/internal.h>
 #include <mruby/khash.h>
 #include <mruby/error.h>
@@ -78,11 +79,14 @@ ary_assoc(mrb_state *mrb, mrb_value ary)
 {
   mrb_value k = mrb_get_arg1(mrb);
 
+  int ai = mrb_gc_arena_save(mrb);
   for (mrb_int i = 0; i < RARRAY_LEN(ary); i++) {
     mrb_value v = mrb_check_array_type(mrb, RARRAY_PTR(ary)[i]);
+    mrb_gc_protect(mrb, v); // v may be removed from ary by mrb_equal()
     if (!mrb_nil_p(v) && RARRAY_LEN(v) > 0 &&
         mrb_equal(mrb, RARRAY_PTR(v)[0], k))
       return v;
+    mrb_gc_arena_restore(mrb, ai);
   }
   return mrb_nil_value();
 }
@@ -106,12 +110,15 @@ ary_rassoc(mrb_state *mrb, mrb_value ary)
 {
   mrb_value value = mrb_get_arg1(mrb);
 
+  int ai = mrb_gc_arena_save(mrb);
   for (mrb_int i = 0; i < RARRAY_LEN(ary); i++) {
     mrb_value v = RARRAY_PTR(ary)[i];
+    mrb_gc_protect(mrb, v); // v may be removed from ary by mrb_equal()
     if (mrb_array_p(v) &&
         RARRAY_LEN(v) > 1 &&
         mrb_equal(mrb, RARRAY_PTR(v)[1], value))
       return v;
+    mrb_gc_arena_restore(mrb, ai);
   }
   return mrb_nil_value();
 }
@@ -409,9 +416,12 @@ ary_init_temp_set(mrb_state *mrb, ary_set_t *set, mrb_int capacity)
 static void
 ary_populate_temp_set(mrb_state *mrb, ary_set_t *set, mrb_value ary)
 {
-  mrb_int len = RARRAY_LEN(ary);
-  for (mrb_int i = 0; i < len; i++) {
-    kh_put(ary_set, mrb, set, RARRAY_PTR(ary)[i]);
+  int ai = mrb_gc_arena_save(mrb);
+  for (mrb_int i = 0; i < RARRAY_LEN(ary); i++) {
+    mrb_value p = RARRAY_PTR(ary)[i];
+    mrb_gc_protect(mrb, p); // p may be removed from ary by kh_put(ary_set, ...)
+    kh_put(ary_set, mrb, set, p);
+    mrb_gc_arena_restore(mrb, ai);
   }
 }
 
@@ -460,12 +470,15 @@ ary_subtract_body(mrb_state *mrb, void *data)
     ary_populate_temp_set(mrb, ctx->set, ctx->argv[i]);
   }
 
+  int ai = mrb_gc_arena_save(mrb);
   for (mrb_int i = 0; i < RARRAY_LEN(ctx->self); i++) {
     mrb_value p = RARRAY_PTR(ctx->self)[i];
+    mrb_gc_protect(mrb, p); // p may be removed from self by kh_get(ary_set, ...)
     khiter_t k = kh_get(ary_set, mrb, ctx->set, p);
     if (kh_is_end(ctx->set, k)) {  /* key doesn't exist in any ary */
       mrb_ary_push(mrb, ctx->result, p);
     }
+    mrb_gc_arena_restore(mrb, ai);
   }
 
   return ctx->result;
@@ -499,13 +512,13 @@ ary_subtract_internal(mrb_state *mrb, mrb_value self, mrb_int argc, const mrb_va
     }
   }
   else {
-    mrb_int self_len = RARRAY_LEN(self);
-    for (mrb_int i = 0; i < self_len; i++) {
+    int ai = mrb_gc_arena_save(mrb);
+    for (mrb_int i = 0; i < RARRAY_LEN(self); i++) {
       mrb_value p = RARRAY_PTR(self)[i];
+      mrb_gc_protect(mrb, p); // p may be removed from self by mrb_equal()
       mrb_bool found = FALSE;
       for (mrb_int j = 0; j < argc; j++) {
-        mrb_int len = RARRAY_LEN(argv[j]);
-        for (mrb_int k = 0; k < len; k++) {
+        for (mrb_int k = 0; k < RARRAY_LEN(argv[j]); k++) {
           if (mrb_equal(mrb, p, RARRAY_PTR(argv[j])[k])) {
             found = TRUE;
             break;
@@ -516,6 +529,7 @@ ary_subtract_internal(mrb_state *mrb, mrb_value self, mrb_int argc, const mrb_va
       if (!found) {
         mrb_ary_push(mrb, result, p);
       }
+      mrb_gc_arena_restore(mrb, ai);
     }
   }
 
@@ -559,12 +573,10 @@ ary_difference(mrb_state *mrb, mrb_value self)
   return ary_subtract_internal(mrb, self, argc, argv);
 }
 
-
 static void
 add_uniq(mrb_state *mrb, mrb_value item, mrb_value result)
 {
-  const mrb_int len = RARRAY_LEN(result);
-  for (mrb_int i = 0; i < len; i++) {
+  for (mrb_int i = 0; i < RARRAY_LEN(result); i++) {
     if (mrb_eql(mrb, item, RARRAY_PTR(result)[i])) {
       return;
     }
@@ -584,15 +596,18 @@ static mrb_value
 ary_union_body(mrb_state *mrb, void *data)
 {
   struct ary_union_ctx *ctx = (struct ary_union_ctx *)data;
+  int ai = mrb_gc_arena_save(mrb);
 
   /* Add unique elements from self */
   for (mrb_int i = 0; i < RARRAY_LEN(ctx->self_copy); i++) {
     mrb_value elem = RARRAY_PTR(ctx->self_copy)[i];
+    mrb_gc_protect(mrb, elem); // elem may be removed from self_copy by kh_get(ary_set, ...)
     khiter_t k = kh_get(ary_set, mrb, ctx->set, elem);
     if (kh_is_end(ctx->set, k)) {
       kh_put(ary_set, mrb, ctx->set, elem);
       mrb_ary_push(mrb, ctx->result, elem);
     }
+    mrb_gc_arena_restore(mrb, ai);
   }
 
   /* Add unique elements from others */
@@ -600,11 +615,13 @@ ary_union_body(mrb_state *mrb, void *data)
     mrb_value other = ctx->argv[i];
     for (mrb_int j = 0; j < RARRAY_LEN(other); j++) {
       mrb_value elem = RARRAY_PTR(other)[j];
+      mrb_gc_protect(mrb, elem); // elem may be removed from other by kh_get(ary_set, ...)
       khiter_t k = kh_get(ary_set, mrb, ctx->set, elem);
       if (kh_is_end(ctx->set, k)) {
         kh_put(ary_set, mrb, ctx->set, elem);
         mrb_ary_push(mrb, ctx->result, elem);
       }
+      mrb_gc_arena_restore(mrb, ai);
     }
   }
 
@@ -636,19 +653,25 @@ ary_union_internal(mrb_state *mrb, mrb_value self, mrb_int argc, const mrb_value
     }
   }
   else {
+    int ai = mrb_gc_arena_save(mrb);
+
     /* Use linear search for small arrays */
     /* Add unique elements from self */
-    mrb_int alen = RARRAY_LEN(self);
-    for (mrb_int i = 0; i < alen; i++) {
-      add_uniq(mrb, RARRAY_PTR(self)[i], result);
+    for (mrb_int i = 0; i < RARRAY_LEN(self); i++) {
+      mrb_value p = RARRAY_PTR(self)[i];
+      mrb_gc_protect(mrb, p); // p may be removed from self by add_uniq()
+      add_uniq(mrb, p, result);
+      mrb_gc_arena_restore(mrb, ai);
     }
 
     /* Add unique elements from others */
     for (mrb_int i = 0; i < argc; i++) {
       mrb_value other = argv[i];
-      mrb_int olen = RARRAY_LEN(other);
-      for (mrb_int j = 0; j < olen; j++) {
-        add_uniq(mrb, RARRAY_PTR(other)[j], result);
+      for (mrb_int j = 0; j < RARRAY_LEN(other); j++) {
+        mrb_value p = RARRAY_PTR(other)[j];
+        mrb_gc_protect(mrb, p); // p may be removed from other by add_uniq()
+        add_uniq(mrb, p, result);
+        mrb_gc_arena_restore(mrb, ai);
       }
     }
   }
@@ -711,13 +734,16 @@ ary_intersection_body(mrb_state *mrb, void *data)
     ary_populate_temp_set(mrb, ctx->set, ctx->argv[i]);
   }
 
+  int ai = mrb_gc_arena_save(mrb);
   for (mrb_int i = 0; i < RARRAY_LEN(ctx->self); i++) {
     mrb_value p = RARRAY_PTR(ctx->self)[i];
+    mrb_gc_protect(mrb, p); // p may be removed from self by kh_get(ary_set, ...)
     khiter_t k = kh_get(ary_set, mrb, ctx->set, p);
     if (!kh_is_end(ctx->set, k)) {
       mrb_ary_push(mrb, ctx->result, p);
       kh_del(ary_set, mrb, ctx->set, k);
     }
+    mrb_gc_arena_restore(mrb, ai);
   }
 
   return ctx->result;
@@ -751,15 +777,15 @@ ary_intersection_internal(mrb_state *mrb, mrb_value self, mrb_int argc, const mr
     }
   }
   else {
-    mrb_int self_len = RARRAY_LEN(self);
-    for (mrb_int i = 0; i < self_len; i++) {
+    int ai = mrb_gc_arena_save(mrb);
+    for (mrb_int i = 0; i < RARRAY_LEN(self); i++) {
       mrb_value p = RARRAY_PTR(self)[i];
+      mrb_gc_protect(mrb, p); // p may be removed from self by mrb_equal()
       mrb_bool found_in_all = TRUE;
 
       for (mrb_int j = 0; j < argc; j++) {
         mrb_bool found_in_current_other = FALSE;
-        mrb_int len = RARRAY_LEN(argv[j]);
-        for (mrb_int k = 0; k < len; k++) {
+        for (mrb_int k = 0; k < RARRAY_LEN(argv[j]); k++) {
           if (mrb_equal(mrb, p, RARRAY_PTR(argv[j])[k])) {
             found_in_current_other = TRUE;
             break;
@@ -773,8 +799,7 @@ ary_intersection_internal(mrb_state *mrb, mrb_value self, mrb_int argc, const mr
 
       if (found_in_all) {
         mrb_bool already_added = FALSE;
-        mrb_int result_len = RARRAY_LEN(result);
-        for (mrb_int j = 0; j < result_len; j++) {
+        for (mrb_int j = 0; j < RARRAY_LEN(result); j++) {
           if (mrb_equal(mrb, p, RARRAY_PTR(result)[j])) {
             already_added = TRUE;
             break;
@@ -784,6 +809,7 @@ ary_intersection_internal(mrb_state *mrb, mrb_value self, mrb_int argc, const mr
           mrb_ary_push(mrb, result, p);
         }
       }
+      mrb_gc_arena_restore(mrb, ai);
     }
   }
   return result;
@@ -854,8 +880,12 @@ ary_intersect_p_body(mrb_state *mrb, void *data)
 
   ary_populate_temp_set(mrb, ctx->set, ctx->shorter_ary_copy);
 
+  int ai = mrb_gc_arena_save(mrb);
   for (mrb_int i = 0; i < RARRAY_LEN(ctx->longer_ary); i++) {
-    khiter_t k = kh_get(ary_set, mrb, ctx->set, RARRAY_PTR(ctx->longer_ary)[i]);
+    mrb_value p = RARRAY_PTR(ctx->longer_ary)[i];
+    mrb_gc_protect(mrb, p); // p may be removed from longer_ary by kh_get(ary_set, ...)
+    khiter_t k = kh_get(ary_set, mrb, ctx->set, p);
+    mrb_gc_arena_restore(mrb, ai);
     if (!kh_is_end(ctx->set, k)) {
       *ctx->found = TRUE;
       break;
@@ -905,12 +935,16 @@ ary_intersect_p(mrb_state *mrb, mrb_value self)
     }
   }
   else {
+    int ai = mrb_gc_arena_save(mrb);
     for (mrb_int i = 0; i < RARRAY_LEN(longer_ary); i++) {
+      mrb_value p = RARRAY_PTR(longer_ary)[i];
+      mrb_gc_protect(mrb, p); // p may be removed from longer_ary by mrb_equal()
       for (mrb_int j = 0; j < RARRAY_LEN(shorter_ary); j++) {
-        if (mrb_equal(mrb, RARRAY_PTR(longer_ary)[i], RARRAY_PTR(shorter_ary)[j])) {
+        if (mrb_equal(mrb, p, RARRAY_PTR(shorter_ary)[j])) {
           return mrb_true_value();
         }
       }
+      mrb_gc_arena_restore(mrb, ai);
     }
   }
 
@@ -1041,6 +1075,7 @@ ary_fill_exec(mrb_state *mrb, mrb_value self)
   }
 
   /* Fill the array */
+  mrb_ary_modify(mrb, ary);
   mrb_value *ptr = ARY_PTR(ary) + start;
   for (mrb_int i = 0; i < length; i++) {
     ptr[i] = obj;
@@ -1058,7 +1093,6 @@ struct ary_uniq_bang_ctx {
   mrb_value self_copy;
   mrb_value self;
   mrb_int *write_pos;
-  mrb_int len;
 };
 
 static mrb_value
@@ -1068,15 +1102,19 @@ ary_uniq_bang_body(mrb_state *mrb, void *data)
 
   ary_populate_temp_set(mrb, ctx->set, ctx->self_copy);
 
-  for (mrb_int read_pos = 0; read_pos < ctx->len; read_pos++) {
+  int ai = mrb_gc_arena_save(mrb);
+  for (mrb_int read_pos = 0; read_pos < RARRAY_LEN(ctx->self); read_pos++) {
     mrb_value elem = RARRAY_PTR(ctx->self)[read_pos];
+    mrb_gc_protect(mrb, elem); // elem may be removed from self by kh_get(ary_set, ...)
     khiter_t k = kh_get(ary_set, mrb, ctx->set, elem);
     if (!kh_is_end(ctx->set, k)) {
-      if (*ctx->write_pos != read_pos) {
+      if (*ctx->write_pos != read_pos && *ctx->write_pos < RARRAY_LEN(ctx->self)) {
+        mrb_ary_modify(mrb, mrb_ary_ptr(ctx->self));
         RARRAY_PTR(ctx->self)[*ctx->write_pos] = elem;
       }
       (*ctx->write_pos)++;
       kh_del(ary_set, mrb, ctx->set, k);
+      mrb_gc_arena_restore(mrb, ai);
     }
   }
 
@@ -1103,28 +1141,32 @@ ary_uniq_bang(mrb_state *mrb, mrb_value self)
     ary_set_t *set = &set_struct;
     ary_init_temp_set(mrb, set, len);
 
-    struct ary_uniq_bang_ctx ctx = { set, self_copy, self, &write_pos, len };
+    struct ary_uniq_bang_ctx ctx = { set, self_copy, self, &write_pos };
     mrb_value result;
     MRB_ENSURE(mrb, result, ary_uniq_bang_body, &ctx) {
       ary_destroy_temp_set(mrb, set);
     }
   }
   else {
-    for (mrb_int read_pos = 0; read_pos < len; read_pos++) {
+    int ai = mrb_gc_arena_save(mrb);
+    for (mrb_int read_pos = 0; read_pos < RARRAY_LEN(self); read_pos++) {
       mrb_value elem = RARRAY_PTR(self)[read_pos];
+      mrb_gc_protect(mrb, elem); // elem may be removed from self by mrb_equal()
       mrb_bool found = FALSE;
-      for (mrb_int j = 0; j < write_pos; j++) {
+      for (mrb_int j = 0; j < write_pos && j < RARRAY_LEN(self); j++) {
         if (mrb_equal(mrb, elem, RARRAY_PTR(self)[j])) {
           found = TRUE;
           break;
         }
       }
       if (!found) {
-        if (write_pos != read_pos) {
+        if (write_pos != read_pos && write_pos < RARRAY_LEN(self)) {
+          mrb_ary_modify(mrb, mrb_ary_ptr(self));
           RARRAY_PTR(self)[write_pos] = elem;
         }
         write_pos++;
       }
+      mrb_gc_arena_restore(mrb, ai);
     }
   }
 
@@ -1373,6 +1415,13 @@ ary_insert(mrb_state *mrb, mrb_value self)
   return self;
 }
 
+struct ary_product_generator {
+  mrb_int total;
+  mrb_int cursor;
+};
+
+static struct mrb_data_type ary_product_generator_type = { "ary_product_generator", mrb_free };
+
 /*
  *  Internal helper for Array#product to construct a group array.
  *  Takes the base array (self), the array of other arrays (arys),
@@ -1380,29 +1429,85 @@ ary_insert(mrb_state *mrb, mrb_value self)
  *  of the group array (group_len).
  */
 static mrb_value
-ary_product_group(mrb_state *mrb, mrb_value self_ary)
+ary_product_fetch(mrb_state *mrb, mrb_value self_ary, mrb_value arys_ary, mrb_int n)
 {
-  mrb_value arys_ary;
-  mrb_int current_i, group_len;
-  mrb_get_args(mrb, "Aii", &arys_ary, &current_i, &group_len);
-
-  mrb_value group = mrb_ary_new_capa(mrb, group_len);
   mrb_int j = RARRAY_LEN(arys_ary); // Corresponds to 'size' in Ruby
-  mrb_int n = current_i;
+  mrb_value group = mrb_ary_new_capa(mrb, j + 1 /* self_ary */);
 
-  while (j > 0) {
-    j -= 1;
+  while (j-- > 0) {
     mrb_value a = RARRAY_PTR(arys_ary)[j]; // arys[j]
     mrb_check_type(mrb, a, MRB_TT_ARRAY);
     mrb_int b = RARRAY_LEN(a);             // a.size
+    if (b <= 0) {
+      mrb_raise(mrb, E_ARGUMENT_ERROR, "cannot compute product with an empty array");
+    }
     mrb_ary_set(mrb, group, j + 1, RARRAY_PTR(a)[n % b]);
     n /= b;
   }
+  if (n >= RARRAY_LEN(self_ary)) {
+    mrb_raise(mrb, E_INDEX_ERROR, "index out of range");
+  }
   mrb_ary_set(mrb, group, 0, RARRAY_PTR(self_ary)[n]);
 
   return group;
 }
 
+static mrb_value
+ary_product_generate(mrb_state *mrb, mrb_value self)
+{
+  mrb_value arys_ary, block;
+  mrb_get_args(mrb, "A&", &arys_ary, &block);
+
+  mrb_int total = RARRAY_LEN(self);
+  for (mrb_int i = 0; i < RARRAY_LEN(arys_ary); i++) {
+    mrb_value a = RARRAY_PTR(arys_ary)[i];
+    mrb_check_type(mrb, a, MRB_TT_ARRAY);
+    mrb_int n = RARRAY_LEN(a);
+    if (n == 0) {
+      total = 0;
+      break;
+    }
+    if (mrb_int_mul_overflow(total, n, &total)) {
+      mrb_raise(mrb, E_ARGUMENT_ERROR, "result too big");
+    }
+  }
+
+  if (mrb_nil_p(block)) {
+    mrb_value result = mrb_ary_new_capa(mrb, total);
+    for (mrb_int i = 0; i < total; i++) {
+      mrb_value group = ary_product_fetch(mrb, self, arys_ary, i);
+      mrb_ary_push(mrb, result, group);
+    }
+    return result;
+  }
+  else if (total > 0) {
+    struct RData *d;
+    struct ary_product_generator *g;
+    Data_Make_Struct(mrb, mrb->object_class, struct ary_product_generator,
+                     &ary_product_generator_type, g, d);
+    g->total = total;
+    g->cursor = 0;
+    return mrb_obj_value(d);
+  }
+  else {
+    return mrb_nil_value();
+  }
+}
+
+static mrb_value
+ary_product_next(mrb_state *mrb, mrb_value self)
+{
+  mrb_value arys;
+  struct ary_product_generator *g;
+  mrb_get_args(mrb, "Ad", &arys, &g, &ary_product_generator_type);
+
+  if (g->cursor >= g->total) {
+    return mrb_nil_value();
+  }
+
+  return ary_product_fetch(mrb, self, arys, g->cursor++);
+}
+
 /*
  *  call-seq:
  *     ary.deconstruct -> ary
@@ -1563,7 +1668,8 @@ static const mrb_mt_entry array_ext_rom_entries[] = {
   MRB_MT_ENTRY(ary_fetch,              MRB_SYM(__fetch),            MRB_ARGS_REQ(3)),
   MRB_MT_ENTRY(ary_insert,             MRB_SYM(insert),             MRB_ARGS_ARG(1,-1)),
   MRB_MT_ENTRY(ary_deconstruct,        MRB_SYM(deconstruct),        MRB_ARGS_NONE()),
-  MRB_MT_ENTRY(ary_product_group,      MRB_SYM(__product_group),    MRB_ARGS_REQ(3)),
+  MRB_MT_ENTRY(ary_product_generate,   MRB_SYM(__product_generate), MRB_ARGS_REQ(1)),
+  MRB_MT_ENTRY(ary_product_next,       MRB_SYM(__product_next),     MRB_ARGS_REQ(2)),
   MRB_MT_ENTRY(ary_combination_init,   MRB_SYM(__combination_init), MRB_ARGS_REQ(2)),
   MRB_MT_ENTRY(ary_combination_next,   MRB_SYM(__combination_next), MRB_ARGS_REQ(1)),
 };

mrbgems/mruby-compiler/core/codegen.c

@@ -3175,8 +3175,12 @@ gen_literal_array(codegen_scope *s, node *tree, mrb_bool sym, int val)
 {
   if (val) {
     int array_size = 0;
+    int first = 1;
+    int slimit = GEN_LIT_ARY_MAX;
     node *current = tree;
 
+    if (cursp() >= slimit) slimit = GEN_VAL_STACK_MAX;
+
     /* Process each segment separated by NODE_LITERAL_DELIM */
     while (current) {
       /* Find the segment boundaries without allocating */
@@ -3213,6 +3217,24 @@ gen_literal_array(codegen_scope *s, node *tree, mrb_bool sym, int val)
 
         /* Only process non-empty segments */
         if (!is_empty_segment) {
+          /* Flush accumulated elements when stack is full */
+          if (cursp() >= slimit) {
+            if (array_size > 0) {
+              pop_n(array_size);
+              if (first) {
+                genop_2(s, OP_ARRAY, cursp(), array_size);
+                push();
+                first = 0;
+              }
+              else {
+                pop();
+                genop_2(s, OP_ARYPUSH, cursp(), array_size);
+                push();
+              }
+              array_size = 0;
+            }
+          }
+
           /* Temporarily terminate the segment by saving and clearing the cdr */
           node *saved_cdr = NULL;
           if (segment_prev) {
@@ -3243,8 +3265,14 @@ gen_literal_array(codegen_scope *s, node *tree, mrb_bool sym, int val)
       }
     }
 
-    /* Generate the array from pushed elements */
-    if (array_size > 0) {
+    /* Handle remaining elements */
+    if (!first) {
+      if (array_size > 0) {
+        pop_n(array_size + 1);
+        genop_2(s, OP_ARYPUSH, cursp(), array_size);
+      }
+    }
+    else if (array_size > 0) {
       pop_n(array_size);
       genop_2(s, OP_ARRAY, cursp(), array_size);
     }
@@ -4427,10 +4455,9 @@ codegen_case_match(codegen_scope *s, node *varnode, int val)
     current_in = current_in->cdr;
   }
 
-  /* No pattern matched - generate nil or error */
-  if (val) {
-    genop_1(s, OP_LOADNIL, cursp());
-  }
+  /* No pattern matched - raise NoMatchingPatternError */
+  genop_1(s, OP_LOADFALSE, cursp());
+  genop_1(s, OP_MATCHERR, cursp());
 
   /* Dispatch all end jumps */
   if (case_end_jumps != JMPLINK_START) {

mrbgems/mruby-compiler/core/parse.y

@@ -3260,7 +3260,7 @@ primary         : literal
                       $<stack>$ = p->cmdarg_stack;
                       p->cmdarg_stack = 0;
                     }
-                  stmt {p->lstate = EXPR_ENDARG;} rparen
+                  compstmt {p->lstate = EXPR_ENDARG;} rparen
                     {
                       p->cmdarg_stack = $<stack>2;
                       $$ = $3;
@@ -4563,13 +4563,13 @@ f_label         : tIDENTIFIER tLABEL_TAG
                     {
                       $$ = $1;
                       local_nest(p);
-                      p->lstate = EXPR_ARG;  /* make newlines significant after label */
+                      p->lstate = EXPR_MID;  /* make newlines significant after label */
                     }
                 | tNUMPARAM tLABEL_TAG
                     {
                       $$ = intern_numparam($1);
                       local_nest(p);
-                      p->lstate = EXPR_ARG;  /* make newlines significant after label */
+                      p->lstate = EXPR_MID;  /* make newlines significant after label */
                     }
                 ;
 

mrbgems/mruby-enum-lazy/mrblib/lazy.rb

@@ -291,11 +291,12 @@ class Enumerator
     #
     def flat_map(&block)
       Lazy.new(self){|yielder, val|
-        ary = block.call(val)
-        # TODO: check ary is an Array
-        ary.each {|x|
-          yielder << x
-        }
+        result = block.call(val)
+        if result.respond_to?(:each)
+          result.each {|x| yielder << x }
+        else
+          yielder << result
+        end
       }
     end
     alias collect_concat flat_map

mrbgems/mruby-enum-lazy/test/lazy.rb

@@ -46,6 +46,18 @@ assert("Enumerator::Lazy#to_enum") do
   assert_equal [0*1, 2*3, 4*5, 6*7], lazy_enum.map { |a| a.first * a.last }.first(4)
 end
 
+assert("Enumerator::Lazy#flat_map with array from block") do
+  assert_equal [1, 10, 2, 20, 3, 30], [1, 2, 3].lazy.flat_map {|x| [x, x*10]}.force
+end
+
+assert("Enumerator::Lazy#flat_map with non-enumerable from block") do
+  assert_equal [1, 2, 3], [1, 2, 3].lazy.flat_map {|x| x}.force
+end
+
+assert("Enumerator::Lazy#flat_map with nested array from block") do
+  assert_equal [[1, 2], [3, 4]], [1, 3].lazy.flat_map {|x| [[x, x+1]]}.force
+end
+
 assert("Enumerator::Lazy#grep_v") do
   lazy_grep_v = (0..).lazy.grep_v(2..4)
   assert_kind_of Enumerator::Lazy, lazy_grep_v

mrbgems/mruby-numeric-ext/src/numeric_ext.c

@@ -190,11 +190,7 @@ int_powm(mrb_state *mrb, mrb_value x)
     return mrb_int_pow(mrb, x, mrb_get_arg1(mrb));
   }
   mrb_get_args(mrb, "oo", &e, &m);
-  if (!mrb_integer_p(e)
-#ifdef MRB_USE_BIGINT
-      && !mrb_bigint_p(e)
-#endif
-      ) {
+  if (!mrb_integer_p(e) && !mrb_bigint_p(e)) {
     mrb_raise(mrb, E_TYPE_ERROR, "int.pow(n,m): 2nd argument not allowed unless 1st argument is an integer");
   }
 #ifdef MRB_USE_BIGINT

mrbgems/mruby-socket/mrblib/socket.rb

@@ -701,13 +701,11 @@ class UDPSocket < IPSocket
   #   data, addr = sock.recvfrom_nonblock(1024)
   #
   def recvfrom_nonblock(*args)
-    s = self
     begin
       self._setnonblock(true)
       self.recvfrom(*args)
     ensure
-      # XXX: self is a SystemcallException here! (should be bug)
-      s._setnonblock(false)
+      self._setnonblock(false)
     end
   end
 

mrbgems/mruby-sprintf/src/sprintf.c

@@ -380,6 +380,13 @@ mrb_str_format(mrb_state *mrb, mrb_int argc, const mrb_value *argv, mrb_value fm
   argc++;
   argv--;
   mrb_ensure_string_type(mrb, fmt);
+  /* Duplicate the format string so that to_s/inspect callbacks invoked
+     during the loop cannot invalidate p/end by mutating the original
+     via String#replace or similar. mrb_str_dup shares the underlying
+     buffer, so this is O(1); String#replace on the original goes
+     through str_replace which decrements the shared refcount, leaving
+     our copy's buffer intact. */
+  fmt = mrb_str_dup(mrb, fmt);
   p = RSTRING_PTR(fmt);
   end = p + RSTRING_LEN(fmt);
   blen = 0;

mrbgems/mruby-sprintf/test/sprintf.rb

@@ -90,3 +90,19 @@ assert("String#% invalid format") do
     "%?" % ""
   end
 end
+
+assert("sprintf with to_s mutating format string") do
+  # The to_s callback must not be able to invalidate sprintf's internal
+  # iteration pointers by mutating the format string.
+  fmt = "%s" + "B" * 200
+  mutator = Object.new
+  $sprintf_test_fmt = fmt
+  def mutator.to_s
+    $sprintf_test_fmt.replace("Z")
+    "ok"
+  end
+  result = sprintf(fmt, mutator)
+  assert_equal 202, result.length
+  assert_equal "ok", result[0, 2]
+  assert_equal "B" * 200, result[2..]
+end

mrbgems/mruby-string-ext/src/string.c

@@ -2201,15 +2201,27 @@ str_prepend(mrb_state *mrb, mrb_value self)
 
   char *p = RSTRING_PTR(self);
 
-  /* Move original content to the end */
+  /* Move original content to the end. The original self data now lives
+     at p + total_prepend_len, which we use as the source for any
+     self-referencing arguments (e.g., s.prepend(s, s)) to avoid reading
+     data that has already been overwritten by earlier copies. */
   memmove(p + total_prepend_len, p, self_len);
 
   /* Copy prepended strings in order */
   mrb_int offset = 0;
   for (mrb_int i = 0; i < argc; i++) {
-    mrb_int arg_len = RSTRING_LEN(argv[i]);
+    const char *src;
+    mrb_int arg_len;
+    if (mrb_obj_eq(mrb, self, argv[i])) {
+      src = p + total_prepend_len;
+      arg_len = self_len;
+    }
+    else {
+      src = RSTRING_PTR(argv[i]);
+      arg_len = RSTRING_LEN(argv[i]);
+    }
     if (arg_len > 0) {
-      memcpy(p + offset, RSTRING_PTR(argv[i]), arg_len);
+      memcpy(p + offset, src, arg_len);
       offset += arg_len;
     }
   }

mrbgems/mruby-string-ext/test/string.rb

@@ -492,6 +492,21 @@ assert('String#prepend') do
   g = "world"
   assert_equal "hello world", g.prepend("", "hello ", "")
   assert_equal "hello world", g
+
+  # Self-referencing arguments (GHSA-3hgj-g76g-878c)
+  h = "A" * 100
+  h.prepend(h, h)
+  assert_equal 300, h.length
+  assert_equal "A" * 300, h
+
+  # Mixed self-reference and literal
+  i = "AB"
+  i.prepend("XYZ", i)
+  assert_equal "XYZABAB", i
+
+  j = "AB"
+  j.prepend(j, "X", j)
+  assert_equal "ABXABAB", j
 end
 
 assert('String#ljust') do

mrbgems/mruby-test/mrbgem.rake

@@ -19,9 +19,11 @@ MRuby::Gem::Specification.new('mruby-test') do |spec|
   file assert_c => [assert_rb, build.mrbcfile] do |t|
     _pp "GEN", t.name.relative_path
     mkdir_p File.dirname(t.name)
-    open(t.name, 'w') do |f|
+    tmpfile = t.name + ".tmp"
+    open(tmpfile, 'w') do |f|
       mrbc.run f, assert_rb, 'mrbtest_assert_irep', cdump: false
     end
+    File.rename(tmpfile, t.name)
   end
 
   gem_table = build.gems.generate_gem_table build
@@ -36,7 +38,8 @@ MRuby::Gem::Specification.new('mruby-test') do |spec|
     file g.test_rbireps => [g.test_rbfiles, build.mrbcfile].flatten do |t|
       _pp "GEN", t.name.relative_path
       mkdir_p File.dirname(t.name)
-      open(t.name, 'w') do |f|
+      tmpfile = t.name + ".tmp"
+      open(tmpfile, 'w') do |f|
         g.print_gem_test_header(f)
         test_preload = g.test_preload and [g.dir, MRUBY_ROOT].map {|dir|
           File.expand_path(g.test_preload, dir)
@@ -117,6 +120,7 @@ MRuby::Gem::Specification.new('mruby-test') do |spec|
         end
         f.puts %Q[}]
       end
+      File.rename(tmpfile, t.name)
     end
   end
 
@@ -134,7 +138,8 @@ MRuby::Gem::Specification.new('mruby-test') do |spec|
   file clib => ["#{build.build_dir}/mrbgems/active_gems.txt", build.mrbcfile, __FILE__] do |_t|
     _pp "GEN", clib.relative_path
     mkdir_p File.dirname(clib)
-    open(clib, 'w') do |f|
+    tmpfile = clib + ".tmp"
+    open(tmpfile, 'w') do |f|
       f.puts %Q[/*]
       f.puts %Q[ * This file contains a list of all]
       f.puts %Q[ * test functions.]
@@ -169,5 +174,6 @@ MRuby::Gem::Specification.new('mruby-test') do |spec|
       end
       f.puts %Q[}]
     end
+    File.rename(tmpfile, clib)
   end
 end

src/class.c

@@ -2748,7 +2748,7 @@ prepare_writer_name(mrb_state *mrb, mrb_sym sym)
 }
 
 static mrb_value
-mod_attr_define(mrb_state *mrb, mrb_value mod, mrb_value (*accessor)(mrb_state*, mrb_value), mrb_sym (*access_name)(mrb_state*, mrb_sym))
+mod_attr_define(mrb_state *mrb, mrb_value mod, mrb_int aargc, mrb_value (*accessor)(mrb_state*, mrb_value), mrb_sym (*access_name)(mrb_state*, mrb_sym))
 {
   struct RClass *c = mrb_class_ptr(mod);
   const mrb_value *argv;
@@ -2765,6 +2765,7 @@ mod_attr_define(mrb_state *mrb, mrb_value mod, mrb_value (*accessor)(mrb_state*,
     }
 
     struct RProc *p = mrb_proc_new_cfunc_with_env(mrb, accessor, 1, &name);
+    p->flags |= aargc == 0 ? MRB_PROC_NOARG : 0;
     mrb_method_t m;
     MRB_METHOD_FROM_PROC(m, p);
     mrb_define_method_raw(mrb, c, method, m);
@@ -2783,7 +2784,7 @@ attr_reader(mrb_state *mrb, mrb_value obj)
 static mrb_value
 mrb_mod_attr_reader(mrb_state *mrb, mrb_value mod)
 {
-  return mod_attr_define(mrb, mod, attr_reader, NULL);
+  return mod_attr_define(mrb, mod, 0, attr_reader, NULL);
 }
 
 static mrb_value
@@ -2799,7 +2800,7 @@ attr_writer(mrb_state *mrb, mrb_value obj)
 static mrb_value
 mrb_mod_attr_writer(mrb_state *mrb, mrb_value mod)
 {
-  return mod_attr_define(mrb, mod, attr_writer, prepare_writer_name);
+  return mod_attr_define(mrb, mod, 1, attr_writer, prepare_writer_name);
 }
 
 static mrb_value

src/gc.c

@@ -541,15 +541,15 @@ mrb_gc_unregister(mrb_state *mrb, mrb_value obj)
   if (!mrb_array_p(table)) return;
   struct RArray *a = mrb_ary_ptr(table);
   mrb_ary_modify(mrb, a);
-  mrb_int len = ARY_LEN(a)-1;
+  mrb_int len = ARY_LEN(a);
   mrb_value *ptr = ARY_PTR(a);
-  for (mrb_int i = 0; i <= len; i++) {
-    if (mrb_ptr(ptr[i]) == mrb_ptr(obj)) {
-      ARY_SET_LEN(a, len);
-      memmove(&ptr[i], &ptr[i + 1], (len - i) * sizeof(mrb_value));
-      break;
+  mrb_int w = 0;
+  for (mrb_int r = 0; r < len; r++) {
+    if (mrb_ptr(ptr[r]) != mrb_ptr(obj)) {
+      ptr[w++] = ptr[r];
     }
   }
+  ARY_SET_LEN(a, w);
 }
 
 MRB_API struct RBasic*

src/range.c

@@ -432,11 +432,7 @@ mrb_get_values_at(mrb_state *mrb, mrb_value obj, mrb_int olen, mrb_int argc, con
   for (mrb_int i = 0; i < argc; i++) {
     mrb_value v = argv[i];
 
-    if (mrb_integer_p(v)
-#ifdef MRB_USE_BIGINT
-        || mrb_bigint_p(v)
-#endif
-        ) {
+    if (mrb_integer_p(v) || mrb_bigint_p(v)) {
       mrb_int i = mrb_as_int(mrb, v);
       mrb_ary_push(mrb, result, func(mrb, obj, i));
     }

src/vm.c

@@ -134,19 +134,29 @@ static inline void
 envadjust(mrb_state *mrb, mrb_value *oldbase, mrb_value *newbase)
 {
   mrb_callinfo *ci = mrb->c->cibase;
-  ptrdiff_t delta = newbase - oldbase;
+  /*
+   * Byte-level calculation to avoid truncation when allocator alignment is
+   * smaller than sizeof(mrb_value).
+   * eg: MRB_NO_BOXING + MRB_INT64 with MRB_32BIT => sizeof(mrb_value)=16
+   *     And when memory allocator's alignment is 8 bytes
+   * Pointer subtraction on mrb_value* would truncate (8/16 -> 0).
+   * So, we use char* for pointer calculation to get the correct offset in bytes,
+   * then apply that offset to mrb_value* pointers.
+   */
+  ptrdiff_t off = (char *)newbase - (char *)oldbase;
 
-  if (delta == 0) return;
+  if (off == 0) return;
   while (ci <= mrb->c->ci) {
     struct REnv *e = mrb_vm_ci_env(ci);
 
+    mrb_value *new_stack = (mrb_value *)((char *)ci->stack + off);
+
     if (e) {
       mrb_assert(e->cxt == mrb->c && MRB_ENV_ONSTACK_P(e));
       mrb_assert(e->stack == ci->stack);
-
-      e->stack += delta;
+      e->stack = new_stack;
     }
-    ci->stack += delta;
+    ci->stack = new_stack;
     ci++;
   }
 }
@@ -2703,11 +2713,10 @@ RETRY_TRY_BLOCK:
       if (kidx < 0 || !mrb_hash_p(kdict=regs[kidx]) || !mrb_hash_key_p(mrb, kdict, k)) {
         RAISE_FORMAT(mrb, E_ARGUMENT_ERROR, "missing keyword: %v", k);
       }
-      v = mrb_hash_get(mrb, kdict, k);
+
+      v = mrb_hash_delete_key(mrb, kdict, k);
       ci = mrb->c->ci;
       regs[a] = v;
-      mrb_hash_delete_key(mrb, kdict, k);
-      ci = mrb->c->ci;
       NEXT;
     }
 
@@ -3113,7 +3122,9 @@ RETRY_TRY_BLOCK:
       {                                                                     \
         mrb_value arg = mrb_int_value(mrb, c);                              \
         mrb_sym mid = MRB_OPSYM(op_name);                                   \
-        regs[a] = mrb_funcall_argv(mrb, regs[a], mid, 1, &arg);             \
+        mrb_value v = mrb_funcall_argv(mrb, regs[a], mid, 1, &arg);         \
+        ci = mrb->c->ci;                                                    \
+        regs[a] = v;                                                        \
         mrb_gc_arena_restore(mrb, ai);                                      \
       }                                                                     \
       break;                                                                \

tasks/presym.rake

@@ -29,7 +29,7 @@ MRuby.each_target do |build|
     end
   end
 
-  file presym.list_path => ppps do
+  presym_task = file presym.list_path => ppps do
     presyms = presym.scan(ppps)
     current_presyms = presym.read_list if File.exist?(presym.list_path)
     if presyms != current_presyms
@@ -41,6 +41,21 @@ MRuby.each_target do |build|
     end
   end
 
+  # Don't directly write dependency tasks in the "task" arguments.
+  # The rake system tracks dependencies recursively
+  # (see Rake::Task#all_prerequisite_tasks and #collect_prerequisites).
+  # Therefore, indirect dependencies from ".o" to ".pi" must be eliminated.
+  # ref. https://github.com/mruby/mruby/issues/6721
+  # This task acts a proxy-like for the "presym.list_path" task.
+  presym_proxy = task "gensym:update:#{build.name}" do
+    presym_task.invoke
+  end
+
+  # Override the "timestamp" method to reflect the presym file.
+  presym_proxy.define_singleton_method :timestamp do
+    presym_task.timestamp
+  end
+
   # Ensure .o files depend on presym headers being generated.
   # This is critical when a build's .o files are compiled during another
   # build's presym scanning chain (before :gensym completes), e.g.:
@@ -50,7 +65,7 @@ MRuby.each_target do |build|
     next unless File.extname(prereq) == build.exts.object
     next unless prereq.start_with?(build_dir)
     next if mrbc_build_dir && prereq.start_with?(mrbc_build_dir)
-    file prereq => presym.list_path
+    file prereq => presym_proxy
   end
 
   task gensym: presym.list_path

test/t/module.rb

@@ -163,6 +163,9 @@ assert('Module#attr_reader', '15.2.2.4.13') do
 
   AttrTestReader.cattr_val = 'test'
   assert_equal 'test', AttrTestReader.cattr
+
+  assert_raise(ArgumentError) { attr_instance.iattr(1) }
+  assert_raise(ArgumentError) { attr_instance.iattr(1, 2, 3) }
 end
 
 assert('Module#attr_writer', '15.2.2.4.14') do

test/t/syntax.rb

@@ -680,6 +680,20 @@ assert 'keyword arguments' do
   assert_equal [{a: 1}, {b: 2}], m({a: 1}, b: 2)
   assert_raise(ArgumentError) { m({a: 1}, {b: 2}) }
 
+  def m1(a: {}) a end
+  assert_equal({}, m1)
+  assert_equal(:abc, m1(a: :abc))
+
+  def m2(a: +1) a end
+  assert_equal(1, m2)
+
+  assert_nothing_raised do
+    def m3 arg:
+      123
+    end
+  end
+  assert_equal(123, m3(arg: 456))
+
   def m(*, a:) a end
   assert_equal 1, m(a: 1)
   assert_equal 3, m(1, 2, a: 3)
@@ -1246,12 +1260,13 @@ assert('pattern matching - NoMatchingPatternError') do
     assert_true e.message.is_a?(String)
   end
 
-  # case/in without else returns nil (no match)
-  result = case 5
-  in 1 then :one
-  in 2 then :two
+  # case/in without else raises NoMatchingPatternError
+  assert_raise(NoMatchingPatternError) do
+    case 5
+    in 1 then :one
+    in 2 then :two
+    end
   end
-  assert_nil result
 end
 
 assert('pattern matching - complex patterns') do