When calling a user function, a pointer retrieved outside of a loop may be invalidated.

Summary of Changes

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This pull request enhances the robustness of the mrb_mt_foreach function by ensuring that method table pointers are consistently valid throughout its iteration. It resolves a potential bug where external modifications to the method table during a loop could lead to invalid pointer access, thereby improving the stability and reliability of the system.

Highlights

Bug Fix / Robustness Improvement: Addresses a potential pointer invalidation issue within the mrb_mt_foreach function. Previously, vals and keys pointers were retrieved once before the loop, which could lead to invalidation if a user function called within the loop modified the underlying method table (mt_tbl).
Pointer Re-evaluation: The retrieval of union mt_ptr *vals and mrb_sym *keys has been moved from outside the for loop (lines 233-234) to inside the loop (lines 234-235). This ensures that these pointers are re-evaluated at each iteration, guaranteeing they always point to valid memory locations even if the method table is altered during the loop's execution.

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