gcc: provide both native and cross forms of gcc.libs libraries #209153
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ofborg
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6.topic: cross-compilation
I would like to use --sysroot=/nix/store/does/not/exist hack
for both `gcc` and `clang` drivers to remove default include
(and library) search paths when we override them with libc.
For `gcc` it works as is. But for `clang` it also drops some of
`gcc` search paths`. Let'sconsider 2 lookups.
Successful lookup (no `--sysroot`):
$ printf "int main(){}" | clang++ -x c++ - -Wl,--verbose |& grep -F stdc++
attempt to open /nix/store/...-gcc-11.3.0/lib/gcc/x86_64-unknown-linux-gnu/11.3.0/libstdc++.so failed
attempt to open /nix/store/...-gcc-11.3.0-lib/x86_64-unknown-linux-gnu/lib/libstdc++.so failed
attempt to open /nix/store/...-clang-11.1.0-lib/lib/libstdc++.so failed
attempt to open /nix/store/...-gcc-11.3.0/lib64/gcc/x86_64-unknown-linux-gnu/11.3.0/libstdc++.so failed
attempt to open /nix/store/...-gcc-11.3.0/lib64/gcc/x86_64-unknown-linux-gnu/11.3.0/../../../../lib64/libstdc++.so failed
/nix/store/...-gcc-11.3.0/lib64/gcc/x86_64-unknown-linux-gnu/11.3.0/../../../../lib64/libstdc++.a
Failed lookup (has `--sysroot`):
$ printf "int main(){}" | clang++ --sysroot=/does/not/exist -x c++ - -Wl,--verbose |& grep -F stdc++
attempt to open /nix/store/...-gcc-11.3.0/lib/gcc/x86_64-unknown-linux-gnu/11.3.0/libstdc++.so failed
attempt to open /nix/store/...-gcc-11.3.0-lib/x86_64-unknown-linux-gnu/lib/libstdc++.so failed
attempt to open /nix/store/...-clang-11.1.0-lib/lib/libstdc++.so failed
attempt to open /nix/store/...-gcc-11.3.0/lib64/gcc/x86_64-unknown-linux-gnu/11.3.0/libstdc++.so failed
/nix/store/...-binutils-2.39/bin/ld: cannot find -lstdc++: No such file or directory
Note how `clang` starts the search roughly from
`gcc-11.3.0-lib/x86_64-unknown-linux-gnu/lib` in both cases. I think
it's our preferred location for both native and cross cases.
The change adds such a symlink:
`gcc-11.3.0-lib` -> `gcc-11.3.0-lib/x86_64-unknown-linux-gnu`
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… from libc I would like to add an extra `gcc` build step during linux bootstrap (NixOS#208412). This makes it early bootstrap compiler linked and targeted against `bootstrapTools` `glibc` including it's headers. Without this change `gcc`'s spec files always prefer `bootstrapTools` `glibc` for header search path (passed in as --with-native-system-header-dir=). We'can't override it with: - `-I` option as it gets stacked before gcc-specific headers, we need to keep glibc headers after gcc as gcc cleans namespace up for C standard by using #include_next and by undefining system macros. - `-idirafter` option as it gets appended after existing `glibc`-includes This `--sysroot=/nix/store/does/not/exist` hack allows us to remove existing `glibc` headers and add new ones with `-idirafter`. We use `cc-cflags-before` instead of `libc-cflags` to allow user to define their own `--sysroot=` (like `firefox` does). To keep it working prerequisite cross-symlink in gcc.libs is required: NixOS#209153
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trofi
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This reverts commit 2c931bd. The NixOS#209153 reverted --sysroot=/ change as it broke other astects of library search paths. While it might still be useful to pull in gcc libraries when non-standard --sysroot= is passed there are no meaningful use cases of it in `nixpkgs` yet. Let's revert it for now.
| @@ -203,6 +203,17 @@ preInstall() { | |||
| ln -s lib "$out/${targetConfig}/lib32" | |||
| ln -s lib "${!outputLib}/${targetConfig}/lib32" | |||
| fi | |||
|
|
|||
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We should migrate this eventually to the normal nix phases and share those between all gcc.
There seems to be also a good chunk of other copy pasted code. Not sure how easily we could group that into a shared file and if it would just reduce readability a lot. Maybe we could also use version ranges when something is not supposed to be done for every gcc version.
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Apr 27, 2024
This reverts commit 2c931bd. The NixOS#209153 reverted --sysroot=/ change as it broke other astects of library search paths. While it might still be useful to pull in gcc libraries when non-standard --sysroot= is passed there are no meaningful use cases of it in `nixpkgs` yet. Let's revert it for now.
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I would like to use --sysroot=/nix/store/does/not/exist hack for both
gccandclangdrivers to remove default include (and library) search paths when we override them with libc.For
gccit works as is. But forclangit also drops some ofgccsearch paths`. Let'sconsider 2 lookups.Successful lookup (no
--sysroot):Failed lookup (has
--sysroot):Note how
clangstarts the search roughly fromgcc-11.3.0-lib/x86_64-unknown-linux-gnu/libin both cases. I think it's our preferred location for both native and cross cases.The change adds such a symlink:
Description of changes
Things done
sandbox = trueset innix.conf? (See Nix manual)nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage./result/bin/)nixos/doc/manual/md-to-db.shto update generated release notes