Go mod replace (patch) only one package of dependency

Question

I have a dependency library in go.mod file, eg foo.bar/dep . I want to patch only one package of this dependency, eg foo.bar/dep/pkg1 and place it somewhere in source repository, eg ./_patch/foo.bar/dep/pkg1 .

When I try to do this and replace it with

go mod edit -replace foo.bar/dep/pkg1=./_patch/foo.bar/dep/pkg1
go mod tidy

and my go.mod looks like

require (
  foo.bar/dep v1.0.0
)

replace foo.bar/dep/pkg1 => ./_patch/foo.bar/dep/pkg1

But when I build and run cmd, the code is still using origin foo.bar/dep/pkg1 module instead of my patch.

Is it possible to replace only some particular package of dependency, or the only way is to replace the whole library?

Answer 1

Is it possible to replace only some particular package of dependency [?]

No.

[...] or the only way is to replace the whole [module]?

Yes, this is the only way.