Clang compilation into sysroot with newer glibc

Question

I'm trying to compile with a sysroot for Ubuntu 22.04 from a Ubuntu 20.04 image, and I'm having quite a bit of trouble, getting linker errors like these:

/usr/bin/ld: ../build_rootfs/x86_64_jammy/lib/x86_64-linux-gnu/libc.so.6: undefined reference to `_dl_audit_symbind_alt@GLIBC_PRIVATE'
/usr/bin/ld: ../build_rootfs/x86_64_jammy/lib/x86_64-linux-gnu/libc.so.6: undefined reference to `_dl_audit_preinit@GLIBC_PRIVATE'
/usr/bin/ld: ../build_rootfs/x86_64_jammy/lib/x86_64-linux-gnu/libc.so.6: undefined reference to `_dl_fatal_printf@GLIBC_PRIVATE'
/usr/bin/ld: ../build_rootfs/x86_64_jammy/lib/x86_64-linux-gnu/libc.so.6: undefined reference to `__nptl_change_stack_perm@GLIBC_PRIVATE'
clang: error: linker command failed with exit code 1 (use -v to see invocation)

The exact same invocation works fine from a Ubuntu 22.04, using the exact same compiler and exact same sysroot.

Here's my setup:

// test.cpp
int main(){}

Compile command:

clang++ --sysroot ../build_rootfs/x86_64_jammy test.cpp

Where ../build_rootfs/x86_64_jammy is a sysroot created with multistrap (I can share a minimized multistrap config if it's relevant, but considering the same sysroot works fine from Ubuntu 22.04, the sysroot seems to not be the issue.

Things I have tried:

• Using lld--same result
• Using clang 14, both from apt.llvm.org and from the binary tarball

Notably, GCC is able to compile it by passing -L/usr/lib/x86_64-linux-gnu/9 -L/usr/lib/x86_64-linux-gnu (yes, even when compiling with --sysroot), but this seems strange as this is linking to libraries on the host system. Adding these flags does let the compilation succeed, but compiling from clang on 22.04 works fine without loading any of the system libraries (allegedly).

I assume this is an issue with glibc verisons, but I can't see how the host glibc version would matter when compiling from a sysroot, and it doesn't seem like any of the linker inputs are actually from the host system, so what's going wrong?

This gist has the verbose logs from clang on focal, gcc on focal, and clang on jammy for reference.