[PATCH] D80300: [Driver] Add DEFAULT_DYLD_PREFIX and DEFAULT_RPATH to complement DEFAULT_SYSROOT

[Hubert Tong via Phabricator via cfe-commits]

hubert.reinterpretcast added a comment.

In D80300#2049679 <https://reviews.llvm.org/D80300#2049679>, @joerg wrote:

> So the general idea is that for turnkey toolchains,
>  we want to allow customizing the "default" target of the toolchain to hard-code options like --sysroot, --target, -Wl,-rpath etc. Those are all related, so when using a different target, they no longer make sense.


I don't think there is anything precluding the packager from setting up the availability of a "turnkey" multi-target toolchain (with fat binaries if necessary) that would still make sense to pass `--target` to.

> One way to deal with all those options in a consistent manner is hook into the logic for determining the current target, if none is explicitly specified on the command line or implicit from the executable name, then prepend some additional flags on the command line based on some cmake variable or so. This flags shouldn't trigger the unused argument warnings, so you can always pass -Wl,-rpath, --sysroot etc, independent of whether the compiler is in preprocessing / compile / assemble / link mode. That seems to be a more general and systematic approach than adding many additional build-time options.

This might make sense if we believe that the ability to add arbitrary "implied default target options" is not harmful. I am not certain people would agree on that point. The solutions do have overlap in terms of the problems they could be applied to, but I think each of them address some use cases that the other does not.


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  https://reviews.llvm.org/D80300/new/

https://reviews.llvm.org/D80300