Refactor r-modules / rPackages / etc - hard to override

[deliciouslytyped]

Sorry if I missed something;
Either the R packages implementation needs more documentation or it needs to be refactored. It seems utterly impossible to override most things.

I was trying to help someone to debug reticle and I would have wanted to recompile with lower optimization levels and/or various changed compilation flags. The current infrastructure does not visibly support this.

Note:
My mostly unsuccessful research suggests that R CMD INSTALL may rely on --configure-vars, --configure-flags, and some kind of "makevars" file, for influencing package compilation.
Out of these, --configure-flags is used at

nixpkgs/pkgs/development/r-modules/generic-builder.nix

Line 39 in 00fe2aa

$rCommand CMD INSTALL $installFlags --configure-args="$configureFlags" -l $out/library .

but I could not see a way to actually override that because everything is called in an opaque way from...IIRC whatever provides rWrapper.

I managed to hack in some stuff by overriding preConfigure on the stdenv passed in to the infrastructure :P , but I was ultimately unsuccessful. Maybe the optimization flags were coming from GCC? - my extra flags did not seem to appear regardless.

TL;DR: confusion and opacity.

[stale]

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