In order to be a fully accepted CMake target, we should have compiler support upstreamed to at least gcc or llvm-project.

Here's the list of things that need done for that do have a chance of succeeding:

This issue is being tracked at the same time on CMake's GitLab here

In SerenityOS/serenity:

Loader/Kernel/LibELF:

• (Optional) Support tls-model other than initial-exec: Will remove a patch from each llvm and gcc
  • https://www.akkadia.org/drepper/tls.pdf

LibC:

• Make<ctype.h> POSIX and C standard compliant. Remove hax from libc++ and libstdc++ patches pretending to be newlib. (#14401)
• (Optional) Unify libdl, libpthread, libc and libm into a mega-library to avoid cyclic dependencies in libstdc++ (#14453)
• scanf improperly reads some integer types on x86_64 (#14189)
• Remove _aligned_alloc and _aligned_free

GNU Autotools:

• config.sub
• config.guess
• libtool.m4

Binutils:

• Possibly find a way to remove the changed default base address of non-PIE executables? Ask on binutils mailing list if the patch is reasonable (#14189)
• Upstream the patch

GCC/libstdc++:

• Split patch up (d0edf26)
• Upstream patches

LLVM:

• Remove _aligned_alloc patches from libc++ (#14401)
• Remove patches from libc++ in <initializer_list> (#14401)
• Upstream patches

LLVM Lit tests:

• Posix Named Semaphores for python3 multiprocessing.Pool (#14578)