closes #25294; adds a test case

[ringabout]

closes #25294

[Copilot]

Pull request overview

Adds a regression test under tests/ccgbugs2 to cover issue #25294 (SIGSEGV when using --mm:refc with an RVO-returning proc and a large object layout), ensuring the scenario is exercised by the test suite going forward.

Changes:

• Adds a new ccgbugs2 test (t25294.nim) that runs the reproducer under a --mm option matrix.
• Introduces a small helper module pair (m25294/c.nim, m25294/t.nim) to model the types and the p() constructor used by the reproducer.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
tests/ccgbugs2/t25294.nim	Adds the regression test entrypoint and test spec matrix for different memory managers.
tests/ccgbugs2/m25294/c.nim	Defines the type setup (generic object + large array field) used to reproduce the issue.
tests/ccgbugs2/m25294/t.nim	Implements p() returning D to trigger the relevant codegen/runtime path.

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[github-actions]

Thanks for your hard work on this PR!
The lines below are statistics of the Nim compiler built from 8771451

Hint: mm: orc; opt: speed; options: -d:release
192375 lines; 12.074s; 801.453MiB peakmem