From: "YO4 (Yoshinao Muramatsu) via ruby-core" <ruby-core@...>
Date: 2026-09-01T12:21:56+00:00
Subject: [ruby-core:126553] [Ruby Bug#22284] Passing an object with to_int to curry as its arity causes problems with LLP64.

Issue #22284 has been reported by YO4 (Yoshinao Muramatsu).

----------------------------------------
Bug #22284: Passing an object with to_int to curry as its arity causes problems with LLP64.
https://bugs.ruby-lang.org/issues/22284

* Author: YO4 (Yoshinao Muramatsu)
* Status: Open
* ruby -v: master
* Backport: 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN
----------------------------------------
The proc_curry function in proc.c is affected by differences in behavior caused by the int size in FIX2INT.
As a result, depending on the arguments, curry may not function correctly on Windows.
```
method(:puts).curry(1r).call(42)
=> #<Proc:0x0000000005e06c58 (lambda)> (Windows)
=> 42 (others)
```
The same thing happens in gems/src/rbs/test/stdlib/Proc_test.rb:113.
It also triggers an assertion in a debug build on windows.
```
irb(main):001> method(:puts).curry(1r).call(42)
S:\git\ruby\ruby\include\ruby/internal/arithmetic/long.h:192: Assertion Failed: rbimpl_fix2long_by_shift:RB_FIXNUM_P(x)
...(snip)
-- C level backtrace information -------------------------------------------
C:\WINDOWS\SYSTEM32\ntdll.dll(NtWaitForSingleObject+0x14) [0x00007FF82F2E0404]
C:\WINDOWS\System32\KERNELBASE.dll(WaitForSingleObjectEx+0xaf) [0x00007FF82C53C11F]
S:\git\ruby\mswin64\x64-vcruntime140-ruby410.dll(rb_print_backtrace+0x3e) [0x00007FFF45D706CA] S:\git\ruby\ruby\vm_dump.c:1137
S:\git\ruby\mswin64\x64-vcruntime140-ruby410.dll(rb_vm_bugreport+0x288) [0x00007FFF45D70958] S:\git\ruby\ruby\vm_dump.c:1482
S:\git\ruby\mswin64\x64-vcruntime140-ruby410.dll(rb_assert_failure_detail+0xbb) [0x00007FFF45C05557] S:\git\ruby\ruby\error.c:1227
S:\git\ruby\mswin64\x64-vcruntime140-ruby410.dll(rb_assert_failure+0x12) [0x00007FFF45C0549A] S:\git\ruby\ruby\error.c:1202
S:\git\ruby\mswin64\x64-vcruntime140-ruby410.dll(proc_curry+0xfa) [0x00007FFF45D48426] S:\git\ruby\ruby\proc.c:4614
...(snip)
```
proc.c:4614 has this
```
        sarity = FIX2INT(arity);
```
FIX2INT is being used, and based on what I've read in doc/extension.rdoc,
I'm not entirely sure if it's correct for curry to use to_int.
So just reporting this for now before submitting a PR.




-- 
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