Re: 'make clean' followed by 'make' in the same Nix shell doesn't work

[Alyssa Ross <hi@alyssa.is>]

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Demi Marie Obenour <demiobenour@gmail.com> writes:

> On 8/5/25 15:33, Alyssa Ross wrote:
>> Demi Marie Obenour <demiobenour@gmail.com> writes:
>> 
>>> On 7/29/25 08:33, Alyssa Ross wrote:
>>>> Demi Marie Obenour <demiobenour@gmail.com> writes:
>>>>
>>>>> The following command fails to rebuild the image:
>>>>>
>>>>> $ nix-shell --run 'make clean && make run-qemu'
>>>>>
>>>>> The following command succeeds:
>>>>>
>>>>> $ nix-shell --pure --run 'make clean' && nix-shell --pure --run 'make run-qemu'
>>>>>
>>>>> Interactive Nix shells exhibit the same problems, and adding
>>>>> --pure to the first invocation does not help.
>>>>
>>>> Works for me on 560fd87 in img/app.  What were you testing?  Logs?
>>>
>>> I think the problem only arises when there is a dependency that
>>> default.nix knows about but the makefile doesn't.  nix-shell
>>> appears to import default.nix directly, so
>>>
>>> $ nix-build default.nix
>>>
>>> inside a Nix shell does not update various paths (like the path
>>> to the kernel) that the makefile needs.
>>>
>>> I think it would be better for the makefile to import the
>>> variables from Nix if possible.
>> 
>> Yeah, that's not how it works.  You need to exit and re-enter the shell.
>> nix-build will not update your shell environment, and that's where Make
>> variables come from.
>
> Ack.  I think it is best to recommend (perhaps in the docs?) that one run
> `nix-shell --pure --run 'make THINGS'`, which avoids all of these problems.
> Providing a that did that would be ideal and should be fairly straightforward.
> Using an interactive shell can be an optimization, but it can also result in
> silently broken builds for at least the reason you mentioned, so I think it
> is best to discourage it except in the repository root.

From what I can tell, that's already the case in the documentation, with
the exception of the one about Jekyll, which I'll fix.

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