That work building “yet another build tool” could have gone in to programmatically generating bazel BUILD files. So, there was an active choice here somewhere; we just don’t know all the information as to why effort was diverted away from Bazel and toward building a new tool.

I trust them to make good decisions, so I would like to understand more. :)

Seems like Siso supports Starlark, so maybe its a step in Bazels direction after all.

It doesn't have any compiler in the distribution itself

It isn't hard to create a basic build system. However there are a lot more rare corner cases than anyone who sets out to create one as a side project realizes and so in almost all cases their build systems work for the easy/common situations, but in lots of weird cases it doesn't work. Often those corner cases will happen on setups that make sense for one exactly person in the world but for everyone else is stupid. (think cross compiling on haiku-os for a vax running netbsd)

Which is to say if you want to create a build system that needs to be your only goal. You can maybe make the goal create the build system that some project needs (Chromium in this case) needs, but you won't be doing any hacking on the project (Chromium) itself because all your time will be spent on the build system.

Since everyone I know thinks of build systems as a side project they should just choose one that works. I use cmake, which works well despite the warts. I've heard good things about build2 and bazel, but I have no experience with either. I have used ninja as well (that is handwritten ninja files), but it isn't intended for that purpose and so in general I wouldn't recommend it.

And in these cases you really see the impact of internal dependencies (building rust/llvm takes around 30-40% of the entire build). The upside is that you can patch and debug absolutely any part of the system.

Bootstrapping everything is exactly how it's done correctly--and how it's actually done in practice in Guix.

I mean sure if you have a business to run you outsource this part to someone else--but you seem to think it's not done at all.

Supply chain attacks have been happening pretty much non-stop the past years. Think it's a good idea to use binary artifacts you don't know how they were made (and thus what's in them)? Especially for build tools, compilers and interpreters.

>And why is that location more valid of a decision than the one that doesn't require building the build system from source?

Because you only have to review a 250 Byte binary (implementing an assembler) manually. Everything else is indeed built from source, including make, all the way up to Pypy, Go, Java and .NET (and indeed Chromium).