Compilation Warnings and Their Fixes

[lior8]

There are multiple compilation warnings in the codebase and I want to try to tackle a few of them. Therefore I have a few questions:

1. Mismatched Types Compilation Errors
   There are quite a few compilation warnings that relate to mismatched return or comparison types.
   For example "int i" instead of "size_t i", which indeed should be size_t i.
   But there are places where it is less obvious, for example unsigned int to int and vice versa. I was thinking of trying to figure out what would be the true appropriate type for them, but I am afraid of it breaking in certain edge cases. Would simple casting be appropriate here or is the former approach preferable?
2. Unused static functions
   I saw that inlining them can fix it, or instead removing the warning for unusued fuctions in the flags for compilation. Is there a preferred approach? I think adding "inline" to them can solve the problem.
3. #pragma mark
   Is this being used for something? I am compiling with GCC 9.4.0 and I get the following warning: "ignoring #pragma mark [-Wunknown-pragmas]"

[nathansttt]

There are a few reasons for these sorts of errors. Using a static_cast would likely fix most of them correctly, but I'm a bit leery of mass replacement, given the possibility of unintended consequences.

[lior8]

I'll mostly look into indexes and do small PRs so they can be verified before pulling in.