I’m trying to diagnose a failure cross-building the runtimes for hexagon linux. Does anyone have a reference build recipe for a bootstrapped cross compiler that they can share? This recipe has been working well with not too many changes for ~a couple years but maybe could stand some improvement.
The main symptom is a cmake failure No known features for CXX compiler ... "Clang" ... version 20.0.0..
The failure started ~a few months ago and I bisected it to [libcxx][libc] Hand in Hand PoC with from_chars (#91651) · llvm/llvm-project@6c4267f · GitHub - see also issue #114591.
I tried disabling the target_compiler_features directive but it seems like that’s not a suitable fix or workaround to land for now.
I would love some advice on how to map the failure above to the relevant portions of $build_dir/CMakeFiles/CMakeError.log. I found a feature test Determining if the function __cxa_throw exists in the stdc++ – this fails w/a link error, because we haven’t got a target C++ library yet.
On one hand it makes some sense that there’s something wrong with the commit I bisected to, if it truly depends on a C++ library in order to build the C++ library. OTOH I assume that there are other people bootstrapping toolchains like this, so maybe I am missing something.