A frustrating thing about inlining in Go is that there's a fairly arbitrary cost model and you sometimes end up fighting it (lookup George Tankersley's talks on YouTube). There have been tons of discussions about whether or not it should be user configurable, if inlining hints should happen at the call sites or function definitions etc.

It's quite a nice discussion that helps people understand the toolchain. It also goes to show that while a self hosted build system is nice, you forgo decades of gcc/llvm optimisations. https://github.com/golang/go/issues/17566