Re: Patching Go software

[Benny Siegert <bsiegert%gmail.com@localhost>]

Hey Jonathan,

Am 20.02.24 um 17:07 schrieb Jonathan Perkin:
> Packaging golang software is becoming increasingly frustrating.  One of 
> the main problems we have with the current setup is that it appears to 
> be impossible to patch dependencies.

This is indeed hard at the moment.

> However, it appears that all of these extracted files are completely 
> redundant.  During the build go will unpack its own copies from GOPROXY 
> into ${WRKDIR}/.gopath:

This is also true. The extraction is redundant, it's there because I did 
not know how to make it skip extraction of module zip files.

However! I recently raised https://github.com/golang/go/issues/64853 
about the misleading "downloading" message during Go builds. I got the 
feedback that we are doing the wrong thing by populating a local module 
proxy, and that we should instead populate a GOMODCACHE with extracted 
module contents. I still need to look into how to do that, but I assume 
once we have that, patching dependencies will be easier.

> work/.gopath/pkg/mod/github.com/sassoftware/go-rpmutils@v0.2.0/fileutil/fileutil_unix.go
>
> and even if I try to patch that file after the build fails, go just 
> extracts a brand new unmodified version in place.

That's true too. You have the go.sum file and the GOSUMDB network access 
(yeah I know), which verifies that you do have unmodified modules.

> Do we have anyone who understands go who can answer why we unpack 
> GO_MODULE_FILES into WRKDIR if they're just going to be ignored, and 
> ideally how we can patch vendor dependencies?

You can insert a replace directive at the end of go.mod, like so:

replace  github.com/sassoftware/go-rpmutils => 
../github.com/sassoftware/go-rpmutils@v0.2.0

That will force the build to use your unpacked version.

> It's not helped by golang upstreams becoming increasingly hostile 
> towards non-Linux platforms, so this is only going to get worse.

This behavior is absolute nonsense, but unfortunately not new :( 
Remember the time when Firefox refused to accept some very simple NetBSD 
/ OpenBSD patches because "we only care about Linux, Windows and macOS"? 
(Ironically, I am writing this in Thunderbird on Linux, of all things.)

--
Benny