cyndyishida wrote: > > However, notably, even on Darwin, if you pass _both_ flags, you still get > > the intended behavior of `-isysroot` affecting headers, and `--sysroot` > > affecting libraries. Your change would break that. > > What's the use-case for this? > > Because for most users, you almost certainly don't want to mix headers and > libraries of different versions, and keeping the existing behavior is > essentially a big footgun when trying to build a useful toolchain on Darwin. > > At Homebrew, we used to configure the toolchain with `DEFAULT_SYSROOT` but > have recently switched that to setting the `--sysroot` flag in a Clang `.cfg` > file.[1](#user-content-fn-1-21a5728b47e790352033de78c44bc2e4) In either case, > if you set `SDKROOT` in your environment or try to run our `clang` using > Apple's `xcrun`, this becomes equivalent to setting `-isysroot` and you most > likely will end up with headers that mismatch the libraries you try to link > to.
The expected flow on Apple platforms is to only pass an `isysroot` argument whether it's inherited from `xcrun -sdk <sdk version> clang` or passed explicitly. Could homebrew instead only pass `isysroot` for Darwin targets? Or check that `sysroot` and `isysroot` inputs are the same when creating an invocation. It's unclear to me how homebrew gets into a situation where there are conflicting sdks passed for `sysroot` and `isysroot` when you effectively want to ignore whatever is passed to `sysroot`. https://github.com/llvm/llvm-project/pull/115993 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
