Ruby 3.4: Backport [Bug #21715]

[hsbt]

merge revision(s) d209e6f1c0a93ad3ce1cc64dd165a6b67672614d: [Backport #21715]

	[PATCH] search_nonascii(): Replace UB pointer cast with memcpy

	Casting a pointer to create an unaligned one is undefined behavior in C
	standards. Use memcpy to express the unaligned load instead to play by
	the rules.

	Practically, this yields the same binary output in many situations
	while fixing the crash in [Bug #21715].

[Copilot]

Pull request overview

This PR backports a fix for Bug #21715 to Ruby 3.4, addressing undefined behavior in the search_nonascii() function. The issue involved casting pointers to create unaligned pointers, which is undefined behavior in C. The fix replaces unsafe pointer casting with memcpy to safely handle unaligned loads.

Changes:

• Incremented the Ruby patchlevel from 72 to 73
• Refactored search_nonascii() to use char pointer iteration with memcpy instead of uintptr_t pointer dereferencing
• Eliminated undefined behavior while maintaining functionally equivalent code

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
version.h	Incremented RUBY_PATCHLEVEL from 72 to 73 for the bug fix release
string.c	Replaced unsafe unaligned pointer casts with memcpy-based loads in search_nonascii() function

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