| 15 Nov 2024 |
 p14 | How do you define "proper sysroot" and how does it help if the compiler can look somewhere you don't want it to look? | 12:03:18 |
 emily | really though there's so many ways for impurities to leak in outside of the sandbox | 12:03:20 |
| p14 | fair. | 12:03:29 |
| emily | In reply to @p14:matrix.org
How do you define "proper sysroot" and how does it help if the compiler can look somewhere you don't want it to look? it's not going to look outside of the sysroot if we provide one | 12:03:36 |
| emily | but there were complications with it needing to be / for something something something | 12:03:47 |
| emily | I forget, it was a few weeks ago | 12:03:51 |
| emily | if you mean -I/usr/include, uhh | 12:03:57 |
| emily | well (a) that's your fault for passing that and (b) we have a joke of a cc command-line parser in the wrappers to try and filter those out | 12:04:14 |
| emily | which ALSO broke Darwin and I had to change it | 12:04:21 |
| emily | (because on Darwin it's relative to the SDKROOT, so e.g. -L/usr/lib/swift is benign) | 12:04:38 |
| p14 | I was under the impression the compiler driver searched usr lib of its own volition | 12:04:41 |
| emily | it searches <sysroot>/lib | 12:04:53 |
| p14 | https://github.com/llvm/llvm-project/blob/d7b669b3a30345cfcdb2fde2af6f48aa4b94845d/clang/lib/Driver/ToolChains/Gnu.cpp#L2930
Oh, right. | 12:05:11 |
| p14 | And, we're not passing sysroot then I take it. | 12:05:22 |
| emily | like I said apparently it has to be / but I forget why | 12:05:36 |
| emily | (on Linux) | 12:05:39 |
| p14 | that sounds odd, what's the point in having a sysroot parameter if that was true? | 12:05:53 |
| emily | it was an arcane reason. ask trofi :) | 12:06:07 |
| emily | In reply to @emilazy:matrix.org
(because on Darwin it's relative to the SDKROOT, so e.g. -L/usr/lib/swift is benign) one possible path I've considered is making this behaviour configurable for all platforms. we pass -treat-all-those-user-specified-paths-as-sysroot-relative-even-though-this-isnt-darwin -sysroot /directory/tree/with/empty/stub/include/and/libs/directories in the wrapper | 12:06:18 |
| emily | then we're safe from /usr/lib and don't need the broken purity hack CLI parsing in the wrapper | 12:06:32 |
| emily | might work. dunno. | 12:06:39 |
| emily | anyway, I think passing -nostdlibinc for non-Darwin targets in the wrapper is the conservative option for now, but we should definitely flag up to the relevant people that it no longer appears necessary for libc++ | 12:07:50 |
| p14 | Bah, pkgsStatic.pkgsLLVM.hello-cpp.stdenv.cc/bin/x86_64-unknown-linux-musl-clang doesn't work, because it fails to find ld. -ld-path=x86_64-unknown-linux-musl-ld fixes it. | 12:09:09 |
| p14 | * Bah, pkgsStatic.pkgsLLVM.hello-cpp.stdenv.cc/bin/x86_64-unknown-linux-musl-clang doesn't work, because it fails to find ld. --ld-path=x86_64-unknown-linux-musl-ld fixes it. | 12:09:17 |
| p14 | "Bah", because, I expected it to already look for the triple-prefixed ld... | 12:09:31 |
| emily | pkgsStatic.pkgsLLVM even does something sensible? | 12:09:36 |
| emily | In reply to @p14:matrix.org
"Bah", because, I expected it to already look for the triple-prefixed ld... wanna revive the "prefix all compilers" PRs? 😆 | 12:09:45 |
| p14 | Looks like it does, sort of? :) | 12:09:48 |
| emily | In reply to @trofi:matrix.org
At least on linux the attempt to use non-standard sysroot broke DT_RUNPATH lookups for libraries not explicitly mentioned in the linking process: https://github.com/NixOS/nixpkgs/pull/213185. Transitive libraries are searched in sysroot only and things break. p14: here's a pointer to the previous discussion | 12:10:44 |
| emily | with the conclusion of basically "we should add more knobs upstream and then twiddle only the ones we need" | 12:11:08 |
