[Largo]

irb starts and runs in a Windows console again, with reline exactly as Ruby ships it. Both bugs were in IronRuby, not in reline.

1. Fiddle looks a Win32 name up as CRuby does

reline asks Fiddle for FillConsoleOutputCharacter, but kernel32 exports only the ...A and ...W variants. In 4.0.2, irb therefore died at startup with unknown symbol "FillConsoleOutputCharacter", piped or not.

On Windows, Handle#[] now tries the name as given, then with the A suffix, then the stdcall decorations @0 to @252, plain and after the A. That is the order of fiddle 1.1.8's fiddle_handle_find_func.

This change is the same as #38's 920e6ca8: FiddleHandle.cs and package-release.sh are byte for byte identical. The test files are not: both PRs add Fiddle_AnsiSuffix1 at the same spot, and this one adds the PackPointer_* tests next to it. So merge this PR before #38. #38 then takes this PR's two test files, which contain everything its own do, reverts its reline change, and updates its 4.0.3 notes. Merged the other way round, #38's reline change would land on master.

2. pack("p") writes a real address

[str].pack("p") and ("P") wrote an index into the packed string's list of Strings, not an address. reline's Win32API hands the console API every buffer as [str].pack("p").unpack("q*") and reads what the call wrote from str. So in a real console, irb crashed with an access violation in fiddle_calli, and so would any gem that passes buffers that way.

• Native block per String: each String that pack points at gets its own native block (PackedPointers), holding its bytes and a NUL for as long as the String lives. pack writes the block's address.
• Copy in and back: Fiddle::Function#call recognises the address among its pointer arguments. It copies the String into the block before the call and the block back into the String after it. In CRuby, the String's own buffer gives the same result.
• unpack("p"): still finds only Strings packed into that same string ("no associated pointer"), now by address.

reline/io/windows.rb is not touched; it stays as upstream has it. #38 changed it to pass Strings to Fiddle instead, and it reverts that once this PR is merged.

Tests

• Fiddle_AnsiSuffix1: the A suffix, and the message for an unknown symbol.
• PackPointer_RealAddress1, all platforms: C reads and writes through pack("p") (strlen, memset, Fiddle::Pointer#to_s); the unpack round trip, nil, and the error for a foreign address. It checks the address before C touches it, so a regression fails the test instead of killing the run. Without the fix it reports the old indexes, [:not_an_address, 1, 1].
• PackPointer_RelineWin32Api1, Windows: reline's own, unmodified Win32API fills a buffer through GetModuleFileNameA. That is the path that crashed.
• CI smoke test and release check: irb is started with piped input on every platform, and must answer 42.
• CI test step: a run that did not finish now fails it. An access violation ends the test process and leaves no > FAILED line to count, so until now such a run passed.

Checked

• ruby/spec core/array/pack and core/string/unpack: 3193 examples, 0 failures. The full C# suite passes.
• A probe that reads, writes and unpacks through pack("p") gives output byte-identical to CRuby 4.0.1.
• Real console (a ConPTY terminal tab): a script queues key events for p 6 * 7, Enter, exit, Enter with WriteConsoleInputW, then runs irb, which reads them through ReadConsoleInputW. CRuby 4.0.1 and this branch show the same thing: the prompt, 42, and a clean exit. On master, irb crashes with 0xC0000005.

Summary by CodeRabbit

• New Features
  • Packing strings as pointers now provides their native memory addresses, allowing packed strings to be used with Fiddle and unpacked back into associated strings.
  • Fiddle symbol lookup on Windows now checks common ANSI-suffixed and stdcall-decorated symbol names.
• Bug Fixes
  • Changes made through Fiddle to eligible packed string buffers are reflected in the associated string. Frozen strings are not modified.

[coderabbitai]

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• Run ID: 9f7335c7-6f7e-4a03-bdf5-3c529abe5798

Commits

Reviewing files that changed from the base of the PR and between 99711fd and 3b486b6.

Files selected for processing: 8

• .github/workflows/ci.yml
• Src/IronRuby.Tests/RubyTests.cs
• Src/IronRuby.Tests/Runtime/MiscTests.cs
• Src/Libraries/Builtins/PackedPointers.cs
• Src/Libraries/Builtins/RubyEncoder.cs
• Src/Libraries/Fiddle/FiddleCall.cs
• Src/Libraries/Fiddle/FiddleHandle.cs
• Util/package-release.sh

Included review availability: This review used your included allowance. Your plan provides up to 1 included review per hour; 0 remain after this review.

Walkthrough

The changes add native addresses for packed Ruby strings, update Fiddle pointer handling and Windows symbol lookup, and add regression tests and startup checks. CI also detects test runs without terminal output.

Changes: Fiddle and runtime integration

Layer / File(s)	Summary
Packed string addresses Src/Libraries/Builtins/PackedPointers.cs, Src/Libraries/Builtins/RubyEncoder.cs, Src/IronRuby.Tests/Runtime/MiscTests.cs	Packed strings now use registered native buffers. Packing stores the buffer address, and unpacking resolves it against associated strings. Regression tests cover pointer reads, writes, round-tripping, nil, and unassociated addresses.
Fiddle packed-pointer calls Src/Libraries/Fiddle/FiddleCall.cs, Src/IronRuby.Tests/RubyTests.cs, Src/IronRuby.Tests/Runtime/MiscTests.cs	Fiddle tracks packed string blocks during native calls and copies eligible changes back. A regression test covers Reline's Windows API call with a packed string buffer.
Windows symbol lookup Src/Libraries/Fiddle/FiddleHandle.cs, Src/IronRuby.Tests/Runtime/MiscTests.cs	Windows symbol lookup tries ANSI-suffixed and stdcall-decorated names. Tests check lookup results and missing-symbol errors.
Startup and CI checks .github/workflows/ci.yml, Util/package-release.sh	Startup checks run an expression through irb on Windows and non-Windows platforms. CI reports an error and prints the last 40 output lines if test output has neither a terminal PASSED line nor a Repro: line.

Priority: Normal

Estimated code review effort: 3 (Moderate) | ~25 minutes

Change: Bug fix

Sequence Diagram(s)

sequenceDiagram
  participant RubyEncoder
  participant PackedPointers
  participant FiddleCall
  participant FiddleTarget
  RubyEncoder->>PackedPointers: Get the string buffer address
  RubyEncoder->>RubyEncoder: Pack the native address
  FiddleCall->>PackedPointers: Find the block for the address
  FiddleCall->>FiddleTarget: Pass the pointer to the native call
  FiddleTarget-->>FiddleCall: Return from the native call
  FiddleCall->>PackedPointers: Copy eligible buffer changes back

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Possibly related PRs

• Largo/ironruby#35: Adds the launcher contract used by the irb smoke checks in this pull request.

Suggested reviewers: claude

Merge Risk: Minimal · up to 3b486

No established issue prevents merging after normal checks.

Pre-merge checks: 5

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly identifies the two main changes: Windows Fiddle symbol lookup for A exports and real native addresses from pack("p").
Docstring Coverage		Docstring coverage is 81.82% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentati…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

Docstring coverage is 81.82% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentation-only edits and deletions within surviving functions are included; unchanged diff context and fully deleted functions are excluded. Analyzed 11 functions across 7 files. (1 skipped: 1 unsupported.)

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