[GSoC] Fix compiler warnings in diagnostics and analyzer - Pre-GSoC Contribution

Hello GCC Community and GSoC Mentors,

My name is Zeinab Ayman, a Computer Engineering student preparing a
proposal for GSoC 2026.

As part of getting familiar with the GCC codebase and showcasing my skills,
I have worked on fixing a set of compiler warnings across diagnostics,
text-art, and analyzer modules (including -Wformat-diag,
-Wmaybe-uninitialized, and -Wdelete-non-virtual-dtor).

Since I am using GitHub to manage my workflow, I have submitted the patch
as a Pull Request on the mirror repository here:
https://github.com/gcc-mirror/gcc/pull/127

  You can also check my GitHub profile here: https://github.com/zeinab304

I would highly appreciate it if mentors could review these fixes. I am
looking forward to contributing more and finalizing my GSoC proposal
document.

Best regards,
Zeinab Ayman