optparse VS rust-fnv

Between -std=c99 and removing these headers, you're missing time definitions (struct timeval, gettimeofday) and option parsing definitions (struct option, getopt_long). Mingw-w64 provides all this for compatibility, but MSVC has none of these, so you'll need to write replacements. I've written embeddable, public domain implementations of getopt and something like getopt_long, in case that helps. These are how I deal with option parsing portability.

getopt_long is a GNU extension, common across unix-like systems, for parsing long options. You can find libraries for functionality as well.

When I need something more sophisticated, where long options would be nice, I reach for my own Optparse.

https://github.com/skeeto/optparse (short and long)

This is bug-free and feature complete so it never needs to be updated. When I need argument parsing in a C program, I just copy-paste that into my source and massage it into place. Sometimes I cut the fprintf() stuff, or replace the isalnum, or otherwise adapt it to fit the program's needs. The point is that it becomes wholly owned by the project using it. It's a similar story for long option parsing.

Use faster hashing function (e.g. fnv, there are other potentially faster options as well). By default Rust std uses a DoS-resistant function, which is relatively slow.

Looking at ripgrep myself, I'm seeing some trivial dependencies. One is fnv. Perhaps you're not aware, but FNV-1a is literally ~4 lines of code. It's about as sophisticated as left-pad. I've written it from scratch a dozen times off the top of my head (the official offset basis and prime are really not special, so you can just generate your own). It would take you about a minute to eliminate it.