That's why you find it in the comments. That is where tools have found a place to add their own syntax without breaking the Go code.

Absolutely you can do the same in Java. It exists to the exact same degree as it does in Go. I expect it isn't done as often in the Java world because it is much harder to parse Java code so the tools don't get built.

Things like "//go:embed" and "//go:build" very much do change the semantics of source code.

The comments above 'import "C"' containing C function definitions and imports change the compilation of go source code.

The "//go" comments contain a mix of ones that must be respected to compile, to being optional, to being entirely ignorable (like generate and fix).

When you take the source code as a whole they do, but the Go parts are unchanged. The Go spec says nothing about //go:embed, or //go:build. These are not Go features. What you are looking at is another programming language that has been added by a particular tool, using Go comments as the gateway to supporting non-standard syntax inline.

> The "//go" comments contain a mix of ones that must be respected to compile

That is true, but in using it you've accepted that you are no longer writing Go. In fact, with respect to your talk of C, "Cgo is not Go" is one of the most oft-repeated lines seen in the Go community. It's not just a silly catchphrase. It is the technical reality. Cgo is literally a different programming language, much like how Objective-C is not C despite supporting everything C does.

So the go stdlib also isn't "the go programming language"? The 'golang.org/x' repositories aren't standard go?

I feel like you're no-true-scottsmanning this into a meaningless definition where the spec defines Go, but all Go code in existence is not actually Go code, it's a different programming language which everyone happens to call Go and think of as Go.

Like, sure, redefine Go like that if you want, but I don't think anyone else in practice thinks "Ah, yes, the go stdlib isn't actually written in Go", so you'll be off by yourself with that definition.

Which standard library? There isn't just one. tinygo's standard library, for example, isn't the same as gc's. They are, in most cases, API compatible, but there are some packages not shared and they are completely different codebases. A standard library is a distribution concern, not a language concern.

Maybe you're caught up thinking in some other kind of language that only has one distribution and trying to apply that misaligned logic to programming at large?

> I feel like you're no-true-scottsmanning this into a meaningless definition

It's not, though. It is actually something you have to think about in the real world. A 100% spec-complaint Go compiler can be completely unable to use gc's standard library code as it contains additional language constructs that are bound to gc specifically.

> I don't think anyone else in practice thinks "Ah, yes, the go stdlib isn't actually written in Go"

Again, its not clear which standard library you are referring to, but if we assume gc's it is mostly written in Go, but it contains extensions that are not Go. If you say that it was written in Go casually, people will know what you mean, but technically, no, it isn't written in Go. At least no more than an Objective-C program is written in C.

But, unlike Objective-C, the extensions are added in such a way that they remain valid Go syntactically. That means you can use, say, a Go language server on gc's standard library without it blowing up on the extensions. It gives the advantage of a new language, but without having to build new language tools.

Whereas the first 50 golang hits are all about the language.

You might have your preferred approach, but there are good reasons for using golang.