Bug #20767: VM_ASSERT fails on clear_method_entry_by_id_in_class() under a specific situation

• Status: Open
• Assignee: -
• Target version: -
• ruby -v: ruby 3.4.0dev (2024-09-27T17:45:22Z vm_assertion_cme_o.. 027ef60500) +PRISM [arm64-darwin23]
• Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN

[tagomoris (Satoshi Tagomori)]

VM_ASSERT in clear_method_entry_by_id_in_class() (vm_method.c) fails when:

• Kernel#require is refined
• Kernel#require is replaced by alias_method and define_method
• User code calls require
• The aliased method entry is undefined

Under this situation, VM_ASSERT(cme->owner == T_CLASS) fails in clear_method_entry_by_id_in_class.
This CI failure shows it: https://github.com/ruby/ruby/actions/runs/11081754435/job/30793895707?pr=11715

In this case, the cme had:

• def->type: CFUNC
• defined_class: Kernel
• owner: Kernel

I couldn't find the root cause of why Kernel is set on cme->owner, and why the owner is checked here.
How should we fix this problem?

• Just delete the VM_ASSERT() (because the cme is just to be invalidated)
• Fix the root cause of the invalid&unexpected cme->owner

[tagomoris (Satoshi Tagomori)]

• ruby -v set to ruby 3.4.0dev (2024-09-27T17:45:22Z vm_assertion_cme_o.. 027ef60500) +PRISM [arm64-darwin23]

[nobu (Nobuyoshi Nakada)]

The test case: https://github.com/ruby/ruby/pull/11715/files

[alanwu (Alan Wu)]

• Status changed from Open to Closed

a838f980f599d95ccf344157f7074e997af31f48 should have fixed this issue.

[alanwu (Alan Wu)]

• Status changed from Closed to Open

Reopening since the assert failed again on CI:
http://ci.rvm.jp/logfiles/brlog.trunk-repeat20-asserts.20241029-211036#L2453