cryptic build errors in syncthing with golang 1.19

[Fabio Valentini]

Hi all,

I've started to see very strange build failures of syncthing since the
update from go 1.18 to 1.19:
https://koschei.fedoraproject.org/package/syncthing?collection=f37

I've looked at build logs, but there's no obvious source of a problem
that I can see in the usual "megabyte-sized wall of inscrutable build
commands / output".  Grepping for "error" does not help, the build
just appears to "fail" at some point.

Could somebody please take a look? I don't know what's going wrong.

Thanks,
Fabio

[Florian Weimer]

* Fabio Valentini:
> Hi all,
>
> I've started to see very strange build failures of syncthing since the
> update from go 1.18 to 1.19:
> https://koschei.fedoraproject.org/package/syncthing?collection=f37
>
> I've looked at build logs, but there's no obvious source of a problem
> that I can see in the usual "megabyte-sized wall of inscrutable build
> commands / output".  Grepping for "error" does not help, the build
> just appears to "fail" at some point.
>
> Could somebody please take a look? I don't know what's going wrong.

Pretty much all Go compiler error messages contain the chracter sequence
“.go:”.  Using that, we end up at:

| _build/src/github.com/syncthing/syncthing/vendor/github.com/lucas-clemente/quic-go/internal/qtls/go119.go:6:13: cannot use "The version of quic-go you're using can't be built on Go 1.19 yet. For more details, please see https://github.com/lucas-clemente/quic-go/wiki/quic-go-and-Go-versions." (untyped string constant "The version of quic-go you're using can't be built on Go 1.19 yet. F...) as int value in variable declaration

Which is pretty self-explanatory.

Thanks,
Florian

[Fabio Valentini]

On Fri, Jul 29, 2022 at 12:53 PM Florian Weimer  wrote:
> Pretty much all Go compiler error messages contain the chracter sequence
> “.go:”.  Using that, we end up at:

Good to know. I'll add it to my mental list of things to "grep" for.
> | _build/src/github.com/syncthing/syncthing/vendor/github.com/lucas-clemente/quic-go/internal/qtls/go119.go:6:13: cannot use "The version of quic-go you're using can't be built on Go 1.19 yet. For more details, please see https://github.com/lucas-clemente/quic-go/wiki/quic-go-and-Go-versions." (untyped string constant "The version of quic-go you're using can't be built on Go 1.19 yet. F...) as int value in variable declaration
>
> Which is pretty self-explanatory.

Thanks, I wouldn't have found that in the wall of text. But true, this
is pretty self-explanatory.
In fact, I've had this problem with quic-go before with major Go
version bumps ...

The quic-go library has specific "forks" that support only one major
Go version each. Syncthing imports them all, and then uses conditional
compilation at build-time, depending on the actual version of the
compiler. So I won't be able to fix this until 1) quic-go releases a
version of their library that's specific to go 1.19, and 2) syncthing
adds support for go 1.19.

I can't fix the resulting FTBFS issue myself, but at least now I know
what's going on.
Still, not getting included in rebuilds for golang CVE fixes now is
kind of a bummer.

Fabio