On a native (host==build==target) build, `${with_build_sysroot}` can
be omitted. In that case, the line modified by this commit is
correct.
However, if `--with-build-sysroot=` is passed to `./configure`, then
`${with_build_sysroot}` will be used, similar to the cross case, and
the headers will be taken from:
${with_build_sysroot}${native_system_header_dir}
See:
https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/configure.ac;h=62bc908b991ff0b700225aef32743cd3d7c4daaf;hb=HEAD#l2439
This commit adjusts the comment to account for the case where
`--with-build-sysroot` is passed to a native compiler.
I'm reasonably confident this is no longer necessary, as uclibc's
libdl.a is empty, and I can cross-build stdenv.cc.cc for
x86_64-unknown-linux-uclibc with libgomp enabled.
LLVM does not provide a drop-in replacement for as(1).
This makes it possible to build a GNU Fortran cross compiler from GNU
to LLVM — e.g. buildPackages.gfortran for
{ system = "aarch64-linux"; useLLVM = true; }
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80431
This bug annoys me because I hit it when working on Nix. It causes
miscompilations in such a way that I am hard-pressed to think how a
program could inadvertainly rely on the bug (such that it would be
broken by the fix).
The bug is longstanding, and the (quite small) applies without
modification to many older GCCs. I have confirmed by running the test in
that commit that does indeed fix the bug with the backports too.
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`
The code was intended to use something like
[ $buildConfig == *linux* ]
but never did and use always-false
[ buildConfig == *linux* ]
As it's in nixpkgs for a few years let's just delete it instead of
restoring.
Fixes build failure on `staging-next` introduced by commit c817efe6
("gcc: extend stripping of .a libraries and .o objects"):
...-bootstrap-stage3-stdenv-linux/setup: line 106: pushd: no other directory
Build failure happens because `libgccjit` has different `outputs` layout
compared to the rest of `gcc` derivations:
outputs = [ "out" "man" "info" ] ++ lib.optional (!langJit) "lib";
The change carves out `$lib` lib handling part to avoid `gcc` rebuild
in `staging-next`.
This commit factors out the conditional which creates the `lib64->lib`
symlink in the `preInstall` phase, and calculates its value in nix
code rather than bash code so touching it doesn't cause a global
rebuild on every platform.
