How does V lang compile to C?

[Kostia06]

Hi everyone, I hope y'all doing good. I am currently working on my own programming language and I am curious how does V compile to C. Does it just translates V code into C code and compile C code? Or does it have another way of compile V code? Also, I understand that V is written in itself like Go and Rust, but how does that even work😅?

[JalonSolov]

V, as most compilers these days, parses the source into an AST. Once the AST is created, the C backend (vlib/v/gen/c) walks the AST and output C code to a temporary file. When that step it finished, it calls the C compiler to generate the binary. This is the current default.

How it works is that it was first bootstrapped in Go, until it could compile itself. Bootstrapping is necessary, of course, because you can't compile anything in a language that doesn't exist, yet. You'll need to do the same with your language if you want it to compile itself.

[Kostia06]

Thank you! So, technically speaking V translate V code into C code into a file and compiles the C code using C compiler. Also, another question when the program compiles the temporary C file, does it use the compiler that is installed on the computer already or does V compiles it?

[JalonSolov]

It uses tcc by default, which the V Makefile installs for you under thirdparty/tcc mainly because it is fast, but it doesn't do optimization. If you use the -prod switch, which turns on optimization, it uses what you have installed. V is not a C compiler, so it can't compile the code itself.

Note that this is only with the default C backend. V also has other backends in various states of usefulness, including JavaScript, WASM, and native (which does direct binary output to an exe file - but is, unfortunately, the least advanced at this time). The native backend will become the default once it is more complete. Someone has even been working on a FreePascal backend.