[R-pkg-devel] Reliably detecting FLIBS on source build of R (w.r.t Rust packages)

[Balasubramanian Narasimhan]

Also, to further clarify, yes I need Rust to determine the linker flags 
since the underlying Clarabel.rs links against BLAS.

-N

On 1/26/25 8:22 AM, Balasubramanian Narasimhan wrote:
> Thank you, Simon and Ivan.  And further thanks to Ivan for R sleuthing 
> of the first order!
>
> That I'm picking up the wrong R makes sense.  I will incorporate your 
> suggestions
>
> Best wishes,
>
> -Naras
>
> On 1/25/25 11:55 PM, Ivan Krylov wrote:
>> В Sat, 25 Jan 2025 08:54:45 -0800
>> Balasubramanian Narasimhan <naras using stanford.edu> пишет:
>>
>>> (https://github.com/blas-lapack-rs/r-src/blob/966266425b1a21a1e979f767c6023e6bf00616fc/build.rs#L160). 
>>>
>> Thank you for providing the link to the code!
>>> The only thing I can think of is that FLIBS is being set outside
>>> config.site or Makevars during the R build.
>> I think this is happening because the r-src crate is running the wrong
>> R executable to determine the linker flags. The check system is running
>> /Users/ripley/R/R-devel/bin/R, while there's also a different R (for
>> example, /usr/local/bin/R) visible on the $PATH. The code ends up
>> getting the linker flags from the latter when it runs "R" [1].
>>
>> I think it should be possible to sidestep this issue altogether if you
>> only enable the static library at [2] and then have R link the package
>> shared library for you from the static library produced by Rust using
>> the flags you're correctly setting in Makevars [3].
>>
>> If you do need Rust to determine the linker flags by itself, make sure
>> to run ${R_HOME}/bin/R, not just R [4].
>>
>> Unrelated but probably important: having 'all' or $(SHLIB) depend on a
>> target that removes the files you've built [5] is a bad idea because
>> Make is allowed to run independent recipes in undefined order,
>> including rm -Rf $(SHLIB) $(STATLIB) $(OBJECTS) while $(STATLIB) is
>> being built [6]. Note how 'rm -Rf ...' is the first command being run
>> in [7], before any compilation happens. The files you're removing as
>> part of the $(STATLIB) recipe should be enough; there shouldn't be any
>> need for the 'C_clean' recipe.
>>
>
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