…repo

The llvm-mirror GitHub repositories have stopped updating. This replaces
the defunct submodule references with vendored copies extracted directly
from the official LLVM monorepo at tag llvmorg-19.1.7.

Changes:
- Remove libcxx and libcxxabi git submodules
- Add scripts/sync-llvm.sh for extracting libcxx/libcxxabi from LLVM
  monorepo tarballs at any tag
- Vendor libcxx and libcxxabi from llvmorg-19.1.7
- Add LLVM_VERSION file tracking the synced tag and date

https://claude.ai/code/session_01HSFVgYuUbCkLuHFNziuJpb

Major changes to support the LLVM 19.1.7 vendored libcxx/libcxxabi:

meson.build:
- Remove references to deleted source files (utility.cpp, debug.cpp,
  cxa_unexpected.cpp, experimental/memory_resource.cpp)
- Add libcxx/include and libcxxabi/include to system include paths so
  LLVM 19's reorganized subdirectory headers are accessible
- Remove obsolete _LIBCPP_DEBUG=0 and _LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS flags

include/c++/meson.build:
- Switch from custom __config.in concatenation to using upstream __config
  directly, generating only __config_site for build configuration
- Generate __assertion_handler from LLVM's vendor template
- Remove references to headers deleted in LLVM 19 (__debug,
  __functional_03, __threading_support, __mutex_base, etc.)
- Update experimental headers list to match LLVM 19

Overlay files:
- Fix __threading_support -> __thread/support.h (cxa_guard.cpp)
- Fix sysetm_error typo (framework_thread.cpp)
- Replace __debug include with __assert (system_error.cpp)
- Add __libcpp_compat.h include to files using removed macros

New files:
- include/c++/__libcpp_compat.h: compatibility shims for macros removed
  between LLVM 10 and 19 (_VSTD, _LIBCPP_FUNC_VIS, etc.)

Other:
- Update __libcxx_config_site.in to match upstream __config_site format
- Fix newlib xlocale.h reference (removed upstream, use baremetal fallback)

https://claude.ai/code/session_01HSFVgYuUbCkLuHFNziuJpb

LLVM 19 requires this define in __config_site or compilation fails with
a hard error. Set to _LIBCPP_HARDENING_MODE_NONE for embedded/baremetal
use (disables all runtime hardening checks, zero overhead).

https://claude.ai/code/session_01HSFVgYuUbCkLuHFNziuJpb

- Add libcxx/src to include directories for both libcxx and libcxxabi
  targets, matching upstream CMake (libcxxabi/src/CMakeLists.txt:60)
- Fix broken relative path in src/c++abi/cxa_handlers.cpp that
  referenced non-existent libcxxabi/src/include/atomic_support.h
- Normalize relative paths in locale.cpp and new_terminate_badalloc.cpp
  to use the new include directory instead of fragile ../../ paths
- Fix Meson declare_dependency to avoid configure_file outputs being
  treated as compilable source files

https://claude.ai/code/session_01HSFVgYuUbCkLuHFNziuJpb

Documents completed fixes, remaining concerns (fragile include paths,
dead code, GCC version requirements), and recommended next steps.

https://claude.ai/code/session_01HSFVgYuUbCkLuHFNziuJpb

Generates patches from this branch's fix commits and applies them to a
target libcpp checkout, with optional --prefix for monorepo subdirectory
layouts and --squash for collapsing into a single commit.

https://claude.ai/code/session_01HSFVgYuUbCkLuHFNziuJpb

Reproduces the complete sequence: remove defunct libcxx/libcxxabi
submodules, vendor LLVM 19.1.7 from the monorepo tarball, write
LLVM_VERSION and scripts/sync-llvm.sh, commit the vendoring, then
apply the three build-system fix patches.

https://claude.ai/code/session_01HSFVgYuUbCkLuHFNziuJpb

Handles monorepos where libcpp lives at a subdirectory with libcxx and
libcxxabi registered as real submodules at that subdirectory. Finds
submodule names by scanning .gitmodules entries rather than assuming
the name matches the basename, preserves other submodule entries in
.gitmodules, extracts the tarball into the prefix directory, and uses
git am --directory for patch application.

https://claude.ai/code/session_01HSFVgYuUbCkLuHFNziuJpb