llvm-core/clang-15 along with two of its dependencies llvm-runtimes/compiler-rt-sanitizers-15 and llvm-runtimes/compiler-rt still have limitation on python revisions and don't allow python 3.13 They all work fine with python 3.13, no issue building or at runtime, so I just patched the ebuild locally bu obviously having upstream allowing 3.13 would be much better. Why update an old LLVM stack ? Because it's needed by intel-compute-runtime, the OpenCL and compute stack for all intel GPU, so it's a pretty damn useful package.
Duplicate of https://bugs.gentoo.org/953824
The above issue doesn't see to mention llvm-runtimes/compiler-rt-sanitizers-15 and llvm-runtimes/compiler-rt which the last time ( when bumping to python 3.12 ) were left out as well and are still using python 3.11 ...