[bug#49602] [PATCH] import: go: Upgrade go.mod parser.

[Maxim Cournoyer]

Hello Sarah,

Sarah Morgensen <iskarian@mgsn.dev> writes:

[...]

>>> +(define (go.mod-requirements go.mod)
>>> +  "Compute and return the list of requirements specified by GO.MOD."
>>> +  (define (replace directive requirements)
>>> +    (define (maybe-replace module-path new-requirement)
>>> +      ;; Do not allow version updates for indirect dependencies
>>> +      ;; TODO: Is this correct behavior? It's in the go.mod for a
>>> reason...
>>
>> According to [1], it seems that yes: "replace directives only apply in
>> the main module's go.mod file and are ignored in other modules.", IIUC.
>>
>> [1]  https://golang.org/ref/mod#go-mod-file-replace
>>
>
> My read of it is that if module A requires module B, replace directives
> in B's go.mod are ignored, but A's go.mod can replace any module, direct
> or indirect. For example, if module B hasn't been updated, but the
> version of module C it depends on has a bug that affects it, module A
> can use a replace in it's go.mod without requiring an upstream update of
> module B. To be fair, this is usually handled by specifying the indirect
> dependency with a specific version as a requirement in module A's
> go.mod, but the replace should be valid as well. 

Thank you for explaining.  It makes sense.  So it seems that we should
honor the replacement for any dependency.

> The reason it was skipped before, I think (if it was intentional), is
> that since we only have the one version of a module in Guix at a time,
> it's not necessary to make the indirect dependency explicitly an input,
> so don't include it.

Sounds plausible!

> On the other hand, if it *was* used to avoid a bug
> in a version used by an indirect dependency, wouldn't we want to make
> sure the Guix package was the fixed version? This is why I was
> questioning whether leaving it out was correct. 

Now that I have a better understanding (I think!), I'd like to propose
the attached patch; it should make the replacement logic more in line
with the upstream specification.

Thanks for the discussion!

0001-import-go-Fix-replacement-directive-behavior.patch
Description: Text Data

Maxim