Prevent ObjectSpace.count_objects from allocating extra arrays

`ObjectSpace.count_objects` could cause an unintended array allocation.
It returns a hash like `{ :T_ARRAY => 100, :T_STRING => 100, ... }`, so
it creates the key symbol (e.g., `:T_STRING`) for the first time. On
rare occations, this symbol creation internally allocates a new array
for symbol management.

This led to a problematic side effect where calling `count_objects`
twice in a row could produce inconsistent results: the first call would
trigger the hidden array allocation, and the second call would then
report an increased count for `:T_ARRAY`.

This behavior caused test failures in `test/ruby/test_allocation.rb`,
which performs a baseline measurement before an operation and then
asserts the exact number of new allocations.

https://rubyci.s3.amazonaws.com/openbsd-current/ruby-master/log/20250716T053005Z.fail.html.gz

>   1) Failure:
> TestAllocation::ProcCall::WithBlock#test_ruby2_keywords [...]:
> Expected 1 array allocations for "r2k.(1, a: 2, &block)", but 2 arrays allocated.

This change resolves the issue by pre-interning all key symbols used by
`ObjectSpace.count_objects` before its counting. This eliminates the
side effect and ensures the stability of allocation-sensitive tests.

Co-authored-by: Koichi Sasada <ko1@atdot.net>

0 files changed, 0 insertions, 0 deletions