[sieve]

Compiler code can be pretty if you have the time to maintain it. Compilers are some of the most modular applications you can build with hard boundaries between subsystems and clear handoffs at each level.

The problem is that people often do not have the time to refactor once they have gotten the thing to work. And the mess keeps growing.

[KolmogorovComp]

And the migrations. Or rather all the half-started migrations that never get through meaning you have to deal with api v1,2,3 all the times.

Those are pervasive in any old and large project but in my experience especially so in compilers.

[sieve]

Management problem more than anything else, I feel.

Compilers should not have so much churn. You decide on a set of language features, stick to it and implement. After that, it should only be bugfixes for the foreseeable future till someone can make a solid case for that shiny new feature.

Scope creep is bane of most projects.